Synthesis and crystallographic, spectroscopic and computational characterization of 3,3′,4,4′-substituted biphenyls: effects of ORsubstituents on the intra-ring torsion angle

Abstract

Presented here are the synthesis, characterization and study (using single crystal X-ray diffraction, Raman scattering, quantum mechanics calculations) of the structures of a series of biphenyls substituted in positions 3, 3 0 , 4 and 4 0 with a variety of R (R = methyl, acetyl, hexyl) groups connected to the biphenyl core through oxygen atoms. The molecular conformation, particularly the torsion angle between aromatic rings has been extensively studied both in the solid as well as in the liquid state. The results show that the compounds appearing as rigorously planar in the solid present instead a twisted conformation in the melt. The solid versus melt issue strongly suggests that the reasons for planarity are to be found in the packing restraints. A 'rule of thumb' is suggested for the design of biphenyls with different molecular conformations, based on the selection of the OR substituent. research papers Acta Cryst. (2020). B76, 366-377 N. Vadra et al. OR substituents effects on the torsion angle of biphenyls 367 † We report here the total sum of the interactions between chains and C-HÁ Á Á (in brackets the numbers of BCP involved in each compound), which individual values range between 0.15-0.55 (for ) and 0.05-0.17 (for r 2 ). See Fig. SI2.