Tetraarylbiphenyl as a New Lattice Inclusion Host by Structure Reductionism: Shape and Size Complementarity Based on Torsional Flexibility

3,3′,5,5′-Tetrakis­(2,6-dimethyl-4-methoxyphenyl)­biphenyl
(TB) was designed as a lattice inclusion host based on
a structure reductionistic approach. TB binds guests
in two different domains based on the premise that the two phenyl
rings of the biphenyl core remain coplanar in the solid state. The
versatility of TB as a host has been demonstrated by
its ability to include different guest molecules in the crystal lattice,
as revealed by X-ray crystal structure analyses. One observes preference
for guest location in the concave domain with the trough domain compromised.
The host TB is found to exploit torsional freedom about
the central σ-bond between the two phenyl rings of the biphenyl
core to adopt discrete structures that are complementary in terms
of shape and size to include a given guest. In other words, TB behaves like a “molecular chameleon” that
undergoes structural adaptation in response to the guest via torsional
twist about the central σ-bond. Quite remarkably, the inclusion
compounds with different guests having similar torsional angles between
the phenyl rings of the biphenyl core are found to be isostructural.
The torsion-induced structural morphosis in response to the guest
is found to completely offset binding in the trough region.