N. L. Zaichenko

Excited-state intramolecular proton transfer in 2,4,5-triarylimidazole molecules

Excited-state intramolecular proton transfer (ESIPT) in the 2,4,5-triarylimidazole molecules was studied by spectral-luminescent technique. For 4,5-diphenyl-(2-hydroxyphenyl)imidazoles, the ESIPT occurs in both liquid and glassy matrices at 77 K. For 4,5-diphenyl-(2-hydroxynaphthyl)imidazole, the ESIPT requires rotation of molecular fragments and is not observed at 77 K.

Merocyanine form of photochromic spirooxazines in acid solutions

Electronic absorption and NMR spectra of solutions of photochromic spironaphthoxazines (SNOs) were studied. The addition of an acid results in the formation of a salt of the colored form of SNO. For SNOs with nitrogen-containing electron-releasing substituents, the structure of the product that formed depends on the acid concentration being the salt of the mono- or dication.

Synthesis of polymerizable photochromic spironaphthoxazines

Hydrogenatjon of 8-nitrospironaphthoxazine (1) resulted in the corresponding amine (2). Acylation of compound 2 yielded the N-methacryloyl derivative (3). Radical polymerization of the latter resulted in its copolymers with styrene, which possess photochromic properties.

Synthesis and photochromic properties of spiro (benzindoline-naphthoxazines)

A new photochromic compound belonging to the class of spiro(indoline-naphthoxazines) was synthesized. Nitration of this compound was carried out and the structures of two photochromic nitro-substituted products were determined. The photochromic properties of the products were studied in solvents of different polarity.

Synthesis and photochromic properties of nitro-substituted spironaphthooxazines

Abstract7-Nitro- and 8-nitroderivatives of 1′,3′,3′-trimethylspiro[indoline-2′,3-3H-naphtho[2,1-b][1,4]oxazine] were synthesized, the last of them being prepared by direct nitration. The introduction of the nitro group stabilizes a bipolar colored form, the highest stability being exhibited when the NO2 group is the 8-position.

Bromination of photochromic spironaphthoxazines

Direct bromination of photochromic compounds of the spironaphthoxazine and spironaphthopyran series was performed using N-bromosuccinimide to obtain both photochromic bromine-substituted spiro compounds and nonphotochromic 2-(naphtho[1,2-d]oxazol-2-yl)-3H-indolium bromides. The structures of the resulting products were established by NMR spectroscopy and mass spectrometry. The mechanism of bromination taking into account the involvement of both closed and open (colored) forms of spiro compounds was proposed.

Aggregation of nitrosubstituted spiropyranes in polymeric films

Absorption, luminescence, and luminescence polarization spectra of associates of photochronic molecules of nitrosubstituted indolinospiropyranes in the closed form in polymeric films at high temperatures were studied. The efficiency of the formation of the associates depends on the structure of the photochrome molecules and the nature of the polymeric matrix. A scheme of phototransformations of the associates taking into account the exciting light wavelength was suggested.

PMR spectra and structure of the open form of spironaphthooxazine

Conclusions1.The PMR spectra of the closed forms of spironaphthopyran and spironaphthooxazine were interpreted. The PMR spectra of the photoinduced forms of these compounds were obtained for the first time.2.The open form of spironaphthooxazine in nonpolar solvents was found to have the quinoid structure of one of the trans isomers, while there is a shift in the equilibrium toward the bipolar structure in polar solvents.

Topomerization of substituted 1-amino- and 1-oxy-Δ2-1,2,3-triazolines

For 1-amino- and 1-oxy-Δ2-1,2,3-triazolines, retardation (on the NMR time scale) is observed for rotation around the exocyclic N-N or N-O bond; the measured barriers to topomerization amount to 8.3–13.8 kcal/mole.

Synthesis and photochromic properties of spiroanthrooxazine

Abstract1′,3′,3′-Trimethylspiro[indoline-2′,3-3H-anthraceno[2,1-b][1,4]oxazine] was synthesized. The compound has photochromic properties in solutions and in polymeric matrices. It was found from the spectral data that the colored form of the spiroanthrooxazine exists in a quinoid form and is characterized by a positive solvatochromic effect.