Control of dimensionality through nitrogen donor disposition in divalent metal perchlorate bis(pyridylmethyl)piperazine coordination polymers

Slow diffusion of aqueous solutions of metal perchlorates with alcoholic solutions of bis(4-pyridylmethyl)piperazine (4-bpmp) or bis(3-pyridylmethyl)piperazine (3-bpmp) afforded crystalline coordination polymer phases whose dimensionality and topology is determined largely by the pyridyl nitrogen donor disposition within the imine components. {[M(H2O)4(4-bpmp)](ClO4)2·4-bpmp·4H2O}n (M = Co, 1-Co; M = Zn, 1-Zn) are isostructural, displaying cationic [M(H2O)4(4-bpmp)]n2n+ 1-D coordination polymer chains connected through extensive hydrogen-bonding pathways involving unligated species. In contrast, use of the 3-bpmp isomer generated compounds with formulation of {[M(H2O)2(3-bpmp)2](ClO4)2·8H2O}n (M = Co, 2-Co; M = Zn, 2-Zn), which manifest achiral 3-fold interpenetrated 66 diamondoid lattices. The zinc derivatives undergo modest blue–violet luminescence on exposure to ultraviolet light.

Graphical abstractDifferent isomers of bis(pyridylmethyl)piperazine (bpmp) generate coordination polymers with radically different topologies. The 4-bpmp phases {[M(H2O)4(4-bpmp)](ClO4)2·4-bpmp·4H2O}n (M = Co, 1-Co; M = Zn, 1-Zn) display cationic [M(H2O)4(4-bpmp)]n2n+ 1-D coordination polymer chains connected through extensive hydrogen-bonding pathways. In contrast, use of the 3-bpmp isomer generated {[M(H2O)2(3-bpmp)2](ClO4)2·8H2O}n (M = Co, 2-Co; M = Zn, 2-Zn), which manifest achiral 3-fold interpenetrated 66 diamondoid lattices.Figure optionsDownload full-size imageDownload as PowerPoint slide