T. M. Valova

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 irreversible photofluorescent organic materials for 3D bitwise optical memory

This paper presents latest own results in the development of reversible photochromic and irreversible photofluorescent polymer systems providing fabrication of multilayer recording media for 3D optical memory with super high information capacity. It was shown that synthesized thermal irreversible photochromic diarylethenes into plastic binders allow to prepare photochromic polymer layers providing nondestructive refractive read-out of optical information. These photochromic polymer layers were used for preparation of six-layer recording media tested with the positive results using the framed optical device. This device imitated layer-by-layer writing, erasure and read-out of optical signals. Experimental evidences for making photochromic polymer layers based on a mixture of photochromic diarylethene and dye — phosphor with nondestructive fluorescent read-out are presented too. Polymer systems based on light-sensitive chromones manifest an irreversible photochemical transformations of these non-fluorescing compounds into the fluorescent products under UV irradiation. Received results open perspectives for making multilayer optical discs for bitwise working (based on photochromic systems) and archival (based on irreversible photofluorescent systems) optical memory with information capacity more 1 TB.

Spectral-kinetic study of phototransformations of new 3-acyl-2-hetarylchromones

Spectral-kinetic and fluorescent properties of 16 new photosensitive compounds of the 2-furyl- and 2-thienyl-3-acylchromone classes, the initial nonluminescent forms of which undergo irreversible phototransformations into fluorescent products, are considered on the basis of their structure and properties responsible for the possibility of their application as photosensitive components of recording media for archive optical disks.

Synthesis and modification of light-sensitive 3-acyl-2-hetarylchromones containing bromomethyl group in the acyl fragment

A synthesis of photosensitive 3-acyl-2-hetarylchromones containing bromomethyl group in the 3-aroyl fragment and their further modification by the reactions with N-, S- and O-nucleophiles are described. A dependence of spectral properties from the structure of compounds was studied.

Spectral-kinetic evidence of interaction of photochromic diarylethenes with silver nanoparticles

Spectral-kinetic investigations of the photochromism of some diarylethenes with sulfur-containing substituents in dimethylsulfoxide solutions with and without silver nanoparticles are performed. It is shown that silver nanoparticles chemically interact with diarylethene molecules, which is manifested in a change in the spectral and kinetic characteristics and photodegradation efficiency.

Photoactivation of fluorescence of rhodamine dyes in the presence of haloalkanes

Organic halogen derivatives, viz., hexachloroethane, 2,2,2-trichloroethanol, 2,2,2-tribromoethanol, butyl trichloroacetate, 2,2,2-trichloroethyl methacrylate, can efficiently activate fluorescence of lactone forms of rhodamine dyes by UV irradiation through the UFS-1 light filter in both solutions and polymer poly(methyl methacrylate) films. This ability is also typical of the copolymer of methyl methacrylate and 2,2,2-trichloroethyl methacrylate, which is promising for the development of detecting media for archive optical data storage with fluorescent readout.

Photochromic fulgimide-containing silicones immobilized on the surface of polyarylate

Photochromic coatings immobilized on the surface of polyarylate films are prepared on the basis of fulgimides, oligosiloxanes, and oligosilazanes. The irradiation of coatings with UV light at a wavelength of @380 nm and visible light at a wavelength above 500 nm results in photoinduced reversible transitions between open and colored cyclic forms. Photochromic polymer films with the most acceptable characteristics are obtained from fulgimide-containing oligoaminosiloxane and oligovinyldimethylsilazane. It is found that the photosensitivity of these films is higher than that of similar films based on 1,2-dihetarylethenes.

Synthesis of photochromic optically transparent polycarbonate glasses and study of their properties

Procedure was developed for surface dyeing of polycarbonate glass with photochromic thermally relaxing compounds from the classes of spiropyrans, spirooxazines, and chromenes via diffusion of photochromic molecules from solutions in cyclohexanone. It was shown that the highest diffusion efficiency of photochromic compounds without loss of the optical surface quality of polycarbonate glass is reached at a temperature of 80°C. Samples of photochromic polycarbonate glasses were obtained and their photochromic properties were studied.

A spectral-kinetic investigation of the negative photochromism of systems based on complexes of spiropyrans with metal ions

A comparative spectral-kinetic study of the negative photochromism of complexes of molecules of nitrosubstituted indoline spiropyrans with metal ions in solutions and polymer matrices is carried out. The possibility of creating polymer coatings with negative photochromism, based on the complexes of spiropyran molecules with metal ions is shown for the first time. It is determined that the efficiency of photochromic transformations of complexes depends on the nature of the polymer binder, the component composition of the polymer film, and the properties of metal cations. During the storage of photochromic polymer films in the dark, a spectral manifestation of the transformation of metal complexes into putative protonated complexes is revealed. It is found that the stability of the complexes is determined by the nature of the polymer binder and the affinity of the metal cations to an electron.