Spectroscopic study of the complexes of poly ( [formula omitted]) and its model molecule with nickel (II)

Abstract

The complexes formed between nickel (II) and a polymeric ligand derived from l-lysine, viz. poly ( N- methacryloyl- l-lysine ) (PNML), have been investigated by potentiometry, electronic absorption and circular dichroism. N- isobutyroyl- l-lysine (NIBL) was also studied for comparison with its polymeric analogue. PNML gives two optically active complexes between the carboxylate and the amine group of one side-chain for the species NiL and of two different side-chains of the polymer for the species NiL 2 (one or two five membered chelates rings). For the model molecule, absorption results suggest a mixture of complexes (NiL + NiL 2) at high pH, but the circular dichroism spectra are typical of a NiL species. Complexes of nickel with NIBL or PNML are glycine-like i.e. the deprotonated amide nitrogen is not involved in complex formation.