Coordination polymers of a bis-isophthalate bridging ligand with single molecule magnet behaviour of the Co analogue

A linear diamine-bisisophthalate bridging linker N , N ′-bis(1,3-dicarboxyphenyl-5-methylene)-1,3-dimethylpropanediamine, designed to incorporate amine/ammonium functionalities in the core of the ligand, has been isolated as the pentahydrate of its dihydrochloride salt (H 6 L)Cl 2 ·5H 2 O. Using this compound, four new coordination polymers have been formed, namely poly-[M(H 2 L)]·4.5H 2 O ( 1M , where M = Co, Zn, Cd) and poly-[Cd(H 2 L)(OH 2 )]·DMF·7H 2 O ( 2 ). Compounds 1M are isostructural 2D coordination polymers that contain 1D channels occupied by water molecules. In the case of 1Co these form a well ordered hydrogen-bonding network as determined by single crystal X-ray studies. Compound 2 , synthesised under similar conditions, is a 1D coordination polymer in which the metal is partially solvated. DC and AC magnetic studies of 1Co , which posseses a mononuclear cobalt( ii ) node, revealed single molecule magnet behaviour (SMM) with an effective barrier height U eff of 37.7 K and τ 0 = 1.02 × 10 −9 s, among the highest reported for Co II coordination polymers. A Co( ii ) coordination polymer shows SMM behaviour with an effective barrier height among the highest reported for such materials.