Luminescence of terbium ions in copolymers containing <Emphasis Type="Italic">N</Emphasis>-vinylcarbazole and vinylamide units of various structures in poly(methyl methacrylate) films

Copolymers of N-vinylcarbazole and N-vinylamides are synthesized by free-radical copolymerization. It is shown that the copolymers of N-vinylpyrrolidone and N-vinylcaprolactam containing 12–21 mol % N-vinylcarbazole units, when dispersed in a poly(methyl methacrylate) matrix, enhance the intensity of luminescence of terbium ions by two orders of magnitude relative to the intensity of luminescence observed in the presence of copolymers with a higher content of N-vinylcarbazole units. This effect is presumably related to the competition of two photophysical processes, excimer formation and electron-excitation energy transfer, occurring in opposite directions.     

Macromolecular ligands carrying side bipyridyl-containing groups and their metal-polymer complexes with iridium

A series of copolyamides carrying side bipyridyl-containing groups and their metal-polymer complexes with iridium were synthesized. The stress-strain, thermal, molecular-weight, and luminescent characteristics of these compounds were examined. All the polymers synthesized exhibit high performance in the stress-strain characteristics and high thermal stability.     

Synthesis of Silver Glyconanoparticles Based on 3-Thiopropionylhydrazones of Mono- and Disaccharides

A method of synthesis of silver glyconanoparticles with average particle size 15–40 nm and low polydispersity index based on available 3-thiopropionylhydrazones of mono- and disaccharides has been elaborated. The prepared compounds have exhibited high antifungal, antibacterial, and antiviral activity and are promising for further comprehensive study.     

Condensation Products of D-Ribose with Thiol-Containing Hydrazides and Gold Glyconanoparticles Thereof

The accessible D-ribose mercaptoacetyl-, 3-mercaptopropionyl-, and 2-mercaprobenzoylhydrazones were used to develop a method of synthesis of gold glyconanoparticles with the average particle diameter of 10–40 nm and a low polydispersity index.     

Polyimides from complexes of benzophenonetetracarboxylic acid diesters with diamines. 5. Mechanism of thermal cyclization of H-complexes

The results of a study, by thermal mass spectrometric analysis and NMR spectroscopy, of the polycondensation of H-complexes are presented from which it is possible to propose a mechanism for the reaction. It is shown that conversion of the H-complexes into polyimides takes place through the formation of intermediate zwitterions with an amino acid bond after initial separation of methanol, following which elimination of water commences in one stage to form an imide ring. The role of theortho position of the functional groups in the acid ester during the formation of the hydrogen bond is discussed.Institute of Macromolecular Compounds, Russian Academy of Sciences, 199004 St. Petersburg. Translated fromIzvestiya Akademii Nauk, Seriya Khimicheskaya, No. 11, pp. 2517–2524, November, 1992.     

Luminescence of Ln3+ lanthanide complexes in polymer matrices

The photoluminescence properties of Tb³⁺ and Eu³⁺ complexes with polymer ligands containing various kinds of complexing groups??namely, carboxyl (5?C20 mol %), pyridylquinoline (5 mol %), or pyridylnaphthyl (5 and 10 mol %) groups??in solution and block are considered. The chemical structure of a neutral comonomer (methyl methacrylate; styrene; isopropyl-, phenyl-, or benzylmethacrylamide; and N-vinylamides) in polymer ligands is varied. The intensity of photoluminescence is dependent not only on the chemical nature of a complexing group but also the chemical nature of a neutral comonomer and a spacer. Variation in the nature of a comonomer and a ligand makes it possible to prepare complexes in which a high luminescence of a low-molecular-mass complex is preserved and advantages inherent in a polymer complex are acquired. The effect of the nature of the polymer matrix (photoactive and photoinert) on the efficiency of electronic-excitation energy transfer is ascertained. The data on the photoluminescence of metal-polymer complexes that are based on polymer ligands containing vinylcarbozole units and that possess hole conductivity make it possible to regard them as materials for electroluminescence. The intensity of photoluminescence of these complexes is related to the competition of oppositely directed photophysical processes in a macromolecule: formation of excimers and migration of electronic excitation energy. An analysis of the published data and of the results of the authors shows that detailed studies of these polymer systems in solution and in matrices are needed to gain insight into the relationship between photo- and electroluminescence properties of metal-polymer complexes, because the matrix plays different roles in photoluminescence and electroluminescence (inner filter or conduction); as a consequence, the emission spectra may differ appreciably. It is shown that the efficiency of electroluminescence may be improved if the transfer of energy from the lanthanide ligand in a complex to the conducting matrix is decreased.     

Third-harmonic and sum-frequency generation in a quadratically nonlinear polymer by time-ordered ultrashort laser pulses

Third-harmonic and sum-frequency generation in quadratically nonlinear azopolymer films is experimentally studied using femtosecond chromium forsterite laser pulses. A noncollinear geometry of sum-frequency and third-harmonic generation developed and implemented in this work allows the influence of the time ordering of ultrashort laser pump pulses on nonlinear-optical phenomena to be experimentally observed. Femtosecond laser pulses induce transitions of azopolymer molecules to an electronically excited state and produce vibrational wave packets, leading to an asymmetry in the dependence of the efficiency of second-and third-order nonlinear-optical processes on the delay time between the pump pulses.     

Synthesis and electrochemical properties of ruthenium(II) complexes with biquinoline-containing polyamic acids—Polybenzoxazinone prepolymers

New polyamic acids with biquinoline units in the backbone, which are prepolymers of polybenzoxazinones, as well as their metal-polymer complexes containing [Ru(bpy)₂]²⁺, were prepared. The electronic structure of these polymers was studied with the use of cyclic voltammetry, electronic absorption spectroscopy, and quantum-chemical calculations, and the location sites of electronic changes upon electrochemical reduction and oxidation were determined.     

Nature of the nonlinear second-order optical susceptibility in molecular materials with C 2v molecular symmetry

The method of second-harmonic generation at the wavelength 1.06 μm is used to study the nonlinear second-order optical susceptibility of polycrystalline molecular materials with C _2v molecular symmetry belonging to the group of 2,6-dibenzadiene substituted cyclohexanes. The magnitude of the second harmonic signal is comparable to or greater than its value for polycrystalline urea and depends on the type of substituent (the stronger the donor properties of the substituent, the stronger the signal). It is shown that in the majority of the compounds investigated the large nonlinear optical polarizability observed is associated with the octupole moment of the molecule. Fiz. Tverd. Tela (St. Petersburg) 39, 1687–1689 (September 1997)     

Film Composites of polyimide with polyaniline and poly(aniline-<Emphasis Type="Italic">co</Emphasis>-anthranilic acid)

New two-component composite polymer films are prepared and studied in terms of thermal stability and stress-strain properties. The matrix component of the composite is polyimide based on 3,3′,4,4′-(1,3-diphenoxybenzene)tetracarboxylic dianhydride and 4,4′-bis(4″-aminophenoxy)diphenyl sulfone. Another component is polyaniline or the copolymer poly(aniline-co-2-aminobenzoic acid). Composite films are cast from mixed solutions of individual polymers in N-methyl-2-pyrrolidone. Interpolymer interactions in polyimide composites with polyaniline or the copolymer of aniline and 2-aminobenzoic acid are investigated via viscometry and IR spectroscopy. The thermal treatment of composite films with poly(aniline-co-2-aminobenzoic acid) results in decarboxylation of the copolymer and formation of polyimide-polyaniline composite films. The morphology, microphase structure, and porosity of the composite films are different from those of the films cast from solutions of polyimide-polyaniline mixtures.