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小木虫论坛-学术科研互动平台 » 材料区 » 微米和纳米 » 07ACS-National Meeting论文Abstract_Inorganic(有Nano的)
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[交流] 07ACS-National Meeting论文Abstract_Inorganic(有Nano的)

INOR 21
Synthesis and characterization of covalently attached polyethyleneimine functionalized single-wall carbon nanotubes
Christopher A. Crouse, Eoghan Dillon, Ramon Colorado Jr., and Andrew R. Barron, Department of Chemistry, Smalley Institute for Nanoscale Science and Technology, Rice University, Houston, TX 77005, crous1ca@rice.edu
The solubility of single-wall carbon nanotubes (SWNTs) in aqueous and organic solvents is a difficult barrier that must be overcome to allow for potential applications in the biomedical and material sciences. Previous work involving the addition of polymers towards the dissolution of SWNTs has focused on the covalent attachment of polymers to the carboxylic acid moieties found at the open ends of SWNTs or the physical adsorption of polymers or surfactants on the sidewalls. In this work the reaction between branched-polyethyleneimine (PEI) and uncut, fluorinated-SWNTs (F-SWNTs) was performed yielding the covalent attachment of the polymer to the sidewalls of the nanotubes. These results were confirmed through solid state NMR, Raman spectroscopy, X-ray photoelectron spectroscopy, UV-vis spectroscopy and thermal gravimetric analysis studies. The resulting PEI functionalized SWNTs (PEI-SWNTs) are shown to have an increased solubility in aqueous media of up to 0.4 mg/mL. The synthesis, characterization, and possible biomedical applications of the newly formed PEI-SWNTs will be discussed.
INOR 22
Synthesis of aligned single-walled carbon nanotube networks
Chris Papadopoulos and Badr Omrane, Department of Electrical and Computer Engineering, University of Victoria, Victoria, BC V8W 3P6, Canada, papadop@uvic.ca
With their excellent combination of mechanical, thermal, chemical and electrical properties, single-walled carbon nanotubes (SWNTs) have emerged as one of the most important materials in nanoscale science and technology. However, the controlled synthesis of SWNTs remains a key challenge for their practical implementation. In particular, controlling the type, size, positioning and orientation of nanotubes will be crucial for translating their fundamental properties into useful structures. Here we employ catalytic chemical vapor deposition coupled with precise nanoscale patterning to promote the alignment of lateral SWNT networks grown on silicon wafers. Results of growth trials and characterization of the networks via electron microscopy and scanning probe methods will be presented. The electronic properties and potential applications of the aligned SWNT networks will also be discussed.



INOR 23
Substrate effects on the growth of single-walled carbon nanotubes (SWNTs) from iron complexes, clusters, and colloids on surfaces
Ramon Colorado Jr., Christopher A. Crouse, Clayton C. Gallaway, Alvin Orbaek, and Andrew R. Barron, Department of Chemistry, Smalley Institute for Nanoscale Science and Technology, Rice University, 6100 Main Street, Houston, TX 77005, colorado@rice.edu
Our investigations of the vapor-solid-liquid (VLS) growth of single-walled carbon nanotubes (SWNTs) from metallic catalysts on solid substrates (e.g. iron nanoparticles on silicon wafers) have suggested that there is a correlation between the nature of the substrate and the activity of the growth catalyst. An understanding of potential catalyst activation and deactivation pathways is essential in developing methods for increasing the total yield of grown SWNTs from catalyst precursors. To this end, we have studied the VLS growth of SWNTs from iron oxide catalyst precursors on various substrates (Si, Spin-on-glass, HOPG, Al2O3) under different growth conditions (i.e. varying growth temperatures and gases). In addition, we have examined how changes in the roughness and morphology of the substrates affect nanotube growth with respect to both the catalyst activity and the orientation of the grown nanotubes. Characterization of the SWNTs by AFM, SEM, and Raman spectroscopy will be presented.
INOR 26
Synthesis of small diameter carbon nanotubes by catalytic decomposition of methane
Xiang-ju Xu and Shao-ming Huang, College of Chemistry and Materials Engineering, Wenzhou University, Wenzhou 325027, China, daisyxxj2003@yahoo.com.cn
Small diameter carbon nanotubes(CNTs) have been synthesized over Fe/Mo/MgO catalyst by catalytic decomposition of methane at 1000°C. The produced carbon material primarily consists of a CNTs bundle with a small amount of individual CNTs. The diameter of an individual CNTs is in the range of 5-10 nm. The as-synthesized CNTs have a yield of over 100% relative to the weight of supplied catalyst. Critical issues for synthesis of small diameter CNTs were further discussed in terms of procedure of catalyst preparation, growth time, and temperature. Our results show that methane can be a very ideal carbon source for the synthesis of small diameter CNTs. We suggest that catalytic decomposition of methane over Fe/Mo/MgO catalyst can promise a large-scale production of small diameter CNTs.
INOR 27
“Green” approach for fabrication of conducting polymer nanocomposite: The catalytic role of carbon nanotubes
Yufeng Ma, Pui Lam Chiu, Arnaldo Serrano, Alex Chen, and Huixin He, Chemistry Department, Rutgers University, 73 Warren Street, Newark, NJ 07102, Fax: 973-353-1264, huixinhe@newark.rutgers.edu
The catalytic behavior of carbon nanotubes (CNTs) just aroused a hot debate. For a long time people believed that the electrocatalytic properties of CNTs can be exploited for a wide variety of applications. However, very recently, Compton and coworkers challenged these general beliefs and demonstrated that the origin of the electrocatalytic behavior of CNTs observed previously is the metal catalyst residues, such as iron oxide particles, that remain in the batch after the fabrication of nanotube and the purification process. In this report, we will present the intrinsic catalytic capability of the single-walled carbon nanotubes (SWNTs). This catalytic capability is not only chirally selective, but also depends on the dispersion methods and dispersion agents used to disperse them into aqueous solutions. Due to the remarkable catalytic capability of the SWNTs, conducting polymer nanocomposites are fabricated by a “greener” process.
INOR 28
Photocatalytic nanofibers and nanotubes made by atomic layer deposition
Markku Leskela, Marianna Kemell, Viljami Pore, Eero Santala, and Mikko Ritala, Department of Chemistry, University of Helsinki, P.O. Box 55, Helsinki FIN-00014, Finland, Fax: +358 9 191 50198, markku.leskela@helsinki.fi
Because of the self-limiting growth principle Atomic Layer Deposition (ALD) suits very well for depositing thin films on nonplanar surfaces. Neither the size of the substrates nor the size of the structural features has any clear threshold value in ALD. ALD suits very well for making and modifying of nanomaterials.
In this presentation the use of ALD for depositing conformal TiO2 films on nonplanar nanostructured surfaces is exemplified by three ways: deposition of thin films on porous alumina, deposition of films on nanofibers made with a porous alumina template, deposition of thin films on nanofibers either on natural fibers like cellulose or electrospun polymer nanofibers. The oxide nanotubes are obtained by annealing in air the TiO2 coated nanofibers and thereby removing the carbohydrate kernel. Photocatalytic activity of the nanomaterials were studied by decomposing methylene blue. The photocatalytic activity could be enhanced by coating the material with noble metal nanoparticles. Reusable magnetic nanofibers were obtained by coating electrospun iron acetate composite fibers with ALD TiO2.
INOR 29
Carbon dioxide as a carbon source for synthesis of carbon nanotubes by chemical vapor deposition
Xiang-ju Xu, College of Chemistry and Materials Engineering, Wenzhou University, Wenzhou 325027, China, daisyxxj2003@yahoo.com.cn
Carbon dioxide was successfully used as carbon source in synthesis of carbon nanotubes(CNTs) by chemical vapour deposition(CVD) over Fe/CaO catalyst. The influence of some reaction parameters, including carbon source, furnace temperature, and types of support media is discussed in this paper. The product was evaluated using both Transmission electron microscopy(TEM) and Raman spectroscopy. Straight, crooked and branching structures of multi-walled carbon nanotubes(MCNTs) were discovered from the TEM micrographs of product. Their average diameters are about 50 nm. Raman spectrum results show that the nanotubes grew perfectly. The formation mechanism of MCNTs in this process was also studied.
INOR 308
Thiol group sidewall functionalization of single walled carbon nanotubes
Heather L. Rhoads1, Christopher N. Brammer2, Donna J. Nelson1, and Ruibo Li1. (1) Department of Chemistry and Biochemistry, University of Oklahoma, 620 Parrington Oval, Norman, OK 73019, Fax: 405-325-6111, hrhoads@ou.edu, (2) Department of Chemical, Biological, and Materials Engineering, University of Oklahoma
Since their discovery, there has been an intense effort to characterize single walled carbon nanotubes (SWNTs) and to understand their properties. This information will allow researchers to develop SWNTs for applications intended to improve all aspects of life from medical to electrical and mechanical technology. Several characterization techniques, such as Raman, near-IR, UV-Vis, and TGA have been employed for years to characterize SWNTs, but more recently, NMR was found to be useful for determining both type and degree of functionalization. Such information will enable more direct syntheses for precise control of nanomaterial applications. To our knowledge, we report the first NMR spectra
demonstrating thiol group sidewall functionalization; NMR data are analyzed in conjunction with Raman, FTIR, UV-Vis, and TGA data. In addition, a brief discussion of planned applications for our product's photoelectric properties will be presented.
INOR 339
Potassium intercalation of graphitic nanofibers
Jason A. Michel and Charles M. Lukehart, Department of Chemistry, Vanderbilt University, 1822 VU Station B, Nashville, TN 37212, Fax: 615-343-1234, j.michel@vanderbilt.edu
Graphitic nanofibers (GNFs), grown by catalytic decomposition of carbonaceous gases, were reacted with potassium metal to form intercalation compounds. Three types of graphitic nanofiber were employed, namely platelet, herringbone, and narrow tubular herringbone, each with unique morphology. The air-sensitive stage 1 and stage 2 intercalation compounds were characterized by powder XRD. Thermionic electron energy distributions (TEED) show that the stage 1 intercalation compound has a work function of φ=2.2 eV, as compared to φ=4.7 eV for pristine GNFs, a reduction of 2.5 eV. The intercalation compounds have also been shown to initiate the polymerization of olefins such as isoprene and styrene to form GNF-polymer composites.
INOR 350
Palladium nanoclusters on carbon nanotubes for flexible hydrogen sensors
Yugang Sun, Center for Nanoscale Materials, Argonne National Laboratory, 9700 South Cass Avenue, Argonne, IL 60439, ygsun@anl.gov, H. Hau Wang, Materials Science Division, Argonne National Laboratory, Qing Cao, Department of Chemistry, University of Illinois at Urbana-Champaign, and John A. Rogers, Department of Materials Science and Engineering, University of Illinois at Urbana-Champaign
Hydrogen sensing represents an important technique in a wide range of applications for ‘hydrogen economy' such as industrial processing, fuel cells, hydrogen storage and separation, etc. Conventional hydrogen sensors are fabricated, in general, on rigid substrates (e.g., glass, quartz, silicon wafers) by using continuous as well as discontinuous palladium films (or wires) with lateral dimensions on the nanometer scales. The rigidity (and/or fragility) of these devices somehow limits their application in systems with curvilinear surfaces that require conformal lamination and mechanical shock-resistance. In contrast, hydrogen sensing devices fabricated on flexible polymeric substrates can find applications complementary to that of the conventional sensors on rigid substrates. We have recently found that nanoclusters of palladium deposited on the support of networks of single-walled carbon nanotubes significantly change the transport property of carbon nanotubes when the composites are exposed to hydrogen. Printing thin films of the Pd/nanotube composites on poly(ethylene terephthalate) (PET) sheets generates light-weight, shock-resistive, flexible hydrogen sensors. The as-fabricated devices have excellent performance which is comparable (even higher) to the conventional sensors. For example, these sensors can detect hydrogen with concentration as low as 30 ppm in air. The response time is as short as 7.5 second when the devices are exposed to 0.1% hydrogen in air at room temperature.

