Investigation of photosensitising behaviour of Ni, Pd and Pt phthalocyanines towards phenolic pollutants
- Authors: Ogunbayo, Taofeek Babatunde
- Date: 2011
- Subjects: Phthalocyanines Pollutants Photochemistry Photosensitizing compounds
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4321 , http://hdl.handle.net/10962/d1004979
- Description: Syntheses of various octasubstituted open-shell (Ni(II), Pd(II) and Pt(II)) metallophthalocyanines and their metal-free analogues have been carried out. Spectroscopic characterizations, photophysical and photochemical studies were carried out to determine the effects of these metals on the molecules using the metal-free phthalocyanine analogues as benchmark. Metal-binding studies of few thio-derivatised phthalocyanines were done to increase the number of palladium metal on the phthalocyanine ligands and determine the effect of increasing number of this metal on phthalocyanine properties. Palladium (PdPc) and platinum phthalocyanines (PtPc) gave good triplet and singlet oxygen quantum yields making them suitable for further investigation in application as photosensitisers. Using 4-nitrophenol as model pollutant, photosensitization reactions were carried out under homogenous and heterogeneous conditions. The reactions were monitored using UV-vis spectroscopy. The MPcs were adsorbed on functionalized single wall carbon nanotube (SWCNT-COOH) to form heterogeneous photosensitizers with PtPc failing to adsorb on the SWCNT-COOH. Under the heterogeneous condition, all the PdPcs photosensitization kinetics was consistent with Langmuir-Hinshelwood reaction model. The best photosenstiser, β-palladium dodecylthio phthalocyanine was also deployed in sensitization of oxidation of 4-chlorophenol and pentachlorophenol under homogenous and heterogeneous conditions to establish the ability of the molecules to sensitize oxidation of wide range of phenolic pollutants. Identifications of the products of the reactions were conducted using gas chromatography and high pressure liquid chromatography (HPLC) hyphenated with mass analyzer (LC-MS). Mechanisms of all the reactions were investigated and all the complexes, in spite of reduced lifetime resulting from open-shell nature of the metals, sensitized the reactions through singlet oxygen mediated pathway. All the heterogeneous sensitisers were recyclable in the 4- nitrophenol oxidation but β-palladium dodecylthio phthalocyanine proved unrecyclable in the oxidation of pentachlorophenol.
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- Date Issued: 2011
The syntheses, characterization and fluorescence spectra of novel, octakis (alkylthiophthalocyanato) nickel (II) and palladium (II) complexes
- Authors: Ogunbayo, Taofeek Babatunde , Ogunsipe, Abimbola , Nyokong, Tebello
- Date: 2009
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/263386 , vital:53623 , xlink:href="https://doi.org/10.1016/j.dyepig.2009.03.009"
- Description: The syntheses, characterization and fluorescence studies of several {octakis(alkylthio)phthalocyanato} palladium(II) and nickel(II) complexes are presented. The absorption spectra of some of the complexes showed extra peaks which are attributable to non-planar distortion, the extent of which, was found to dependent on alkyl chain length. The fluorescence excitation spectra of the nickel(II) derivatives were not in agreement with their absorption spectra, owing to structural changes upon excitation. Fluorescence quantum yields were very low (more than 1%) for all complexes as a consequence of the open-shell electronic structures of nickel(II) and palladium(II).
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- Date Issued: 2009