Self-Assembly of Antiferromagnetically-Coupled Copper(II) Supramolecular Architectures with Diverse Structural Complexities

Abstract

The self-assembly of 2,6-diformyl-4-methylphenol (DFMP) and 1-amino-2-propanol (AP)/2-amino-1,3-propanediol (APD) in the presence of copper(II) ions results in the formation of six new supramolecular architectures containing two versatile double Schiff base ligands (H3L and H5L1) with one-, two-, or three-dimensional structures involving diverse nuclearities: tetranuclear [Cu4(HL2−)2(N3)4]·4CH3OH·56H2O (1) and [Cu4(L3−)2(OH)2(H2O)2] (2), dinuclear [Cu2(H3L12−)(N3)(H2O)(NO3)] (3), polynuclear {[Cu2(H3L12−)(H2O)(BF4)(N3)]·H2O}n (4), heptanuclear [Cu7(H3L12−)2(O)2(C6H5CO2)6]·6CH3OH·44H2O (5), and decanuclear [Cu10(H3L12−)4(O)2(OH)2(C6H5CO2)4] (C6H5CO2)2·20H2O (6). X-ray studies have revealed that the basic building block in 1, 3, and 4 is comprised of two copper centers bridged through one μ-phenolate oxygen atom from HL2− or H3L12−, and one μ-1,1-azido (N3−) ion and in 2, 5, and 6 by μ-phenoxide oxygen of L3− or H3L12− and μ-O2− or μ3-O2− ions. H-bonding involving coordinated/uncoordinated hydroxy groups of the ligands generates fascinating supramolecular architectures with 1D-single chains (1 and 6), 2D-sheets (3), and 3D-structures (4). In 5, benzoate ions display four different coordination modes, which, in our opinion, is unprecedented and constitutes a new discovery. In 1, 3, and 5, Cu(II) ions in [Cu2] units are antiferromagnetically coupled, with J ranging from −177 to −278 cm−1.

Keywords

• self-assembly of supramolecular architectures
• antiferromagnetically-coupled copper(II) complexes
• magneto-structural correlations
• phenolate and azido bridged copper(II) complexes