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NMR relaxation study of the interaction of N-alkyl nicotinamides with micelles

Author

Xueyun Sharon Wang, University of the Pacific

Date of Award

1992

Document Type

Thesis - Pacific Access Restricted

Degree Name

Master of Science (M.S.)

Department

Graduate School

First Advisor

Michael J. Minch

First Committee Member

Richard P. Dodge

Second Committee Member

Charles A. Matuszak

Abstract

The mobility of N-alkyl nicotinamides and their solubilization equilibria in surfactant micellar solution were investigated using an NMR paramagnetic relaxation method. The spin-lattice relaxation times (Tl) . for protons of these compounds were measured in pure D₂0 and in cationic surfactant solution in the presence and absence of · a low concentration of paramagnetic Ma²⁺ ions. The rotational motion of these molecules in aqueous phase became slower when the alkyl group changed from methyl to octyl. The increase of the ¹H spinlattice relaxation rate (Rl) of the molecules, when surfactants are added, implies the penetration of these solubilizates into micellar phase. The micelle to water phase distribution coefficient, 1-p, was determined by monitoring the change of Rl of the solubilizates upon addition of paramagnetic ions to the aqueous phase. The mole fraction based distribution coefficient, K_x, as well as the free energy of transfer of N-alkyl nicotinamides from the aqueous phase to the micellar phase were calculated. A model was postulated for the interaction of N -alkyl nicotinamide with micelles. Hydrophobic force between the alkyl chains of the solubilizates and the surfactants accounts for the solubilization of N -alkyl nicotinamides and can force the binding of cationic compounds to cationic micelles · despite charge repulsion. With increasing of the alkyl chain length, the hydrophobic force increases, and the interaction between them becomes stronger, and more N -alkyl nicotinamides are solubilizated into the micellar phase.

Pages

119

Recommended Citation

Wang, Xueyun Sharon. (1992). NMR relaxation study of the interaction of N-alkyl nicotinamides with micelles. University of the Pacific, Thesis - Pacific Access Restricted. https://scholarlycommons.pacific.edu/uop_etds/2233