Polymer Gel with Tunable Conductive Properties: A Material for Thermal Energy Harvesting.

The spontaneous gelation of poly(4-vinyl pyridine)/pyridine solution produces materials with conductive properties that are suitable for various energy conversion technologies. The gel is a thermoelectric material with a conductivity of 2.2-5.

Light-Induced Reactions within Poly(4-vinyl pyridine)/Pyridine Gels: The 1,6-Polyazaacetylene Oligomers Formation.

Cyclic 6-membered aromatic compounds such as benzene and azabenzenes (pyridine, pyridazine, and pyrazine) are known to be light-sensitive, affording, in particular, the Dewar benzene type of intermediates. Pyridine is known to provide the only Dewar pyridine intermediate that undergoes reversible ring-opening. We found that irradiation of photosensitive gels prepared from poly(4-vinyl pyridine) and pyridine at 254 or 312 nm leads to pyridine ring-opening and subsequent formation of 5-amino-2,4-pentadienals.

Blue-violet photoluminescence of 4-isopropyl-pyridine hydroxide crystals.

There is continuing interest in determining essential structural features of polymer gels, which display photoelectric and/or thermoelectric behavior. One such gel is the blend, poly(4-vinylpyridine-co-butyl methacrylate)/poly(4-vinylpyridine), dissolved in liquid pyridine. Following extended aeration of a three-component mixture, which serves as a model for the gel side chain interactions, crystallization of a new molecule, 4-isopropylpyridine hydroxide (IPPOH), occurs.

Photoinduced proton transfer in a pyridine based polymer gel.

We describe an experimental and theoretical consideration of photoexcited proton transfer in a poly(4-vinyl pyridine)/pyridine gel. Evidence was found for two states of a multiple state process analyzed by DFT modeling. According to the latter, following irradiation at 385 nm, the proton donor is the CH group of the polymer main chain and the proton acceptor is the nitrogen of the polymeric pyridine side chain.

4-isopropylpyridine hydroperoxide crystals resulting from the aerobic oxidation of a 4-isopropylpyridine/4-propylpyridine mixture.

We model the interaction of side-chain and end-chain groups of poly(4-vinylpyridine) by a 5:1 molar ratio mixture of 4-isopropylpyridine (side-chain model) and 4-propylpyridine (end-chain model). We find that the 4-isopropylpyridine in the mixture is oxidized in a slow air flow to produce 4-isopropylpyridine hydroperoxide which in turn precipitates as lamellar crystals with monoclinic structure. The fact that the peroxide group is exchanged for the hydrogen of the tertiary carbon demonstrates the high activity of the latter and gives strong support for its involvement in the self-protonation mechanism proposed earlier for the poly(4-vinylpyridine)/pyridine gel.

Photoactive proton conductor: poly(4-vinyl pyridine) gel.

We describe a hydrogen-bonded poly(4-vinyl pyridine)-based dielectric material, in which conductivity can be induced due to the presence of side-chain protonated species that form spontaneously when the polymer is dissolved in pyridine. The conductivity of the proton conductive gel can be controlled by direct irradiation at the proton-transfer center: a reversible change of conductivity was observed in response to the on/off switching of 385 nm wavelength radiation. Over most of the range of intensities used, the proton conductivity exhibited a bimolecular character.

Dynamic of the fluorescence of the complex Zn++/bis-N-carbazolyl-distyrylbenzene.

The discrimination between similar concentrations of the different metal ions is one of the important roles of fluorescent sensors. Here we present the study of the fluorescence dynamic of the chromophore bis-N-carbazolyl-distyrylbenzene (BCDSB) in acetonitrile/water (mmol/L), doped with metal ions such as K+; Ca++; Mg++; Zn++(10 micromol/L). BCDSB has the fluorescence with lambda(max) at 448 nm by excitation at lambda(exc) = 378 nm, lifetime 1.