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The structures of four stereomers (enantiomers) of photochromic indolinospirobenzothiopyran (ISTP) in the closed form were studied by the DFT method. The most stable structure was found. IR spectra of ISTP in KBr pellets and as a film on single-crystalline KBr plates (in the region 400–4000 cm −1 ) and as a powder between polyethylene plates (100–400 cm −1 ) were measured. An interpretation of the obtained IR spectra was proposed. Specific features of normal modes of ISTP caused by the presence of the spiro center were revealed.

The structures of four stereoisomers (enantiomers) of the closed form of an indolinospiropyran were studied by the DFT method. The most stable structure was found. IR absorption spectra of the compound as fi lms on single-crystalline KBr plates (400–4000 cm–1) and as powders between polyethylene plates (100–400 cm–1) were measured. An interpretation of the obtained IR spectra and literature Raman spectra was proposed. Specifi cs of the normal vibrations of the indolinospiropyran that were caused by the spiro node in its structure were revealed.

We have measured IR and Raman spectra of molecules of a closed form of the photochromic compound indolinespirophenanthroxazine. Using the density-functional method, we have optimized the structures of the closed and open forms of this molecule and calculated its normal vibrations. Based on these calculations, we propose an interpretation of the obtained vibrational spectra. We have determined the spectral range of manifestation, 700–900 cm−1, and have found wavenumbers of normal vibrations through which the spiro structure of the indolinespirophenanthroxazine molecule in an excited state is likely to be rearranged into a merocyanine structure.

IR absorption spectra of indolinospironaphthooxazine (ISNO) are presented. The geometric structure and normal coordinates of the ISNO molecule have been calculated using a quantum mechanical DFT method. The IR spectrum of ISNO in its original spiro form has been interpreted for the first time. Four normal modes in the range 800–1200 cm–1 with the largest amplitudes of Cspiro–O bond change are identified. The excited ISNO molecule spiro form may experience photoconversion to the merocyanine form through them.

A photochemically bifunctional compound was obtained. Its molecule includes the spironaphthoxazine and dansylamino fragments. This compound exhibits both photochromic and luminescent properties. Its spectroscopic characteristics were studied in different solvents. The electronic systems of two constituent fragments do not interact with each other.

In an approximation of the generalized valence force field, the frequencies and forms of the normal vibrations of the free molecule of spiroanthraceneoxazine (SAO) are calculated. The vibrational spectra of SAO are measured: the IR absorption spectra in an NaCl disk and the Raman spectra in a KBr disk. The calculated and experimental data were correlated with the aid of a method of refined initial data. The results obtained agree with the calculated and experimental spectra of model and related compounds.

Spectral and photochromic properties of spironaphthooxazines (SNOs) with piperidine and morpholine substituents have been studied at different temperatures in various solvents. It has been recognized that introduction of these substituents in naphthooxazine fragment leads to fluorescence of the initial form of SNO molecules at low temperatures, which disappears with temperature rise. The dependences of the photoinduced form in non-polar solvents. It is proposed that the coloured form of substituted SNOs has a bipolar structure with a positive charge on piperidine or morpholine nitrogen atom contrary to the quinonoic form of unsubstituted SNO.

The spectral and photochromic properties of bispiroanthro-bis-oxazine (bis-SAO) in toluene, DMF, and polystyrene films were investigated in the 77–300 K interval. It is shown that the long-wave part of the absorption spectrum of the starting form of the molecule is formed by three-electron transitions localized in the anthro-bis-oxazine fragment. The directions of the oscillators of these transitions relative to the nuclear. backbone of the molecule are proposed on the basis of luminescence polarization data. It is proposed that the photochromic properties of the solutions are determined by the existence of bis-SAO molecules in dimer form.

The photochromic properties of 1′,3′,3′-trimethylspiro[indolin-2′,3-3H-anthraceno[2,1-b][1,4]-oxazine] (SAO) in solutions of different polarity [n-BuOH and petroleum ether (PETh)] were studied. It was established that the quantum yield of the photocoloration φAB and the energy of activation of the thermal decolorization Ea in the PETh depend on the temperature; this is not the case in n-BuOH. The luminescence properties of SAO were investigated. It was found that the spectrum of the excitation of the luminescence in PETh depends on the temperature. These features, as well as the slower thermal decolorization of the colored form of SAO in PETh by comparison with the solutions in n-BuOH, are explained by the presence of dimers of the SAO molecules in nonpolar media in the temperature range investigated (77–300 K), whereas the SAO molecules already occur in the monomeric state at 150 K in the polar n-BuOH.

The influence of temperature and concentration on the spectral polarization properties of the luminescence and absorption of molecules of the original form of photochromic spiroanthrooxazine (SAO) in petroleum ether and polyethylene was investigated. It was shown that the long-wave part of the absorption spectra of the molecules is formed by at least two π-π*-type electronic transitions, the oscillators of which are mutually orthogonal. It is suggested that the SAO molecules form dimers in nonpolar media through dipole-dipole interaction, and at high concentrations they also form higher associates. Dimers stable in the ground state dissociate when excited to the second electronic transition with a rate constant of 1012–1013 s−1.

Electrochromic properties of 1′,3′,3′-trimethyl-6-piperidino- and-morpholinospiro[indoline-2′,3-3H-naphtho[2,1-b][1,4]-oxazines] resulting from their ionization and the formation of intermediate products were studied. The characteristic features of the photochromic behavior of these compounds are positive solvatochromism for absorption spectra of a colored form and an increase in the rate constant for thermobleaching with increasing solvent polarity.