24小时热门版块排行榜

返回列表

当前只显示满足指定条件的回帖，点击这里查看本话题的所有回帖

pepahuang

铜虫 (小有名气)

应助: 0 (幼儿园)
金币: 284
帖子: 123
在线: 1.1小时
虫号: 454475
注册: 2007-11-09

[交流] 急求助论文修改已有10人参与

我在Journal of Chemical Crystallography上发表的一篇论文，急求贵人帮忙修改，审稿意见如下：
One problem with this manuscript is that the title compound is refered to as a mixtre of 2-amino-4,6-dimethylpyrimide and 2-hydroxybenzoic acid, whereas it is an ionic compound, which should be described as 2-amino-4,6-dimethylpyrimidium 2-hydroxybenzoate (or 2-amino-4,6-dimethylpyrimidium salicylate).

The beta angle should be included in the abstract.

The hydrogen bonding links two pyrimidinium cations and two hydroxybenzoate anions into a discrete unit, not a 1D polymer.  These units, in turn, are linked together by C-H..O interactions.

The structure appears to be 2D not 3D (the CCDC software package Mercury was used, with all contacts expanded and a diagram orientation looking down the b-axis.  There is also a H9...H9 (2-x, -y, 2-z) "contact" which could falsly suggest 3D, if included in the contact expansion.

The symmetry operators given in the manuscript are incorrect and do not refer to the coordinates in the CIF file. As the coordinates are:

O2 0.8146 0.00861 0.61580
N1 0.6171 0.93998 0.37977

Only (x,1+y,z), not (-x, -y, 1-z), brings these atoms close together.

Figure 2 should only show one of the descrete dimeric units. I note that the atomic coordinates are such that the pyrimidinium cation and the 2-hydroxybenzoate anion are not in the same H-bonded unit.  It might make it easier (diagrams, discussion) if the the coordinates of the pyrimidinium cation were changed (by x, y-1, z) to put it into the same H-bonded unit as the 2-hydroxybenzoate anion.

Figure 3 is not necessary and should be removed.  Figure 4 should be labelled with the axes. Figure 5, the a-axis label should be included.

Regarding the statement "as well as a C5-H5C... i ((i) 1+x, y, z) interaction; the distance between C5 and centroid of benzene ring is 3.586 Å." This aromatic ring to appears to be the benzoate ring, the symmetry operator seems to be 1-x, 1-y, 1-z.  What is the distance between the centroid of the ring and H5C?  How strong is the interaction compared to other examples?  Reference?

Overall, the results and discussion section lacks clarity; the suggested rewrite is something like:

"The molecular structure of the title compound is shown in Fig. 1.  The selected bond lengths and angles are shown in table 2, while the torsion and dihedral angles are shown in table 3.

The 2-amino-4,6-dimethylpyrimidine has been protonated due to the migration of the proton from the carboxyl group of the 2-hydroxybenzoate, which is accompanied by an increase in the internal angle around N1 (C1-N1-C4 121.17°) compared to 116.2° in neutral pyrimidine [20]. All other parameters are typical of aromatic heterocycles.

In the hydroxybenzoate anion both C-O distances are similar [1.265 Å and 1.253 Å], while the O-C-O angle is 123.4 °. As usual, an intermolecular hydrogen bond is observed between the hydroxyl group and a carboxyl oxygen atom [O1-H1...O3; O1...O3  2.511 Å] with graph-set R1 1(6); the torsion angles are O1-C7-C8-C13 -1.5° and C7-C8-C13-O3 3.7°. The dihedral angle between pyrimidinium ring and hydroxybenzoate is 3.79°.

Both nitrogens of the pyrimidinium cation are involved in H-bonded interactions (Table 4) with the carboxylate oxygen atoms of an adjacent hydroxybenzoate anion (N1-H2 ... O2ii and N3-H3B...O3ii (ii: x, 1+y, z) resulting in a ion pair containing a R2 2(8) ring. Two such ion pairs are linked via two hydrogen bonds between neighbouring pyrimidinium cations (N3-H3A...N2iii iii: 1-x, 2-y, -z), leading to the formation of a dimer (Figure 2), containing an eight-membered cyclic ring with gragh-set R21(8).  These discrete dimers link together into a 2D zigzag sheets (Figure 4), parallel to the (1 0 1) direction, by C5-H5A...O1iv (iv: 1/2+x, 1/2-y, 1/2+z) interactions. The packing arrangement of the title compound, along the c-axis, is shown in Fig. 5."

Note: Should the atomic coordinates of the pyrimidinium cation be changed, as suggested above, the symmetry operators will also need to be changed

The abstract should also be changed, to be consistent with the Results and Discussion section
不胜感谢！！！

回复此楼