Luminescent cadmium phenylenedipropionate coordination polymers with long-spanning dipyridine ligands

Hydrothermal synthesis has generated oxoanion-free divalent cadmium 1,4-phenylenedipropionate (phdp) coordination polymers containing either bis(4-pyridylmethyl)piperazine (bpmp) or bis(4-pyridylformyl)piperazine (bpfp) ligands. The coordination environment at cadmium appears to dictate the overall dimensionality of the resulting coordination polymer crystal structure. {[Cd(phdp)(bpfp)(H2O)]·4H2O}n (1) possesses pentagonal bipyramidal coordination at cadmium with trans pyridyl donors and displays a simple 2-D (4,4) grid network. {[Cd(phdp)(bpmp)]·5H2O}n (2) exhibits distorted octahedral coordination with cis pyridyl donors, resulting in a 3-D 3-fold interpenetrated diamondoid network. Both 1 and 2 show visible-light luminescence upon ultraviolet excitation, with the emission maximum depending on the nature of the dipyridyl coligand.