Kinetics of intra-polymer electron-transfer reactions in macromolecule–metal complexes

Abstract

A macromolecul~metal complex with redox centres on the same polymer chain of partially quaternized poly(1vinylimidazole) (QPVlm) has been designed. In this complex, Co(tfacacen) (tfacacen = N,N'-ethylenebis(l,l,ltrifluoro-4-iminopentan-2-one), a Cot'-Schiff base complex, and quaternized imidazolium residues, an oxidizing agent, are both linked to a polymer backbone. The mechanism of the electron-transfer reaction between Co(tfacacen) and the quaternized imidazolium residue on this macromolecular complex have been investigated. The electron-transfer rate depends linearly on the concentration of Co" residues and the degree of quaternization but is independent of the concentration of quaternized imidazolium residue. These dependencies indicate that, under the experimental conditions, an intra-polymer electron-transfer reaction occurs in this system. The reaction product formed by reduction of the quaternized imidazolium residue was identified by means of 'H NMR and absorption spectroscopies. The results show that the predominant reduction product is 3-ethyl-4imidazoline-containing polymer.

High Current Density Ferrocene-Modified Linear Poly(ethylenimine) Bioanodes and Their Use in Biofuel Cells

“…27 To address this issue, we carried out studies to optimize the spacer length between LPEI and the ferrocene moiety, as previous studies had shown that extending the redox center away from the polymer backbone could improve the performance of the sensors by increasing the electron diffusion rates. 5,28,29 This study showed that a 6-carbon spacer ͑Fc-C 6 -LPEI͒ improved the stability while reducing the maximum current density ͑ j max ͒ of the sensors, while a polymer with a 3-carbon spacer ͑Fc-C 3 -LPEI͒ both improved the stability and produced a j max of approximately 1 mA/cm 2 . 27 The high current densities obtained with these polymers led us to investigate the possibility of using them as materials for biofuel cell anodes.…”

Synthesis, X-Ray Crystallography, Thermal Analysis, and DFT Studies of Ni(II) Complex with 1-Vinylimidazole Ligand

“…The imidazole ligand is of particular interest due to its important role in many biological systems, especially as the side group in histidine which plays an essential role in the active motif of many enzymes [7]. Imidazole in polymers has traditionally been utilized in a variety of applications such as immobilized catalysts [8,9], redox reactions [10], water purification [11,12], hydrometallurgy/metal recovery [13,14], and ion and proton conductors [15].…”

Synthesis and polymerisation of maleoyl-L-histidine monomers and addition of histidine to an ethylene-alt-maleic co-polymer

“…The imidazole ligand is of particular interest due to its important role in many biological systems, especially as the side group in histidine which plays an essential role in the active motif of many enzymes [8]. Imidazole in synthetic polymers and biopolymers has traditionally been utilised in a variety of applications such as immobilised catalysts [9,10], redox reactions [11], water purification [12,13], hydrometallurgy/metal recovery [14,15], ion and proton conductors [16], chelating resin adsorbents [12][13][14][15] etc. The majority of the these applications and functions exploit the fact that the imidazole group is very strongly and selectively coordinated by metal ions, in particular Cu(II) and Zn(II) [8].…”

“…the pyrrole nitrogen (see Scheme 1), e.g. poly (1-vinylimidazole) or poly(N-vinylimidazole) [11,[20][21][22][23], since the monomer is synthesised by attaching the vinyl group to the electronegative pyrrole nitrogen [24]. However in histidine, the most common naturally existing type of imidazole ligand, the imidazole is attached at the 4 th position C 4 , leaving the pyrrole nitrogen unsubstituted.…”