In situ generation of functionality in a reactive binicotinic-acid-based ligand for the design of multi-functional copper(ii) complexes: syntheses, structures and properties†
Abstract
Under hydrothermal conditions, including tuning the reaction ratio and reaction temperature, three-dimensional (3D) porous {[Cu3(hbpdc)(OH)2(H2O)]·2H2O} (1), two-dimensional (2D) sheet {Cu2(hbpdc)(H2O)2}n (2), dinuclear [Cu(hbpdc)0.5(H2O)2] (3), dimer [Cu2(mbpdc)2(py)2]·9H2O (4), and mononuclear [Cu(hbpdcH2)(H2O)2] (5) have been synthesized via in situ ligand transformation reaction, in which 3,3′-dimethoxy-2,2-bipyridine-6,6′dicarboxylic acid (mbpdcH2) undergoes demethylation to 3,3′-dihydroxy-2,2′bipyridine-6,6′-dicarboxylic acid (hbpdcH4). The detailed coordination patterns of the hbpdcH4 ligand have been revealed by single-crystal X-ray diffraction. The catalytic results demonstrate that polymers 1 and 2 can function as heterogeneous and reusable catalysts for the Strecker reaction of various imines. In addition, magnetic susceptibility measurements of complexes 1, 2 and 4 reveal antiferromagnetic coupling between the copper(II) ions. Complex 1 follows the Curie–Weiss law, while 2 and 4 obey the Bleaney–Bowers dinuclear model.