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)]­·1/2H2O (2), [Ag­(dpma)]­(CF3SO3)­·1/2H2O (3), [Ag­(dpma)]­(BF4)­·3/2H2O (4), [Ag3(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.