[ Last edited by lingyun79 on 2007-3-25 at 14:26 ]
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INOR 351
Palladium nanoparticles supported on polyaniline nanofibers as catalysts for the formation of C-C bonds
Benjamin Gallon1, Robert W. Kojima2, Richard B. Kaner2, and Paula L. Diaconescu1. (1) Department of Chemistry and Biochemistry, University of California, Los Angeles, 607 Charles E. Young Drive East, Los Angeles, CA 90095, bgallon@gmail.com, (2) Department of Chemistry and Biochemistry and California NanoSystems Institute, University of California, Los Angeles
Palladium nanoparticles supported by polyaniline nanofibers generate systems that are stable, work in water and air and, besides the ease and reproducibility of their synthesis, combine a redox active metal with a redox active support. Such a combination may provide unique characteristics, which could prove beneficial in catalytic cycles since most of them involve redox processes. Our studies on C-C bond forming reactions show that we are in the possession of very active catalysts for the Suzuki coupling of aryl halides and boronic acids in water. The role of the polyaniline support is investigated and certain reactions indicate that it can function as an electron reservoir and regenerate catalytically active species.
INOR 357
Carbon nanotube contrast agents for MRI and CT
Valerie C. Moore1, Pratixa Joshi1, and Jodie L. Conyers2. (1) Department of Internal Medicine, University of Texas Health Science Center at Houston, 6770 Bertner Avenue THI C964A, Houston, TX 77030, Fax: 832-355-9368, Valerie.Moore@uth.tmc.edu, (2) The University of Texas Health Science Center at Houston
Nanoparticles hold great promise for medical imaging. Our lab is investigating the use of single walled carbon nanotubes as a container for CT and MR active atoms. Two filling methods have been utilized, sublimation and liquid intercalation, to encapsulate a variety of atoms - iodine, gadolinium, erbium, barium, iron, chromium, and manganese. With subsequent PEG functionalization, the filled nanotubes are biocompatible as determined through a variety of in vitro assays. This poster will describe theoretical calculations regarding contrast efficacy, comparisons of different filling and subsequent functionalization methods, and the current results from in vitro and in vivo biocompatibility studies.
INOR 364
One-step synthesis of core-shell mesoporous carbon nanofibers using anodic alumina membranes as template
Mingbo Zheng, Jieming Cao, Xingfei Ke, Guangbin Ji, Yongping Chen, and Jie Tao, Nanomaterials Research Institute,College of Materials Science & Technology, Nanjing University of Aeronautics & Astronautics, 29 Yudao Street, Nanjing 210016, China, Fax: 0086-25-84895289, zheng329@yahoo.com.cn, jmcao@nuaa.edu.cn
One-dimensional mesoporous carbon materials possess the specialities of the one-dimensional nanomaterials as well as the properties of mesoporous carbon materials. In this work, we synthesized new core-shell mesoporous carbon nanofibers using pluronic F127 (EO106PO70EO106)/resol mixture solution as the precursor solution and the anodic alumina membranes (AAM) with different diameter sizes (80 nm and 300 nm) as the templates. The as-synthesized samples were characterized by scanning electron microscope (SEM), transmission electron microscope (TEM) and nitrogen adsorption-desorption methods. The results of SEM and TEM revealed the core-shell structure of the nanofibers. Parallel mesopores, which were produced from the removal of pluronic F127, were observed in the shells of the nanofibers. The core of the sample synthesized from the AAM with 300 nm diameter had the circular mesopore architecture. Nitrogen adsorption-desorption characterizations indicate that these materials had large BET surface area and pore volume. The formation mechanism of these new materials was studied.
INOR 376
Growth of carbon nanotubes from nanoparticulate catalysts generated by in situ laser ablation of metal targets
Bradley D. Fahlman and Leontios A. Nezeritis, Department of Chemistry, Central Michigan University, Dow Science 357, Mount Pleasant, MI 48859, Fax: 989-774-3883, fahlm1b@cmich.edu
A variety of metallic nanoparticles have been used to catalyze the growth of carbonaceous nanostructures (e.g., nanotubes, nanofibers, etc.). The most heavily used compositions include Fe, FexOy, Co, Ni, Ni/Y, and Co/Ni species. Carbon nanotubes are thought to grow from these catalysts via a vapor-liquid-solid (VLS) mechanism, which was first postulated ca. 30 years ago for the growth of semiconductor wires. We recently discovered a method to generate carbonaceous nanostructures via a surface-nucleation mechanism, whereby growth occurs at room temperature – far below the melting point of the catalyst seed. Whereas this method employed iron oxide nanoparticles encapsulated within a dendritic macromolecular host, we wish to simplify the nature of the catalyst through in situ generation of nanoparticles via laser ablation of metal targets with a Nd:YAG laser (1064 nm) within our reaction flask. The carbon source for nanostructural growth will be tetrachloroethylene, which will be dechlorinated through interaction with potassium metal within an organic solvent. The resultant product will be characterized by FESEM and TEM/EDS/EELS.
INOR 531
The effect of physical characteristics on biocompatibility and cellular internalization of carbon nanotubes
Valerie C. Moore1, Ashley Leonard2, Brandi K. Price2, Jodie L. Conyers3, and James M. Tour4. (1) Department of Internal Medicine, University of Texas Health Science Center at Houston, 6770 Bertner Avenue THI C964A, Houston, TX 77030, Fax: 832-355-9368, Valerie.Moore@uth.tmc.edu, (2) Rice University, (3) The University of Texas Health Science Center at Houston, (4) Departments of Chemistry, Mechanical Engineering and Materials Science, Rice University
Single walled carbon nanotubes are being investigated as nanovector platforms because of their unique near infrared absorption and fluorescence spectra and their size and shape. We have investigated the effect of length, surface functionalization, and purity on biocompatibility and cellular internalization. The surface functionalization, not length or purity, is the predominant property that determines biocompatibility. PEG functionalization renders nanotubes with average lengths for 30 nm to 300 nm nontoxic while PEI wrapping exhibits some toxicity. Additionally, the cellular distribution for the two functionalizations is different, PEG distributes relatively evenly throughout the cytoplasm, while the PEI distributes in vacuoles and in some cases appears to associate with the nucleus. Biocompatibility was assessed by AnnexinV/PI and viability assays with both chronic and acute exposures. Cellular uptake was monitored and quantified with fluorescence and co-localization staining. Studies with longer nanotube (> 1 micron) are underway, final results will be presented at the meeting.
INOR 536
Impact of carbon nanomaterial size regimes on smooth muscle cell growth
Pavan M. V. Raja1, Jennifer Connolley2, Gopal P. Ganesan3, Lijie Ci4, Pulickel M. Ajayan5, Omkaram Nalamasu6, and Deanna M. Thompson2. (1) Chemical and Biological Engineering, Rensselaer Polytechnic Institute, CII 9015 - CIE, 110 8th Street, Troy, NY 12180, rajap@rpi.edu, (2) Biomedical Engineering, Rensselaer Polytechnic Institute, (3) Center for Integrated Electronics, Rensselaer Polytechnic Institute, (4) Department of Material Science and Engineering, Rensselaer Polytechnic Institute, (5) Department of Materials Science and Engineering, Rensselaer Polytechnic Institute, (6) Center for Integrated Electronics and Department of Materials Science and Engineering, Rensselaer Polytechnic Institute
Carbon nanotubes (CNTs) are unique carbon nanomaterials (CNMs) possessing diverse application potential ranging from electronic devices to therapeutic constructs. However, their potential impact on human health requires careful evaluation, prior to their commercialization. CNT - mammalian cell interaction studies could help understand this impact, on an in vitro basis. CNTs typically form polydisperse aggregates in cell culture medium. Smaller size regimes of non-aggregated CNTs and associated amorphous and graphitic carbon may also be present, which can be isolated by centrifugation and/or filtration of the medium. Our work addresses the impact of these size regimes in purified singlewalled carbon nanotubes (SWNTs), on the growth kinetics of rat aortic smooth muscle cells (SMCs). Our initial trends show that finely dispersed SWNT-related nanomaterials could significantly affect the SMC growth behavior. We further extend this study to compare the effects of the SWNTs with other sister CNMs, such as activated carbon, and carbon black.

