Thermodynamics Research Today is a free monthly online journal that collates and summarizes the latest research about Thermodynamics, including details on enthalpy, entropy, energy transitions.

A thermodynamic study on the complexation between riboflavin and a diaminotriazine derivative mediated by triple hydrogen bonds at water/oil interfaces.

Ishizaka S, Nishijima Y, Kitamura N

Division of Chemistry, Graduate School of Science, Hokkaido University, Kita-ku, Sapporo, 060-0810, Japan.

The changes in Gibbs free energy (DeltaG (int)), enthalpy (DeltaH (int)) and entropy (TDeltaS (int)) upon complexation between riboflavin (RF) and N,N-dioctadecyl-[1,3,5]triazine-2,4,6-triamine (DTT), mediated by triple hydrogen bonds at water/carbon tetrachloride, trichloroethylene and chloroform interfaces, were determined via temperature-controlled interfacial tension measurements. It was shown that hydrogen bonding interactions between RF and DTT were best characterized by large and negative DeltaH (int) values, unlike those predicted from either the polarity in each phase or the arithmetic average of the polarities in the two phases. Furthermore, the DeltaH (int) values became more positive as the dielectric constant of the oil phase was increased. These results strongly indicate that DeltaH (int) is governed by the dielectric properties of the oil phase. Adsorption of RF, DTT and the RF-DTT complex at the water/oil interface gave rise to restrictions on the translational and rotational motions of these species, as demonstrated by the DeltaS (int) values observed, which is another characteristic of interfacial complexation. The thermodynamic parameters evaluated in the present study revealed the characteristic complexation behavior that occurs at a water/oil interface, as mediated by hydrogen bonding.

Published 25 September 2006 in Anal Bioanal Chem, 386(3): 749-58.
Full-text of this article is available online (may require subscription).

© 2005-2008 Thermodynamics Research Today. All Rights Reserved.