Atropisomerism in bisphenols: free jet absorption millimeter wave study of 2,20-biphenol

The rotational spectrum of 2,20-biphenol has been investigated by millimeter wave absorption free jet spectroscopy. The two sides of the phenyl rings with attached the hydroxyl group form a dihedral angle of 112.78. Each hydroxyl group is nearly co-planar to the ring to which it belongs, and points towards the p system of the adjacent ring. q 2004 Elsevier B.V. All rights reserved