Influence of Counteranions on the Structural Modulation of Silver-Di(3-pyridylmethyl)amine Coordination Polymers

The coordination chemistry of a flexible N-donor ligand di(3-pyridylmethyl)amine (dpma) with silver salts has been investigated. Six new silver coordination polymers, namely, [Ag(dpma)(H2O)](NO3) (1), [Ag(dpma)-(CF3CO2)]center dot 1/2H(2)O (2), [Ag(dpma)](CF3SO3)]center dot 1/2H(2)O (3), [Ag(dpma)](BF4)center dot 3/2H(2)O (4), [Ag-3(dpma)(2)(H2O)](ClO4)(3) (5), and [Ag(dpma)](PF6) (6), have been prepared by slow diffusion reactions. All the polymeric structures of compounds 1-6 are described as topologic binodal networks in terms of Ag and dpma building blocks. Compounds 1-4 show a one-dimensional ladder-like chain structure, with both Ag and dpma as three-connected T-nodes; compound 5 is an uncommon one-dimensional metallamacrocycle-based chain structure, with Ag as two-connected I-node and dpma as three- connected T-node; compound 6 is a two-dimensional honeycomb-like layer structure, with both Ag and dpma as three-connected Y-nodes. Within the structures, the dpma ligand adopts a variety of structure conformations including gauche trans anti (1 and 2), trans-trans-anti (3 and 4), trans-trans-syn (3), gauche-gauche-syn (5), and trans-gauche-syn (6) conformations. For these Ag-dpma coordination polymers, the structural diversity and complexity are most likely attributed to the different coordinating nature, hydrogen-bonding propensity, and templating effect of the counteranions and solvent molecules. Solution studies suggest that compounds 1-6 would disaggregate to break down the polymeric structures and then to give multiple rapidly exchanging solution species in DMSO or acetonitrile. The thermal stabilities of compounds 1-6 are examined. In addition, the photoluminescent properties of compounds 1-6 are investigated in the solid state at room temperature.