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INOR 676
Optical sensors for DNA-drug interactions: An application of single-walled carbon nanotubes
Daniel A. Heller1, Dhaval Patel2, Brittany M. Martinez2, Jong Hyun Choi2, and Michael S. Strano2. (1) Department of Chemistry, University of Illinois at Urbana-Champaign, RAL Box 93-5 MC-712, 600 S Mathews Ave, Urbana, IL 61801, dheller1@uiuc.edu, (2) Department of Chemical and Biomolecular Engineering, University of Illinois at Urbana-Champaign
Complexes of DNA-encapsulated carbon nanotubes serve as sensitive markers for the activity of chemotherapeutic drugs which alkylate DNA. The intrinsic fluorescence of single-walled carbon nanotubes, which exhibits environmental sensitivity, is employed for optical transduction of drug binding events to the DNA-nanotube complex. The emission, between 800 and 1600 nm, is photostable under continuous excitation and penetrates biological media which normally absorbs or scatters light at visible wavelengths. The complexes exhibit a concentration-dependent red-shift in emission energy of up to 6 meV upon binding to alkylating agents such as nitrogen mustards and platinum compounds. Within single cells, the nanotubes detect alkylating activity and transmit real-time information about the activity of the drugs. The sensors will be employed to investigate drug degradation as well as multi-drug resistance in cancer therapy.
INOR 669
Synthesis of graphite nanorods by CVD method
Xiang-ju Xu, College of Chemistry and Materials Engineering, Wenzhou University, Wenzhou 325027, China, daisyxxj2003@yahoo.com.cn
Graphite nanorods were prepared by chemical vapor deposition(CVD) of methane at temperature 865°C to 930°C. X-ray Diffraction(XRD) and Raman spectroscopy results indicate that the product has graphite structure with high purity. Transmission Electron Microscopy(TEM) confirmed that the product has the shape of rods. The average diameters of the product is about 16.3 nm and lengths of up to 800 nm.
INOR 716
Solubilization of single-walled carbon nanotubes for nanostructure solar cells
Tingying Zeng and Jianxin Geng, Chemistry, Western Kentucky University, 1906 College Heights Blvd-11079, Bowling Green, KY 42101-1079, Fax: 270-745-5361, tingying.zeng@wku.edu
SWCNT has high electrical conductivity, mechanical strength and Young's modules, as well as good thermal conductivities. The high metallic property of SWCNTs offers amazing possibilities to create nanoelectronic/nanoscale optoelectronic devices. If attached by photoactive conjugated polymer, SWCNT would lead to a strong electrical field formed to dissociate excitons, which results from the interaction of SWCNTs through its graphitic layer with conjugated polymer. The high electrical conductivity will increase the polymer thin film conductivity by increasing the charge carrier mobilities. All these advantages would significantly improve the power conversion efficiency and mechanical properties of carbon nanotube-modified polymer photovoltaics. Here we report our preliminary research on the solubilization of SWNTs using poly(3-hexylthiophene) (P3HT) and the corresponding nanoarchitecture property characterizations for nanostructured solar cells.
INOR 85
The use of single walled carbon nanotubes for detection of DNA hybridization: Kinetics, thermodynamics, and applications
Esther S Jeng, Department of Chemical and Biomolecular Engineering / Strano Research Group, University of Illinois Urbana-Champaign, 600 S. Mathews Ave., Urbana, IL 61801, ejeng@uiuc.edu, and Michael S. Strano, Department of Chemical and Biomolecular Engineering, University of Illinois at Urbana-Champaign
Single-walled carbon nanotubes (SWNT) can be used for studies with biological materials. When individually dispersed, semiconducting SWNT exhibit band-gap photoluminescence at near-infrared (nIR) wavelengths. The nIR region is critical in many biological detection schemes, as interference from cell autofluorescence and light absorption of whole blood and tissue are low at these wavelengths. The addition of complementary DNA to nanotubes with pre-adsorbed probe DNA causes a modulation in nIR photoluminescence. DNA-SWNT therefore allow for label-free nanoscale detection of hybridization. We studied the kinetics and thermodynamics of this process on the nanotube, and investigate further applications for this sensor.
INOR 30
Controlling the anatase/brookite ratio in sol-gel synthesized titanium dioxide nanoparticles
Sara L. Isley and R. Lee Penn, Department of Chemistry, University of Minnesota, 139 Smith Hall, 207 Pleasant St. S.E, Minneapolis, MN 55455, Fax: 612-626-7541, isley@chem.umn.edu
Titanium dioxide nanoparticles with different anatase/brookite ratios have been prepared via sol-gel syntheses. Rietveld refinements of X-ray diffraction patterns are used to quantitatively track the brookite content and particle sizes as functions of synthetic and hydrothermal aging variables. Results demonstrate that both brookite content and anatase particle sizes decrease with decreasing Ti/H2O ratio. The presence of chloride has the most influence over the brookite content during the sol-gel synthesis and not during hydrothermal aging. Increasing ionic strength during synthesis and hydrothermal aging influences the final anatase/brookite ratio and the particle size. Substantial control over the anatase and brookite contents can be achieved by modifying synthetic and hydrothermal aging variables.
INOR 31
Characterization of porous catalysts by N2 sorption and small angle neutron scattering (SANS) studies
Sharath R Kirumakki1, Houston P. Perry2, Abraham Clearfield3, Sai Venkatesh Pingali4, and P. Thiyagarajan4. (1) Chemistry Department, Texas A&M University, College Station, TX 778432, skirumakki@mail.chem.tamu.edu, (2) Department of Chemistry, Texas A&M University, (3) Department of Chemistry, Texas A & M University, (4) Intense Pulsed Neutron Source, Argonne National Laboratory
There is great technological interest in the design of multifunctional porous materials. We have synthesized families of porous potential catalysts including layered zirconium phosphonates1 and porous NiO-Al2O3-SiO2 systems2 with high surface areas ranging from 250 m2/g-600 m2/g. N2 sorption studies were carried out to determine the pore sizes of these materials. Gas adsorption methods have long been employed for this purpose but their interpretation has been a subject of ongoing debate. The Small Angle Neutron Scattering (SANS) data will be utilized to complement and validate the pore sizes determined. Contrast matched SANS will help differentiate between open pores and closed pores in the materials. Pore connectivity can also be determined by this method. The pore sizes in the layered materials are greater than their interlayer distance and therefore it is very important for us to understand the nature of these pores. Based on the N2 sorption and SANS techniques we will try to describe the pore structure of our materials.
Ref: 1. A. Clearfield, Z. Wang, J. Chem. Soc., Dalton Trans, 2002, 2937 – 2947. 2. S.R. Kirumakki, B.G. Shpeizer, G.V. Sagar, K. V.R. Chary, A. Clearfield, Journal of Catalysis, 242, 319-331 (2006)
INOR 32
Synthesis and structures of bis(2-dimethylaminoethyl)amine adducts of strontium bis(2,2,6,6-tetramethylheptane-3,5-dionate) and their use in the chemical vapor deposition of cubic strontium-doped hafnium dioxides
Wayne L. Gladfelter1, Bing Luo1, Dan Yu2, Benjamin E. Kucera1, and Stephen A. Campbell2. (1) Department of Chemistry, University of Minnesota, 207 Pleasant Street SE, Minneapolis, MN 55455, gladfelt@chem.umn.edu, (2) Department of Electrical and Computer Engineering, University of Minnesota
Monomeric, eight-coordinate Sr(tmhd)2[HN(CH2CH2NMe2)2](EtOH) (1), where tmhd is 2,2,6,6-tetramethylheptane-3,5-dionato, was synthesized from the reactions of HN(CH2CH2NMe2)2, H-tmhd and Sr(OEt)2(EtOH)4. Heating compound 1 at 130 °C dissociated EtOH to form monomeric, seven-coordinate Sr(tmhd)2[HN(CH2CH2NMe2)2](2). In a cold-wall, low-pressure chemical vapor deposition reactor, 2 was used as a liquid precursor at 115 to 175 °C to deposit high-κ dielectric strontium hafnium oxide films in combination with the use of Hf(OtBu)4. The Sr/(Sr + Hf) atomic ratios of the films ranged from 0 to 0.83. XRD showed that films with low Sr doping, e.g. ≤ 0.15, exhibited a crystalline phase consistent with Sr-stabilized cubic hafnia while films with higher Sr contents were amorphous. The dielectric constants of the films increased as the proportion of the cubic phase increased. A maximum value of 25 was obtained for the film with a Sr/(Sr + Hf) ratio of 0.07.
INOR 35
Hybrid silica-polymer composites for radiation detection applications
Banu Kesanli and Sheng Dai, Chemical Sciences Division, Oak Ridge National Laboratory, 1 Bethel Valley Rd, Oak Ridge, TN 37831-6201, kesanlib@ornl.gov
Optically transparent, flexible silica-polymer composites were prepared through sol-gel processing. Sol-gel precursors tetraethyl orthosilicate (TEOS) and 1,4-bis(triethoxysilyl)benzene, (BzTEOS) were hydrolyzed in the presence of HCl in THF and commercially available poly[styrene-b-(styrene-co-butadiene)-b-styrene] triblock copolymer, Styroflex, yielding transparent monoliths. The samples were characterized with TGA and 29Si NMR techniques. Studies revealed that these crack-free, transparent hybrid materials are also efficient matrices to be explored as plastic scintillators for radiation detection applications. The hybrid composites were doped with organic scintillator and lithium-6 which is the neutron absorber. Their alpha particle and neutron detection performances were evaluated. The samples revealed emissions at 421 nm upon doping with PPO/POPOP organic scintillator solution. Hybrid silica polymer samples doped with 3.5 wt% 6Li+ showed high scintillation efficiencies for thermal neutrons.
INOR 36
Bifunctional mesoporous nanocatalysts by solvent-assisted postgrafting synthesis
Tewodros Asefa and Krishna K. Sharma, Department of Chemistry, Syracuse University, 111 College Place, 1-048 Ceneter for Science and Technology, Syracuse, NY 13244, Fax: 315-443-4070, tasefa@syr.edu
The design, synthesis and self-assembly of inorganic, organic and organometallic molecules into solid state nanoscale structures is important for the development nanostructured materials for various electronics, catalytic, sensing, separation, biological and medical applications. For instance, by supramolecular self-assembly of alkoxysilanes, mesoporous solid-state silica materials, which are important host materials for a variety of catalytic groups, results. Subsequent postgrafting on the surface silanols of these materials with aminororganosilanes produces solid base catalysts for a number of reactions. In this talk, I will discuss a one-step method we have recently discovered for postfunctionalization synthesis of efficient, bifunctional acid-base mesoporous solid catalysts containing high surface areas and tunable pore sizes at the nanometer scale. By judicious choices of solvents, control over their structures and catalytic properties has also possible. The synthesis, structures and compositions as well as the catalytic properties of the materials towards a Henry reaction (nitroaldol condensation) will also be discussed.
INOR 37
From platinum and [Ge2Se6]4- and [GeSe4]4- precursors to hexagonal mesostructured chalcogenides: Detailed investigation of the solution behavior
Santanu Bag and Mercouri G. Kanatzidis, Department of Chemistry, Northwestern University, 2145 Sheridan Road, Evanston, IL 60208, s-bag@northwestern.edu
Mesostructured chalcogenide materials have the potential to be promising candidates for novel semiconducting devices. Using Zintl anions and linking metals in suitable solvents and templating surfactants can lead to porous chalcogenides. We will present the surfactant templated synthesis of mesostructured materials based on [Ge2Se6]4- and [GeSe4]4- and Pt2+ as linking metal. Both surfactant head group and chain length can be varied systematically to study their effect on the long range order of the final mesostructures. These materials show sharp band gap transitions in the range of 1.3-1.7 eV. The solvent dependence of these building blocks is of great interest because it affects the nature of the structures. The solution behavior and interspecies equilibria were investigated in detail with variable temperature NMR spectroscopy. Reaction chemistry was employed to shift the exchange equilibria and prevent the formation of undesired species.
INOR 41
Triplet valence states and atomic-scale p-n junctions in manganese perovskite oxides from hydrothermal systems
Shouhua Feng, Hongming Yuan, Zhan Shi, Yan Chen, Keke Huang, Guangsheng Pang, Jixue Li, and Ying Hou, College of Chemistry, Jilin University, 1788 Linyuan Road, Changchun 130012, China, Fax: +86-431-5168624, shfeng@mail.jlu.edu.cn
Perovskite oxides have provided magical structural models for superconducting and colossal magnetoresistance, and the search for nano-scale and/or atomic-scale devices with particular properties by specific preparations in the same systems has been extensively conducted. We present here the triplet valence states (three oxidation states) of manganese (Mn3+, Mn4+, Mn5+) in the perovskite oxide, La0.66Ca0.29K0.05MnO3, which most interestingly show the rectifying effect as atomic-scale p-n junctions of single crystals. The family of cubic perovskite oxides was synthesized by the so-called hydrothermal disproportionation reaction of MnO2 under the condition of strong alkali media. The new concept of the atomic-scale p-n junctions, based on the ideal I-V curves for the p-n junctions in the single crystal, basically originates from the structural linkages of [Mn3+-O-Mn 4+-O-Mn5+], where Mn3+(t2g 3eg 1) and Mn5+(t2g 2eg0) in octahedral symmetry serve as a donor and an acceptor, respectively, corresponding to the localized Mn4+(t2g3eg 0).

