Continuously Changing the Conformational Dependence of Saponite Hybrid Materials on the Intercalation Degree: Electric Linear Dichroism of Stilbazolium Derivatives Intercalated in Saponite Clay

Abstract

Abstract The molecular alignmet of 2- and 4-[4-(dimethylamino)styryl]-1-ethylpyridinium cations (2- and 4-DASEP, respectively) adsorbed on saponite clay and suspended in N,N-dimethylformamide (DMF) has been investigated by the electric linear dichroism (ELD) method. An ELD analysis of the saponite clay complex involving 4-DASEP molecules in DMF indicated that although the tilt angle of the 4-DASEP molecular plane increased considerably from 14.1 to 32.1°, the roll angle remained constant at ca. 31°, with a coverage of 10 to 100% of 4-DASEP molecular in saponite. In contrast, the tilt and roll angles of the corresponding positional isomer, 2-DASEP, on the clay surfaces slightly increased with the same coverage degrees. The change in tilt and roll angles in the 2- and 4-DASEP molecules may be significantly influenced by the structural variation of the guest molecules, especially the steric hindrance around the pyridinium N+ atoms. The conformational structure of the adsorbed stilbazolium cations in saponite is discussed based on these results.