ISSN:
0360-6376
Keywords:
Physics
;
Polymer and Materials Science
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
Notes:
The strong influence of medium composition (water/2-propanol mixtures) on the rate of oxidation of 1-substituted dihydronicotinamides by a flavin-containing polyelectrolyte was studied. We found that the coil dimensions of the corresponding copolymer of styrene and vinylbenzyltriethylammoniumchloride without flavin groups dramatically depend on the solvent. Viscometric measurements revealed compact coil conformations in solvents of both high water and high 2-propanol content, but pronounced coil expansion in intermediate mixtures. These changes of polyelectrolyte coil dimensions are related to changes in electrostatic potential of the microreactors. Addition of 2-propanol also results in decrease of substrate enrichments, caused by weakening of nonpolar polymer-substrate interactions, as was demonstrated for 1-carbamoylmethyl-, 1-benzyl-, and 1 decyl-substituted 1,4-dihydronicotinamide substrates. The enormous decrease in rate constant for oxidation of DNAH by 2 upon increasing the 2-propanol content from 10 to 40% (v/v), from k = 3120 to 21 M-1 s-1, can thus be explained as a cooperation of both effects. Evidence for the formation of a charge transfer complex between the polyelectrolyte-bound flavin and the dihydronicotinamide having a long-wavelength absorption is also presented.
Additional Material:
7 Ill.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/pol.1984.170220918
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