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.

Different 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 as PowerPoint slide