Chiral and achiral layered divalent metal aromatic ortho-dicarboxylate coordination polymers with bis(4-pyridylmethyl)piperazine ligands: Luminescent behavior and magnetic properties

Four divalent metal coordination polymers containing bis(4-pyridylmethyl)piperazine (4-bpmp) and the ortho-dicarboxylate ligands phthalate (pht) or 4-methylphthalate (mpht) have been prepared by solvent diffusion or hydrothermal methods. {[Cu2(pht)2(H4-bpmp)2(H2O)2](NO3)2·H2O}n (1) and {[Cu2(pht)2(H4-bpmp)2(H2O)2](SO4)·2H2O}n (2) possess chiral cationic layer motifs formed by the junction of [Cu(H2O)(pht)]n chains by tethering curled-conformation H4-bpmp+ ligands. {[Co(pht)(H2O)(4-bpmp)]·5.5H2O}n (3) displays a (4,4) grid constructed from anti-syn carboxylate-bridged {Co2(H2O)2(pht)2} dimeric clusters linked by open-conformation 4-bpmp ligands. {[Cd2(mpht)2(H2O)2(4-bpmp)(H4-bpmp)]ClO4·4H2O}n (4) manifests cationic layered motifs based on neutral [Cd2(H2O)2(mpht)2] dinuclear units with {CdOC4O}2 12-membered circuits, linked by open-conformation 4-bpmp and H4-bpmp+ ligands. Variable-temperature magnetic data indicate likely concomitant zero-field splitting and ferromagnetic coupling in 3. Violet light emission is observed when 4 is subjected to ultraviolet irradiation.