The title compound 1,3,3,5,2'-pentamethylspirooxazine (I) is synthesized and identified by 1R, 1H NMR and elemental analysis. The time-resolved transient absorption spectra of I are investigated by nanosecond lase...The title compound 1,3,3,5,2'-pentamethylspirooxazine (I) is synthesized and identified by 1R, 1H NMR and elemental analysis. The time-resolved transient absorption spectra of I are investigated by nanosecond laser flash photolysis. The photolysis of I in solution excited by 248 nm laser pulse results in two different colored species. One of them is a short-lived species (CT intermediate), which has two absorption maxima at 440 and 640 nm in acetonitrile, and 450 and 640 nm in cyclohexane. The corresponding lifetimes are 12 and 0.8 us, respectively. The absorption spectra of CT intermediate are not influenced by solvent polarity. This fact indicates that the structure of CT is between the zwitterionic and quinoidal ones. The much longer lifetime of CT in acetonitrile than in cyclohexane is due to the electron donating effect of methyl in position 5 of indolino ring. The long-lived colored species (>>80 us) proves a planar photomerocyanine (PMC) structure, whose absorption spectra in acetonitrile and cyclohexane show the absorption maxima at 640 and 600nm, respectively.展开更多
1,3,3-tnmethyl-spiro[mdolino-2,3’-[2H]naphtho[2,1-b] [1,4]oxazine(SP1) and 1,3,3-trimen-thyl-9-methoxy-spiro[indolino2,3’-[2H]naphtho[2,1-b] [ 1,4]oxazine] (SP2) react with hydrochloric acid to form the complex SP H...1,3,3-tnmethyl-spiro[mdolino-2,3’-[2H]naphtho[2,1-b] [1,4]oxazine(SP1) and 1,3,3-trimen-thyl-9-methoxy-spiro[indolino2,3’-[2H]naphtho[2,1-b] [ 1,4]oxazine] (SP2) react with hydrochloric acid to form the complex SP HCl in isopropanol solution at room temperature The absorption maxima of these complexes are 440 and 463 nm respectively In acidic media,the opening form of spirooxazine can react with hydrochloric acid to form the complex PMC HCl via zwittenon form The absorption spectra of PMC HCl are obviously hypsochromic shifted compared with the reported spectra of the complex in neutral media In the mean time,the thermal stability of the complex is increased.The first order kinetics for the decoloration process of the acidichromic product of the opening form was determined and the lifetimes of these products are 180 and 200 s,respectively.展开更多
The photochromic properties and reaction mechanism of title compounds have been examined with steady method on compounds 3-phenyl-3-[3-methylbenzothiophene-2-yl]-3H-naphtho[2,1-b]pyran (1) and 3-phenyl-3-[benzofuran-2...The photochromic properties and reaction mechanism of title compounds have been examined with steady method on compounds 3-phenyl-3-[3-methylbenzothiophene-2-yl]-3H-naphtho[2,1-b]pyran (1) and 3-phenyl-3-[benzofuran-2-yl]-3H-naphtho[2,1-b]pyran (2) and nanosecond laser flash photolysis techniques on compound 3-phenyl-3-[1,2-dimethylindol-3-yl]-3H-naphtho[2,1-b]pyran (3). The influence of oxygen on transient spectra and decay kinetics of compound 3 has been investigated. Both excited singlet state and triplet state are involved in the photochromic mechanism of compound 3. The influence of molecular structure on photochromic behavior has been studied also. Decay kinetics indicated that the lifetime of colored forms of 1 and 2 were several orders of magnitude longer than that of 3.展开更多
A new spirooxazine,1,3,3,2′-tetramethy1-9′-methoxyspiro [-2H-indole-2,3′-[-3H] naphth[2,1-b] [-1,4′] oxazine] (Ⅰ) was synthesized.Its photochromic process was studied using nanosecond time-resolved absorption spe...A new spirooxazine,1,3,3,2′-tetramethy1-9′-methoxyspiro [-2H-indole-2,3′-[-3H] naphth[2,1-b] [-1,4′] oxazine] (Ⅰ) was synthesized.Its photochromic process was studied using nanosecond time-resolved absorption spectroscopy techniques.After irradiation of I with 248 nm laser pulse,a short-lived col-ored species with two absorption bands was observed.In cyclohexane the two bands appear at 470 nm and640 nm,while in acetonitrile at 460 nm and 670 nm.The kinetics for the decay of the colored species is first-order,and its lifetimes are 0.5 μs in cyclohexane and 1.3 μs in acetonitrile.From these results,this short-lived species is assumed to be an intramolecular charge-transfer (CT) intermediate instead of photomero-cyanines (PMC).No absorption band of PMC has been found.The phenomenoncan be interpreted by theproposed potential energy curve.展开更多
基金Project supported by the National Natural Science Foundation of China and Chinese Academy of Sciences.
