Iron(II) coordination to bipyridyl-based hydrogel polymers

• Published in: Polymer (Guilford) Vol. 37; no. 23; pp. 5313 - 5316
• Main Authors: Chaggar, Rajinder S., Hall, Andrew J., David Miller, J.
• Format: Journal Article
• Language: English
• Published: Oxford Elsevier Ltd 01.11.1996; Elsevier
• Subjects: Applied sciences; bipyridyl; complex formation; Exact sciences and technology; Exchange resins and membranes; Forms of application and semi-finished materials; iron(II); kinetics; mechanism; Polymer industry, paints, wood; Technology of polymers; bipyridyl; iron(II); complex formation; kinetics; mechanism; Colloidal gel; Complexation; Iron II; Temperature effect; Metal ion; Pyridine derivative copolymer; Ion transport; Membrane; Hydroxyethyl methacrylate copolymer; Kinetics; Experimental study; Mechanism
• ISSN: 0032-3861; 1873-2291
• DOI: 10.1016/0032-3861(96)00422-3

Hydrophilic membranes composed of copolymers of 0.3% by weight 4-methyl-4′-vinyl-2,2′-bipyridyl with 2-hydroxyethyl methacrylate were prepared, and the coordination of iron(II) from aqueous solutions of the sulfate, perchlorate and chloride salts to form the tris(2,2′-bipyridyl)iron(II) species was studied at a range of temperatures in order to extend earlier findings. In the case of the chloride the rate equation was found to differ from that previously reported. Values for the enthalpy and entropy changes for an equilibrium involving the obstruction of potential ligand sites by existing coordination centres, and the activation enthalpies and entropies for the slow steps during complex formation, are determined. They are interpreted as showing that the slow steps in all cases involve segmental rotation within the copolymer chains to permit further coordination to occur.