title: Coordination polymers from a highly flexible alkyldiamine-derived ligand: structure, magnetism and gas adsorption studies.
abstract: The synthesis and structural, magnetic and gas adsorption properties of a series of coordination polymer materials prepared from a new, highly flexible and internally functional tetrakis-carboxybenzyl ligand H4L derived from 1,2-diaminoethane have been examined. The compound poly-[Ni3(HL)2(OH2)4]·2DMF·2H2O 1, a two-dimensional coordination polymer, contains aqua- and carboxylato-bridged trinuclear Ni(II) clusters, the magnetic behaviour of which can be well described through experimental fitting and ab initio modelling to a ferromagnetically coupled trimer with a positive axial zero-field splitting parameter D. Compound poly-[Zn2L]·2DMF·3H2O 2, a three-dimensional coordination polymer displaying frl topology, contains large and well-defined solvent channels, which are shown to collapse on solvent exchange or drying. Compound poly-[Zn2(L)(DMSO)4]·3DMSO·3H2O 3, a highly solvated two-dimensional coordination polymer, displayed poor stability characteristics, however a structurally related material poly-[Zn2(L)(bpe)(DMSO)2]·DMSO·3H2O 4 was prepared under similar synthetic conditions by including the 1,2-bis(4-pyridyl)ethylene bpe co-ligand. Compound 4, containing small one-dimensional solvent channels, shows excellent structural resilience to solvent exchange and evacuation, and the evacuated material displays selective adsorption of CO2 over N2 at 273 K in the pressure range 0-1 atm. Each of the coordination polymers displays subtle differences in the conformation and binding mode of the ligand species, with switching between two distinct conformers (X-shaped and H-shaped), as well as a variable protonation state of the central core, with significant effects on the resulting network structures and physical properties of the materials.
authors.affiliation: School of Chemistry, 19 Rainforest Walk, Monash University, Clayton, VIC 3800, Australia. david.turner@monash.edu stuart.batten@monash.edu.
authors.forename: Chris S
authors.initials: CS
authors.lastname: Hawes
authors.forename: Nicholas F
authors.initials: NF
authors.lastname: Chilton
authors.forename: Boujemaa
authors.initials: B
authors.lastname: Moubaraki
authors.forename: Gregory P
authors.initials: GP
authors.lastname: Knowles
authors.forename: Alan L
authors.initials: AL
authors.lastname: Chaffee
authors.forename: Keith S
authors.initials: KS
authors.lastname: Murray
authors.forename: Stuart R
authors.initials: SR
authors.lastname: Batten
authors.forename: David R
authors.initials: DR
authors.lastname: Turner