Continuously changing the conformational dependence of saponite hybrid materials on the intercalation degree: Electric linear dichroism of stilbazolium derivatives intercalated in saponite clay

The molecular alignmet of 2- and 4-[4-(dimethylamino)styryl]-1-ethylpyridin ium cations (2- and 4-DASEP, respectively) adsorbed on saponite clay and su spended in N,N-dimethylformamide (DMF) has been investigated by the electri c linear dichroism (ELD) method. An ELD analysis of the saponite clay compl ex involving 4-DASEP molecules in DMF indicated that although the tilt angl e of the 4-DASEP molecular plane increased considerably from 14.1 to 32.1 d egrees, the roll angle remained constant at ca. 31 degrees, 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 su rfaces slightly increased with the same coverage degrees. The change in til t and roll angles in the 2- and 4-DASEP molecules may be significantly infl uenced by the structural variation of the guest molecules, especially the s teric hindrance around the pyridinium N+ atoms. The conformational structur e of the adsorbed stilbazolium cations in saponite is discussed based on th ese results.