The effects of aliphatic alcohol on the twisted intramolecular charge transfer (TICT) of p-N, N-dimethylaminobenzoic acid (DMABOA) in cetyltrimethylammonium bromide (CTMAB) micelle were examined by the TICT-typical du...The effects of aliphatic alcohol on the twisted intramolecular charge transfer (TICT) of p-N, N-dimethylaminobenzoic acid (DMABOA) in cetyltrimethylammonium bromide (CTMAB) micelle were examined by the TICT-typical dual fluorescence. The introduction of aliphatic alcohol (CnH2n+10H, n=1, 2, 3, 4, 6, 8, 14, 16, 18) to CTMAB Ancellar solution does not change the positions of the dual fluorescence bands of DMABOA,but results in a decrease in the fluorescence intensities with that of the longer-wavelength TICT band (a band) more repidly, the latter is demonstrated by a linear decrease of the fluorescence intensity ratio of a band to b band (shorter-wavelength normal band) with the concentration of the alcohol added. The logarithm of the absolute value of the linear slope is positively linearly correlated with the carbon number(n) of the alkyl chain in the alcohol molecule when the chain is relatively short (<8), whereas a negatively linear correlation is observed when the chain length (n=14, 16, 18) is comparable with that of CTMAB. In pure aqueous solution, the intensities and positions of the dual fluorescence bands are not varied by the same concentration of added alcohol. The decrease of the charge density of micellar surface due to the solubilization of alcohol in micelle is considered to be the cause of the alcohol effects on the TICT in charged micelle.展开更多
Intramolecular charge transfer(ICT) dual fluorescence of p-dimethylamino-benzoylhydrazine(DMABH) in acetonitrile was found to show a highly selective response to HSO - 4 over several other anions. The intensity ratio ...Intramolecular charge transfer(ICT) dual fluorescence of p-dimethylamino-benzoylhydrazine(DMABH) in acetonitrile was found to show a highly selective response to HSO - 4 over several other anions. The intensity ratio of the CT to LE emission and the total fluorescence intensity of DMABH decreased with increasing bisulfate concentration. While the dual fluorescence response was very similar to that of DMABA at a low HSO - 4 concentration, the CT intensity decreased drastically and the LE intensity remained almost constant, however, the difference was observed at a high HSO - 4 concentration, in which both the CT and LE intensities of DMABH decreased. A different recognition mechanism from that of DMABA was suggested for DMABH in which hydrogen bonding and protonization were the recognition interactions at low and high HSO - 4 concentrations, respectively.展开更多
Several cross-conjugate enone compounds with different electron withdrawing substituents have been synthesized. The spectroscopy and photophysical behavior of these compounds in different conditions were studied. Resu...Several cross-conjugate enone compounds with different electron withdrawing substituents have been synthesized. The spectroscopy and photophysical behavior of these compounds in different conditions were studied. Results show that TICT formation which depends strongly on the solvent polarity and electron withdrawing ability of substituents was observed for compounds with different electron withdrawing groups.For compound (Ⅳ) which possesses strong electron withdrawing ability, the TICT formation can be ob served in weak polar solvent, such as in toluene. But, for compounds (Ⅱ) and (Ⅲ), it can be observed in THF and ethyl ether, respectively. It can also be observed that the fluorescence quanum yields of these compounds are varied with the solvent polarity, and a maximum appears in this variation. Results obtaind have been discussed preliminary.展开更多
The fluorescence spectra in cyclohexane of a series of benzanilides(BAs) with different \%para\% substituents at the anilino moiety revealed that BAs emitted dual fluorescence, with one normal weak emission at ca . 33...The fluorescence spectra in cyclohexane of a series of benzanilides(BAs) with different \%para\% substituents at the anilino moiety revealed that BAs emitted dual fluorescence, with one normal weak emission at ca . 330 nm and an abnormally long wavelength emission ranging from 460 to 550 nm. The long wavelength emission was found strongly dependent of the electron donating capacity of the substituent at the anilino moiety and a stronger electron donating substituent led to a red shift in the emission. The energies of the long wavelength emission of the BAs were correlated to the oxidation potentials of the donors, E \-\{D/D +\}, and a nice linear correlation was found with a slope of +0 66, which clearly pointed to the charge transfer character of the emissive state for the long wavelength emission and the high decoupling extent of the charges in the CT state. This is the first report that shows the direct evidence for the CT nature. The results might be of significance in understanding the photophysics of peptide and protein and in designing novel fluorescent chemosensors.展开更多
