Electrochemical, spectroelectrochemical, and pyridine binding properties of tetrathia macrocycle-bridged dimeric cobalt phthalocyanine

Yilmaz I., KOCAK M.

POLYHEDRON, vol.23, no.7, pp.1279-1285, 2004 (SCI-Expanded) identifier identifier

  • Publication Type: Article / Article
  • Volume: 23 Issue: 7
  • Publication Date: 2004
  • Doi Number: 10.1016/j.poly.2004.02.009
  • Journal Name: POLYHEDRON
  • Journal Indexes: Science Citation Index Expanded (SCI-EXPANDED), Scopus
  • Page Numbers: pp.1279-1285
  • Keywords: phthalocyanine, electrochemistry, spectroelectrochernistry, pyridine binding, ELECTRONIC-SPECTRA, REDOX PROPERTIES, REDUCTION, MONONUCLEAR, ELECTROCHROMISM, SUBSTITUENTS, IRON(II), SENSOR, MEDIA
  • Istanbul Technical University Affiliated: Yes


Tetrathia macrocycle-bridged dimeric cobalt phthalocyanine, [(RS)(6)CoPc](2)CR where R=C6H13, CR=[1,4,7,10-tetrathia-(12-crown-4)], was investigated electrochemically and spectroelectrochemically. Pyridine binding properties of the complex were also investigated by spectrophotometric technique in the solution of dichloromethane. The neutral complex undergoes two quasi-reversible two-electron-oxidations and two quasi-reversible two-electron-reductions in CH2Cl2 containing 0.1 M tetra-n-butylammonium perchlorate (TBAP). The half-wave potentials for oxidation of the hexylthio substituted complex are located at E-1/2 = 0.65 and 1.28 V, while the two reductions are located at E-1/2 = -0.38 and -1.37 V vs. SCE. These potentials of the complex show little or no difference compared to those of unsubstituted CoPc and other SR substituted phthalocyanines under the same experimental condition, thus suggesting the weak electron-donating properties of the peripheral hexylthio substituents on the phthalocyanine rings. Evaluation of the well-defined UV-Vis spectra of the neutral complex and its electrochemically oxidized and reduced, {[(RS)(6)Co(2+)Pc(-)](2)CR}(2+), {[(RS)(6)Co(+)Pc(2-)](2)CR2-, and {[(RS)(8)Co(+)Pc(3-)](2)CR}(4-), species obtained with applied potentials in thin layer cell showed that neutral and mono-oxidized species remained its highly aggregation properties while mono- and doubly reduced complexes behave as monomeric form in the solution as a result of a weak coupling effect. The complex was also investigated as to pyridine-binding ability in dichloromethane/pyridine mixtures. Spectroscopic changes were monitored by UV-Vis spectrophotometry where the Q band of the neutral complex resulted in an increase in intensity, which was associated with the formation of pyridine mono-adduct for binuclear cobalt phthalocyanine complex, [(RS)(6)CoPc](2)CR. (C) 2004 Elsevier Ltd. All rights reserved.