We have presented the synthesis and characterization of three new bromo substituted stilbene derivatives, p-3,4,5-trimethoxy-p′- 2,3,4,5,6-pentabromostilbene （C1）, p-N,N-dimethylamino-p′-2,3,4,5,6-pentabromostilbe...We have presented the synthesis and characterization of three new bromo substituted stilbene derivatives, p-3,4,5-trimethoxy-p′- 2,3,4,5,6-pentabromostilbene （C1）, p-N,N-dimethylamino-p′-2,3,4,5,6-pentabromostilbene （C2） and p-N,N-diphenylamino-p′- 2,3,4,5,6-pentabromostilbene （C3） in this letter. The UV/vis absorption and photoluminescence were investigated in various solvents. The maximal absorption wavelength of C1 exhibited blue-shift to those of C2 and C3 in different solvents. No florescence emission could be detected for these compounds at room temperature. Singlet oxygen could be efficiently produced with these sensitizers under near-ultraviolet and visible light irradiation.展开更多
The singlet excited state lifetime of the chlorophyll a (Chl a) in cytochrome b6f (Cyt b6f) complex was reported to be shorter than that of free Chl a in methanol, but the value was different for Cyt b6f com-plexes fr...The singlet excited state lifetime of the chlorophyll a (Chl a) in cytochrome b6f (Cyt b6f) complex was reported to be shorter than that of free Chl a in methanol, but the value was different for Cyt b6f com-plexes from different sources (~200 and ~600 ps are the two measured results). The present study demonstrated that the singlet excited state lifetime is associated with the detergents n-dodecyl-β-D- maltoside (DDM) and n-octyl-β-D-glucopyranoside (β-OG), but has nothing to do with the different sources of Cyt b6f complexes. Compared with the Cyt b6f dissolved in β-OG, the Cyt b6f in DDM had a lower fluorescence yield, a lower photodegradation rate of Chl a, and a shorter lifetime of Chl a excited state. In short, the singlet excited state lifetime, ~200 ps, of the Chl a in Cyt b6f complex in DDM is closer to the true in vivo.展开更多
The solvent viscosity dependence of the photophysical and photochemical properties of tetra(tert-butylphenoxy)phthalocyaninato zinc(II) (ZnTBPPc) is presented. The fluorescence quantum yields (ΦF) and Stern-Volmer′s...The solvent viscosity dependence of the photophysical and photochemical properties of tetra(tert-butylphenoxy)phthalocyaninato zinc(II) (ZnTBPPc) is presented. The fluorescence quantum yields (ΦF) and Stern-Volmer′s constant (KSV) for ZnTBPPc fluorescence quenching by benzoquinone in all the solutions followed a semi-empirical law that depends only on the solvent viscosity. ΦF values vary between 0.08 in tetrahydrofuran (THF) and 0.14 in dimethylsulphoxide (DMSO). Triplet quantum yields (ΦT) and lifetimes (τT) also exhibit clear solvent viscosity dependence with the values being higher in the most viscous solvents. The interaction of the ZnTBPPc triplet state with oxygen was found to be diffusion- controlled, but higher rate constants were observed in low-viscosity solvents like THF and toluene. Absolute values of singlet oxygen quantum yields (ΦΔ) were determined, and the values are comparable in all the solvents, which is attributed to the proximity of the ZnTBPPc triplet energies in different solvents.展开更多
In this paper, the photophysical and photosensitive properties of Elsinochrome A (EA), another member of perylenequinone photosensitizers derived via artificially biological synthesis, were stud- ied by taking hypocre...In this paper, the photophysical and photosensitive properties of Elsinochrome A (EA), another member of perylenequinone photosensitizers derived via artificially biological synthesis, were stud- ied by taking hypocrellin A (HA) and hypocrellin B (HB) as the references. It was found that the quantum yield of singlet oxygen produced via the photosensi- tization of EA was 0.98 with HB (0.84) as a reference. Furthermore, the semiquinone anion could be pro- duced via photosensitization of EA in oxygen-free solution. Besides, taking advantage of nanosecond time-resolved spectral technique, the transient triplet absorption spectra and the lifetime of EA in cyclo- hexane were determined by the use of the ground- state depletion method.展开更多
基金support from National Natural Science Foundation of China(Nos. 20776165,20702065,20872184)Key Foundation of Chongqing Science and Technology Commission"(No.CSTC 2008BA4020)+1 种基金"A Foundation for the Author of National Excellent Doctoral Dissertation of PR China(200735)"for financial supportsponsored by the Scientific Research Foundation for the Returned Overseas Chinese Scholars,State Education Ministry as well(Nos.20071108-1, 20071108-5).