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lingyun79

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INOR 42
Direct synthesis of monolayer-proctected silver nanocrystals: Effect of capping molecules
Kwi Jong Lee, Young Il Lee, In Keun Shim, Byung Ho Jun, and Jaewoo Joung, eMD Lab, Central R&D Institute, Samsung Electro-Mechanics, 314, Maetan3-Dong, Yeongtong-Gu, Suwon, Gyunggi-Do, South Korea, Fax: 82-31-300-7900(4553), kwijong.lee@samsung.com
In this study, we attempted to present a direct synthesis of narrowly dispersed silver nanoparticles in highly concentrated organic phase (> 2 M) without use of a size-selection process. The fully organic phase system contains silver nitrate as a silver precursor, n-butylamine as a media dissolving silver salt, toluene as a media, and NaBH4 as a reducing reagent. Variable types of fatty acids were used as a capping molecule. Even using only generic chemicals, monodispersed silver nanocrystals with size of 7 nm were easily synthesized at 100 gram-scale in 1 liter reactor. In addition, systematic studies revealed that the silver nanocrystals synthesized through in situ ligand exchange were stabilized through bidentate bridging of carboxyl group.
INOR 94
Nanoporous semiconductors for photocatalytic applications
Pingyun Feng, Department of Chemistry, University of California at Riverside, Pierce Hall, Riverside, CA 92521, Fax: 951-827-4713, pingyun.feng@ucr.edu
Semiconductor-based heterogeneous systems for photocatalytic production of hydrogen from water is one of the simplest and most economical methods for solar energy utilization. However, the low conversion efficiency of the current materials limits their practical application. Crystalline nanoporous semiconductors offer promise as efficient photocatalysts because they uniquely integrate semiconductivity, crystallinity, high surface area, and uniform porosity. Here, we describe synthesis, structure, and photocatalytic properties of a family of porous semiconducting materials, many of which are built from nanosized clusters. Furthermore, these open-framework semiconductors can function as host to accommodate optically active species with complementary properties, which provides an additional level of control over photocatalytic properties in these materials.
INOR 95
Development of H2 evolution sites for overall water splitting on particulate photocatalysts
Kazunari Domen, School of Engineering, The University of Tokyo, 7-3-1,Hongo, Bunkyo-ku, Tokyo 113-8656, Japan, Fax: +81-3-5841-8838, domen@chemsys.t.u-tokyo.ac.jp
Nanoparticles of various transition-metal oxides are studied as cocatalysts for H2 evolution in overall water splitting. We present on two types of new cocatalysts: (1) mixed-oxides consisting of Cr and another transition-metal and (2) noble-metal/Cr2O3 (core/shell) nanoparticles. These cocatalysts are loaded on particulate photocatalysts (e.g. GaN:ZnO solid solution) by an impregnation or an in-situ photodeposition method. When GaN:ZnO is used as a base photocatalyst, loading Rh2-yCryO3 nanoparticles results in the largest improvement in the activity. Rh2-yCryO3-loaded GaN:ZnO functions as an active and stable photocatalyst for overall water splitting under visible light irradiation (> 400 nm), achieving the quantum efficiency of 2-3% at 420-440 nm. In this presentation, the structures and photocatalytic properties of such cocatalysts will be presented in detail.
INOR 106
Surface chemistry of gold nanostructures deposited on oxides: Oxide-specific O2 interactions with supported gold
Suljo Linic and Siris Laursen, Department of Chemical Engineering, University of Michigan, Ann Arbor, MI 48109, linic@umich.edu
Oxide-supported Au nanostructures are promising low-temperature oxidation catalysts. It is generally observed that Au supported on reducible oxides is more active than the Au supported on irreducible oxides. Recent studies also suggest that cationic Au+ is responsible for the unique Au/oxide catalytic activity. This observation is contrary to the conventional perception that oxide supports donate electronic charge to Au. We have utilized DFT calculations and ab initio thermodynamic studies to investigate the oxidation state of Au nanostructures deposited on reducible and irreducible supports. We find that there are fundamental differences in the electronic structure of Au deposited on the different oxides. We propose a simple model, grounded in the first principles calculations, which attempts to explain the oxide-specific catalytic activity of Au nanostructures and which can account for the presence and the role of cationic Au+.
INOR 108
How do we achieve nanocatalysis by design?
Anne M. Chaka, Physical and Chemical Properties Division, National Institute of Standards and Technology, 100 Bureau Drive, Stop 8380, Gaithersburg, MD 20899-8380, Fax: 301-869-4020
Nanocatalysis by design is highly desirable but remains elusive for many reasons, such as limited data on well-characterized systems, and the challenges of bridging the ideal conditions of single crystal UHV surface science and computational models with realistic industrial processes. Questions of how to design a catalyst are complicated by the fact that materials with identical chemical compositions can have very different reactivity depending upon processing conditions for synthesis, plus the size and morphology of the resultant particles. This presentation will discuss how we can develop a synergy between experiment, theory, and modeling to delineate the essential chemistry and physics required for quantitative predictions and transferability of models to novel systems to enable design. Examples will be presented from metal oxide catalysts for oxidation, and gold-palladium nanoclusters.
INOR 114
Monodisperse, mesoporous silica spheres as a sensor substrate
Thomas A. Schmedake, Ronald B. Soriano, and Adam M. Jakob, Department of Chemistry, University of North Carolina at Charlotte, 9201 University City Blvd., Charlotte, NC 28223-0001, Fax: 704-687-3151, tschmeda@email.uncc.edu
Mesoporous, monodisperse silica spheres are a versatile substrate for gas phase and solution phase sensing applications. The synthesis of monodisperse colloidal silica with diameters much less than 1,000 nm and with ordered mesoporosity is possible by the hydrolysis of a tetraalkoxysilane in the presence of an alkylamine surfactant under basic conditions. Mesoporous spheres were grown through a sol-gel self-assembly process which utilized cetyltrimethylammonium bromide as a porogen. The procedure produces highly monodisperse sub-micron spheres with hexagonally arrayed pores. The ~ 2.5 nanometer pores enable analyte specific fluorescent dyes to be incorporated into the spheres following surfactant removal. A common fluorescent dye for determining oxygen concentration, Ru(bipy)32+, could be incorporated up to loading levels of 2% by weight. The resulting dye filled spheres were evaluated as sensors for oxygen. The small size of the spheres results in very rapid response times of a few seconds. The monodispersity also provides opportunities to assemble spheres into colloidal arrays for additional functionality.
INOR 115
Incorporation of niobium into cage-like silica mesostructures
Izabela Nowak, Faculty of Chemistry, Adam Mickiewicz University, Grunwaldzka 6, 60-780 Poznan, Poland, Fax: +48-61-8658008, nowakiza@amu.edu.pl, and Mietek Jaroniec, Department of Chemistry, Kent State University
Cage-like ordered mesoporous silicas with incorporated niobium, NbSBA-16, were obtained by direct insertion of metal ions during one-pot synthesis using two different recipes. It was shown that NbSBA-16 materials have the BET specific surface of about 800-1000 sq. m/g and mesopore pore volume of about 1.0 cu. cm/g, similar to those observed for purely siliceous SBA-16. As expected for SBA-16 silicas, 20-50% of the total pore volume in the NbSBA-16 samples
studied belongs to the complementary pores (micropores and interconnecting cage apertures) depending on the synthesis temperature. The mesopore diameters were about 7.0-11.0 nm. The samples obtained by both recipes contained niobium located in the framework as well as an extra-framework niobia deposited on the pore walls. The aforementioned synthesis recipes allowed us to synthesize three-dimensional NbSBA-16 structures of various morphology and different contributions of complementary, ordered and textural pores, which is of great importance from catalysis viewpoint.
INOR 116
Ratiometric quantum dot chemosensors based on modulation of Fluorescence Resonance Energy Transfer
Rebecca C. Somers, Preston T. Snee, Andrew B. Greytak, Moungi G Bawendi, and Daniel G. Nocera, Department of Chemistry, Massachusetts Institute of Technology, 77 Massachusetts Ave, Rm 2-209, Cambridge, MA 02139, rsomers@mit.edu
A reversible and ratiometric nanocrystal pH sensor was synthesized by tethering CdSe/ZnS (also known as quantum dots, QDs) to fluorescent sensing dyes. The construct combines the advantages offered by the QDs such as broad excitation profiles and high quantum yields, with the specific sensing ability of the dye. Fluorescence Resonant Energy Transfer (FRET) between donor QDs and acceptor dyes in the sensing construct is modulated by analyte concentration. The presence of an isosbestic point between the two emission maxima allows the sensor to be self-calibrating. The pH-sensing construct is the first example of a CdSe nanocrystal based sensor that is both reversible and ratiometric. The synthetic approach utilized in our constructs is general and can be exploited for sensing other analytes both reversibly and ratiometrically. Applications in biological studies incorporating the QD sensors will also be discussed.
INOR 117
Optical properties of nanoparticles with hollow structures: A single nanoparticle spectroscopy study
Min Hu1, Jingyi Chen1, Younan Xia1, Gregory V. Hartland2, and Manuel Marquez3. (1) Department of Chemistry, University of Washington, Seattle, Seattle, WA 98195, Fax: 206-685-8665, mhu2@u.washington.edu, (2) Department of Chemistry and Biochemistry, University of Notre Dame, (3) INEST Group, Research Center, Philip Morris USA, Inc
The optical properties of hollow structured nanoparticles (Au-Ag nanoboxes and nanocages) were investigated by performing Rayleigh scattering spectroscopy measurements on single nanoparticles, whose morphology and composition had been analyzed by Scanning Electron Microscopy (SEM). This single nanoparticle spectroscopy study removed the inhomogeneous broadening effect and enables us to precisely determine how the homogeneous line widths depend on the dimensions and morphology of the particles. The results show that both radiation damping and electron surface scattering make significant contributions to the linewidth. The electronic dephasing times for these systems was determined to be ca. 4 fs. The sensitivity of the plasmon resonance with respect to the local environment has also studied for these nanoparticles. The results suggest that both the inner and outer surfaces of hollow nanoparticles determine the spectral line shift with respect to the local environment change.
INOR 118
Long-range electronic energy transfer in quantum dot nanocomposites: Toward lowering the optical gain threshold of quantum dots
Mahmoud Emara, Scott Burya, and P. Gregory Van Patten, Department of Chemistry and Biochemistry, Ohio University, Clippinger Laboratories, Athens, OH 45701, me217103@ohio.edu
Antenna-like clusters of nanocrystals have been assembled and studied in colloidal suspension. These clusters contained a single CdTe nanocrystal surrounded by a group of smaller CdTe nanocrystals and/or multiple Au nanocrystals. Controlled assembly was achieved through the use of complementary ligands on the different nanocrystals that formed clusters either through electrostatic assembly or through covalent bonding of the ligands. These clusters are designed to enhance excitation probability at the central acceptor nanocrystal through Förster Resonance Energy Transfer or via plasmon-assisted absorption. The clusters have been characterized by dynamic light scattering and TEM imaging, as well as steady-state and time-resolved absorption and photoluminescence spectroscopies. The enhanced production of excitons at the central nanocrystal is proposed as a means to reduce the optical gain threshold of colloidal semiconductor nanocrystals.
INOR 119
High-efficiency carrier multiplication and ultrafast charge separation in semiconductor nanocrystals
Richard D. Schaller, Milan Sykora, Sohee Jeong, and Victor I. Klimov, Chemistry Division, Los Alamos National Laboratory, MS-J567, Los Alamos, NM 87545, Fax: 505-667-0440, rdsx@lanl.gov
We demonstrate novel methods for the study of multiple exciton generation from a single photon absorption event in semiconductor nanocrystals that are complementary to our previously reported transient absorption method. By monitoring the time-dependence of photoluminescence from nanocrystals via time-resolved emission, we find that carrier multiplication is observable due to the Auger decay of biexcitons. Additionally, we observe spectral signatures of multiple excitons produced from the absorption of a single photon. Photoluminescence spectra at short times following excitation with high-energy photons are red-shifted compared to the single-exciton emission band, which is consistent with previous observations of significant exciton-exciton interactions in nanocrystals. We then show that charge transfer between a nanocrystal and a Ru-based catalyst model compound takes place on a timescale that is faster than Auger recombination, which points toward a possible design of donor-acceptor assemblies that can be utilized to take advantage of carrier multiplication.

