Solvatochromism of Heteroaromatic Compounds: XXVI. Solvent Effect on the Solvatochromic Parameters of IR Bands of <Emphasis Type="Italic">N</Emphasis>-Methylanilines and Related Hydrogen Bond Donors

Formation of a hydrogen bond between molecules of a proton donor (phenol, pyrrole, N-methylanilines) and a solvent decreases the sensitivity of the XH stretching frequency to the polarity/polarizability of solvents. A change in the bond configuration in the amine moiety of N-methylaniline and related compounds upon formation of a solvation H complex is manifested in that the absolute terms of the solvatochromic equations for inert and protophilic media are different. The spectroscopic effect from the geometric reorganization of molecules is determined by their structure and the capability to act as hydrogen bond donors. Multicentered hydrogen bond with π bases affects the geometry of the amine fragment of N-substituted anilines to a lesser extent than does two-centered H bond with onium bases.__________Translated from Zhurnal Obshchei Khimii, Vol. 75, No. 4, 2005, pp. 642–649.Original Russian Text Copyright © 2005 by Vokin, Oznobikhina, Shulunova, Ustinov, Bozhenkov, Levkovskaya, Turchaninov.For communication XXV, see [1].     

Influence of the position of the nitro group on the structural and spectroscopic characteristics of N"-(nitrobenzylidene)isonicotinic hydrazides in the crystalline state

N"-Substituted isonicotinic hydrazides of the general formula Py—C(=O)—N(H)-N"=C(H)—R, where R is o- (1), m- (2), or p-nitrophenyl (3), were studied by IR spectroscopy and X-ray diffraction analysis. The position of the nitro group in these compounds has no effect on the type of the crystal structure. The crystal packings are based on stacks consisting of antiparallel planar molecules. The molecules from the adjacent stacks are linked to each other via the N—H...N_Py hydrogen bonds. Depending on the position of the nitro group, the N...N_Py distance increases in the series 3 > 1 > 2 and the energy of the hydrogen bonds decreases (according to the IR spectroscopic data) from 3.9 to 3.1 kcal mol^–1. Analysis of the IR spectra demonstrated that the intensity of absorption in the (C—H) stretching region of the pyridine ring increases substantially as the the N—H...N_Py hydrogen bond is strengthened. Some regularities of the changes, which are observed for the (NO₂) bands in the spectra of the nitrophenyl-containing conjugated molecules in solutions, persist in the crystalline state.     

Some Possibilities for the Enhancement of Light Sensitivity of Silver Halide Photographic Materials for Holographic Recording by Counter Propagating Continuous- and Pulsed-Radiation Beams

An experimental approach to the development of high-resolution photographic materials for holographic recording by pulsed counterpropagating beams was proposed. The approach features an increase in size of emulsion grains as compared with photographic emulsions for reflection holography using continuous lasers. It was shown that the base industrial process for the fabrication of photographic emulsions designed for recording by copropagating beams might be used to manufacture holographic materials with controllable silver halide grain size and that the holographic sensitivity to both continuous and pulse radiation could be enhanced.__________Translated from Khimiya Vysokikh Energii, Vol. 39, No. 4, 2005, pp. 293–296.Original Russian Text Copyright © 2005 by Ryabova, Vorzobova, Kurilova, Popenko.     

Peculiarities of holographic media based on electron donor oligomers of linear and radial structures

The information properties of holographic recording media for photothermoplastic recording with films of oligomer composites based on carbazolyl-containing linear and star co-oligomers with branching centers on silicon and germanium atoms have been studied. The media based on the star oligomers possess higher holographic sensitivity due to greater plasticity and ability to accumulate space electrical charge during exposure. The buildup of space electrical charge results from the capture of photogenerated holes by energy traps created by dimers formed from terminal carbazolyl groups, whose amount is larger in macromolecules of radial oligomers than in linear oligomers.     

Photopolymerizable recording media for three-dimensional holographic optical memory

The development of investigations in recent years on photopolymerizable recording holographic media for using as photosensitive layers of holographic optical disks, which satisfy the conditions for the application in archive optical memory is analyzed. It is shown that the main emphasis in the development of photopolymerizable holographic recording media is put on the improvement of their component composition. Formulations that permit joint radical and cationic photopolymerization were designed for thermally stable holographic recording. The holographic characteristics achieved for these media ensure the fabrication of single-layer optical disks 150 mm in diameter with the information capacity of 200 GB instead of 5 GB for modern optical disks. Ways of improving photopolymerizable holographic recording media for the manufacture of optical disks with an information capacity of more than 1 Tb cm^?3 are considered.     

