Effect of peripheral fused ring substitution on the optical spectroscopy and electronic structure of metal phthalocyanine complexes
- Authors: Chidawanyika, Wadzanai J U , Mack, John , Shimizu, Soji , Kobayashi, Nagao , Nyokong, Tebello
- Date: 2009
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/263353 , vital:53620 , xlink:href="https://doi.org/10.1142/S1088424609001339"
- Description: In this paper the impact of peripheral substitution with a strongly withdrawing fused ring group on the optical spectroscopy of a metal phthalocyanine complex is analyzed. We report the synthesis of [9 (or 10), 16 (or 17), 23 (or 24)-tri-tert-butylimidophthalocyaninato]zinc(II) (ZnttbIPc), which should eventually prove to be a useful precursor for forming dimeric compounds. The electronic structure is analyzed through a detailed analysis of the UV-visible absorption and magnetic circular dichroism spectra and time-dependent density functional theory calculations. Other than a marked splitting of the Q band, the spectrum is broadly similar to that of ZnPc in terms of the main π → π* electronic bands. The vibrational bands differ markedly in the Q band region when an imido group is added to ligand periphery, relative to what is observed in the case of zinc mononaphthotribenzotetraazaporphyrin (Zn3B1N) with an additional fused benzene ring. The absorption and emission spectra lack mirror symmetry as is the case with ZnPc and thus provide possible evidence for a second set of electronic origins in the Q band region arising from n → π* rather then π → π* transitions.
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- Date Issued: 2009
Metal (Co, Fe) tribenzotetraazachlorin–fullerene conjugates
- Authors: Ozoemena, Kenneth I , Mamuru, Solomon A , Fukuda, Takamitsu , Kobayashi, Nagao , Nyokong, Tebello
- Date: 2009
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/263464 , vital:53630 , xlink:href="https://doi.org/10.1016/j.elecom.2009.04.011"
- Description: Novel hexabutylsulphonyltribenzotetraazachlorin–fullerene (C60) complexes of iron (FeHBSTBTAC–C60) and cobalt (CoHBSTBTAC–C60) have been synthesized and their electrochemistry and oxygen reduction reaction (ORR) compared with their octabutylsulphonylphthalocyanine analogues (FeOBSPc and CoOBSPc). It is proved that electron-withdrawing substituents (–SO2Bu and C60) on phthalocyanine macrocycle exhibit distinct impact on the solution electrochemistry of these metallophthalocyanine (MPc) complexes. The more electron-withdrawing C60 substituent suppressed ORR compared to the –SO2Bu in alkaline medium. FeOBSPc showed the best ORR activity involving a direct 4-electron mechanism, a rate constant of ∼1 × 108 cm3 mol−1 s−1 and a Tafel slope of −171 mV dec−1.
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- Date Issued: 2009