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Pyridine Units (pyridine + unit)

Distribution by Scientific Domains
Polymers and Materials Science50%
Chemistry50%

Selected Abstracts

Synthesis, Structures, and Biological Activities of New 1H-1,2,4-Triazole Derivatives Containing Pyridine Unit.

CHEMINFORM, Issue 38 2007
Jian-Bing Liu
Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF. [source]

Oligosiloxanediols as building blocks for supra­molecular chemistry: hydrogen-bonded adducts with amines form supramolecular structures in zero, one and two dimensions

ACTA CRYSTALLOGRAPHICA SECTION B, Issue 2 2000
Brian O'Leary
The structure of 1,1,3,3,5,5-hexaphenyltrisiloxane-1,5-diol,pyrazine (4/1), (C36H32O4Si3)4·C4H4N2 (1), contains finite centrosymmetric aggregates; the diol units form dimers, by means of O,H,O hydrogen bonds, and pairs of such dimers are linked to the pyrazine by means of O,H,N hydrogen bonds. In 1,1,3,3,5,5-hexaphenyltrisiloxane-1,5-diol,pyridine (2/3), (C36H32O4Si3)2·(C5H5N)3 (2), the diol units are linked into centrosymmetric pairs by means of disordered O,H,O hydrogen bonds: two of the three pyridine molecules are linked to the diol dimer by means of ordered O,H,N hydrogen bonds, while the third pyridine unit, which is disordered across a centre of inversion, links the diol dimers into a C33(9) chain by means of O,H,N and C,H,O hydrogen bonds. In 1,1,3,3-tetraphenyldisiloxane-1,3-diol,hexamethylenetetramine (1/1), (C24H22O3Si2)·C6H12N4 (3), the diol acts as a double donor and the hexamethylene­tetramine acts as a double acceptor in ordered O,H,N hydrogen bonds and the structure consists of C22(10) chains of alternating diol and amine units. In 1,1,3,3-tetraphenyldi­siloxane-1,3-diol,2,2,-bipyridyl (1/1), C24H22O3Si2·C10H8N2 (4), there are two independent diol molecules, both lying across centres of inversion and therefore both containing linear Si,O,Si groups: each diol acts as a double donor of hydrogen bonds and the unique 2,2,-bipyridyl molecule acts as a double acceptor, thus forming C22(11) chains of alternating diol and amine units. The structural motif in 1,1,3,3-tetra­phenyldisiloxane-1,3-diol,pyrazine (2/1), (C24H22O3Si2)2·C4H4N2 (5), is a chain-of-rings: pairs of diol molecules are linked by O,H,O hydrogen bonds into centrosymmetric R22(12) dimers and these dimers are linked into C22(13) chains by means of O,H,N hydrogen bonds to the pyrazine units. 1,1,3,3-Tetraphenyldisiloxane-1,3-diol,pyridine (1/1), C24H22O3Si2·C5H5N (6), and 1,1,3,3-tetraphenyldisiloxane-1,3-diol,pyrimidine (1/1), C24H22O3Si2·C4H4N2 (7), are isomorphous: in each compound the amine unit is disordered across a centre of inversion. The diol molecules form C(6) chains, by means of disordered O,H,O hydrogen bonds, and these chains are linked into two-dimensional nets built from R66(26) rings, by a combination of O,H,N and C,H,O hydrogen bonds. [source]

3,4-Ethylenedioxythiophene,Pyridine-Based Polymers: Redox or n-Type Electronic Conductivity?

ADVANCED MATERIALS, Issue 24 2002
C.J. DuBois
A family of polymers based on alternating bi-EDOT and pyridine units is reported. Poly(BEDOT-PyrPyr-Ph2), with a bandgap of 1.2 eV, has four electrochemically accessible colors (dark gray, burgundy, lime green, and light gray) each corresponding to a distinct redox state. In-situ conductance measurements illustrate high n-type doping conductances only thirty times less than those of the p-type doping conductances. [source]

Polymer electrolyte membranes for high-temperature fuel cells based on aromatic polyethers bearing pyridine units

POLYMER INTERNATIONAL, Issue 11 2009
Joannis K Kallitsis
Abstract This review is focused on the design and synthesis of new high-temperature polymer electrolytes based on aromatic polyethers bearing polar pyridine moieties in the main chain. Such materials are designed to be used in polymer electrolyte fuel cells operating at temperatures higher than 100 °C. New monomers and polymers have been synthesized and characterized within this field in respect of their suitability for this specific application. Copolymers with optimized structures in order to combine excellent film-forming properties with high mechanical, thermal and oxidative stability and controlled acid uptake have been synthesized which, after doping with phosphoric acid, result in ionically conducting membranes. Such materials have been studied in respect of their conductivity under various conditions and used for the construction of membrane-electrode assemblies (MEAs) which are used for fuel cells operating at temperatures up to 180 °C. New and improved, in terms of oxidative stability and mechanical properties in the doped state, polymeric membranes have been synthesized and used effectively for MEA construction and single-cell testing. Copyright © 2009 Society of Chemical Industry [source]