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lingyun79

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INOR 120
All monolayers are not created equal: Functionlized porous silicon stability studies
Lon A. Porter Jr., Department of Chemistry, Wabash College, Crawfordsville, IN 47933
Borrowing from solution phase synthetic methods, a selection of hydrosilylation reactions has been recently developed for functionalizing organic groups onto oxide-free, hydride-terminated porous silicon surfaces. These monolayers, bound through direct silicon-carbon bonds are produced via thermal, microwave, carbocation, and Lewis acid mediated pathways. All of these wet, benchtop methods result in the formation of stable monolayers which protect the underlying silicon surface from ambient oxidation and chemical attack. However, no direct comparison of monolayer stability resulting from these diverse mechanisms has been reported. A variety of alkyl monolayers were prepared on porous silicon using the hydrosilylation routes describe above and then subjected to a range of chemically demanding environments. Deterioration and substrate oxidation was be monitored via transmission mode Fourier transform infrared spectroscopy (FTIR). Our initial semiquantitative results indicate that methods employing chemical catalysts incorporate these species within the monolayer as defects, producing less robust surfaces compared to catalyst-free reactions.
INOR 121
A novel silver nanostructure with fluorescence and giant Raman enhancement
Jie Zheng1, Yong Ding2, Bozhi Tian1, Zhonglin Wang2, Charles M. Lieber1, and Xiaowei Zhuang3. (1) Department of Chemistry and Chemical Biology, Harvard University, 12 Oxford Street, Cambridge, MA 02138, jiezheng@fas.harvard.edu, (2) School of Materials Science & Engineering, Georgia Institute of Technology, (3) Department of Chemistry and Chemical Biology and Department of Physics, Harvard University
A comprehensive understanding of cell biology demands new probes which can be integrated with single-molecule imaging techniques to offer quantitative chemical information on biological processes at the molecular level. To meet this demand, we developed a new class of silver nanostructures which exhibit extremely strong fluorescence with cross section about 10-14/cm2 and enormous Raman enhancement with factors on the order of 1014-1015. A unique electronic structure of these novel fluorescent and Raman active silver nanoparticles is manifested by continuous excitation and discrete emission. The ultrabright emission allows single particles of such nanostructures to be readily detected in live cells. The giant Raman enhancement effect allows visualizating vibrational information of a single small molecule in the vicinity of the silver nanoparticle Robust emission, giant Raman enhancement and high optical purity make these silver nanoparticles promising bioprobes with an extra capability of providing chemical information on the microenvironments inside living cells.
INOR 248
Quantification of small molecule and peptide-modified intracellular MRI contrast agents
Paul J. Endres, Department of Chemistry and the International Institute for Nanotechnology, Northwestern University, 2145 Sheridan Rd., Evanston, IL 60208-3113, p-endres@northwestern.edu, Keith W. Macrenaris, Department of Biochemistry, Molecular Biology, and Cell Biology, Northwestern University, and Thomas J. Meade, Chemistry, Biochemistry and Molecular and Cell Biology, Northwestern University
Current magnetic resonance (MR) imaging probes which are confined to extracellular and vascular regions of an organism are quickly cleared by the reticuloendothelial system. Although the use of these first generation contrast agents has made MR one of the most popular imaging modalities for the clinical diagnostic community, they have limited utility for investigating cellular processes or cycles in developmental biology. Therefore, we coupled DOTA and DTPA based contrast agents to either a known cell penetrating peptide or a lipophilic stilbene to achieve a biologically compatible intracellular contrast agent set. In order to fully exploit the cell transduction efficiency and optimize the intracellular lifetime of the synthesized agents, a second set of contrast agents was synthesized with disulfide linkages between the Gd(III) chelator and the transduction moiety. The entire agent set was tested in three mammalian cell lines to confirm and quantify the transduction efficiency of each chelator-transporter combination.
INOR 250
Self-assembly of Co(II)-meso-mono-4(3)-pyridyl-tri-phenyl porphyrins in sublimed layers: Interaction with nitrogen dioxide and NO2 gas sensing properties
Tigran S. Kurtikyan1, Astghik A. Hovhannisyan1, Hrachya M. Nazaryan1, Robert K. Ghazaryan2, and John A. Goodwin3. (1) Laboratory of Optical Spectroscopy, Molecule Structure Research Center (MSRC), NAS, 374014, Yerevan 375014, Armenia, Fax: 37410-282-267, kurto@netsys.am, (2) Department of Chemistry, Medical State University, (3) Department of Chemistry and Physics, Coastal Carolina University
Self-assembly of Co(II)-meso-mono-4(3)-pyridyl-tri-phenyl porphyrins (CoM4(3)PyTPP) in sublimed layers leads to the formation of coordination oligomers through the binding of pyridyl nitrogen atoms with the Co-ions of adjacent molecules in the layer. The degree of oligomerization depends on the position (4 or 3) of the nitrogen in the pyridyl ring and is higher for the CoM3PyTTP. Interaction of these layers with NO2 results in the formation of two types of nitro-complexes – 5-coordinate at the end of the oligomeric chains and 6-coordinate within. The electrical conductivity of such films increases significantly in the presence of low pressure NO2 (10 -100ppm). Immediate evacuation (within a few tenths of a second) completely restores the initial values of conductivity, implying that these layers can serve as electrical NO2 sensors. FTIR studies have been performed with these films to throw light on the nature of such behavior. Acknowledgments. The financial support of NFSAT/CRDF (Project ARC2-3231-YE-04) and ISTC (Project #A-484) is greatly acknowledged.
INOR 258
A zinc-activated MRI contrast agent
Jody L Major, Department of Chemistry, Northwestern University, 2145 Sheridan Rd, Evanston, IL 60208, j-major@northwestern.edu, and Thomas J. Meade, Chemistry, Biochemistry and Molecular and Cell Biology, Northwestern University
Magnetic Resonance Imaging (MRI) has been established as a noninvasive technique for obtaining in vivo images of living tissues and organisms. Recent advances in the area of MRI offer the ability to image biological processes and structures at cellular resolution. To generate images based on physiological events, we have been developing new functional MR agents that are activated by enzymes and extracellular messengers. Zinc(II) plays a critical role as an essential component of numerous enzymes, transcription factors, and synaptic vesicles. While zinc has been linked to a variety of physiological processes, the mechanism is less understood. To this end, we have developed a Zn(II) activated MRI contrast agent that undergoes an intramolecular rearrangement upon Zn(II) binding resulting in an increase in intensity. This agent is specific for Zn(II) in the presence of Ca(II) and Mg(II) while also displaying reversibility. NRMD measurements and MR images showing concentration dependence will be presented
INOR 265
Design and synthesis of an interweaving MOF possessing Pt3O4-net constructed from metal-coordination-supported organic ligand
Daofeng Sun and Hong-Cai Zhou, Department of Chemistry and Biochemistry, Miami University, Oxford, OH 45056, Fax: 513-529-8091, sund@muohio.edu
Hierarchical organization is the most conspicuous property in biological systems and biomaterials such as proteins, viruses and biogenic crystals.1 Recently, hierarchical assembly has been successfully applied in the construction of stable porous MOFs. For examples, by use of structural hierarchy, Fèrey and co-workers designed and synthesized a series of porous MOFs based on trigonal-prismatic {(Cr3O)(CO2)6} units and carboxylate ligands.2 Yaghi and co-workers successfully synthesized a ferric metal-organic framework with a hierarchical system of pores and tetrahedral building and the authors illustrated how a “one-pot” reaction can yield a crystalline solid with four distinct level of complexity.3 All the examples mentioned above are focusing on the metal cluster or building block (unit) by hierarchical assembly: firstly, the metal cluster as building unit was synthesized or computationally predicted, then the cluster was further extended into high dimensional framework by organic ligand. Currently, no examples were focused on extending the organic ligand through metal coordination into nano-sized ligand, then the new ligand connects the existing SBU or building unit to form porous MOF hierarchically. We describe a new metal-organic framework, CuI3CuII1.5(dmpba)3(py)0.5(H2O)•dma•5H2O (1) (dmpba = 4-(3,5-dimethyl-1H-pyrazol-4-yl)-benzoic acid), possessing Pt3O4-net constructed from metal-coordination-supported organic ligand, hierarchical assembly containing oxidation-reduction phenomena.
INOR 297
Synthesis of peptide-bridged macrocycles as bioactivatable magnetic resonance imaging contrast agents
Bradley D. Ulrich and Thomas J. Meade, Department of Chemistry, Northwestern University, 2145 Sheridan Rd., Evanston, IL 60614, bdulrich79@yahoo.com
Magnetic Resonance Imaging (MRI) is a non-invasive imaging modality that can create 3-D images of whole animals. A new family of bioactivated contrast agents is emerging that has the ability to report on enzymatic processes in vivo and provide this information in the form of an image. Towards this goal, we have prepared a new class of peptide-bridged contrast agents. A strategy has been developed in which a Gd(III) chelator is covalently attached to the side chains of a peptide while the peptide is anchored to a solid phase resin. This methodology allows for facile modification of the peptide such that the amino acid sequence can be changed to target a variety of proteases. A paradigm of this new class of agents is exemplified by a caspase agent that was synthesized in 24 steps. This methodology was extended to include a contrast agent for the detection of matrix metalloproteinases.
INOR 300
Polyelectrolytes-organometallic multilayers for efficient photocurrent generation: [polypropylviologen/RuL2(NCS)2/(PEDOT;PSS)]n on ITO
Mira Park1, Won Joo Lee1, Sun Ki Min1, Gangri Cai1, and Sung Hwan Han2. (1) Department of Chemistry, Hanyang University, Sungdong-Ku, Haengdang-dong, Seoul 133-791, South Korea, Fax: +822-2299-0762, pandora0826@hotmail.com, (2) Department of Chemistry, Hangyang University
The polyelectrolytes-organometallic system is prepared and applied to the photocurrent generation. The viologen-containing polymers (polyproylviologen) have two Br- counter ions and are easily soluble in water. The viologen-containing polyelectrolyte multilayers were formed by layer-by-layer deposition method. And as a photosensitizer, RuL2(CNS)2 are easily incorporated in the multilayer films by a ion-exchange method. The energy levels of LUMO of RuL2(CNS)2, viologen, and ITO are well arranged and form an acceptor-sensitizer system. The photocurrent measurement of the systems shows excellent photocurrent generation: 1200 nA/cm2 under A.M 1.5 condition for 4.5 bilayers sample.
INOR 302
Photocatalytic water splitting using platinum and metal oxide decorated niobate nanosheets
Owen C. Compton, Jin Y. Kim, and Frank E. Osterloh, Department of Chemistry, University of California, Davis, One Shields Avenue, Davis, CA 95616, Fax: 530-752-8995
The photochemical cleavage of water into H2 and O2 using visible light is an alternative to fossil fuels that utilizes abundant solar energy as a renewable energy resource. Semiconducting perovskite nanosheets of TBAx[(H1-x)Ca2Nb3O10] (TBA = Tetrabutylammonium) are catalysts for this reaction. Functionalized with 3-aminopropyltrimethoxysilane, the sheets can be decorated with both citrate-coated metal oxide and platinum nanoparticles that modify the catalytic properties. Transmission electron microscopy, x-ray photoelectron spectroscopy, and infrared spectroscopy were used to characterize the structure and composition of the catalysts. Gases evolved during irradiation in water were analyzed with gas-chromatography. The effects
INOR 305
Designing mixed-metal supramolecular assemblies as photochemical molecular devices: Applications in solar hydrogen production
Shamindri M. Arachchige, Mark Elvington, Jared Brown, and Karen J. Brewer, Department of Chemistry, Virginia Tech, Blacksburg, VA 24060, arachsm@vt.edu
Photocatalytic water splitting is a clean and renewable technology to produce hydrogen through solar energy conversion schemes. Mixed-metal supramolecular complexes provide promising structural motifs for solar energy conversions. We recently reported a mixed-metal supramolecular complex

