Protonation of some non-transition metal phthalocyanines – Spectral and photophysicochemical consequences
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Date
2012-07
Authors
Ogunsipe, A.O.
Idowu, M.A.
Ogunbayo, T.B.
Akinbulu, I.A.
Journal Title
Journal ISSN
Volume Title
Publisher
Journal of Porphyrins and Phthalocyanines
Abstract
The photophysics and photochemistry of phthalocyanine complexes of magnesium
(MgPc), aluminum chloride (ClAlPc) and zinc (ZnPc) are studied in N,N′-dimethylformamide
(DMF). The values obtained for the photophysical and photochemical parameters are normal for
simple metallophthalocyanine (MPc) complexes. Protonation of the azomethine bridges reduced the
photoactivities of the complexes considerably; however the excited triplet states of the protonated species
are more stable towards ground state oxygen. The interaction of the non-protonated MPcs with ground
state oxygen is shown to be diffusion-assisted, with bimolecular rate constant values of the order of 1010
M-1.s-1. MgPc could not be protonated; it was easily demetalated by the protonating acid. The kinetics of
the demetalation yielded the rate equation: Rate = 0.1[MgPc][H+
]
2/3.
Description
Keywords
phthalocyanine , protonation , demetalation , photophysics , oxygen
Citation
Ogunsipe, Abimbola & Idowu, Mopelola & Ogunbayo, Taofeek & Akinbulu, Adebayo. (2012). Protonation of some non-transition metal phthalocyanines — spectral and photophysicochemical consequences. Journal of Porphyrins and Phthalocyanines. 16. 10.1142/S1088424612500988.