Spectroscopic and laser characteristics of new efficient luminophores for a wide spectral range based on complexes of dipyrrolylmethene derivatives with difluorine borate

We have studied the spectral-luminescent, lasing, photochemical, and endurance characteristics of a series of new efficiently emitting difluorine borate complexes with dipyrrolylmethenes of different structures. Experimental data have been obtained in polar and nonpolar organic solvents and in solid polymer films involving the participation of silicate structures. We have discussed relations of the structure of investigated compounds and formed solvates with their optical characteristics, and have given guidelines on the use of particular compounds as active media of tunable lasers for determining spectral ranges.     

Kinematic and electrooptical anharmonicity in the semiempirical intensity theory of IR and raman spectra of polyatomic molecules

Saratov State University, 83 Astrakhanskaya Str., Saratov, 410601, Russia. Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 62, No. 6, pp. 49–57, November–December, 1995.     

Calculation of the Normal Vibrations of Benzene in the First Singlet Electron-Excited State 1 B 2u

Using the CIS/6-311+G^** method, the normal vibrations of the benzene molecule in the first singlet electron-excited state ¹ B _2u have been calculated. The algorithm of calculation of the force field in dependent coordinates by the method of generalized inversion is described. A method of autoscaling in dependent natural coordinates is suggested. For six groups of natural coordinates scaling factors have been obtained, the use of which has led to agreement between the calculated and experimental frequencies of the vibrations of benzene. The frequencies of the B _1u -symmetry-type vibrations, for which there is no experimental assignment, have been calculated. The problem of selection of the force field in dependent coordinates is discussed.     

Stability of nonplanar N-methylporphyrins and their zinc complexes

Resistance of N-methyl-substituted porphyrins and their Zn(II) complexes to thermooxidative degradation and to the action of a DMSO-AcOH proton-donor solvent was studied by thermogravimetry and chemical kinetics. The fairly low stability of the complexes is caused by decreased planarity and, as a consequence, aromaticity of the macrorings and also by the tendency of the complexes to demethylation. The stability of the zinc complexes in AcOH varies in parallel with the degree of nonplanarity and resistance to thermooxidative degradation of their ligands.     

Electronic Absorption Spectra of Alkyl-Substituted Dipyrromethenes and Biladienes-a,c in Organic Solvents

3,3',5,5'-Tetramethyl-4,4'-dibutyldipyrromethene-2,2' and 1,3,7,13,17,19-hexamethyl-2,8,12,15-tetrabutylbiladiene-a,c hydrobromides undergo deprotonation in electron-donor solvents or in the presence of nucleophilic reagents. The rate and depth of the process depend on the electron-donor properties of the solvent, concentration, and degree of self-association of the chromophore molecules. Under analogous conditions, partial decomposition of the biladiene-a,c chromophore occurs.     

Acid–Base Interactions in Complexation of Magnesium Acetylacetonate with Tetraazaporphyrins in Dimethyl Sulfoxide–Benzene System

Complexation of magnesium acetylacetonate with tetraazaporphine, tetrachlorotetraazaporphine, tetrabromotetraazaporphine, octa(p-bromophenyl)tetraazaporphine, or octa(p-nitrophenyl)tetraazaporphine in DMSO–benzene system was studied. The acid properties of tetrapyrrole were shown to affect the rate and activation parameters of the process. The key role of acid–base interactions in the formation of Mg(II) complex with tetraazaporphyrins was established. The mechanism of the processes under study was suggested.     

Pair association and complexation with water of matrix-isolated pyridine N-oxide: A theoretical study of their manifestations in the IR spectrum

The structure and the IR spectra of three types of pair associates of pyridine N-oxide, as well as of three different complexes of this compound with one or two water molecules, are calculated in terms of the supramolecular approach by the B3LYP/6-311+G(d, p) hybrid density functional method. The experimentally observed IR spectrum of pyridine N-oxide in a low-temperature Ar matrix is theoretically interpreted in detail. The agreement in sign and magnitude between all the calculated and observed frequency shifts of fundamental vibrations shows that the hydrogen-bonded complexes make the main contribution to the formation of complex bands of self-associates.     

Photovoltaic effect in cuprous oxide-copper junctions in relation to the optical absorption spectrum of cuprous oxide

The spectral dependence of the photovoltaic effect (PVE) of Cu₂O-Cu cells, annealed in three distinct ways, was measured. The copper contact was formed by high temperature reduction of the surface of the oxide. The measurements were made for different thicknesses of oxide, and with front wall and back wall illumination. Two types of absorption constant were calculated from PVE measurements and compared with directly measured absorption constants from transmission data. The results allow us to distinguish between electronically active absorption near the bandgap and electronically inactive absorption at longer wavelengths.