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β‐cyclodextrin and carboxymethylated β‐cyclodextrin polymer film modified electrodes, hosting cobalt porphyrins, as sensors for electrocatalytic determination of oxygen dissolved in solution
Author(s) -
D'Souza Francis,
Hsieh YiYing,
Wickman Heang,
Kutner Wlodzimierz
Publication year - 1997
Publication title -
electroanalysis
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.574
H-Index - 128
eISSN - 1521-4109
pISSN - 1040-0397
DOI - 10.1002/elan.1140091412
Subject(s) - porphyrin , cobalt , catalysis , aqueous solution , chemistry , inorganic chemistry , tetraphenylporphyrin , polymer chemistry , photochemistry , organic chemistry
New oxygen sensors, based on polymer film modified electrodes, were prepared and applied for electrocatalytic determination of dioxygen dissolved both in aqueous and aqueous‐organic, mixed solvent solutions. The sensors were made of gold electrodes coated with thin polymer film matrices of either neutral β‐cyclodextrin polymer, β‐CDP, or cation‐exchange carboxymethylated β‐cyclodextrin polymer, β‐CDPA, hosting electrocatalytically active centes of cobalt tetraphenylporphyrin, (TPP)Co, cobalt tetrakis‐( N ‐methylpyridyl)porphyrin, (TMPyP)Co, or cobalt tetrakis‐(4‐sulfonatophenyl)porphyrin, (TPPS)Co. Films were cast from aqueous solutions of the respective β‐cyclodextrin prepolymer, cobalt porphyrin and glutaric dialdehyde used as the polycondensation crosslinking reagent. Catalytic dioxygen electroreduction at the electrode coated with polymer film hosting the cobalt porphyrin catalyst involves two electrons and two protons resulting in the formation of hydrogen peroxide. The sensitivity of dioxygen determination largely increases in the order (TPPS)Co <(TPP)Co<(TMPyP) Co for the β‐CDPA film electrodes, being governed by ion‐exchange equilibria with respect to the cobalt porphyrin catalyst, while it depends only slightly on the nature of the cobalt porphyrin catalyst for the β‐CDP film. The catalytic rate constant of the dioxygen reaction with the cobalt porphyrin catalyst in the film was estimated as k ≈ 2 × 10 4 M −1 s −1 being larger than those for either adsorbed or electropolymerized catalyst at the electrode and close to that for the catalyst present in solution. The performance of the sensors is presented with respect to the detection signal linearity, reproducibility, long‐term stability, reversibility regarding dioxygen binding and response time.