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lizijing

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多谢了,好东西收藏了!
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lingyun79

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which has the ability to photochemically collect reducing equivalents on a metal center (Inorg. Chem. 2006, 45, 5242). This complex can photocatalyze the production of hydrogen from water. Studies directed towards understanding the photocatalytic activity of the supramolecular complex in more detail and component modification to optimize solar hydrogen production from water will be described. The application of high throughput Light Emitting Diode (LED) arrays aids in the analysis of this system. The authors wish to acknowledge the financial collaboration of Phoenix Canada Oil Company which holds long term license rights to commercialize the technology. [{(bpy)2Ru(dpp)}2RhCl2}]5+

INOR 307
SiC nanoporous membrane derived from polycarbosilane for hydrogen separation at high temperature
Younghee Kim, Soo Ryong Kim, Woo Teck Kwon, and Vikram Dabhade, Eco-materials Team, Korea Institute of Ceramic Engineering and Technology, 233-5, Geumcheon Ku, Gasan-Dong, Seoul 153-801, South Korea, Fax: 822-3282-2430, yhkokim@kicet.re.kr
Ceramic membranes having nano sized pores have great potential for gas separation at high temperature since they have a good stability at high temperatures. Moreover, nanoporous silicon carbide membrane can be expected to use under hydrothermal condition at high temperature as membrane reactors for conversion enhancement in steam reforming reaction of natural gas. The use of membrane allowed separating simultaneously hydrogen gas during the steam reforming reaction. In this research, nanoporous SiC membrane has been developed for the hydrogen separation using preceramic polymers such as polycarbosilane using a spin coating technique. The prepared SiC membrane was characterized with SEM, TEM, FT-IR and thin film XRD and so on. H2 permeance was about 10-6 mol m-2s-1Pa-1 and selectivity of H2 to N2 was about 5-20. The nanoporous hydrogen selective SiC membranes show promise for application in membrane reactor for steam reforming reaction of natural gas and water gas shift reactions.
INOR 309
Effect of dye-semiconductor electronic coupling on solar energy conversion efficiency in dye sensitized solar cells
Ana O. Ramirez1, Chunxing She2, Kyoung-Tae Youm1, Tianquan Lian2, and Joseph T. Hupp1. (1) Department of Chemistry, Northwestern University, 2145 Sheridan Road, Evanston, IL 60208, a-ramirez@northwestern.edu, (2) Department of Chemistry, Emory University
Dye sensitized solar cells have proven a promising approach for solar energy conversion. Optimization of overall efficiency has primarily focused on modification of dye absorption/spectral coverage, electrodes, and electrolyte composition. An important remaining issue is how the absorbed-photon-to-current efficiency (APCE) is effected by the dye-semiconductor electronic coupling. This coupling may be significantly dependent upon the linker, which serves to both anchor the dye to the surface and also mediates the electron transfer. This work focuses on the effect of structural modification of the linker group on charge injection and therefore the solar to electrical energy conversion efficiency. The role of frontier orbital energy levels, orbital geometry, and dye substitution pattern (meso or beta positions) is probed to understand the role of electronic coupling and subsequently any effect on efficiency.
INOR 310
Fragile-free ZnO micro-cone flower-like architecture based 2.21% efficient dye-sensitized solar cells
Ju Hyun Ahn1, Sung Hwan Han2, Jin-Ho Chang1, and Hwang-yong Ko1. (1) DEPARTMENT OF CHEMISTRY, HANYANG UNIVERSITY, SUNGDONG-KU, HAENGDANG-DONG, Seoul 133-791, South Korea, Fax: +822-2299-0762, -mybaby-@hanmail.net, (2) Department of Chemistry, Hanyang University
Here, we report the crystal structural and morphological studies of different thicknesses ZnO films fabricated by repeated chemical depositions. As-grown ZnO films up to 8 ìm thickness showed elongated micro-cones along c-axis perpendicular to substrate surface. However; dye loving micro-cone based flowerlike architecture was observed for higher thicknesses. DSSCs formed with
11 ìm thick ZnO electrode in modified lithium iodide electrolyte showed photoconversion efficiency of 2.21% with IPCE of 46%.
INOR 311
Catalytic combustion of methane over nano ZrO2 supported copper-based catalysts
Fenfen Qu1, Wei Chu2, Limin Shi2, Muhua Chen2, Jinyan Hu1, and Shizhong Luo2. (1) Department of Environmental Science and Engineering, Sichuan University, Chengdu, P. R. China, Fax: 86-28-85463870, lab230.scu.cn@163.com, (2) Department of Chemical Engineering, Sichuan University, Chengdu, China, Fax: 86-28-85463870, lab230.scu.cn@163.com
Supported Cu-based catalysts for methane oxidation have been attracted much attention in recent years. In this work, the ZrO2 supported copper-based catalysts were investigated by means of N2 adsorption, XRD, H2-TPR techniques and test of methane combustion. Two kinds of ZrO2 (ZrO2-1 and ZrO2-2) were obtained from the commercial ZrO2 and thermal decomposition of zirconium nitrate, respectively. It was found that the CuO/ZrO2-2 catalyst was more active, over which the temperature corresponding to 90% methane conversion was as low as 691 K, while that over CuO/ZrO2-1 was 843 K .The ZrO2-2 and CuO/ZrO2-2 were in the tetragonal ZrO2 form. There was a better reduction property for CuO/ZrO2-2 than that of CuO/ZrO2-1, and also a larger specific surface area. The higher activity of the CuO/ZrO2-2 catalyst could be issued and explained.
INOR 312
Synthesis of mesoporous titanium dioxide without using organic templates and their photocatalytic activities under visible light
Jun Shen, Zhao Zhang, Mingjun Zhang, and Ni Lou, Department of Chemical Engineering, Sichuan University, 24# South Section 1,Yihuan Road, Chengdu 610065, China, Fax: 86-28-85401819, junranshen@yahoo.com.cn, zzhangscu@hotmail.com
Mesoporous anatase TiO2 was successfully synthesized without using any organic compounds as templates. Based on two-step hydrolysis of industrial titanyl sulfate solution to form mesoporous metatitanic acid and followed by calcinations at 500°C for 2h, the mesoporous TiO2 with a surface area of 202.2 m2/g and an average pore diameter of 2.8 nm was obtained. The samples were characterized by powder X-ray diffraction (XRD), nitrogen adsorption isotherms, scanning electron microscopy (SEM), Fourier transform infrared spectroscopy
(FT-IR), energy dispersive X-ray spectroscopy (EDS) and diffuse reflectance UV-visible spectroscopy (DRS). The mesoporous TiO2 exhibits super-acidic property and photocatalytic activity under visible light. Characterization results indicate that SO42- is bonded to the free hydroxyl groups on the pore walls of the mesoporous metatitanic acid during calcination, which acts as a structural directing agent and pore structure support. Electron induction effect of S=O in SO42- bonded with TiO2 not only make adjacent Ti atoms show super-acidic property but also make the absorption spectrum red shift 30 nm, and it's photocatalytic activity be enhanced obviously.
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7楼2007-03-25 14:15:55
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lingyun79

