Hierarchical multicomponent assembly utilizing sequential metal–ligand and hydrogen-bonding interactions

Abstract

The solid state structures of the copper(II) Schiff base complexes [{Cu(1)}(H2O)], [Cu(1)(OH2)]·MeCN and [({Cu(1)}(H2O))2(2)] (H21 = N,N′-(1R,2R)-(–)-1,2-cyclohexylenebis(3-ethoxysalicylideneamine) and 2 = naphthalene-2,6-dicarboxylic acid) exhibit two recurring structural motifs: host–guest, hydrogen-bonded recognition of H2O in the O,O′,O″,O‴-cavity of [Cu(1)], and face-to-face stacking of [Cu(1)] units with non-bonded Cu⋯Cu separations of 3.54–4.89 A. In [{Cu(1)}(H2O)], the H2O molecule is non-coordinated to the copper(II) centre whereas in [Cu(1)(OH2)]·MeCN it is axially bound to the copper(II) atom while retaining its role as a hydrogen-bonded guest in the O,O′,O″,O‴-cavity of an adjacent [Cu(1)] molecule. The guest H2O molecule in [{Cu(1)}(H2O)] can function as a hydrogen bond donor as illustrated by the assembly of [({Cu(1)}(H2O))2(2)]. Solution (in THF) electronic spectroscopic data for the complexes are consistent with dissociation of the building blocks including the cleavage of the Cu–OH2 coordination bond. The self-assembly and structural diversity are discussed in terms of a series of hierarchical events.