文摘The effects of aliphatic alcohol on the twisted intramolecular charge transfer (TICT) of p-N, N-dimethylaminobenzoic acid (DMABOA) in cetyltrimethylammonium bromide (CTMAB) micelle were examined by the TICT-typical dual fluorescence. The introduction of aliphatic alcohol (CnH2n+10H, n=1, 2, 3, 4, 6, 8, 14, 16, 18) to CTMAB Ancellar solution does not change the positions of the dual fluorescence bands of DMABOA,but results in a decrease in the fluorescence intensities with that of the longer-wavelength TICT band (a band) more repidly, the latter is demonstrated by a linear decrease of the fluorescence intensity ratio of a band to b band (shorter-wavelength normal band) with the concentration of the alcohol added. The logarithm of the absolute value of the linear slope is positively linearly correlated with the carbon number(n) of the alkyl chain in the alcohol molecule when the chain is relatively short (<8), whereas a negatively linear correlation is observed when the chain length (n=14, 16, 18) is comparable with that of CTMAB. In pure aqueous solution, the intensities and positions of the dual fluorescence bands are not varied by the same concentration of added alcohol. The decrease of the charge density of micellar surface due to the solubilization of alcohol in micelle is considered to be the cause of the alcohol effects on the TICT in charged micelle.
文摘Intramolecular charge transfer(ICT) dual fluorescence of p-dimethylamino-benzoylhydrazine(DMABH) in acetonitrile was found to show a highly selective response to HSO - 4 over several other anions. The intensity ratio of the CT to LE emission and the total fluorescence intensity of DMABH decreased with increasing bisulfate concentration. While the dual fluorescence response was very similar to that of DMABA at a low HSO - 4 concentration, the CT intensity decreased drastically and the LE intensity remained almost constant, however, the difference was observed at a high HSO - 4 concentration, in which both the CT and LE intensities of DMABH decreased. A different recognition mechanism from that of DMABA was suggested for DMABH in which hydrogen bonding and protonization were the recognition interactions at low and high HSO - 4 concentrations, respectively.
文摘Several cross-conjugate enone compounds with different electron withdrawing substituents have been synthesized. The spectroscopy and photophysical behavior of these compounds in different conditions were studied. Results show that TICT formation which depends strongly on the solvent polarity and electron withdrawing ability of substituents was observed for compounds with different electron withdrawing groups.For compound (Ⅳ) which possesses strong electron withdrawing ability, the TICT formation can be ob served in weak polar solvent, such as in toluene. But, for compounds (Ⅱ) and (Ⅲ), it can be observed in THF and ethyl ether, respectively. It can also be observed that the fluorescence quanum yields of these compounds are varied with the solvent polarity, and a maximum appears in this variation. Results obtaind have been discussed preliminary.
文摘The fluorescence spectra in cyclohexane of a series of benzanilides(BAs) with different \%para\% substituents at the anilino moiety revealed that BAs emitted dual fluorescence, with one normal weak emission at ca . 330 nm and an abnormally long wavelength emission ranging from 460 to 550 nm. The long wavelength emission was found strongly dependent of the electron donating capacity of the substituent at the anilino moiety and a stronger electron donating substituent led to a red shift in the emission. The energies of the long wavelength emission of the BAs were correlated to the oxidation potentials of the donors, E \-\{D/D +\}, and a nice linear correlation was found with a slope of +0 66, which clearly pointed to the charge transfer character of the emissive state for the long wavelength emission and the high decoupling extent of the charges in the CT state. This is the first report that shows the direct evidence for the CT nature. The results might be of significance in understanding the photophysics of peptide and protein and in designing novel fluorescent chemosensors.