文摘We have presented the synthesis and characterization of three new bromo substituted stilbene derivatives, p-3,4,5-trimethoxy-p′- 2,3,4,5,6-pentabromostilbene （C1）, p-N,N-dimethylamino-p′-2,3,4,5,6-pentabromostilbene （C2） and p-N,N-diphenylamino-p′- 2,3,4,5,6-pentabromostilbene （C3） in this letter. The UV/vis absorption and photoluminescence were investigated in various solvents. The maximal absorption wavelength of C1 exhibited blue-shift to those of C2 and C3 in different solvents. No florescence emission could be detected for these compounds at room temperature. Singlet oxygen could be efficiently produced with these sensitizers under near-ultraviolet and visible light irradiation.
基金Supported by the National Natural Science Foundation of China (Grant Nos.39890390 and 20673144)
文摘The singlet excited state lifetime of the chlorophyll a (Chl a) in cytochrome b6f (Cyt b6f) complex was reported to be shorter than that of free Chl a in methanol, but the value was different for Cyt b6f com-plexes from different sources (~200 and ~600 ps are the two measured results). The present study demonstrated that the singlet excited state lifetime is associated with the detergents n-dodecyl-β-D- maltoside (DDM) and n-octyl-β-D-glucopyranoside (β-OG), but has nothing to do with the different sources of Cyt b6f complexes. Compared with the Cyt b6f dissolved in β-OG, the Cyt b6f in DDM had a lower fluorescence yield, a lower photodegradation rate of Chl a, and a shorter lifetime of Chl a excited state. In short, the singlet excited state lifetime, ~200 ps, of the Chl a in Cyt b6f complex in DDM is closer to the true in vivo.
基金supported by the Department of Science and Technology(DST) and National Research Foundation(NRF)of South Africa throughDST/NRF South African Research Chairs Initiative for Professor of Medicinal Chemistry and Nanotechnology and Rhodes University
文摘The solvent viscosity dependence of the photophysical and photochemical properties of tetra(tert-butylphenoxy)phthalocyaninato zinc(II) (ZnTBPPc) is presented. The fluorescence quantum yields (ΦF) and Stern-Volmer′s constant (KSV) for ZnTBPPc fluorescence quenching by benzoquinone in all the solutions followed a semi-empirical law that depends only on the solvent viscosity. ΦF values vary between 0.08 in tetrahydrofuran (THF) and 0.14 in dimethylsulphoxide (DMSO). Triplet quantum yields (ΦT) and lifetimes (τT) also exhibit clear solvent viscosity dependence with the values being higher in the most viscous solvents. The interaction of the ZnTBPPc triplet state with oxygen was found to be diffusion- controlled, but higher rate constants were observed in low-viscosity solvents like THF and toluene. Absolute values of singlet oxygen quantum yields (ΦΔ) were determined, and the values are comparable in all the solvents, which is attributed to the proximity of the ZnTBPPc triplet energies in different solvents.
基金This research was supported by the National Natural Science Foundation of China （Grant No. 20262007 ） the Natural Science Foundation of Yunnan Province （Grant No. 2000C0106M）.
文摘In this paper, the photophysical and photosensitive properties of Elsinochrome A (EA), another member of perylenequinone photosensitizers derived via artificially biological synthesis, were stud- ied by taking hypocrellin A (HA) and hypocrellin B (HB) as the references. It was found that the quantum yield of singlet oxygen produced via the photosensi- tization of EA was 0.98 with HB (0.84) as a reference. Furthermore, the semiquinone anion could be pro- duced via photosensitization of EA in oxygen-free solution. Besides, taking advantage of nanosecond time-resolved spectral technique, the transient triplet absorption spectra and the lifetime of EA in cyclo- hexane were determined by the use of the ground- state depletion method.
