Role of arene interactions and substituent effects in conformational (syn/anti) control of 1,2-diarylethanes

Conformational analysis of nine designed flexible 1,2-diarylethanes with different substituents show syn conformation due to pi-pi interactions by H-1 NMR in solution, this carries over to the solid state for three compounds while two show anti conformation in the solid state by X-ray crystallography and the remaining compounds do not give diffraction quality crystals.