Alexander L. Rusanov

Aromatic Symmetric Cyclotrimers and Poly(arylenevinylene)s with Branched Aromatic Substituents in Vinylene Groups. Synthesis and Optical Properties

New poly(arylenevinylene)s were realized by Ni 0 -catalyzed polymerization of aromatic dibromides, containing vinylene groups substituted completely with branched oligophenylenes. The monomers were synthesized by acylation of 1,3,5-triphenylbenzene or 1,3,5-tri-diphenylyl)benzene with 4-bromobenzoyl chloride followed by the McMurry homocondensation in the presence of TiCl 4 and Zn. Model cyclotrimers with 1,3,5-trisubstituted benzene core were synthesized and characterized. Their molar extinction coefficients and luminescence quantum yields were in the ranges (0.5-1.5) . 10 5 M -1 . cm -1 and 29-72%, respectively. The highest quantum yield 92% promising for further photophysical investigation was found for the cyclotrimer with tolan as substitutent. The quantum yield of the cyclotrimers depended on both the symmetry of molecules and the amount of benzene rings in the ambience. The incorporation of the substituents of three-dimensional structure instead of benzene rings led the polymers to become rather highly emissive with fluorescence quantum yields of 22-23% in comparison to the value of 1% of polymer with benzene rings.

Preparation and Characterization of Sulfonated Polyphenylquinoxalines

Poly(phenylquinoxaline)s.(PPQs) are a family of aromatic condensation polymers known for their outstanding thermal and chemical stability. The pendant phenyl groups and chains isomerism improve the solubility and processing characteristics of these polymers. PPQs have also been shown to possess excellent thermo-oxidative stability and thermohydrolytic stability. This stability makes these polymers candidates for development as proton exchange membranes (PEMs) to be used in fuel cells. In addition to thermohydrolytic stability, PEMs require high protonic conductivity and, in order to achieve this they also require high water uptake. Aromatic condensation polymers do not possess these properties, but ionomers derived from them may. The usual method to derivatiziting these polymers is through sulfonation. In the frames of the present investigation we have carried out sulfonation of two PPQs using an H2SO 4—oleum mixture (4 : 1) as sulfonating agent at 125 3C. As a quinoxaline ring is readily formed in acidic medium synthesis of sulfonated PPQs (SPPQs) was also carried out directly from monomers using an H 2SO4—oleum mixture as solvent, catalyst and as sulfonating agent. Depending on the conditions of the reaction (temperature, duration, and the ratio of components in a sulfonating mixture) the polymers containing 0.2—6.7% S were prepared. SPPQs are soluble in polar organic solvents1 from the solutions of SPPQs high strength films (3 = 80—100 MPa) were cast. On the basis of sulfonated PPQs new cation-exchange membranes were prepared and investigated. Among the cation-exchange membranes developed those of the greatest interest are proton-exchanging membranes for fuel cells. Proton conductivity of the membranes prepared strongly depends on relative humidity and comparable with the conductivity of Nafion 117.

Benzophenone-Type Unsymmetrical Substituted Aromatic Diamines and Organosoluble Polyimides Therefrom

Benzophenone-type unsymmetrical substituted aromatic diamines of general formula were prepared starting with p-nitrobenzoyl chloride and substituted benzenes. Interaction of the diamines obtained with aromatic tetracarboxylic acids dianhydrides under the conditions of high-temperature solution polycyclocondensation in m-cresol led to the formation of new high molecular weight organosoluble polyimides.

New Poly(arylene ether sulfone)s Containing Phenolphthalein and Fluorene Moieties in the Main Chain

New poly(arylene ether sulfone)s have been synthesized by solution polycondensation reaction of 2,4-bis[(4-chlorophenyl)sulfonyl]-1-(phenylthio)benzene)] with 4,4-(9-fluorenylidene) bisphenol (FBP) and phenolphthalein (PP). The chemical structure of the polymers was confirmed by using both spectroscopical (FTIR, 1H-NMR) and elemental analysis methods. All the polymers were soluble in aprotic dipolar solvents. The thermal properties were investigated by differential scanning calorimetry and thermogravimetric analysis, and they, were discussed in connection with the chemical structure of the polymers. The investigation of optical properties by photoluminescence spectroscopy revealed that all the polymers displayed one emission peak in the blue domain beetwen 449 and 460 nm.

