Copper(II) coordination polymer based on l-arginine as a supramolecular hybrid inorganic–organic material: synthesis, structural, spectroscopic and magnetic properties
Karol Musioł, Jan Janczak, Katarzyna Helios, Maciej Witwicki, Magdalena Fitta, Robert Pełka, Agnieszka Wojciechowska
Abstract
Abstract 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. Graphical Abstract