Dihedral angle of biphenyl in solution and the molecular force field

Abstract

The dihedral angle between the rings of biphenyl is determined to be 32 ± 2° in the molten and solution states. Observed vibrational frequency shifts on going from the planar configuration held in the crystal to the non-planar solution state are compared with computed frequency shifts. To improve the accuracy in the computed frequencies the force constants were refined. The values of the force constants associated with the inter-ring bond are discussed.