Aromatic Polyethers based on Meta-activated Dinitrocompounds

Aromatic polyethers containing phenyl sulfone side groups were prepared using aromatic nucleophilic nitrosubstitution reaction. As starting compounds TNT-derived 3,5-dinitrodiphenyl sulfone and 4,4′-bis-[(3-nitro-5-phenylsulfonyl)phenylsulfonyl]diphenyl sulfone containing functional nitro groups activated with electron-withdrawing phenylsulfone meta-substituents were used. Polymers obtained are soluble in wide range of organic solvents and demonstrate large ‘windows’ between their softening and degradation temperatures.

Association Phenomena of Poly(arylene ether sulfone)s in Dimethylformamide

Three poly(arylene ether sulfone)s (two polymers and one copolymer) containing diphenylfluorene, phenolphthalein and 2,4-bis[(4-chlorophenyl)sulfonyl]-1-(phenyltio) benzene)] units were synthesized by the classical Williamson polyetherification reaction. The association phenomenon in N,N-dimethylformamide (DMF) was investigated by different methods: gel permeation chromatography (GPC), viscosity, atomic force microscopy (AFM), fluorescence spectroscopy and dynamic light scattering (DLS). Both AFM and DLS measurements evidenced the formation of aggregates with spherical or ellipsoidal shape at a concentration around 0.05 wt.%. This behavior could be explained by dipole-dipole interactions between macromolecular chains, probably with the participation of solvent molecules, and by H-bonds involving hydroxyl end groups.

New Sulfonated Polyethers and Polynaphthylimides based on TNT Derivatives

New sulfonated and non-sulfonated monomers — dinitro and diamino compounds — were prepared on the basis of 1,3,5-trinitrobenzene (TNB) which is the demethylation product of 2,4,6-trinitrotoluene (TNT). The sulfonated dinitrocompounds interacted with different binuclear bis-phenols under the conditions of aromatic nucleophilic nitrodisplacement reactions. Polyethers of moderate molecular weights were prepared on the basis of dinitrocompound containing electron-withdrawing 3,5-dinitrodiphenyl sulfone-4′-sulfonic acid “bridging” groups. Copolymers and blends with other sulfonated polymers were prepared to improve the film-forming properties of the polyethers developed on the basis of 3,5-dinitrodiphenyl sulfone-4′-sulfonic acid. High molecular weight sulfonated polynaphthylimides were prepared by the interaction of sulfonated diamine containing electron-donating ether group — 3,5-diaminodiphenyl ether-4′-sulfonic acid — with bis(naphthalic anhydride)s. The sulfonated polyethers and polynaphthylimides thus obtained contain sulfonic acid groups in the side chains.

QUANTUM-CHEMICAL STUDY OF REACTIVITY OF CARBOXYLIC ACID DICHLORIDES

ConclusionsThe energies of the lower vacant molecular orbitals can be used as a criterion of the reactivity of carboxylic acid chlorides towards amines.

Quantum chemical interpretation of donor-acceptor properties of aromatic heterocycles

Conclusions1.From quantum mechanical calculations, such heterocyclic substituents as benzoxazol-2-yl, benzimidazol-2-yl, N-phthalimidyl, N-naphthylimidyl and others are electron acceptors relative to the aminogroup.2.The electron affinity of heteryl(phthalic)anhydrides is determined not only by the acceptor properties of the heterocycles, but also by the dimensions of the conjugation system.

A study of the thermal and hydrolytic stability of a number of heterocyclic compounds modelling “ladder-like” polyheteroarylenes

1. n nThe thermal and hydrolytic stability of compounds modelling some “ladder-like” polyhetero-arylenes has been studied in the temperature range from 250 to 550°C. n n n n n2. n nCompounds with benzoylenebenzimidazole rings decompose by two competing mechanisms — homolytic and heterolytic. The decomposition of compositions containing naphthoylenebenzimidazole and benzimidazoloquinazoline rings is determined mainly by radical decomposition reactions. n n n n n3. n nHeterocyclic systems containing s-triazole rings are thermally less stable than systems based on benzimidazole.