Sequential protonation of meso-(p-(dimethylamino)phenyl)porphyrins : charge-transfer excited states producing hyperporphyrins

Successive protonation by trifluoroacetic acid of meso-tetraphenylporphyrin derivatives bearing one, two, or four p-dimethylamino groups gives rise to new types of spectra. With one free amino group, the spectrum of the centrally protonated porphyrin shows a strong far-red band, a broad, flat absorp...

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Bibliographic Details
Published in:Journal of physical chemistry (1952) 1993-12, Vol.97 (50), p.13192-13197
Main Authors: OJADI, E. C. A, LINSCHITZ, H, GOUTERMAN, M, WALTER, R. I, LINDSEY, J. S, WAGNER, R. W, DROUPADI, P. R, WENDING WANG
Format: Article
Language:English
Subjects:
140505 - Solar Energy Conversion- Photochemical, Photobiological, & Thermochemical Conversion- (1980-)
400201 - Chemical & Physicochemical Properties
ABSORPTION SPECTRA
AMINES
Atomic and molecular physics
CARBOXYLIC ACIDS
CHARGE TRANSPORT
CHEMICAL REACTIONS
Chemistry
ENERGY LEVELS
Exact sciences and technology
EXCITED STATES
HETEROCYCLIC ACIDS
HETEROCYCLIC COMPOUNDS
HYDROGENATION
IMINES
INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL CHEMISTRY
Kinetics and mechanisms
Molecular properties and interactions with photons
Molecular spectra
ORGANIC ACIDS
Organic chemistry
ORGANIC COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
PHOTOCHEMICAL REACTIONS
PHOTOSYNTHESIS
PHOTOSYNTHETIC REACTION CENTERS
Physics
PORPHYRINS
Reactivity and mechanisms
SCHIFF BASES
SOLAR ENERGY
SPECTRA
SYNTHESIS
Visible spectra
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Summary:Successive protonation by trifluoroacetic acid of meso-tetraphenylporphyrin derivatives bearing one, two, or four p-dimethylamino groups gives rise to new types of spectra. With one free amino group, the spectrum of the centrally protonated porphyrin shows a strong far-red band, a broad, flat absorption in the visible, and a less intense Soret band. With two or more free amino groups, the Soret band of the centrally protonated porphyrin is further split into two components. Complete protonation, including the peripheral amino groups, in all cases restores the spectral structure of the unsubstituted tetraphenylporphyrin dication. The spectra of the dianions of tetraanilino- and tetraphenylporphyrins are also similar. These results, and the related behavior of p-oxyphenylporphyrins and protonated Schiff base porphyrins, lead to a general interpretation of hyperporphyrin spectra in terms of charge-transfer excited states, involving charge movement either into or out of the porphyrin ring. 26 refs., 4 figs., 2 tabs.
ISSN:0022-3654
1541-5740
DOI:10.1021/j100152a025