Valery A. Barachevsky

Coumarinyl(thienyl)thiazoles: Novel photochromes with modulated fluorescence

Novel photochromic 5-(3-coumarinyl)-4-(3-thienyl)thiazoles have been synthesized. These compounds display intensive fluorescence emission in the open form A, which is modulated by light. Fluorescence intensity decreases significantly upon irradiation of A with UV-light (lambda<400 nm) due to formation of the cyclic form B. Irradiation of B with visible light (lambda>470 nm) promotes its opening and the recovering of fluorescence. Novel dihetarylethenes undergo photochromic modulation of fluorescence both in solution and in polymeric matrices.

Synthesis and characterization of nonsymmetric cyclopentene-based dithienylethenes.

Nonsymmetric cyclopentene-based dithienylethenes, containing both thienyl and benzothienyl units, have been synthesized for the first time, employing intramolecular McMurry reaction as a key transformation to target compounds 10 and 16. Photochromic properties of these compounds were examined in toluene and acetonitrile solutions, PMMA layers, solid films, and crystal phase. To explain an unprecedented single-crystalline photochromism phenomena of 10, X-ray crystallographic analysis was performed, revealing a significant influence of strong S···S interatomic interactions on the intramolecular distance between two photochemical reaction centers in the molecule. Compound 16 could be further synthetically modified in a step-by-step manner, thus serving as potential key intermediate to various complex bifunctional photochromic molecules.

Synthesis and reactivity of 1-aryl-9H-thieno[3,4-b]chromon-9-ones

Methods were developed for the synthesis of 1-aryl-9H-thieno[3,4-b]chromon-9-ones based on the reaction of bromo and dibromo derivatives of 2-methyl-4H-chromon-4-one with thioacetamide in DMF. The thienochromones were modified and their fluorescence properties were studied. Bis(thienochromones) were synthesized by the reaction of thienochromones with ketoaldehydes.

Photochromic and nonlinear optical properties of Langmuir–Blodgett dye films

Abstract The analysis of the results received recently in the field of the study of photochromic and nonlinear optical properties of Langmuir–Blodgett based on the certain dyes is presented. The prime object of this study is determination of the effect of intermolecular interactions on these properties. It was demonstrated that intermolecular interaction, as a rule, decreases the efficiency of photochromic transformations. Aggregation and complex formation of dyes are favorable to effective generation of laser radiation harmonics.

Photochromism of Aryloxyquinones

The photochromic transformation mechanism, the dependence of properties upon the structure of photochromic compounds of aryloxyquinone class as well as their possibility of application are performed in the present review.

Synthesis and photochromic properties of ferrocenyl substituted benzo- and dibenzochromenes

The synthesis, photochromic behaviour, photodegradation parameters and fluorescence spectra of a range of benzo- and dibenzochromenes substituted by a ferrocenyl group in the 2-position have been investigated. The ferrocenyl group leads to two absorption bands in the visible spectrum of the photomerocyanine species, in contrast to the single band observed with corresponding phenyl substituted derivatives. It also increases the thermal rate of bleaching of the photomerocyanine.

Photoluminescent organic recording media

A review on the development of photoluminescent organic recording media is presented. Particular emphasis has been placed on positive photoluminescent materials for irreversible and reversible recording of optical information. The results of the study of light-sensitive systems based on irreversible and reversible photochemical transformations or organic molecules are discussed. The fundamental characteristics for made photoluminescent polymeric materials based on these photochemical systems and perspectives of their application as recording media, especially in the modern photography and 3D- optical memory devices, are given adequate consideration.

Synthesis, structure and photochromic properties of hybrid molecules based on fullerene C60 and spiropyrans

The 1,3-dipolar cycloaddition of azomethine ylides to fullerene C60 was utilized to perform the synthesis of spiropyran-containing photochromic pyrrolidinofullerenes. It was found that photochromism is observed only for the hybrid compound containing an NO2 group in the pyran moiety, whereas the pyrrolidinofullerenes with Cl or F atoms in the spiropyran moiety do not possess photochromism. The photochromic fullerene hybrid is characterized by lower light sensitivity and photodegradation parameters compared to the initial spiropyrans, which can be attributed to reabsorption of activating radiation.

Light-sensitive organic media with nonlinear optical properties

The analysis of nonlinear optical effects in organic media, namely generation of harmonics of laser radiation, two- photon absorption, and photoinduced birefringence, is presented. The possibilities of their application for recording and processing optical information as well as for transformation of laser radiation are discussed.

Spectral Data Base on Photochromic Organic Compounds

Abstract A data base containing properties and chemical structures of photochromic organic compounds along with the UV and visual absorption spectra of both initial and photoinduced forms has been created. This data base improves efficiency of basic researches for the structure-property relationships