Thermal back-isomerization of spirocyclic naphtho-oxazine and phenanthro-oxazine derivatives in alcohols, nitriles, and poly(alkyl methacrylates)
The thermal back-isomerization of spiro[indole-naphtho-oxazine] 1 and spiro[indole-phenanthro-oxazine] 2 was studied in a series of primary alcohols, nitriles, and poly(methylmethacrylate), poly(ethylmethacrylate), and poly(isobutyl methacrylate) films by laser-flash photolysis in the temperature ra...
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2001
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paper:paper_0018019X_v84_n9_p2751_Volker2025-07-30T17:21:44Z Thermal back-isomerization of spirocyclic naphtho-oxazine and phenanthro-oxazine derivatives in alcohols, nitriles, and poly(alkyl methacrylates) Activation energy Derivatives Glass transition Organic compounds Photolysis Polarization Polymers Viscosity Thermal back-isomerization Isomerization alcohol naphthol derivative nitrile oxazine derivative phenanthroline derivative poly(ethyl methacrylate) poly(isobutyl methacrylate) poly(methyl methacrylate) polymethacrylic acid solvent spiro compound spiro(indolenaphthooxazine) spiro(indolephenanthrooxazine) unclassified drug article isomerism phase transition photolysis polymerization temperature dependence thermal analysis viscosity The thermal back-isomerization of spiro[indole-naphtho-oxazine] 1 and spiro[indole-phenanthro-oxazine] 2 was studied in a series of primary alcohols, nitriles, and poly(methylmethacrylate), poly(ethylmethacrylate), and poly(isobutyl methacrylate) films by laser-flash photolysis in the temperature range of 0-70°. The decay is monoexponential in fluid solution, but deviates strongly from this behavior in polymeric environments even above the glass transition temperature of the polymers (Tg). In liquids, a very small solvent effect is observed on the isomerization rate constants (kiso) for 1, which is attributed mostly to the solvent viscosity η. The values of kiso for 2 show influence of solvent viscosity and polarity, which were studied by application of a semiempirical relationship that accounts for non-Markovian processes. The decay kinetics in polymers was described by a Gaussian distribution of the activation energy and by a kinetic model that takes into account the simultaneous relaxation of the probe and the environment. For 1 and 2, the rate constant at the center of the Gaussian distribution is very similar to the first-order rate constant in nonpolar solvents. The Gaussian width of the distribution (σ) decreases with temperature and is very similar in all polymers under Tg, and, above Tg, σ decreases more abruptly. We make comparisons of the parameters derived from analysis of both 1 and 2 in polymers, as well as of their behaviors in solution and in polymers. 2001 https://bibliotecadigital.exactas.uba.ar/collection/paper/document/paper_0018019X_v84_n9_p2751_Volker http://hdl.handle.net/20.500.12110/paper_0018019X_v84_n9_p2751_Volker |
| institution |
Universidad de Buenos Aires |
| institution_str |
I-28 |
| repository_str |
R-134 |
| collection |
Biblioteca Digital - Facultad de Ciencias Exactas y Naturales (UBA) |
| topic |
Activation energy Derivatives Glass transition Organic compounds Photolysis Polarization Polymers Viscosity Thermal back-isomerization Isomerization alcohol naphthol derivative nitrile oxazine derivative phenanthroline derivative poly(ethyl methacrylate) poly(isobutyl methacrylate) poly(methyl methacrylate) polymethacrylic acid solvent spiro compound spiro(indolenaphthooxazine) spiro(indolephenanthrooxazine) unclassified drug article isomerism phase transition photolysis polymerization temperature dependence thermal analysis viscosity |
| spellingShingle |
Activation energy Derivatives Glass transition Organic compounds Photolysis Polarization Polymers Viscosity Thermal back-isomerization Isomerization alcohol naphthol derivative nitrile oxazine derivative phenanthroline derivative poly(ethyl methacrylate) poly(isobutyl methacrylate) poly(methyl methacrylate) polymethacrylic acid solvent spiro compound spiro(indolenaphthooxazine) spiro(indolephenanthrooxazine) unclassified drug article isomerism phase transition photolysis polymerization temperature dependence thermal analysis viscosity Thermal back-isomerization of spirocyclic naphtho-oxazine and phenanthro-oxazine derivatives in alcohols, nitriles, and poly(alkyl methacrylates) |
| topic_facet |
Activation energy Derivatives Glass transition Organic compounds Photolysis Polarization Polymers Viscosity Thermal back-isomerization Isomerization alcohol naphthol derivative nitrile oxazine derivative phenanthroline derivative poly(ethyl methacrylate) poly(isobutyl methacrylate) poly(methyl methacrylate) polymethacrylic acid solvent spiro compound spiro(indolenaphthooxazine) spiro(indolephenanthrooxazine) unclassified drug article isomerism phase transition photolysis polymerization temperature dependence thermal analysis viscosity |
| description |
The thermal back-isomerization of spiro[indole-naphtho-oxazine] 1 and spiro[indole-phenanthro-oxazine] 2 was studied in a series of primary alcohols, nitriles, and poly(methylmethacrylate), poly(ethylmethacrylate), and poly(isobutyl methacrylate) films by laser-flash photolysis in the temperature range of 0-70°. The decay is monoexponential in fluid solution, but deviates strongly from this behavior in polymeric environments even above the glass transition temperature of the polymers (Tg). In liquids, a very small solvent effect is observed on the isomerization rate constants (kiso) for 1, which is attributed mostly to the solvent viscosity η. The values of kiso for 2 show influence of solvent viscosity and polarity, which were studied by application of a semiempirical relationship that accounts for non-Markovian processes. The decay kinetics in polymers was described by a Gaussian distribution of the activation energy and by a kinetic model that takes into account the simultaneous relaxation of the probe and the environment. For 1 and 2, the rate constant at the center of the Gaussian distribution is very similar to the first-order rate constant in nonpolar solvents. The Gaussian width of the distribution (σ) decreases with temperature and is very similar in all polymers under Tg, and, above Tg, σ decreases more abruptly. We make comparisons of the parameters derived from analysis of both 1 and 2 in polymers, as well as of their behaviors in solution and in polymers. |
| title |
Thermal back-isomerization of spirocyclic naphtho-oxazine and phenanthro-oxazine derivatives in alcohols, nitriles, and poly(alkyl methacrylates) |
| title_short |
Thermal back-isomerization of spirocyclic naphtho-oxazine and phenanthro-oxazine derivatives in alcohols, nitriles, and poly(alkyl methacrylates) |
| title_full |
Thermal back-isomerization of spirocyclic naphtho-oxazine and phenanthro-oxazine derivatives in alcohols, nitriles, and poly(alkyl methacrylates) |
| title_fullStr |
Thermal back-isomerization of spirocyclic naphtho-oxazine and phenanthro-oxazine derivatives in alcohols, nitriles, and poly(alkyl methacrylates) |
| title_full_unstemmed |
Thermal back-isomerization of spirocyclic naphtho-oxazine and phenanthro-oxazine derivatives in alcohols, nitriles, and poly(alkyl methacrylates) |
| title_sort |
thermal back-isomerization of spirocyclic naphtho-oxazine and phenanthro-oxazine derivatives in alcohols, nitriles, and poly(alkyl methacrylates) |
| publishDate |
2001 |
| url |
https://bibliotecadigital.exactas.uba.ar/collection/paper/document/paper_0018019X_v84_n9_p2751_Volker http://hdl.handle.net/20.500.12110/paper_0018019X_v84_n9_p2751_Volker |
| _version_ |
1840325597097623552 |