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INOR 327
Novel ligands for structural control of photogenerated nanoscale materials
Chandrima De and Sherine O. Obare, Department of Chemistry, Western Michigan University, 1903 W. Michigan Avenue, 3425 Wood Hall, Kalamazoo, MI 49008, Fax: 269-387-2909, chandrima.de@wmich.edu
We have designed and developed a series of novel ligands derived from dipyrido[2'3'-a:3'2'-c]phenazine (DPPZ). With the appropriate functional groups, these ligands have shown excellent control over the size and shape of metal nanoparticles such as gold and silver generated via photochemical processes. Monodisperse nanoparticles were fabricated in a one-step photochemical reaction and the resulting nanoparticles required no size selection procedure. We extended this methodology toward the synthesis of core-shell semiconductor-metal nanoparticles including TiO2@Au and TiO2@Ag. The generated nanoparticles were stable at room temperature for months. Various parameters leading to the monodisperse nanoparticles, including concentration of the metal salt and the ligand, temperature, environmental conditions, and solvent character will be presented.
INOR 328
Sol-gel synthesis of aluminosilicate glasses
Serah Ndegwa and Eric J. Voss, Department of Chemistry, Southern Illinois University Edwardsville, Edwardsville, IL 62026-1652, Fax: 618-650-3556, sndegwa@siue.edu
We are interested in synthesizing optically transparent aluminosilicate glass monoliths with potential applications in holographic data storage. Our initial efforts have been in preparing high quality samples of varying aluminum content via the sol-gel process. The sol is formed by mixing a silicon alkoxide precursor (TEOS or TMOS), water, co-solvent (ethanol, methanol, or butanol), acid catalyst (hydrochloric acid, nitric acid, or zinc chloride), and aluminum reagent (aluminum nitrate or aluminum tri-sec-butoxide). Our studies have included varying the
aluminum to silicon molar ratio, the type of catalyst, the period of ageing and drying, the solvent type, and also the use of drying control chemical additives (DCCAs). An advantage to the sol-gel process is that the glass can be doped with an optically active lanthanide during the mixing stage. For example, europium-doped glasses have a strong red emission at 610 nm. Strategies to overcome synthetic challenges including insolubility of aluminum reagents and sample cracking will also be discussed.
INOR 329
Study phase formations of zinc titanate nanocrystal powders via sonochemical synthesis
Feng Chen, Mark Hilton, and Beth Manhat, Department of Chemistry, Biochemistry, and Physics, Rider University, 2083 Lawrenceville Road, Lawrenceville, NJ 08648, Fax: 609-895-5782, fchen@rider.edu, hiltonm@rider.edu
Among three major reported zinc titanate phases (Zn2TiO4, ZnTiO3,and Zn2Ti3O8) in ZnO-TiO2 system, recent studies have shown that ZnTiO3 with illmenite structure could be a good candidate for low temperature co-fired microwave dielectric ceramics (LTCC). However, it is very difficult to prepare ZnTiO3 in pure form by conventional solid-state reaction, because the compound decomposes to Zn2TiO4 and rutile at ~945°C. In this study, a novel sonochemical method to prepare nanocrystalline zinc titanate has been developed. Effects of sonochemical synthetic conditions on forming ZnTiO3 have been investigated. The dependence of phase formation and microstructure evolution of the system on various heating temperatures were carefully studied. The relationship of the crystal size and shape with the above factors from the sonochemical approach will also be discussed in this paper.
INOR 330
Synthesis and characterization of Mg doped lithium ion-sieve adsorbent derived from LiMn2O4
Qian Dong, Xianglan Piao, and Shenlin Zhu, Department of Chemical Engineering, Tsinghua University, Beijing 100084, China, dq@mails.tsinghua.edu.cn, zhusl@tsinghua.edu.cn
A new type of lithium adsorbent was synthesized from LiMn2O4 followed by acid treatment. The solid-state reaction of LiOH•H2O with MnO2 under high temperature of calcinations was used for the preparation of the precursors. The conversion of precursor spinel lithium manganese oxide (LiMn2O4) to normal ion exchange formed the new type of lithium ion-sieve adsorbent and showed markedly ion-exchange and lithium absorption capacity and relatively high discharge capacity retention. The new Mg-doped adsorbent also exhibited excellent chemical stability during repeated adsorption/desorption of salt-lake brine containing lithium ions. lithium adsorbent λ-MnO2 by acid treatment resulted in the display of lithium adsorption capacity out of salt-lake brine. Magnesia was doped to modify a new type of lithium ion-sieve adsorbent derived from the spinel lithium manganese oxide. Experiments results showed the optimum calcination temperature and other conditions for the best adsorption capacity. The material powders doped with MgO were calcined at 800°C in air and remained for at least 5 hours, where the weight loss remained at about 35%. The XRD characterization results showed the perfect spinel structure and confirmed that Mn and Mg were uniformly distributed throughout the crystalline oxide particles. After treating by a 0.5 mol/dm3 solution, the H+/Li+
INOR 331
Synthesis and post-synthetic elaboration of metal-organic frameworks
Tendai Gadzikwa1, Bi-Shun Zeng1, SonBinh T. Nguyen2, and Joseph T. Hupp3. (1) Department of Chemistry and the Institute for Catalysis in Energy Processes, Northwestern University, 2145 N Sheridan Rd., Evanston, IL 60208, t-gadzikwa@northwestern.edu, (2) Department of Chemistry and the International Institute for Nanotechnology, Northwestern University, (3) Department of Chemistry, Northwestern University
A series of 4,4'-ethynylenedibenzoic acids was synthesized and used in the construction of mixed-ligand metal-organic frameworks (MOFs). The variation of functionality in the 3- and 3'- positions of these linkers allowed for the construction of a diverse collection of MOFs with differing connectivities and varying levels of interpenetration. The syntheses, crystal structure determinations, and gas uptake capabilities of these materials will be presented. By way of post-synthetic elaboration, the functional groups present in the 3,3' positions of the di(benzoic acid) ligands in some of these MOF materials can be altered, leading to new MOFs with different cavity chemistries from the parent starting material. From the topological perspective, this strategy can yield MOF materials having different network structures but bearing similar chemical functionalities. Such a methodology can serve as an efficient and rational tool to discriminate the effects of topology and chemical functionality on the material properties of MOFs.
INOR 332
Synthesis of metal-organic-, covalent-organic-, and zeolitic imidazolate frameworks (MOFs, COFs, and ZIFs)
Adrien P Côté, Department of Chemistry and Biochemistry, California NanoSystems Institute, University of California, Los Angeles, 607 Charles E. Young Drive East, Los Angeles, CA 90095, Fax: 310 825-0874, apcote@chem.ucla.edu, and Omar M. Yaghi, Department of Chemistry and Biochemistry, Center for Reticular Chemistry at the California NanoSystems Institute, University of California Los Angeles
Synthesis of porous solids using molecular building blocks is a rapidly growing area of solid-state chemistry and contributed many advances for the field of porous materials. Exceptionally porous materials with large pore volumes and surface areas have been produced and are emerging as materials with great promise for gas storage/separation technology and catalysis. Our research has involved the synthesis of metal-organic frameworks (MOFs), covalent-organic frameworks (COFs), and most recently zeolitic-imidazolate frameworks (ZIFs); materials that are linked togther by bonds of varying strengths that are formed with varying degrees of reversibilty. To synthesize these materials one must carefully consider and explore reaction conditions which will yield crystalline phases. This presentation will give an overview of our strategies that have been successful for synthesis of MOFs, COFs, and ZIFs
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8楼2007-03-25 14:17:17
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lingyun79