文摘The title compound 1,3,3,5,2'-pentamethylspirooxazine (I) is synthesized and identified by 1R, 1H NMR and elemental analysis. The time-resolved transient absorption spectra of I are investigated by nanosecond laser flash photolysis. The photolysis of I in solution excited by 248 nm laser pulse results in two different colored species. One of them is a short-lived species (CT intermediate), which has two absorption maxima at 440 and 640 nm in acetonitrile, and 450 and 640 nm in cyclohexane. The corresponding lifetimes are 12 and 0.8 us, respectively. The absorption spectra of CT intermediate are not influenced by solvent polarity. This fact indicates that the structure of CT is between the zwitterionic and quinoidal ones. The much longer lifetime of CT in acetonitrile than in cyclohexane is due to the electron donating effect of methyl in position 5 of indolino ring. The long-lived colored species (>>80 us) proves a planar photomerocyanine (PMC) structure, whose absorption spectra in acetonitrile and cyclohexane show the absorption maxima at 640 and 600nm, respectively.
基金Project supported by the National Natural Science Foundation of Chinathe Chinese Academy of Sciences
文摘1,3,3-tnmethyl-spiro[mdolino-2,3’-[2H]naphtho[2,1-b] [1,4]oxazine(SP1) and 1,3,3-trimen-thyl-9-methoxy-spiro[indolino2,3’-[2H]naphtho[2,1-b] [ 1,4]oxazine] (SP2) react with hydrochloric acid to form the complex SP HCl in isopropanol solution at room temperature The absorption maxima of these complexes are 440 and 463 nm respectively In acidic media,the opening form of spirooxazine can react with hydrochloric acid to form the complex PMC HCl via zwittenon form The absorption spectra of PMC HCl are obviously hypsochromic shifted compared with the reported spectra of the complex in neutral media In the mean time,the thermal stability of the complex is increased.The first order kinetics for the decoloration process of the acidichromic product of the opening form was determined and the lifetimes of these products are 180 and 200 s,respectively.
基金Acknowledgements This work was supported by the National Research Fund for Fundamental Key Projects of China (Grant No. G1999033005) and National Natural Science Foundation of China (Grant No. 29832030).
文摘The photochromic properties and reaction mechanism of title compounds have been examined with steady method on compounds 3-phenyl-3-[3-methylbenzothiophene-2-yl]-3H-naphtho[2,1-b]pyran (1) and 3-phenyl-3-[benzofuran-2-yl]-3H-naphtho[2,1-b]pyran (2) and nanosecond laser flash photolysis techniques on compound 3-phenyl-3-[1,2-dimethylindol-3-yl]-3H-naphtho[2,1-b]pyran (3). The influence of oxygen on transient spectra and decay kinetics of compound 3 has been investigated. Both excited singlet state and triplet state are involved in the photochromic mechanism of compound 3. The influence of molecular structure on photochromic behavior has been studied also. Decay kinetics indicated that the lifetime of colored forms of 1 and 2 were several orders of magnitude longer than that of 3.
基金the National Natural Science Foundation of Chinapartially supported by the Laboratory of Radiation Chemistry,Shanghai Institute of Nuclear Research.
文摘A new spirooxazine,1,3,3,2′-tetramethy1-9′-methoxyspiro [-2H-indole-2,3′-[-3H] naphth[2,1-b] [-1,4′] oxazine] (Ⅰ) was synthesized.Its photochromic process was studied using nanosecond time-resolved absorption spectroscopy techniques.After irradiation of I with 248 nm laser pulse,a short-lived col-ored species with two absorption bands was observed.In cyclohexane the two bands appear at 470 nm and640 nm,while in acetonitrile at 460 nm and 670 nm.The kinetics for the decay of the colored species is first-order,and its lifetimes are 0.5 μs in cyclohexane and 1.3 μs in acetonitrile.From these results,this short-lived species is assumed to be an intramolecular charge-transfer (CT) intermediate instead of photomero-cyanines (PMC).No absorption band of PMC has been found.The phenomenoncan be interpreted by theproposed potential energy curve.