Poly(ester urethane acrylates) and holographic properties of formulations on their basis

Poly(ester urethane acrylates) with unsaturated bonds in stiff blocks have been synthesized from oligo(ester acrylates) containing functional groups. The structure and mechanical properties of the block copolymers thus prepared have been studied before and after UV cure. On the basis of the said poly(ester urethane acrylates), light-sensitive formulations for holographic recording have been designed. The formation of holographic gratings under illumination by an Ar laser light has been investigated. The formations under study offer promise as photostructuring media for holography.     

新型全息用光致聚合物的研究

研制了一种新型全息用光致聚合物材料,其成膜树脂为胺固化环氧体系,全息记录组分为光引发自由基聚合体系.用新合成的高效光敏染料DEAMC做光敏剂,通过配方调整,制备了一系列的样片,以457 nm的蓝光为记录光,632.8 nm的红光为探针光,研究了样片的衍射效率、灵敏度、折射率调制度等全息性能.结果表明,通过调整材料的配方组成、各组分的含量及样片的膜厚等因素,可以优化样片的全息性能.对样片的信噪比损失(LSNR)测试结果表明,在全息存储的曝光量范围内对样片曝光引起的图像信噪比损失仅有0.40 dB,说明样片的光学质量高,在全息存储上将具有很好的应用前景.     

<Emphasis Type="Italic">p</Emphasis>-Hydroxyphenyldiazonium Cation and Conjugated Base: A Quantum Chemical Study

Structural parameters and IR spectra of p-hydroxyphenyldiazonium cation and its conjugated base and of their monohydrates in the free state and in aqueous solution were calculated by the B3LYP/6-311G** method. The effects of aqueous medium were taken into account using the polarizable continuum model (PCM). The conjugated base is not a quasiaromatic p-diazoniophenolate zwitterion but has an essentially quinoid structure of 4-diazocyclohexa-2,5-dien-1-one. Its dipole moment in water (8 D) is much lower than that of p-diazoniobenzenesulfonate zwitterion (24 D).__________Translated from Zhurnal Obshchei Khimii, Vol. 75, No. 5, 2005, pp. 809–814.Original Russian Text Copyright © 2005 by Semenov, Sigolaeva.     

Image Intensification in Silver Halide Photographic Materials for Detection of High-Energy Radiation by Reprecipitation of Elemental Silver

A process for the intensification of silver images on AgHal photographic materials designed for detection of high-energy (X- and γ-ray) radiation was proposed, which is based on the “reprecipitation” of elemental silver and a decrease in its dispersion and comprises the treatment of silver with an aqueous solution containing potassium hexacyanoferrate(III) and potassium chloride or bromide at the first step and with a solution containing tin(II) chloride, potassium thiocyanate, sodium N,N′-ethylenediamine tetraacetate, and potassium hydroxide at the second step. By this process, the optical densities of image over a wide (0.5–2.0) range was increased by a factor of 3–5; as a result, the photographic sensitivity S _0.85 and S _2.00 was enhanced by almost an order of magnitude with the retained or slightly increased gradient g, fog density D ₀, and resolving power of the material.__________Translated from Khimiya Vysokikh Energii, Vol. 39, No. 5, 2005, pp. 373–378.Original Russian Text Copyright © 2005 by Mikhailov, Kondakov, Krikunenko.     

A photosensitive material based on methyl methacrylate-acrylic acid copolymer

The possibility of recording holographic images in a photosensitive material based on methyl methacrylate-acrylic acid copolymer, which is more heat-resistant than poly(methyl methacrylate) used as a base for optical recording media, was examined. Introduction of acrylic acid units into poly(methyl methacrylate) macromolecule does not prevent recording and reconstruction of holographic images, but, at the same time, affects the dynamics of variation of the diffraction efficiency of diffraction lattices recorded in this polymer.     

