Divalent metal homophthalate coordination polymers with long-spanning dipyridyl ligands containing piperazine moieties

Hydrothermal reaction of a metal nitrate salt, homophthalic acid (H2hmph), and a long-spanning dipyridyl ligand bearing a central piperazine moiety afforded three new divalent metal homophthalate coordination polymers, which were structurally characterized by single-crystal X-ray diffraction. [Zn2(hmph)2(3-bpmp)]n (1, 3-bpmp = bis(3-pyridylmethyl)piperazine) exhibits a 2D (4,4) grid topology formed from the 3-bpmp linkage of [Zn2(hmph)2]n 1D chains featuring{Zn2(OCO)4} paddlewheel clusters. {[Co(H2O)4(4-bpfp)][Co(hmph)2(4-bpfp)]·6H2O}n (2, 4-bpfp = bis(4-pyridylformyl)piperazine) possesses alternating anionic [Co(hmph)2(4-bpfp)]n2n− and cationic [Co(H2O)4(4-bpfp)]n2n+ chains. [Ni(hmph)(4-bpfp)(H2O)]n (3) manifests [Ni(H2O)(hmph)]n chains formed through anti–syn carboxylate bridging. In turn these are connected into a (4,4) grid via tethering 4-bpfp ligands. Variable temperature magnetic susceptibility data indicates weak ferromagnetic superexchange along the embedded [Ni(OCO)]n chain subunits (g = 2.272(4), J = 0.25(1) cm−1). The d10 derivative 1 undergoes ligand-centered blue-violet luminescence upon exposure to ultraviolet light (λmax = 417 nm). Thermal decomposition behavior is also explored.