Conformational study and stereodynamics of ortho-substituted ortho-terphenyl and its derivatives

Derivatives of 2,2″-dimethyl-ortho-terphenyl have been prepared and their conformational study was carried out by variable temperature NMR analysis. These molecules showed presence of atropisomers due to the restricted rotation about the aryl-aryl (ArAr) and aryl-CH2 (ArCH2) bonds. The barrier of their interconversion was determined as a function of ΔG‡, the transition state free energy at coalescence temperature.