In this hypothetical example of an interaction between a chiral stationary phase (left) with an enantiomer of a biphenyl derivative (right), there is a three-point interaction, with the carboxy groups aligning with the amino groups and the aromatics lining up with each other to form pi stacking interactions. The enantiomer of this biphenyl would not be able to have all three of these interactions because its groups would not be aligned correctly, and, consequently, it would stick less to the chiral stationary phase and filter off the column first.
Substituted biphenyls and have many uses. They are prepared by various coupling reactions including the Suzuki-Miyaura reaction and the Ullmann reaction . Polychlorinated biphenyls were once used as cooling and insulating fluids and polybrominated biphenyls are flame retardants . The biphenyl motif also appears in drugs such as diflunisal and telmisartan . The abbreviation E7 stands for a liquid crystal mixture consisting of several cyanobiphenyls with long aliphatic tails used commercially in liquid crystal displays . A variety of benzidine derivatives are used in dyes and polymers. Research into biphenyl liquid crystal candidates mainly focuses on molecules with highly polar heads (for example cyano or halide groups) and aliphatic tails.