The "one-pot" synthesis and characterization of a large 28-mer macrocycle (H(4)L(2)) with oxamido units capable of complexing guest ions through oxygen or nitrogen donor atoms is reported. Single-crystal structure determination of H(8)L(2)(NO(3))(4) and (Cu(2)[H(2)L(2)](H(2)O)(2))(NO(3))(2) demonstrated that the macrocycle contains two sites capable of complexing two nitrate anions or two copper(II) ions, involving a large structural reorganization in the conformation of the macrocyclic framework on coordination of the copper(II) ions when compared to the nitrate. Electrochemical and magnetic susceptibility measurements on the dinuclear Cu(II) complex and the related mononuclear and trinuclear Cu(II) complexes derived from the related 14-mer macrocycle were carried out and illustrate the role of the oxamido groups in mediating metal-metal interaction and delocalization.

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Complexes of the ligand 2,3-dioxo-1,4,8,11-tetraaza-cyclotetradecane (exoO(2)-cyclam) have been prepared of formula [M(1){M(2)(exoO(2)-cyclam)}(2)][BPh(4)](2) where M(1)M(2) = CoCo (3), ZnZn (4), MnCu (5), FeCu (6), CoCu (7), NiCu (8), ZnCu (9), and [(bipy)(2)Ru{Cu(exoO(2)-cyclam)}][NO(3)](2) (10). Complex 10 crystallised in the space group C2/c and shows Jahn-Teller distorted Cu(II) with axial nitrate ligands. The {Cu(exoO(2)-cyclam)} moiety chelates to the Ru with Ru-O distances of 2.082(5) A. Complexes 5-10 show a Cu(II)/Cu(III) redox process and additional metal-centred (6, 8, 10) processes and ligand-centred (10) processes. The electrochemical and UV-Vis spectroelectrochemical study of suggested two closely-spaced oxidations based on the Cu and Ru centres which suggests that substituted derivatives of will be of interest for enhanced charge separation in dye-sensitised solar cells. Magnetic susceptibility measurements revealed dominant antiferromagnetic coupling within the trinuclear species 3, 5-8. Complex 10 showed Curie-Weiss behaviour with weak intermolecular interactions.