Template-directed hierarchical copper(II)-organophosphonate compounds: Syntheses, crystal structures, magnetic and luminescence properties

Abstract Three new copper organodiphosphonate compounds, [C4N2H14][Cu(hedph2)2], I, [C4N2H12][Cu3(hedp)2(H2O)4], II and [C6N2H18][Cu3(hedp)2].4H2O, III have been synthesized hydrothermally in the presence of copper nitrate, 1-hydroxyethane-1,1-diphosphonic acid (hedpH4) and various organic aliphatic amines. Molecular structure of compound I is formed in presence of templated 1,4-diaminobutane (DAB). One-dimensional ladder structure of compound II and two-dimensional layer structure of III are observed in the presence of templated piperazine (PIP) and 1,6-diaminohexane (DAH), respectively. The coordination behaviour of the diphosphonate ligand and the organic amines play the crucial role for isolating the different dimensionality amongst the hybrid structures. Although, the compounds II and III display eight-membered rings assembled through vertex-sharing Cu-polyhedra and CPO3 tetrahedra, but the higher coordination mode of diphosphonate ligand can make the 2D layer structure of II instead of 1D ladder of I. The dc-magnetic measurements and theoretical fitting of interacting Cu•••Cu exchange interactions exhibit the antiferromagnetic ordering with weak ferromagnetic coupling in higher-dimensional structures. All the compounds are well characterized by powder XRD, IR, elemental and thermal analysis. The magnetic and luminescence properties of compounds I‒III have also been studied.