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摘要
UV, FL and IR spectra of isomer A (in DCM) and isomer B (in DMAc) of N-confused 5,10,15,20-terra(o-methoxyphenypporphyrin (o-isomer, 1), N-confused 5,10,15,20-tetra(m-methoxyphenyl)porphyrin (m-isomer, 2) and N-confused 5,10,15,20-tetra(p-methoxyphenyl)porphyrin (p-isomer, 3) were investigated. Significant red shifts are observed from o-isomer (1) to p-isomer (3) in UV-vis absorption and fluorescence spectra. The fluorescence lifetime (tau(fl)) of isomer A and isomer B of the samples (1, 2 and 3) are ca. 1.39 similar to 1.79 ns and 1.68 similar to 2.09 ns, respectively. In addition, the order of fluorescence quantum yield for isomer A is 1 >2 > 3, but for isomer B it is 1 < 3 <2. The isomer B of 2 shows the strongest emission in accord with the strongest absorption. The isomer A of 1 shows the strongest emission with the fluorescence quantum yield of 0.045, which is nearly double that of 3. The introduction of the methoxy group at the ortho position increases steric hindrance, the molecular rigidity and the flow of pi-electron, thereby favourable to the fluorescence enhancement. The IR absorption peaks of 1, 2 and 3 were investigated and empirically assigned. The effects of the position of the substituents on the absorption frequency were also discussed. The absorption frequency of the C=C phenyl stretching in plane changed obviously by conjugative effect and steric effect when the methoxy group was at the ortho or meta position in comparison with para position.
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单位宜春学院; 中山大学
