The Role of the Coordination Modes of a Flexible Bis(pyridylamide) Ligand in the Topology of 2D Copper(II) Complexes

Two new two-dimensional copper(II) coordination polymers, [Cu(L)(BDC)center dot H2O (1) and [Cu-2(L)(0.5)(SIP)(OH)(H2O)]center dot 2H(2)O (2) [L = N,N'-bis(3-pyridylamide)-1,6-hexane, H2BDC = 1,3-benzenedicarboxylic acid, H3SIP = 5-sulfoisophthalic acid (3,5-dicarboxybenzenesulfonic acid)], have been synthesized hydrothermally by self-assembly of the flexible bis-pyridyl-bis-amide ligand L and the aromatic polycarboxylate ligands H2BDC or H3SIP. X-Ray diffraction analysis reveals that complex 1 displays a metal-organic coordination layer with a binodal (3,5)-connected {4(2).6(7).8}{4(2).6} topology, in which the L ligands adopt a mu(2)-bridging mode (via ligation of the pyridyl nitrogen atoms). Complex 2 also exhibits a layered network based on tetranuclear copper clusters [Cu-4(mu(3)-OH)(2)(H2O)(2)(O2C-)(4)], L ligands and SIP anions, showing a binodal (4,8)-connected network with {4(14).6(10).8(4)} {4(4).6(2)} topology, in which the L ligands adopt a mu(6)-bridging coordination mode (via ligation of the pyridyl nitrogen and carbonyl oxygen atoms). Adjacent layers in 1 and 2 are further linked by hydrogen bonding interactions to form three-dimensional supramolecular frameworks. The electrochemical behavior of the two complexes in bulk-modified carbon paste electrodes has been investigated.