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INOR 335
Electrochemical morphogenesis of micron-size Cu2O crystals
Matthew J. Siegfried and Kyoung-Shin Choi, Department of Chemistry, Purdue University, 560 Oval Drive, West Lafayette, IN 47907, msiegfri@purdue.edu
Morphological control of crystals provides a means of tailoring the interfacial arrangement of atoms and has a vital role in enhancing the desired reactivity of a material. In this presentation we demonstrate how two main processes that determine crystal shape (i.e., crystal habit and branching growth) can be independently regulated in the electrocrystallization of Cu2O. Crystal habit can be regulated by introducing additives that preferentially adsorb onto specific crystallographic planes. We will discuss the effect and efficiencies of various additives in stabilizing {100}, {111}, and {110} surfaces of Cu2O crystals. While crystal habit is controlled by the composition of the plating solution, the degree of branching can be simultaneously regulated by the overpotential and current density. Combining the ability to control habit and branching growth with the intrinsic advantages of electrodeposition, we demonstrate how numerous novel crystal architectures can be assembled by rationally designing growth conditions and a growth chronology.
INOR 336
Facile solvothermal routes to main-group and transition metal nitrides, oxides and phosphides
Brian M Barry1, Edward Gillan2, and Jong Lak Choi2. (1) Chemistry Department, University of Iowa, Iowa City, IA 52242, brian-m-barry@uiowa.edu, (2) Department of Chemistry, University of Iowa
The utility of binary main-group and transition metal pnictides and chalcogenides encompasses optics, electronics, magnetics and ceramics. Conventional syntheses of these materials typically involve extreme condition reactions of the elements or deposition techniques using volatile precursors. These routes are limited to thermodynamically stable phases and thin films, respectively. Because of this, a great deal of research is being focused on “bottom-up” routes that allow for metastable phases and morphologies with nano-dimensions. In this research we employ a solvothermal route involving a metal halide and a variety of nitride, oxide and phosphide sources. For synthesis of the nitrides (Ge3N4, AlN), a metathesis reaction occurs between the metal halide and either NaN3 or NaNH2 to form an energetically unstable precursor, which then decomposes in situ to the metal nitride. The oxide syntheses (SnO2, GeO2) utilize a very similar metathesis route with a metal halide and Na2O2 as the oxygen source. Synthesis of the phosphides (e.g. many phases of NixPy) involve elemental P4 reacted directly with a metal azide or metal halide.
INOR 337
Influence of microwave irradiation on the reaction of MgO and Al2O3 slurries to form layered double hydroxide
Sharon J. Mitchell, Ian R. Baxendale, and William Jones, Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge CB2 1EW, United Kingdom, Fax: 0044 1223 336362, sjm202@cam.ac.uk Layered Double Hydroxides (LDHs) are utilised for a diverse range of applications. The ability to rapidly and reproducibly synthesise LDHs with accurate structural control is therefore of importance in terms of physical properties and thus application. Microwave irradiation (MI) is known to enhance the rate of nucleation and growth of crystals in many inorganic reactions, dramatically reducing the required synthesis times and resulting in environmental and economic benefits. We report on the use of MI in the hydrothermal reaction of MgO and Al2O3 slurries to form Mg-Al LDHs. MI was found to increase the rate of formation of both the 3R1 and 3R2 polytypes of the LDH without significant changes in the PXRD patterns of the products obtained from the two routes.
INOR 342
Synthesize functionally porous silica nanoparticles for heavy metal removal
Tingying Zeng and Wenbing Li, Chemistry, Western Kentucky University, 1906 College Heights Blvd-11079, Bowling Green, KY 42101-1079, Fax: 270-745-5361, tingying.zeng@wku.edu
Advanced sol-gel technology allows to synthesize large a number of functional colloidal nanoparticles for different applications. This presentation reports a new biomimetic self-assembly approach based on advanced sol-gel technology to synthesize silica mesoporous nanoparticles, which are formed by functionalized colloidal silica nanopartilces. The silica nanopartilces were synthesized using silanes that contain functional groups or atoms to capture heavy metal and its ions from trace contaminated flow sources, which was designed to form chemical metal compounds on the surface of the silica nanoparticles. Functional surfactants were used to template the biomimetic three-dimensional self-assembly. Removing the surfactant molecules by solvents and drying the nanoparticles obtain 3D mesoporous nanoparticles, which have high surface area and active sites to capture heavy metals and their ions.
INOR 343
Ultrasonic nozzle and microwave-assisted preparation of mixed metal oxide nanoparticles
Edward K Nyutu, Department of Chemistry, University of Connecticut, 55 N Eagleville Rd U 3060, Storrs, CT 06269, edward.nyutu@uconn.edu, and Steven L. Suib, Department of Chemistry, Department of Chemical Engineering, Institute of Material Sciences, University of Connecticut
A continuous system has been developed for preparation of phase pure mixed metal oxide nanoparticles with the aid of an in-situ ultrasonic nozzle mixing and microwave irradiation, herein referred to as INM (In-situ mixing Nozzle Microwave) method. The reactions were carried out in ambient pressure (1 atm), microwave power (0 - 600 W), and ultrasonic nozzle frequency of 48 & 120 kHz. The effect of the nozzle and microwave on purity of the prepared products were compared and analyzed by XRD, FE-SEM, TEM, Raman, and FT-IR.
INOR 344
Fluorescence enhancement of ruthenium complex on silver nanoparticles coated with different chain length carboxylic acid terminated thiols as spacers
Jong-Sung Yu, Nitin Chaudhari, Min Sik Kim, and Jung Ho Kim, Department of Chemistry, Hannam University, 133 Ojeong-dong, Daejeon 306-791, South Korea, Fax: +1-82-42-629-7469
The fluorescence enhancement of Ruthenium complex (Ru(bpy)32+) was studied on the silver surface deposited by simple Tollens mirror reaction and CVD. The plasmon effects on spacer distance, silver concentration, and deposition methods are studied. Silver nanoparticles prepared were coated with different chain length carboxylic acid terminated thiols as spacers. The distance varied from 0.4 to 2.3 nm and the silver concentration from 0.01 M to 0.15 M for the formation of silver film on the glass substrate. The enhancement factor was found to increase with the distances between silver surface and dye. The silver concentration and surface morphology of silver film also plays important role in the emission. The results show that for the metal surface enhancement of fluorescence a specific distance of dye from metal surface and concentration of metal plays very important role.
INOR 345
Large-area patterning of nanoscale transition metal chalcogenides
Christopher Leo Stender and Teri Odom, Department of Chemistry, Northwestern University, 2145 Sheridan Rd, Evanston, IL 60208, c-stender@northwestern.edu
We will present a general strategy for patterning nanoscale transition metal chalcogenide structures on surfaces and for generating free-standing nanostructures by combining top-down nanoscale patterning techniques with bottom-up chemical methods. This approach first patterns metal nanostructures and then chemically converts them to their semiconducting counterparts. Our method can be used to pattern arbitrary shapes with independent control over height, width, length, pitch.
Nanostructured ceramic thin films for photocatalytic applications
Yixin Zhao, Xiaofeng Xiaofeng Qiu, and Clemens Burda, Department of Chemistry, Case Western Reserve University, 2074 Adelbert Road Millis Building G14, Cleveland, OH 44106, yxz59@case.edu
A series of nanostructured ceramic thin films (TiO2, ZrO2, CeO2 and SnO2) have been successfully developed and characterized. The photocatalytic performances of nanoparticles were evaluated by photodecomposition of stearic acid, a commonly used model pollutant to probe photocatalytic activity, under the irradiation of UV-vis light source. Transmission IR absorption spectroscopy was used to monitor the kinetics of the decomposition by the peak height of characteristic stearic acid absorption at 2916 cm-1 and 2848 cm-1. It is found that the activities of these materials are very different and are affected by morphologies and the crystallinity of the thin films. We also find that the band gap energies of these materials are of great importance to their photocatalytic performance.
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9楼2007-03-25 14:17:38
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lingyun79

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INOR 353
Solid-state NMR and FTIR studies of CdS nanoparticle/polymer composites
Saida Y. Ortiz-Colón1, Matthew Espe1, Ron F. Ziolo2, and Felicia S. Manciu3. (1) Department of Chemistry, The University of Akron, Akron, OH 44325-3601, syo1@uakron.edu, (2) Centro de Investigación en Química Aplicada, (3) Department of Physics, University of Texas at El Paso
CdS nanoparticles synthesized in sulfonated polystyrene (PSS) resin or films are analyzed by 113Cd solid-state NMR (SSNMR) and FTIR. Similar 113Cd chemical shift but a broader peak, relative to bulk material, shows that the internal Cd sites of the nanoparticles have adopted the Wurtzite structure with some structural heterogeneity. Surface selective SSNMR studies reveal that the surface structure is highly ordered and similar to the internal component, consistent with the synthesis occurring under sulfur rich conditions. The surfaces of these non-passivated nanoparticles are observed to undergo oxidation upon exposure to ambient conditions for several weeks. Depth profiling by SSNMR shows that the oxide material is only several layers thick. Interactions between the polymer and the surface of the nanoparticles have been probed to characterize the nanoparticle/polymer interactions. The FTIR and FT-Raman studies show the presence of nanoparticles, which may be part of a thin semiconductor layer of a core-shell structure.
INOR 354
The electrical and thermal properties of kaolinite/polyaniline hybrid nanocomposite
Bao-xiang Wang, Yong Shi, and Dong-feng Xue, Department of Materials Science and Chemical Engineering, Dalian UniVersity of Technology, 158 Zhongshan Road, Dalian 116012, China, bxwang@dlut.edu.cn
Abstract: A novel polyaniline nanofiber/kaolinite nanoplatelet hybrid nanocomposite was synthesized by the in-situ polymerization. The resultant polyaniline/kaolinite hybrid nanocomposite were characterized by means of different techniques, such as thermogravimetric analysis, X-ray diffraction, Fourier transform infrared spectroscopy and transmission electron microscopy methods. The results show that 2D nanoclay platelet randomly disperse into the 1D polyaniline nanofibers. The nanoclay platelets not only improve the thermal stability of polyaniline nanofibers, but also adjust the conductivity from the insulating to metallic regime depending on the variation of kaolinite. This facile method provides a novel path for the design of low-dimensional hybrid nanocomposite.

INOR 355
A bioinspired synthesis of barium titanate nanoparticles for use in positive temperature coefficient of resistivity (PTCR) applications
Richard L. Brutchey, Guosheng Cheng, Edward S. Yoo, and Daniel E. Morse, Institute for Collaborative Biotechnologies, University of California, Santa Barbara, Santa Barbara, CA 93106, brutchey@lifesci.ucsb.edu
Biological systems fabricate a remarkable diversity of 3-D nanoscale materials – often under the mild physiological conditions of low temperatures, ambient pressures, and near neutral pH. We have successfully “re-engineered” these biological mechanisms into a fabrication method not reliant on biomolecules but rather wholly controlled by chemical physics. We have demonstrated, for the first time, that well-defined 6-nm nanoparticles of BaTiO3 can be synthesized at very low temperatures (16 °C) using this low energy, low cost fabrication method. These small nanoparticles are perfectly suited for positive temperature coefficient of resistivity (PTCR) applications – a technologically important phenomenon that occurs via grain boundary effects. Materials that exhibit PTCR characteristics display an exponential increase in resistance at the Curie temperature (Tc), at which point BaTiO3 undergoes a ferroelectric-paraelectric transition associated with a crystallographic change from tetragonal (P4mm) to cubic (Pm3m) symmetry. We are investigating the effects of sintering temperature, donor dopant level, and the resulting nano- and microstructure on the PTCR characteristics.
INOR 356
Application of metal chalcogenide aerogels to gas sensing
Qinghong Yao and Stephanie L. Brock, Department of Chemistry, Wayne State University, 5101 Cass Avenue, Detroit, MI 48202, Fax: 313-577-8822, qhyao@chem.wayne.edu
Aerogels are highly porous inorganic polymers consisting of a three-dimensional solid network interconnected by nanometer scale building blocks. These materials exhibit large porosity, low densities, and high internal surface areas, features that facilitate interaction with molecular analytes, making these suitable for sensing platforms. However, until recently, aerogels were limited to insulating or wide band-gap oxide materials, and therefore not suitable for optical sensing in the visible region except by introduction of secondary phase inclusions. Our group has developed systematic strategies for the synthesis of metal chalcogenide aerogels from nanoparticle assembly. These materials exhibit luminescence in the visible spectrum, and these properties are very sensitive to surface groups. In this presentation, the optical response of CdSe aerogels towards triethylamine will be described and compared to results on discrete nanoparticles and single crystals. The effects of aerogel surface treatment, such as heating and etching on subsequent gas sensing will also be studied.
INOR 357
Carbon nanotube contrast agents for MRI and CT
Valerie C. Moore1, Pratixa Joshi1, and Jodie L. Conyers2. (1) Department of Internal Medicine, University of Texas Health Science Center at Houston, 6770 Bertner Avenue THI C964A, Houston, TX 77030, Fax: 832-355-9368, Valerie.Moore@uth.tmc.edu, (2) The University of Texas Health Science Center at Houston
Nanoparticles hold great promise for medical imaging. Our lab is investigating the use of single walled carbon nanotubes as a container for CT and MR active atoms. Two filling methods have been utilized, sublimation and liquid intercalation, to encapsulate a variety of atoms - iodine, gadolinium, erbium, barium, iron, chromium, and manganese. With subsequent PEG functionalization, the filled nanotubes are biocompatible as determined through a variety of in vitro assays. This poster will describe theoretical calculations regarding contrast efficacy, comparisons of different filling and subsequent functionalization methods, and the current results from in vitro and in vivo biocompatibility studies.
INOR 360
Luminescent colloidal silica
Ronald B. Soriano, Essoyodou Kpatcha, Adam M. Jakob, and Thomas A. Schmedake, Department of Chemistry, University of North Carolina at Charlotte, 9201 University City Blvd., Charlotte, NC 28223-0001, rbsorian@email.uncc.edu
The calcination of aminopropylsilica colloidal spheres leads to monodisperse, luminescent silica spheres. The optical properties of the luminescent spheres (refractive index, absorbance, and photoluminescence) depend on the quantity of (aminopropyl)-triethoxysilane (APTES) in the precalcined material and on calcination conditions. This provides a “one-pot” process for growing gram-scale quantities of tailorable, brightly luminescent, monodisperse silica spheres under basic conditions without the subsequent addition of inorganic or organic
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10楼2007-03-25 14:17:56
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