Molecular recognition: Use of metal-containing molecular clefts for supramolecular self-assembly and host-guest formation

Molecular clefts consisting of a rigid spacer linked to two parallel cofacially disposed terpy-M-X (M = Pd2+, pt(2+)) units, which can vary in separation from 6.6 to 7.2 angstrom, have been used as molecular receptors and for self-assembly with linear and triangular linkers to produce rectangles and trigonal prisms, respectively. Aromatic molecules form multiple host-guest adducts with the molecular cleft receptors and with the rectangles and trigonal prisms. Planar complexes of pt(2+) also form host-guest adducts. The forces that control this molecular recognition, namely, pi-pi interactions, charge-induced dipole interactions, charge-charge forces, weak metal-metal interactions and solvation effects, are discussed and assigned to the various adducts. (c) Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005.