The Absolute Assignment of the Electronic Transitions of α,β,γ,δ-Tetraphenylporphine

Anex, Basil G.; Umans, Robert S.

doi:10.1021/ja01076a073

Cited by 44 publications

(15 citation statements)

References 1 publication

Supporting

Mentioning

Contrasting

Order By: Relevance

“…While NDDO-G predicts the excited state 3 1 B 3u to be 0.26 eV higher than the experimental value of the N peak, the assignment is identical to the traditional interpretation, which is also supported by the CCSD calculation . All methods correctly predict the ordering of the Q and B bands deduced from polarization experiments . The first and second L peaks may be assigned to states 3 1 B 2u and 4 1 B 2u , respectively.…”

Section: Resultsmentioning

confidence: 51%

Extension of the Neglect of Diatomic Differential Overlap Method to Spectroscopy. NDDO-G Parametrization and Results for Organic Molecules

1999

View full text Add to dashboard Cite

A new semiempirical scheme, referred to as NDDO-G, for calculating geometries and spectroscopic properties of molecules, is described. The method is based on the NDDO (neglect of diatomic differential overlap) approximation. It uses the point-charge model and the Mataga−Nishimoto formula to evaluate two-center two-electron integrals. The NDDO-G model has been parametrized for the elements H, C, N, and O. Molecular geometries of organic molecules are well predicted by NDDO-G; for 60 molecules, the mean absolute error of bond lengths is 0.014 Å and that of bond angles is 1.9°. The spectroscopic variant of the NDDO-G scheme provides electronic excitations using configuration interaction of singly excited states (CIS). It has been applied to calculate absorption spectra (vertical transitions) of several dozens organic molecules and photoelectron spectra within Koopmans' approximation. These NDDO-G results are compared with experimental results and with results of high-level ab initio calculations. The mean absolute error of NDDO-G excitation energies is 0.13 eV = 1050 cm-1 (196 comparisons). First and several higher ionization potentials are reproduced with a mean absolute error of 0.24 eV (123 comparisons). The proposed method may be used for studying structures of large organic and biological molecules and for interpreting and predicting their absorption and photoelectron spectra. As an example, we discuss the spectroscopy of free-base porphin.

show abstract

Section: Resultsmentioning

confidence: 51%

Extension of the Neglect of Diatomic Differential Overlap Method to Spectroscopy. NDDO-G Parametrization and Results for Organic Molecules

1999

View full text Add to dashboard Cite

show abstract

“…There has been relatively little crystal spectroscopy on pure porphyrin or metalloporphyrin crystals. Except for the measurements of Annex and Umans on the free base of tetraphenyl porphin (128), there has been no reflectance measurements. Antenson (15) and Hanson (16) have carried out the only absorption studies.…”

Section: Heme Proteinsmentioning

confidence: 99%

Linear Dichroism of Biological Chromophores

Hofrichter¹,

Eaton²

1976

Annu. Rev. Biophys. Bioeng.

113

View full text Add to dashboard Cite

“…where DA is the angle between the transition moment vectors of both molecules and D and A are the angles between these respective vectors and the direction D -> A. Spectroscopic studies by Gurinovich et al (1961), Gouterman & Stryer (1962 and Anex & Umans (1964) have established that the last band of porphyrin is 100% polarized in the plane of the molecule, but its direction within the plane remains in some doubt (Corwin et al, 1968).…”

Section: Quenching Ofporphyringlobin Fluorescence By Haemoglobinmentioning

confidence: 99%

A study of the properties of hybrids of oxyhaemoglobin and deoxyhaemoglobin with two porphyringlobin species

Treffry

Ainsworth

1974

Biochemical Journal

View full text Add to dashboard Cite

The fluorescence of porphyringlobin is quenched on adding haemoglobin to its solutions. It is suggested that this result indicates the formation of hybrids (comprising a dimer of porphyringlobin and a dimer of haemoglobin) in which quenching occurs by energy transfer from the porphyrin to the haem groups of the protein. From an analysis of fluorescence quenching, dissociation constants were calculated for the hybrids of oxy- and deoxyhaemoglobin with the fast- and slow-moving porphyringlobin species isolated by chromatography on CM-Sephadex (Treffry & Ainsworth, 1974). The values obtained are: deoxyhaemoglobin-fast-moving porphyringlobin, 0.8x10(-9)m; deoxyhaemoglobin-slow-moving porphyringlobin, 5x10(-10)m; oxyhaemoglobin-fast-moving porphyringlobin, 0.8x10(-6)m; oxyhaemoglobin-slow-moving porphyringlobin, 1.2x10(-7)m. The rates of reactions of solutions of haemoglobin and porphyringlobin, containing hybrids, with the thiol reagent 4,4'-dithiodipyridine showed that the thiol groups of the hybrids deoxyhaemoglobin-fast-moving porphyringlobin and oxyhaemoglobin-slow-moving porphyringlobin react more slowly than expected on the basis of composition alone: this result indicates that the deoxy and slow-moving conformations are the more stable, imposing themselves partially on to the fast-moving or oxy dimer of the hybrid. Also the rate of the reaction of CO with deoxyhaemoglobin is decreased when slow-moving porphyringlobin is added to its solutions: this is reflected in a movement of the oxygen equilibrium curve of such a mixture to higher oxygen partial pressures. Similar experiments with deoxyhaemoglobin solutions containing fast-moving porphyringlobin, showed an initial increase in the rate of CO uptake. Correspondingly, the oxygen equilibrium curve of the mixture showed an increased affinity for oxygen. Approximate calculations to determine the oxygen equilibria of the hybrids indicate that a functional dimer retains co-operative characteristics even when the dimer accompanying it within the tetramer has the reacted conformation.

show abstract

The Absolute Assignment of the Electronic Transitions of α,β,γ,δ-Tetraphenylporphine

Cited by 44 publications

References 1 publication

Extension of the Neglect of Diatomic Differential Overlap Method to Spectroscopy. NDDO-G Parametrization and Results for Organic Molecules

Extension of the Neglect of Diatomic Differential Overlap Method to Spectroscopy. NDDO-G Parametrization and Results for Organic Molecules

Linear Dichroism of Biological Chromophores

A study of the properties of hybrids of oxyhaemoglobin and deoxyhaemoglobin with two porphyringlobin species

Contact Info

Product

Resources

About