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Fig. 15 shows the relationship between the peak positions of the two absorption bands,l1 andl2, of the compounds and the water fraction. It can be seen that thel1 values had almost no change during water addition. However, l2 exhibited a red-shifted abrupt change corresponding to the abrupt change in PL spectra. This indicates that the aggregation has a pronounced effect onp–p* transitions. Thel2of1B-TPA, 2B-TPAand3B-TPAin the 90 : 10 (v/v) water–DMF mixture in relation to those in DMF solution red-shifted by 7, 6 and 7 nm, respectively |