Hideyuki Minami

Molecular Self-Assembling of -Methylacetamide in Solvents

The self-association of 𝑁-methylacetamide (NMA), which is one of the most simple compound having a peptide bond, in various solvents such as carbon tetrachloride (CCl4), chloroform, dichloromethane, and acetonitrile was studied through the near-infrared (NIR) spectroscopic observation at various temperatures and concentrations. An analysis assuming a successive association processes for the NMA molecules was applied to the sharp 1470-nm band (the first-overtone band of NH stretching vibration mode attributed to free NH group of NMA monomer and partly to the free, terminal NH group of NMA aggregate); the mean association number for NMA in CCl4 increases with increasing concentration and decreases with increasing temperature. Comparisons of the association number of NMA in various solvents indicate that the degree of association is in the following order: CCl4≫ chloroform ≒ dichloromethane > acetonitrile. Interestingly, the association number of NMA in CCl4 is thought to be larger than that in its pure liquid.

Equilibrium Spreading Pressure of Steroids

Abstract Equilibrium spreading pressure (ESP) for the three kinds of steroids, i.e., (I) 5-cholesten-3β-ol, (II) 5α-cholestan-3β-ol, and (III) 5β-cholestan-3α-ol, was measured as a function of temperature and discussed thermodynamically in connection with their π-A relationships and the thermal results such as the melting point and the heat of fusion. It became clear that the direction of the OH moiety positioned at the 3rd-carbon atom of the steroid molecule gives a considerably large effect on the various thermodynamic properties in the solid states or in the monolayers on the water surface.