Construction of coordination polymers based on methylenebis(3,5-dimethylpyrazole) and varied aromatic carboxylic acids

Six new coordination polymers, namely, [Co(Cl-BDC)(H2MDP)]center dot 0.5H(2)O (1), [Cd(Cl-BDC)(H2MDP)] (2), [Cd(OH-ip) (H2MDP)(2)]center dot H2O (3), [Mn(NO2-ip)(H2MDP)(H2O)] (4), [Cu(BTEC)(1/2)(H2MDP)] (5), and [Co(BTEC)(1/2)(H2MDP)]center dot H2O (6) (H2MDP = methylenebis(3,5-dimethylpyrazole), Cl-H2BDC = 2,5-dichloroterephthalic acid, OH-H(2)ip = 5-hydroxy-1,3- benzenedicarboxylic acid, NO2-H(2)ip = 5-nitro-1,3-benzenedicarboxylic acid, H4BTEC = 1,2,4,5-benzenetetracarboxylic acid) have been hydrothermally synthesized by using H2MDP as the main ligand and varying aromatic acids as auxiliary ligands, and characterized by single-crystal X-ray structure determination, FT-IR, elemental analysis, and powder X-ray diffraction. It was found that in complexes 2, 3, 4, and 6 the H2MDP ligands adopt a cis-conformation and tend to form M2L2-type metallocyclic units (SBU-1). These metallocyclic units further serve as linkers to connect the {metal-aromatic carboxylate}(n) chains to form two-dimensional frameworks with different structural features and topologies, i.e. 2D 6(3)-hcb network for 2, (4,4) net for 3, undulated 6(3)-hcb layered framework for 4, and dual (3,4)-connected net for 6 with point (Schlafli) symbol of (4 center dot 6(2))(2)(4(2)center dot 6(2)center dot 8(2)). In complexes 1 and 5, the H2MDP ligands adopt a trans-conformation, and tend to link {metal-aromatic carboxylate}(n) chains into a higher dimensional framework, i.e. 3D triply interpenetrated dia network for 1 and dual (4,4)-connected double-layered structure for 5 with point (Schlafli) symbol of (5(4)center dot 6(2))(5(5)center dot 8(1))(2). Moreover, the magnetic properties of complexes 1 and 6, and photoluminescent properties of 3 have also been investigated.