Photochemical properties of sulphonated phthalocyanine complexes of aluminium, zinc, tin and silicon, and octa-carboxyphthalocyanine complexes of aluminium and zinc have been investigated. These water-soluble metallophthalocyanine (MPc) complexes, especially the sulphonated aluminium and zinc phthalocyanines, were found to be good photosensitisers for the transformation of the toxic mono-, tri- and penta-chlorophenols in aqueous solutions. The efficiency of MPc sensitiser towards photo-transformation of chlorophenols depends on its effectiveness to generate singlet oxygen as well as its photostability. Octa-substituted thiol-derivatised phthalocyanine complexes of cobalt, iron and zinc were synthesized and their spectral and electrochemical properties investigated. The photochemical properties ofthe zinc phthalocyanine complexes in non-aqueous solutions were comparable to those in literature. Ultrathin films of the octasubstituted thiol-derivatised phthalocyanine complexes of cobalt, iron and zinc were, for the first time, immobilized onto gold electrodes using the self-assembling technique. Surface electrochemistry indicates that the ultrathin films are surface-confined self-assembled monolayer (SAM) species. Gold electrodes modified with the redox-active SAMs of cobalt and iron phthalocyanine complexes proved to be potential electrochemical sensors for the detection of thiols (L-cysteine, homocysteine and penicillamine) and thiocyanate in aqueous solutions (pH 4). The limits of detection for the thiols and thiocyanate were in the range of ∼ 10⁻⁷ and 10⁻⁶ mol dm⁻³, respectively. The modification process was reproducible and the modified electrodes showed good stability and, if stored in pH 4 buffer solutions, could be used for the analysis of thiols and thiocyanate for about a month without the need for recalibration. Etching of gold marred electrochemical detection of cyanide with the MPc-SAM-modified gold electrodes. Interestingly, however, kinetic and equilibria studies revealed strong interaction of octabutylthiophthalocyaninatoiron (II), FeOBTPc, with cyanide in both DMF and DMSO solutions.
| Identifer | oai:union.ndltd.org:netd.ac.za/oai:union.ndltd.org:rhodes/vital:4089 |
| Date | January 2003 |
| Creators | Ozoemena, Kenneth Ikechukwu |
| Publisher | Rhodes University, Faculty of Science, Biochemistry, Microbiology and Biotechnology |
| Source Sets | South African National ETD Portal |
| Language | English |
| Detected Language | English |
| Type | Thesis, Doctoral, PhD |
| Format | 297 leaves, pdf |
| Rights | Ozoemena, Kenneth Ikechukwu |
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