Functional monomers and polymers, 43. ESR study on the copper(II) complexes of polymers containing imidazolyl groups and of their monomeric analogs

ESR spectroscopy was conducted on Cu(II) complexes of poly(1‐vinylimidazole), poly[4(5)‐vinylimidazole], and poly(2‐methyl‐1‐vinylimidazole) and compared with those of the corresponding low‐molecular‐weight Cu(II) complexes. At 293 K, an averaging of the anisotropy was observed for monomeric [Cu(imidazole) 4 ] 2+ complex, however, it was not for polymeric Cu(II) complexes. On the other hand, both monomeric and polymeric complexes showed typical asymmetric spectra of Cu(II) complex in a tetragonal coordination at 77K. Structure of the intramolecular [CuL 4 ] 2+ type of polymeric complexes was kept stable in the case if the ligand L to Cu(II) mole ratio was over 10:1, but it tended to change by increasing the pH value of the systems, with a conformational change of the polymeric ligand in aqueous solution. A distorted form was suggested for the polymeric Cu(II) complexes at lower pH.