Synthesis and photochromic properties of 4-[2-(anthracen-9-yl)-5-methyloxazolyl] fulgide

New photochromic fulgide, viz., 4-{1-[2-(anthracen-9-yl)-5-methyloxazol-4-yl]ethylidene}-3-isopropylidenetetrahydrofuran-2,5-dione, with fluorescent properties was synthesized. Studies by electronic, IR, and ¹H NMR spectroscopy and X-ray diffraction demonstrated that this fulgide exists in the Z form. Light irradiation of its solutions at a wavelength of 365 nm causes Z/E isomerization giving rise to the thermally stable cyclic form. The latter is transformed into the starting E isomer under light irradiation at λ = 436 nm. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 1, pp. 97–101, January, 2006.     

New materials for sorption of hydrogen

The influence of temperature, duration of thermal treatment, and oxidation modes of the aluminum base on processes in which intermetallic compounds LiLaAl are formed by the method of electrochemical cathodic intercalation was studied. The optimal modes of formation of LiLaAl_ox compounds exhibiting high sorption capacity for hydrogen were determined.Translated from Zhurnal Prikladnoi Khimii, Vol. 77, No. 9, 2004, pp. 1516–1519.Original Russian Text Copyright © 2004 by Olshanskaya, Sobgaida, Popova.     

IN SITU IR SPECTROSCOPIC STUDIES OF HCOOH DECOMPOSITION OVER V-TI-O CATALYST

Decomposition of formic acid over V-Ti-O catalysts was studied by in situ IR spectroscopy. Four surface compounds, among which are H-bonded acid, one mono- and two bidentate formates (BF1 and BF2), were identified in the temperature range of 100-190°C. The activation energy and rate of the BF2 decomposition were found equal to those for the CO formation. This equality points to the involvement of BF2 in the HCOOH decomposition into carbon monoxide.     

N-Benzyl Derivatives of Leucine Esters

Leucine methyl and ethyl esters reacted with 3-bromobenzaldehyde and 4-chlorobenzaldehyde in anhydrous methanol in the presence of magnesium sulfate to afford the coresponding Schiff bases of the general formula (CH3)2CHCH2CH(COOR¹)N=CHR² [R¹ = CH3, C2H5, R²= 3-BrC6H4, 4-ClC6H4]. Their reduction with sodium tetrahydridoborate yielded N-benzyl derivatives (CH3)2CHCH2CH(COOR¹)NHCH2R², which were converted into N-acyl-N-benzyl derivatives (CH3)2CHCH2CH(COOR¹)N(COR³)CH2R²[R³= CH₃, C₆H₅].     

Kinetics of Anodic Dissolution of Lithium out of Li x C6 Electrodes in Nonaqueous Lithium Perchlorate Solutions

Kinetics of processes occurring during anodic dissolution of Li _x C₆ electrodes formed in structures of carbonized fiber and cloth (CC) in solutions of lithium perchlorate in a mixture of propylene carbonate and dimethoxyethane is studied. It is shown that the Li _x C₆ (CC) electrodes have an approximately three times greater intercalation capacity, which is caused by specific features of the structure of CC. Values of the initial concentration of lithium defects in the structure of a surface layer of the CC matrix and the diffusion coefficients for lithium in the temperature range 293–323 K are calculated.     

Analytical characteristics of combined gas chromatographic systems: Packed precolumn-open tubular column

The peculiarities of the flow splitting technique for sample injection into a capillary column have been discussed. A comparative investigation of reproducibility of the analytical results obtained for two gas chromatographic systems using flow splitting [1) sample injector-packed predolumn-splitter-open tubular capillary column and (2) sample injector-splitter-open tubular capillary column] has been carried out. It was experimentally shown that the first system ensures considerably better reproducibility for the results concerning the composition of the analyzed mixtures. Other advantages of the first system are also discussed.     

Syntheses and Properties of Two Heterocyclically Substituted Hypericin Derivatives: 10,11-Dibenzothiazolyl-10,11-didemethylhypericin and 10,11-Dibenzoxazolyl-10,11-didemethylhypericin

Summary. The syntheses of the two heterocyclically substituted title hypericin derivatives were achieved starting either from 6-benzothiazolyl-tri-O-methyl-6-demethylemodin or 6-benzoxazolyl-tri-O-methyl-6-demethylemodin. The use of microwave assisted synthesis for the preparation of these anthraquinone synthons and the chemical as well as photochemical properties of the corresponding unique hypericin derivatives, which might constitute new photodynamic therapy agents, are reported. The tautomeric and stereochemical aspects of these hypericin derivatives were investigated by means of semiempirical calculations (AM1).