Self-assembly of rigid three-connecting mesitylenetribenzoic acid: Multifarious supramolecular synthons and solvent-induced supramolecular isomerism

摘要

We have explored O-H···O hydrogen bonded self-assembly of rigid three-connecting mesitylenetribenzoic acid (H_3MTB). The triacid is shown to exploit the acid dimer motif and self-assemble, in the solid state, into a 6-fold interpenetrated (6,3) honeycomb net with the pores of the dimension of ca. 24-26 ?. It is shown that crystallization of H_ 3MTB with K~+/NH_4~ + salts in the presence of 18-crown-6 leads to mono-deprotonation followed by self-assembly of the resultant H_2LMTB~- into multicomponent crystals of different network structures sustained by charge-assisted hydrogen bonds. The X-ray crystal structure analyses reveal that the solvent employed to access the multicomponent crystals plays the role of a chaperon in modifying the supramolecular structures adopted. Crystallization of H_3MTB in the presence of dibenzo-18-crown-6 is found to lead likewise to a (6,3) net that is 6-fold interpenetrated with K~+?dibenzo-18-crown-6 occupying the voids. Thus, the strategy involving partial deprotonation of rationally designed polycarboxylic acids with KX/crown is shown to lead to multicomponent crystals sustained by charge-assisted hydrogen bonds. The structural studies have led to identification of water-mediated paddlewheel and carboxylate·· ·carboxylate dimer synthons.