Twist Angles and Torsional Potentials of 2,2’-Bibenzothiophene, 2,2’-Biindole, and 2,2’-Bibenzofuran

Twist angles and torsional potentials of 2,2'-bibenzothiophene (bi-BT), 2,2'-biindole (bi-BP), and 2,2'-bibenzofuran (bi-BF) were obtained using HF/6-31G(d) methods.Due to the effect of fused benzene rings, both compounds were revealed to have higher rotational barriers and more planar structures at energy minima than 2,2-bithiophene (bi-T), 2,2'-bipyrrole (bi-P), and 2,2'-bifuran (bi-F), respectively.Calculations on 2,2'-binaphtho[2,3-b]thiophene (bi-BBT), 2,2'-bibenzo[h]indole (bi-BBP), and 2,2'-binaphtho[2,3-b]furan (bi-BBF) were also conducted to study the effect of an additional fusion of another benzene ring.