Zinc maleate and fumarate coordination polymers containing hydrogen-bonding capable organodiimines featuring ligand dependent in situ cis–trans isomerization

Solution phase reaction at ambient temperature of zinc nitrate, maleic acid and 4,4′-dipyridylamine (dpa) afforded {[Zn2(maleate)2(dpa)2]·5H2O}n (1), which displayed parallel (4,4)-grid like coordination polymer layers interdigitated into double layer slab motifs via hydrogen bonding. A similar reaction employing bis(4-pyridylmethyl)piperazine (bpmp) caused in situ cis–trans isomerization of maleic acid to fumarate, and generation of [Zn(fumarate)(bpmp)(H2O)2]n (2). Compound 2 also manifested (4,4)-grid coordination polymer layers similar to those in 1; however, the larger apertures in 2 permit 2d + 2d → 3D mutually inclined interpenetration. Thermogravimetric and luminescence studies are also reported for 1 and 2.