The importance of electron correlation for the ground state structure of porphycene and tetraoxaporphyrin-dication

Malsch, Karsten; Roeb, Martin; Karuth, Volker; Hohlneicher, Georg

doi:10.1016/s0301-0104(97)00294-2

Cited by 39 publications

(69 citation statements)

References 54 publications

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“…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]. The experimental [272,283,284] and calculated [275] bondlengths of the three macrocycles are reported in Figure 45.…”

Section: Porphyrinsmentioning

confidence: 99%

“…Three ground state isomeric structures of porphycene differing for the inner hydrogen positions are trans, cis-A and cis-B (see Figure 54). Their energies were estimated using ab-initio calculations methods with the trans geometry more stable than cis-A by few kcal/mol [281,321]. The cis-B structure was calculated at much higher energy [321].…”

Section: Porphycenesmentioning

confidence: 99%

“…The cis-B structure was calculated at much higher energy [321]. Infrared and Raman spectra have been measured [322] and compared with calculated vibrational data of the trans and cis-A isomers [281,321,322].…”

Section: Porphycenesmentioning

confidence: 99%

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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%

Section: Porphycenesmentioning

confidence: 99%

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

Gellini

Salvi

2010

Symmetry

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“…[4] These dicationic porphyrin variants should be viewed as resonance hybrids (carbenium and onium ion structures) in which special importance is attributed to carbenium ion structures with 4n2 p electrons on the 4(n1) carbon perimeterÐin agreement with both experiment and theory. [5] O…”

Section: Dedicated To Professor Dieter Seebachmentioning

confidence: 99%

Furan-Based Porphyrins: Tetraoxa[4n+2]porphyrin Dications with 18π-, 22π-, or 26π-Electron Systems

Vogel

Jux

Dörr

et al. 2000

Angew. Chem. Int. Ed.

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A reference example for the significance of molecular symmetry in UV/Vis spectroscopy is shown by the spectra of the three planar octaethyltetraoxa[4n+2]porphyrin dications 1 – 3 (n=4 – 6). Whereas the D4h‐symmetric 18π and 26π dications 1 and 3 (the symmetry refers to the ring framework) exhibit very sharp Soret bands with record values for the molar extinction coefficients ε, the 22π dication 2, which only possesses C2h symmetry, shows a split Soret band with greatly reduced molecular extinction.

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“…This different behavior of the two ab initio models may be partially attributed to the influence of the electron correlation for porphyrin properties, as pointed out previously. 23 Note that the correlation is partially included in the BPW91 functional. The trlrl and tlrrl forms (see Table 1) correspond to TPP conformations found in tetragonal and triclinic crystals, respectively.…”

Section: Geometry Of Tppmentioning

confidence: 99%

Vibrational circular dichroism of tetraphenylporphyrin in peptide complexes? A computational study

et al. 2000

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The Raman and absorption spectra of tetraphenylporphyrin (TPP) were calculated and compared to experiment. The computation was based on the harmonic molecular force field and electric tensors obtained ab initio at the BPW91/6‐31G* level. Good agreement was found between experimental and calculated frequencies and intensities. In order to estimate whether induced optical activity in chiral complexes interferes with the signal of peptide vibrations, the vibrational circular dichroism (VCD) spectra of TPP were simulated. The magnetic field perturbation theory (MFP) and the gauge‐invariant atomic orbitals (GIAO) were used for the simulation. Such spectra were compared to theoretical VCD intensities of a model tripeptide as well to experimental spectra of a complex of the peptide and tetrakis(p‐sulfonatophenyl)porphyrin (TSPP). No significant contribution to VCD signal from the TPP residue was found in experimental spectra. Thus, possible peptide conformational changes occurring during the complexation can be monitored directly in the amide I frequency region. Chirality 12:191–198, 2000. © 2000 Wiley‐Liss, Inc.

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The importance of electron correlation for the ground state structure of porphycene and tetraoxaporphyrin-dication

Cited by 39 publications

References 54 publications

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

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

Furan-Based Porphyrins: Tetraoxa[4n+2]porphyrin Dications with 18π-, 22π-, or 26π-Electron Systems

Vibrational circular dichroism of tetraphenylporphyrin in peptide complexes? A computational study

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