Halo and Pseudohalo Cu(I)-Pyridinato Double Chains with Tunable Physical Properties

The properties recently reported
on the Cu­(I)-iodide pyrimidine nonporous 1D-coordination polymer [CuI­(ANP)]n (ANP = 2-amino-5-nitropyridine) showing
reversible physically and chemically driven electrical response have
prompted us to carry a comparative study with the series of [CuX­(ANP)]n (X = Cl (1), X = Br (2), X = CN (4), and X = SCN (5))
in order to understand the potential influence of the halide and pseudohalide
bridging ligands on the physical properties and their electrical response
to vapors of these materials. The structural characterization of the
series shows a common feature, the presence of −X–Cu­(ANP)–X–
(X = Cl, Br, I, SCN) double chain structure. Complex [Cu­(ANP)­(CN)]n (4) presents a helical single
chain. Additionally, the chains show supramolecular interlinked interactions
via hydrogen bonding giving rise to the formation of extended networks.
Their luminescent and electrical properties have been studied. The
results obtained have been correlated with structural changes. Furthermore,
the experimental and theoretical results have been compared using
the density functional theory (DFT). The electrical response of the
materials has been evaluated in the presence of vapors of diethyl
ether, dimethyl methylphosphonate (DMMP), CH2Cl2, HAcO, MeOH, and EtOH, to build up simple prototype devices for
gas detectors. Selectivity toward gases consisting of molecules with
H-bonding donor or acceptor groups is clearly observed. This selective
molecular recognition is likely due to the 2-amino-5-nitropyridine
terminal ligand.