Self-assembly of D-penicillaminato M6M'8 (M = Ni(II), Pd(II), Pt(II); M' = Cu(I), Ag(I)) clusters and their organization into extended La(III)M6M'8 supramolecular structures.

A series of chiral M(6)M'(8) cluster compounds having twelve free carboxylate groups, M(6)M'(8)(D-pen-N,S)(12)X (M/M'/X = Pd(II)/Ag(I)/Cl(-) (1), Pd(II)/Ag(I)/Br(-) (2), Pd(II)/Ag(I)/I(-) (3), Ni(II)/Ag(I)/Cl(-) (4), Pt(II)/Ag(I)/Cl(-) (5), Pd(II)/Cu(I)/Cl(-) (6); D-H(2)pen = D-penicillamine), in which six cis-M(D-pen-N,S)(2) square-planar units are bound to a M'(8)X cubic core through sulfur-bridges, was synthesized by the reactions of cis-M(D-pen-N,S)(2) with M' in water in the presence of halide ions. These M(6)M'(8) clusters readily reacted with La(3+) in aqueous buffer to form La(III)(2)M(6)M'(8) heterotrimetallic compounds, La(2)1, La(2)2, La(2)3, La(2)4, La(2)5 and La(2)[6]Cl, in which the M(6)M'(8) cluster units are linked by La(3+) ions through carboxylate groups in a 1 : 2 ratio. While the La(III)(2)M(6)Ag(I)(8) compounds derived from 1, 2, 3, 4 and 5 have a 1D helix supramolecular structure with a right-handedness, the La(III)(2)Pd(II)(6)Cu(I)(8) compound derived from 6 has a 2D sheet-like structure with a triangular grid of the Pd(II)(6)Cu(I)(8) cluster units. When aqueous HCl was added to the reaction solution of 6 and La(3+), another La(III)(2)Pd(II)(6)Cu(I)(8) heterotrimetallic compound, La(2)[6]Cl·HCl, in which the Pd(II)(6)Cu(I)(8) cluster units are linked by La(3+) ions to form a 2D structure with a rectangular grid, was produced. The solid-state structures of these La(III)(2)M(6)M'(8) compounds, determined by single-crystal X-ray crystallography, along with the spectroscopic properties of the M(6)M'(8) cluster compounds in solution, are described.