Titanium(IV) <Emphasis Type="Italic">tert</Emphasis>-Butoxide-<Emphasis Type="Italic">tert</Emphasis>-Butyl Hydroperoxide System as Oxidant for C-H Bonds in Hydrocarbons and Oxygen-containing Compounds

The system Ti(IV) tetra-tert-butoxide-tert-butyl hydroperoxide in mild conditions (20°C) oxidizes C-H bonds of methyl (toluene), methylene (hexane, ethylbenzene, benzyl ethyl ether), and methine (1, 1-diphenylethane, triphenylmethane) groups. The role of oxidant is played by the oxygen generated by the system. The process involves free radicals and produces hydroperoxides and Ti(IV) peroxides. The latter decompose both with preservation and decomposition of the hydrocarbon skeleton.__________Translated from Zhurnal Obshchei Khimii, Vol. 75, No. 4, 2005, pp. 545–551.Original Russian Text Copyright © 2005 by Stepovik, Gulenova, Martynova.     

Holographic grating recording in azobenzene functionalized polymers

A group of 22 polymers have been synthesized to test their suitability for recording holographic gratings. Polyamides, polyimides, polyesters and their combinations were functionalized with pendant azobenzene groups containing single or double N=N. The polymers were studied using a standard degenerate two-wave mixing technique, which enables measurement of light-induced periodic modification of polymer refractive index and absorption coefficient by analysis of the diffracted light. Two qualitatively different configurations of the holographic polarization recording were used, s-s and s-p. The relationship between structural properties of polymer matrix and azobenzene groups and the holographic grating recording kinetics and light diffraction efficiency was investigated.     

Reaction of Organoelement Hydrides R<Subscript>3</Subscript>EH (E = Si,Ge) with Metal <Emphasis Type="Italic">tert</Emphasis>-Butylate (M = Al,Ti)-<Emphasis Type="Italic">tert</Emphasis>-Butyl Hydroperoxide Oxidative Systems

Trialkyl(aryl)silanes and -germanes effectively react with metal (Al, Ti) tert-butylate-tert-butyl-hydroperoxide under mild conditions (room temperature, benzene or tetrachloromethane) mainly by the element-hydrogen bond. The character of the products depends on the nature of the element, the structure of the radical bound to it, and the solvent. The process is radical in nature. It includes the stages of formation of element-centered radicals and their reaction with the oxygen generated by the system. The intermediate organometallic peroxides can also acts as oxidants for the element (Si, Ge)-hydrogen bonds.__________Translated from Zhurnal Obshchei Khimii, Vol. 75, No. 7, 2005, pp. 1161–1170.Original Russian Text Copyright © 2005 by Stepovik, Gulenova, Martynova, Skvortsov, Cherkasov.     

Polarization holographic optical recording based on a new photochromic diarylethene compound

A new unsymmetrical photochromic diarylethene, namely1-[2-methyl-5-(p-N,N-dimethylaminophenyl)-3-thienyl]-2-[2-methyl-5-(3-methoxylphenyl)-3-thienyl] perfluorocyclopentene (1a), was synthesized. The compound showed good photochromism, high sensitivity and remarkable fatigue-resistance both in solution and in poly(methyl methacrylate) (PMMA) matrix with UV/Vis light irradiation. The absorption maximum of its closed-ring isomer was observed at 624 nm in PMMA amorphous film. It is a nice match for the wavelength of the recording laser (633 nm). Using this target compound as recording medium, four types of polarization holographic optical recordings were performed successfully using a He-Ne laser. The results showed that only the orthogonal circular polarization recording could obtain a hologram with high diffraction efficiency and high signal-to noise-ratio. With multiplexing recording technology, three types of polarization multiplexing holographic optical recordings, including angular multiplexing, polarization multiplexing, and angular plus polarization multiplexing holographic recording, were also carried out perfectly based on its photoinduced anisotropic phenomenon accompanying the photochromic reaction by photoirradiation. The results demonstrate that the multiplexing recording technology is an effective method to improve recording capacity when using diarylethene 1 as recording medium.     

