Only a small part of the numerous photochemical reactions in organic compounds result in reversible structural changes. The latter are accom panied by a change in physical properties, in particular, of electronic spectra. It is tempting to try to use this photochromic effect in various systems for controlling and regulating light fluxes and for data recording. Eventually an independent trend emerged in photochemistry - the study of the photochromism of organic compounds to establish relationships between structure and photochemical behavior, the theoretical analysis of these relationships to predict structures with pre-set photochromic parameters, and, finally, the identification of suitable areas for the application of photochromism. This monograph summarizes the results of recent studies carried out by a number of research institutions in the USSR and the GDR. Devoted to an important aspect of applied photochemistry, this monograph contains a detailed exposition of the chemical photochromes referred to briefly in the earlier editions of "Introduction to the Photochemistry of Organic Compounds" (Khimiya Press, Moscow, 1976) and "Photochemical Proces ses in Layers" (Khimiya Press, Moscow, 1978).
|Edition description:||Softcover reprint of the original 1st ed. 1990|
|Product dimensions:||6.69(w) x 9.61(h) x 0.02(d)|
Table of Contents1 Theoretical Studies of the Photochromism of Organic Compounds.- The Use of Qualitative Models and the Woodward-Hoffmann Rules for Describing Photochromic Systems.- Quantum-Chemical Calculations of the Spectra of Photochromic System Components and Statistical and Dynamic Indices for Estimating Their Reactivity.- Photochromic Spiropyrans.- Chromenes and related compounds.- Reversible photocyclizations and cycloadditions.- Photochromism of indigoids.- Photoisomerization of azines.- Hydrogen migration in photochromic systems.- Discussion of the Mechanisms of Photochromism using Current Ideas on Potential Energy Surfaces.- E/Z-Photoisomerizations.- Reversible photocyclizations.- Hydrogen phototransfer.- The Influence of Solvent on Photochromism.- References.- 2 Photochromic Thioindigoid Dyes.- The Structure and Spectra of Thioindigoids.- Production, Thermal Stability, and Spectra of Z-Isomers of the Thioindigoids.- On the Mechanism of the Photoisomerization of Indigoid Dyes.- The Effect of the Heteroatom of an Indigoid Dye on ?E?R. The Reasons for the Absence of Photochromism in Indigo.- The Influence of Substituents and Environmental Parameters on ?E?R.- Addendum.- References.- 3 Photochromic Compounds with N=N and C=N Chromophores.- The Principal Paths of Photochemical and Thermal E/Z-Isomerization.- Direct and triplet-sensitized photoisomerization.- Photocatalytic isomerizations.- Photochromic Azo Compounds.- Electronic absorption spectra.- Luminescence.- The mechanisms of E/Z-photo- and thermal isomerization and photo- and thermal dissociation.- The application of the photochromism of azo compounds.- Photochromic Aryldiazo Compounds.- Electronic spectra.- The mechanisms of Z/E-photo- and thermal isomerization and photo- and thermal decomposition.- The uses of the photochromic properties of aryldiazo compounds.- The Photochromism of Compounds Containing the C=N Chromophore.- Electronic spectra.- The mechanisms of the E/Z-photo- and thermal isomerization of compounds with the C=N chromophore.- References.- 4 Photochromic Tautomeric Systems.- Photochromism of (Nitroaryl) (hetaryl) alkanes.- Structural features of photochromic (nitroaryl) (hetaryl) alkanes.- The nature of photoinduced forms of (nitroaryl) (hetaryl) alkanes and the mechanism of their formation.- The effect of structure on the color of observed photochromes.- The decoloration of colored forms.- The quantum yields of photocoloration.- Irreversible photodissociation.- The photochromism of (nitroaryl) (hetaryl) alkanes in crystals, melts, and polymer films.- Photochromic peri-Aryloxy-p-quinones.- The structure of the photoinduced form.- The relation between the structure and photochromism of aryloxyquinones.- Absorption and luminescence.- The mechanism of photoisomerization.- Potential practical applications.- Reversible Photoacylotropic Regroupings.- References.- 5 Organic Photochromes for Solar Energy Storage.- The Principle of Accumulating Light Energy as the Energy of Strained Metastable Structures.- Efficiency Criteria.- Various Photochromic Systems for Solar Energy Accumulation and Their Mechanisms.- Geometric isomerizations.- Valence isomerizations.- Dissociation reactions and dimerization.- A Basic Scheme of the Engineering Solution to the Problem of Solar Energy Storage and Release in the Form of Thermal Energy.- Acylotropic Azomethine Systems A New Type of Solar Energy Storage Battery.- References.- 6 Luminescence of Photochromic Compounds.- Polyacenes and Their Analogs.- Diarylethylenes.- Thioindigoids.- Arylmethane Derivatives.- Spiropyrans.- Azomethineimines.- Compounds with an Intramolecular Hydrogen Bond.- Conclusion.- References.