Yu. S. Alekseenko

Photo-and thermochromic spiranes. 24*. Novel photochromic spiropyrans from 2,4 -dihydroxyisophthalaldehyde

Novel series of photochromic indoline and benzoxazine spiropyrans containing ortho-placed formyl and hydroxyl groups in the benzene ring of the chromene part of the molecule have been prepared. X-ray analysis has shown that, depending on the structure of the heterocyclic component in the spiro cyclization reaction different, nonequivalent formyl groups of 2,4-dihydroxyisophthalaldehyde can participate. The synthesized compounds were used as original analogs of salicylaldehyde. The novel photochromic bispyropyrans prepared contain two different asymmetric spiro carbon atoms.

New photochromic nonsymmetric bis-spiropyran of the 2,3-dihydro-4-oxonaphtho[2,1-e][1,3]oxazine series

New nonsymmetric bis-spiropyran of the 2,3-dihydro-4-oxonaphtho[2,1-e][1,3]oxazine series was prepared. On the basis of the results of photochemical study and quantum-chemical calculations, it has been shown that both pyran cycles experience opening during irradiation of a bis-spiropyran solution with unfiltered light.

Photo-and thermochromic spiranes. 29. New photochromic indolinospiropyrans containing a quinoline fragment

A new photochromic spiropyran of the indoline series, containing a quinoline fragment, has been synthesized. The photochromic properties of the spiropyran and its iodomethylate have been studied. Features of the molecular structure of the compounds were determined by X-ray structural investigations. It was established that the pyridopyran fragments of the cations in the crystal of the iodomethylate salt, unlike those in the crystal of the neutral spiropyran, emerge from 21-stacks, disposed jointly with I− ions, which causes their higher mobility and aids the course of reversible photoconversions on UV irradiation in solution.

Spiropyrans Containing the Reactive Substituents in the 2H-Chromene Moiety

Some spiropyrans containing functional substituents in the [2H]-chromene part of the molecule were synthesized and their photochromic properties in solution and solid state were investigated. The presence of the formyl group in the [2H]-chromene fragment enhances the possibility to show photochromic properties in solution.

Photochromic and Thermochromic Spiropyrans. 22. Spiropyrans of the 4-Oxo-3,4-dihydro-3H-1,3-benzoxazine Series Containing π-Accepting Substituents at Position 8'

New spiropyrans of the benzoxazinone series were synthesized by modification of the formyl group in compounds containing an asymmetric spiro carbon atom. It was shown that 1H NMR identification of the spiropyrans containing π-accepting hydrazone substituents must be conducted at elevated temperatures by following the presence of and degree of subsequent “recovery”. According to X-ray crystallographic analysis, crystal solvates can form, depending on the solvent used for crystallization of the hydrazones of the spiropyrans.

Photochromism of the Spiropyran Thin Solid Films

ABSTRACT New spiropyrans of indoline and benzoxazinone series were synthesized. Photochromic properties of this compounds in thin solid films have been investigated.

Structural Thermo‐ and Phototransformations of Oxaindane Spiropyrans Adsorbed on Silver Films

Using giant Raman scattering spectroscopy methods, we have studied the structure and also the thermo‐ and phototransformations of dimethylphthalanspirobenzopyran (PhSBP) adsorbed on the surface of silver films. It is shown that on adsorption of PhSBP from ethanol solutions, on the surface of the silver films there are predominantly open forms of molecules which do not exhibit photochromic properties. It is established that cooling of the specimen to 77 K initiates thermoreversible reconstruction of the adsorption layer with formation of the aggregates of the PhSBP molecules. These reversible structural changes in frozen specimens are enhanced on exposure to the light of a visible range.

NEW PHOTOCHROMIC BISPIROPYRAN

The photochromic properties of spiropyrans are a function not only of the contribution of the hetarene fragment but also, to a greater extent, to the substituents in the 2H-chromene part of the molecule [1]. We have obtained a new spiropyran 1, which is a unique salicylaldehyde analog, and used this compound to synthesize spiropyran 2, containing two different spirocyclic sites and, thus, two asymmetric carbon atoms.

Photo- and thermochromic spirans 36.* Synthesis, structure and photochromic properties of 7',7"-{1,4-phenylenedi(methylene)-bis(5-chloro-1,3,3-trimethyl-1,3-dihydrospiro-[indole-2,3'-pyrano[3,2-f]quinolinium])} diiodide

A synthesis is reported for a new photochromic indoline bisspiropyran salt containing a quinoline fragment. This compound exists as a racemic mixture. The photochromic properties of this symmetrical bisspiropyran were studied.

Synthesis of Formyl Derivatives of 2-Hetarylimidazoles Annelated with Naphthalene and Phenanthrene Rings

The formylation reaction of a series of 2-hetarylimidazoles, annelated by naphthalene and phenanthrene rings, using hexamethylenetetramine in PPA and the Vilsmeier reagent has been studied. The furyl and thienyl derivatives form principally the 5-formyl-substituted and the pyrrolylimidazoles were found to give a mixture of the α- and β-formyl derivatives.