Synthesis and electrochemical characterisation of α-and β-tetra-substituted oxo (phthalocyaninato) titanium (IV) complexes
- Authors: Tau, Prudence , Nyokong, Tebello
- Date: 2006
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/283869 , vital:55998 , xlink:href="https://doi.org/10.1016/j.poly.2005.11.025"
- Description: The synthesis, spectroscopic and electrochemical characterisation of the following oxotitanium tetra-substituted phthalocyanines are reported: 1,(4)-(tetraphenoxyphthalocyaninato)titanium(IV) oxide (5a); 1,(4)-(tetra-tert-butylphenoxyphthalocyaninato)titanium(IV) oxide (5b); 2,(3)-(tetraphenoxyphthalocyaninato)titanium(IV) oxide (6a) and 2,(3)-(tetra-tert-butylphenoxyphthalocyaninato)titanium(IV) oxide (6b). Complexes 5a and 5b are substituted at the non-peripheral (α) positions, whereas complexes 6a and 6b are substituted at the peripheral (β) positions. Cyclic voltammograms of all four complexes are similar, with three reversible reduction couples and three quasi-reversible to irreversible oxidations. The first two reductions are two-electron processes, confirmed by spectroelectrochemistry to be due to TiIVPc−2/TiIIPc−3 and TiIIPc−2/TiIPc−3 redox processes. Spectroelectrochemistry showed that upon oxidation, the molecule decomposes. Oxidation is expected to occur at the ring. Chronocoulometry confirmed two electron transfer at the first and second reduction steps; and a one electron transfer at the third reduction.
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- Date Issued: 2006
Synthesis and photophysical properties of octa-substituted phthalocyaninato oxotitanium (IV) derivatives
- Authors: Tau, Prudence , Nyokong, Tebello
- Date: 2006
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/283881 , vital:55999 , xlink:href="https://doi.org/10.1142/S1088424606000399"
- Description: The synthesis, spectral and photophysical properties including fluorescence quenching of the following octa-substituted oxotitanium phthalocyanines are reported: 2,3,9,10,16,17,23,24-octaphenoxyphthalocyaninato titanium(IV) oxide, 2,3,9,10,16,17,23,24-[octakis(4-t-butylphenoxyphthalocyaninato)]titanium(IV) oxide, 2,3,9,10,16,17,23,24-{octakis[(4-benzyloxy)phenoxy]phthalocyaninato}titanium(IV) oxide and 2,3,9,10,16,17,23,24-octaphenylthiophthalocyaninato titanium(IV) oxide. The complexes are characterized by 1H NMR, IR and UV-vis spectroscopies. Their photophysical properties are presented where moderate fluorescence quantum yields (0.14-0.19) and lifetimes were determined. Varied triplet quantum yields were obtained and the triplet lifetimes (40-100 μs) were short.
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- Date Issued: 2006
Unique electrochemical behavior of tantalum (V) phthalocyanine
- Authors: Tau, Prudence , Nyokong, Tebello
- Date: 2006
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/286139 , vital:56243 , xlink:href="https://doi.org/10.1142/S1088424606000090"
- Description: The electrochemical and spectroscopic behavior of tantalum(V) phthalocyanine are presented. The NMR spectra is consistent with the lack of symmetry of the complex. Cyclic (CV) and square wave (SWV) voltammetries, and spectroelectrochemistry, were employed in the study of the complex. Two one-electron reductions and a simultaneous 4-electron reduction were observed. Reduction occurs first at the metal to form a Ta(IV) species, followed by ring based processes.
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- Date Issued: 2006