Molecular Structure of Bis(trimethylsilyl) Hypophosphite HP(OSiMe3)2 by Gas-Phase Electron Diffraction and Quantum Chemistry

Geometric parameters and conformation of the bis(trimethylsilyl)hypophosphite molecule were determined by gas-phase electron diffraction and quantum-chemical calculations. The molecule has an asymmetric structure, including an asymmetric P(OSiMe₃)₂ group. The principal geometric parameters are as follows: (r _a; in parentheses are standard deviations): bond lengths: P-O 1.616 and 1.633(1), Si-O 1.670(1), Si-C 1.892(1), C-H 1.097(3) Å; bond angles: OPO 100.8(8), POSi 133.3, and 138.4(3)°; torsion angles about P-O bonds 120(2) and 41.(3)°; and torsion angles about Si-O bonds are 145 and −178(4)°.__________Translated from Zhurnal Obshchei Khimii, Vol. 75, No. 6, 2005, pp. 897–902.Original Russian Text Copyright © 2005 by Naumov, Oberhammer, Tafipol’skii.     

Photophysical properties of polymers with a system of conjugated bonds and their use in light energy conversion processes

We consider the photophysical properties of polymers with a system of conjugated bonds and their use in light energy conversion processes. Based on our analysis of literature data we show that conjugated polymers of different classes (capable of exhibiting the properties of a dielectric, a semiconductor, or a metal) are characterized by efficient photoconductivity, photoluminescence, and electroluminescence. We determine the regularities in the dependence of the photophysical characteristics on the nature and structure of the conjugated polymers, their degree of doping, the energy and intensity of the incident light, the temperature, etc. In a series of polymers we show that conjugated polymers can be used in particular as photoconductors, electrophotographic materials, materials for lasers, electroluminescent diodes, and also solid-state photoconverters of light energy etc.Translated from Teoreticheskaya i Éksperimental'naya Khimiya, Vol. 30, No. 5, pp. 241–263, September–October, 1994.     

Self-Processing,Diffusion-Based Photopolymers for Holographic Applications

The new photopolymers for holographic applications described herein are based on a cross-linked matrix in which the holographic grating is formed by photo-polymerization of guest monomers in an interference pattern of the recording light. Diffusion of monomer, triggered by this photo-polymerization, from the dark to the bright fringes of the interference pattern is the key parameter for creating high modulation in refractive index Δn during hologram recording. This leads to bright visual volume holograms with high diffraction efficiency. The holographic photopolymers are self-processing. After recording the hologram only (incoherent) light exposure is necessary to bleach the final product and fix the hologram. Unlike earlier photopolymers used in holography, these new materials offer the advantages of no chemical or thermal processing combined with low shrinkage and detuning. Additionally, due to good light sensitivity the formation of the holograms is fast and the film obtained after curing is highly transparent, which makes the material suitable for both, reflection and transmission holography.     

Vibrational spectra,structures, and conformations of conjugated azomethines — 3-imidazoline derivatives

The possibility of the use of the ratios of the intensities of the v _C=N bands in the Raman spectra of the compounds to establish the conformations of the conjugated C=N bonds was demonstrated in the case of conjugated azomethines — derivatives of 2,2,5,5-tetramethyl-3-imidazoline and — 3-imidazoline 3-oxide.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 6, pp. 792–797, June, 1987.     

Photodielectric Polymers for Holographic Use

The use of polymeric materials as “thick” recording media for holographic applications is discussed. These materials offer some interesting applications owing to their high diffraction efficiency, high storage density, excellent angular and spectral discrimination, as well as in situ real-time recording. The present state of art is outlined, as are prospects for the future.     

Extending bond orbital-connection matrix method to the QSPR study of alkylbenzenes: Some thermochemical properties

The properties of alkylbenzenes were estimated, using the contributions of the σ bonds, the conjugated π bond and the steric effect in alkylbenzene molecule. And a novel bond orbital-connection matrix, conjugated π bond orbital-connection matrix in aromatic molecules, was proposed. The eigenvalues of the conjugated π bond orbital-connection matrix can well express the contribution of the conjugated π bond to the properties of aromatic molecules. Using this eigenvalue together with the parameters proposed in our early works, the bond orbital-connection matrix method was extended successfully to the QSPR studies of alkylbenzenes and a general model was obtained to evaluate the thermochemical properties of alkylbenzenes, that is,

p_{(alkylbenzene)}=aN_C–C+b∑X_1CC+cN_C–H+d∑X_1CH+eS_Z/E+k∑X_1π,