Copper(II) coordination polymer based on l-arginine as a supramolecular hybrid inorganic–organic material: synthesis, structural, spectroscopic and magnetic properties

We report the synthesis and structural, spectroscopic and magnetic properties of new 1D coordination polymeric complex {[Cu( μ- l- Arg) 2 ]SO 4 ⋅1.5H 2 O} n ( 1 ) that contains asymmetric μ −O,O’ carboxylic bridge linking distorted square-pyramidal [Cu( μ- l- Arg) 2 ] 2+ coordination units. In 1D, the syn − anti − μ 2 − η 1 : η 1 zigzag polymer conformation, the adjacent Cu(II) ions are distanced by 5.707 Å, and the subsequent Cu∙∙∙Cu proximity in 1D-coordination chain equals 6.978 Å. Detailed interpretation of IR and Raman spectra of l- arginine and 1 was performed. The principal components of the g tensor determined from EPR experiments ( g x = 2.059, g y = 2.075, g z = 2.228) indicate nearly axial symmetry of Cu(II) coordination sphere and correspond to the unpaired electron occupying the d x 2– y 2 orbital. The single broad band at 16,200 cm –1 , characteristic of d−d transition, is assigned to the dominant dublet-dublet 2 B 1 g ( d x 2– y 2 )→ 2 E g ( d yz≈ d xz ) transition. Magnetic susceptibility measurements have revealed ferromagnetic coupling between the Cu(II) ions within the 1D-coordination chain, while the intermolecular coupling is antiferromagnetic.