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
Dual fluorescence at ca . 447 nm and 545 nm was observed from the aqueous 1 naphthylamine (NA) solutions at pH higher than 13 6. Similar dual fluorescence was also found with sodium 1 naphthylaminoacetate(NAA) , but n...Dual fluorescence at ca . 447 nm and 545 nm was observed from the aqueous 1 naphthylamine (NA) solutions at pH higher than 13 6. Similar dual fluorescence was also found with sodium 1 naphthylaminoacetate(NAA) , but not with N, N disubstituted 1 aminonaphthalenes such as sodium 1 naphthylaminodiacetate(NADA) and 1 dimethylaminonaphthalene(DMAN). No change in absorption spectra of NA and NAA was observed in this pH region.It was proposed that the dual fluorescence observed with NA and NAA was due to the excited state dissociation of the primary and secondary amines at high pH. From the dual fluorescence intensity ratio pH titration curve, the p K * as of NA and NAA were estimated to be between 14 and 15 which are much lower than the ground state p K a. The novel approatch is such a simple, convenient and frequent analysis technique that it can be widely used in detecting the substitutional derivatives of aminonaphthalene.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
In this paper we described the construction of a novel dual fluorescent film sensor using fluorescent dye Acridine Orange(AO) as an internal standard and CdTe as a fluorescent probe.Poly-sodium-4-styrenesulfonate(PSS)...In this paper we described the construction of a novel dual fluorescent film sensor using fluorescent dye Acridine Orange(AO) as an internal standard and CdTe as a fluorescent probe.Poly-sodium-4-styrenesulfonate(PSS) and Chitosan(CS) were respectively assembled between AO and CdTe.The constructed self-assembly multilayers,Quartz/APES/PSS/AO/PSS/CS/CdTe,emits dual fluorescence at 600 and 530 nm,respectively.AO is shielded effectively by the assembled PSS and CS and thus its fluorescent intensity I1 doesn′t change with the variation of the analyte concentration,thereby acting as an internal standard to provide reference signal.The ratio of dual fluorescence intensities of the thus constructed film sensor is not affected by the variations of the external environment factors such as excitation intensity and sensor position in the cell holder.A good linear relationship was found between dual fluorescence intensity ratio and DNA concentration over 0-250 ng/L.Quartz/APES/PSS/AO/PSS/CS/CdTe film is capable of an extremely highly sensitive detection for DNA with a detection limit of 6.6 ng/L.The analysis based on dual fluorescent self-assembled multilayers bearing a fluorescent internal standard would greatly improve the detection accuracy.展开更多
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Dual fluorescence at ca . 447 nm and 545 nm was observed from the aqueous 1 naphthylamine (NA) solutions at pH higher than 13 6. Similar dual fluorescence was also found with sodium 1 naphthylaminoacetate(NAA) , but not with N, N disubstituted 1 aminonaphthalenes such as sodium 1 naphthylaminodiacetate(NADA) and 1 dimethylaminonaphthalene(DMAN). No change in absorption spectra of NA and NAA was observed in this pH region.It was proposed that the dual fluorescence observed with NA and NAA was due to the excited state dissociation of the primary and secondary amines at high pH. From the dual fluorescence intensity ratio pH titration curve, the p K * as of NA and NAA were estimated to be between 14 and 15 which are much lower than the ground state p K a. The novel approatch is such a simple, convenient and frequent analysis technique that it can be widely used in detecting the substitutional derivatives of aminonaphthalene.
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.
文摘In this paper we described the construction of a novel dual fluorescent film sensor using fluorescent dye Acridine Orange(AO) as an internal standard and CdTe as a fluorescent probe.Poly-sodium-4-styrenesulfonate(PSS) and Chitosan(CS) were respectively assembled between AO and CdTe.The constructed self-assembly multilayers,Quartz/APES/PSS/AO/PSS/CS/CdTe,emits dual fluorescence at 600 and 530 nm,respectively.AO is shielded effectively by the assembled PSS and CS and thus its fluorescent intensity I1 doesn′t change with the variation of the analyte concentration,thereby acting as an internal standard to provide reference signal.The ratio of dual fluorescence intensities of the thus constructed film sensor is not affected by the variations of the external environment factors such as excitation intensity and sensor position in the cell holder.A good linear relationship was found between dual fluorescence intensity ratio and DNA concentration over 0-250 ng/L.Quartz/APES/PSS/AO/PSS/CS/CdTe film is capable of an extremely highly sensitive detection for DNA with a detection limit of 6.6 ng/L.The analysis based on dual fluorescent self-assembled multilayers bearing a fluorescent internal standard would greatly improve the detection accuracy.
