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Calixarene–Poly(dithiophene)‐Based Chemically Modified Electrodes
Author(s) -
Giannetto Marco,
Mori Giovanni,
Notti Anna,
Pappalardo Sebastiano,
Parisi Melchiorre F.
Publication year - 2001
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/1521-3765(20010803)7:15<3354::aid-chem3354>3.0.co;2-u
Subject(s) - potentiometric titration , calixarene , selectivity , monomer , chemistry , cyclic voltammetry , titration , alkali metal , inorganic chemistry , electrode , proton nmr , electrochemistry , polymer , organic chemistry , molecule , catalysis
The stepwise synthesis of cone and partial cone 1,3‐bridged n ‐propoxy‐calix[4]crown ethers (“monomers” 2 and 3 ) with an electropolymerizable 2,2′‐dithiophene‐3‐yl‐hexylene functionality at the lower rim, is described. The potential of 2 and 3 as sensing agents for alkali metal ions was investigated by 1 H NMR titration experiments with NaSCN and KSCN. The results obtained have confirmed that the presence of the heterocyclic subunit does not affect the well‐known size‐selectivity observed with calix[4]crowns. Monomers 2 and 3 were electropolymerized (Pt as a working electrode, CH 2 Cl 2 /CH 3 CN, Bu 4 NPF 6 ) to produce the title chemically modified electrodes (CMEs). After coating with a PVC membrane containing a lipophylic cation exchanger, CMEs based on calix[4]crown‐5 2 b (cone) and 3 b (partial cone) were tested for the potentiometric recognition of alkali metal ions in aqueous solution. In agreement with NMR titration studies, a satisfactory potentiometric response in terms of K + /Na + selectivity was obtained only with CME 2 b (p K K/Na 1.51). The amperometric responses of PVC‐uncoated CMEs were studied by cyclic voltammetry (CV) experiments in CH 3 CN solution. High Na + selectivity was found with the CME based on partial cone calix[4]crown‐4 3 a , and frequency response analysis (FRA) measurements support this finding.