4-Tritylbenzoic acid. A molecular scaffold for wheel-and-axle host-guest inclusion compounds with a supramolecular axis

4-Tritylbenzoic acid crystallises via the carboxy dimer supramolecular synt hon to produce a wheel-and-axle host lattice that includes different aromat ic solvents in its microporous framework. The clathrate structures were cha racterised by single crystal X-ray diffraction. Solvents like xylenes, chlo robenzene and anisole are included in a channel of cross-sectional area 42 Angstrom(2) with 2:1 host-guest stoichiometry while mesitylene occupies a c hannel of 71 Angstrom(2) as a 1:1 clathrate. The host architecture is robus t and yet adaptive. The carboxy dimer synthon together with the phenyl-phen yl interactions (edge-to-face, ef and offset face-to-face, off) produce rec urring, zigzag tapes of wheel-and-axle supermolecules. A plethora of aromat ic ef and off motifs in the intra- and inter-tape regions modulate the cavi ty area to accommodate solvents of different size/shape. The ability to tun e the pore volume and still retain the target wheel-and-axle topology is a notable feature in this family of isomorphous structures. The unsolvated ac id adopts a different crystal packing with the triphenylmethyl groups filli ng the voids in the structure.