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

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posted on 2015-05-06, 00:00 authored by Ishita Neogi, Alankriti Bajpai, Govardhan Savitha, Jarugu Narasimha Moorthy
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.