Five redox stages of tetraoxaporphyrin: a UV/visible/near-IR, ESR, and MO theoretical study

Bachmann, Rainer; Gerson, Fabian; Gescheidt, Georg; Vogel, Emanuel

doi:10.1021/ja00053a022

Cited by 44 publications

(36 citation statements)

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“…Diprotonated porphyrin has a non planar structure mimicking that of non planar porphyrinic prosthetic groups [271]. Tetraoxaporphyrin dication, the oxygen analogue of porphyrin, has the highly symmetrical D 4h structure [272,273] which may be modulated through five redox stages [274]. The structural parameters of the three molecular species have been the object of a large number of computational studies all of which indicate that the stable forms of porphyrin and tetraoxaporphyrin have D 2h and D 4h geometries, respectively, when electron correlation is taken into account [275][276][277][278][279][280][281][282].…”

Section: Porphyrinsmentioning

confidence: 99%

Structures of Annulenes and Model Annulene Systems in the Ground and Lowest Excited States

Gellini

Salvi

2010

Symmetry

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The paper introduces general considerations on structural properties of aromatic, antiaromatic and non-aromatic conjugated systems in terms of potential energy along bond length alternation and distortion coordinates, taking as examples benzene, cyclobutadiene and cyclooctatetraene. Pentalene, formally derived from cyclooctatetraene by cross linking, is also considered as a typical antiaromatic system. The main interest is concerned with [n]annulenes and model [n]annulene molecular systems, n ranging from 10 to 18. The rich variety of conformational and configurational isomers and of dynamical processes among them is described. Specific attention is devoted to bridged [10]-and [14]annulenes in the ground and lowest excited states as well as to s-indacene and biphenylene. Experimental data obtained from vibrational and electronic spectroscopies are discussed and compared with ab initio calculation results. Finally, porphyrin, tetraoxaporphyrin dication and diprotonated porphyrin are presented as annulene structures adopting planar/non-planar geometries depending on the steric hindrance in the inner macrocycle ring. Radiative and non-radiative relaxation processes from excited state levels have been observed by means of time-resolved fluorescence and femtosecond transient absorption spectroscopy. A short account is also given of porphycene, the structural isomer of porphyrin, and of porphycene properties.

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Section: Porphyrinsmentioning

confidence: 99%

Structures of Annulenes and Model Annulene Systems in the Ground and Lowest Excited States

Gellini

Salvi

2010

Symmetry

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“…Central to the chemistry of 1 are nucleophilic additions (and subsequent transformations) and the tetraoxaporphyrin redox system, which is derived from the dication and is interesting from many viewpoints. [4] 9 F The recently synthesized tetrathiaporphyrin dication 2 (as its perchl~rate)[~,~] and the tetraselenaporphyrin dication 3,c51 which has until now only been obtained in solution, both resemble 1 in terms of their reactivity and spectral characteristics, even though the ring system deviates significantly from planarity because of the steric interactions of the heteroatoms. Since the study of 1-3 is adversely affected by problems associated with solubility and/or crystallization, it is sensible to follow the lead of porphyrin chemistry and turn to the octaethyl compounds 4-6.…”

Section: Dedicated To Professor Marianne Baudler On the Occasion Of Hmentioning

confidence: 99%

Octaethyltetraselenaporphyrin Dication

Vogel

Fröde

Breihan

et al. 1997

Angew. Chem. Int. Ed. Engl.

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“…For the radical anions of 9-11, the coupling constants of the protons at the perimeter are strongly affected by deviations of the latter from planarity and can serve as a measure of such deviations (121). Structurally related to annulenes is porphyrin, of which some novel isomers and derivatives were recently converted to radical ions (124,125).…”

Section: Moderate Electron Acceptors and Donorsmentioning

confidence: 99%