Densities, electrical conductances, and spectroscopic properties of glycyl dipeptide +ionic liquid ([C_(12)mim]Br) +water mixtures at different temperatures

摘要

Densities, conductivity, fluorescence and UV-vis absorption spectroscopy of glycyl dipeptide + ionic liquid (l-dodecyl-3-methylimidazolium bromide ([C_(12)mim]Br))+water mixtures have been measured at different temperatures. From density data, the standard partial molar volume (V_(2,?)~0),standard partial molar volume of transfer for three glycyl dipep tides from water to aqueous [C_(12)mim]Br solutions (A_tV~0), partial molar expansibility (E_?~0) and Hepler's constant have been calculated. Through the electrical conductivity measurements, the critical micellar concentration (c_(cmc)) and a series of thermodynamic parameters of micellization of [C_(12)mim]Br in aqueous glycyl dipeptide solutions are evaluated. Effects of temperature and hydrocarbon chain length of the glycyl dipeptides on the volumetric properties of dipeptides and critical micelle concentration (c_(cmc)) of [C_(12)mim]Br were examined. The pyrene fluorescence spectra were used to study the change of micropolarity produced by the interactions of [C_(12)mim]Br with glycyl dipeptides, and the aggregation behavior of [C_(12)mim]Br. From the results of UV-vis absorption spectra, the binding constant between dipeptide and [C_(12)niim]Br above the c_(cmc) was determined.