Consequences of oxidation in nonplanar porphyrins. Molecular structure and diamagnetism of the [pi] cation radical of copper(II) octaethyltetraphenylporphyrin

Journal Article · Wed Sep 21 00:00:00 EDT 1994 · Journal of the American Chemical Society; (United States)

DOI:https://doi.org/10.1021/ja00098a019· OSTI ID:6960788

Renner, M W; Barkigia, K M; Zhang, Y; Fajer, J ^[1]; Medforth, C J; Smith, K M ^[2]

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1. Brookhaven National Lab., Upton, NY (United States)
2. Univ. of California, Davis, CA (United States)

Crystal structures are reported for the sterically crowded porphyrin Copper(II) 2,3,7,8,12,13,17,18-octaethyl-5,10,15,20-tetraphenylporphyrin (Cu(OETPP), 1) and its [pi] cation radical Cu(OETPP)[sup [sm bullet]+]ClO[sub 4][sup [minus]] (2). 1 was chosen to assess the consequences of oxidation in a nonplanar porphyrin on the expectation that its multiple peripheral substituents not only induce an S4 saddle conformation on the macrocycle but should also prevent the dimerizations in the solid that have complicated several previous crystallographic studies of porphyrin [pi] cation radicals. Interest in the consequences of oxidation arises from the presence of nonplanar bacteriochlorophylls in photosynthetic reaction centers in which the chromophores lie in van der Waals contact so that even small structural changes induced by electron transfer would alter the electronic coupling between the [pi] cation and anion radicals generated by the primary photochemical charge separation. Oxidation of 1 does indeed result in further conformational changes in 2: an additional ruffling is imposed on the original saddle shape of 1 in which the pyrrole rings twist, the meso carbons move alternately up and down out of the porphyrin plane by approximately 0.2 angstroms, and the phenyl groups rotate further into that plane by more than 10[degree]. 61 refs., 11 figs., 4 tabs.

• OSTI ID: 6960788
• Journal Information: Journal of the American Chemical Society; (United States), Journal Name: Journal of the American Chemical Society; (United States) Vol. 116:19; ISSN JACSAT; ISSN 0002-7863
• Country of Publication: United States
• Language: English

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CARBOXYLIC ACIDS
CATIONS
CHARGED PARTICLES
CHEMICAL REACTIONS
CHLOROPHYLL
COMPILED DATA
COMPLEXES
COPPER COMPLEXES
CRYSTAL STRUCTURE
DATA
HETEROCYCLIC ACIDS
HETEROCYCLIC COMPOUNDS
INFORMATION
IONS
MOLECULAR STRUCTURE
NUMERICAL DATA
ORGANIC ACIDS
ORGANIC COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
OXIDATION
PHOTOCHEMICAL REACTIONS
PHOTOSYNTHESIS
PHYTOCHROMES
PIGMENTS
PORPHYRINS
PROTEINS
RADICALS
SPECTROSCOPY
SYNTHESIS
TRANSITION ELEMENT COMPLEXES