Konfiguration der Elektronen-Donator-Acceptor-Komplexe

Briegleb, G.

doi:10.1007/978-3-642-86555-8_10

Cited by 80 publications

(110 citation statements)

References 65 publications

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“…Possibly the most general method is to determine the rank of a matrix relating the absorbancies of solutions at different wavelengths to the differing concentrations (Briegleb, 1961). However, practical use of this method is severely limited by experimental error.…”

Section: Resultsmentioning

confidence: 99%

Spectra of Molecular Complexes of Porphyrins in Aqueous Solution^*

Mauzerall¹

1965

Biochemistry

105

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The changes in the absorption and emission spectra of porphyrins in various molecular complexes in aqueous solution have been studied. These complexes are formed with a variety of molecules including large organic cations and planar neutral heterocyclic molecules. Spectral analysis by the method of continuous variation, the lack of isosbestic points, and a new analysis based on band widths all point to the formation of a series of complexes with several addends clustered about the porphyrin ring. Ionic and dispersion forces contribute to the stability of the complexes, but the water structure about these large hydrophobic molecules is an equally important factor. An estimate of the latter interaction based on interfacial tension is given.T he unique absorption spectra of the porphyrin pigments has allowed their identification and study throughout the biological realm. The large over-all variation of spectra with changes of structure has been used to identify these pigments. However, much information concerning the nonbonded or weakly bonded environment of these pigments remains untapped in minor spectral variations.In the course of experiments on the photoreactions of porphyrins, a marked effect of pyridinium salts (NAD' models) on the photochemistry was traced to the formation of complexes with the porphyrin. These complexes were found to occur with a wide class of compounds, many of biological importance. Their description is relevant to the problem of deciphering the effect of environment on porphyrin pigments in vivo. Moreover, some insight is gained into both the theory of porphyrin spectra and the binding of molecular complexes in aqueous solution. . This investigation was aided by a grant (GM 04922) from the U.S. Public Health Service.Abbreviation used in this work: NAD, nicotinamideadenine dinucleotide.The spectral changes, particularly the broadening of the Soret band and not of the red band I , are interpreted as a change in the nearly degenerate x and y components of the energy levels, and a model of the complex is derived.Studies at extreme dilution M), an analysis of the optical effects of aggregation on the spectra, and the absence of polarization of fluorescence all favor the view that the uroporphyrin is monomolecularly dispersed. A suggestion is made that such complexes occur in heme proteins as part of the phosphorylating mechanism and that the widespread occurrence of heterocyclic molecules in biological systems is related to the formation of complexes. otherwise stated, uroporphyrin isomer 111 or a mixture of isomers, mostly isomer 111, was used in this work. Most of the quaternary salts were synthesized in the laboratory and their melting points, analysis, and absorption spectra agreed with previously published data. Other compounds were the purest commercially available and were recrystallized when necessary, e.g., hexadecyltrimethylammonium bromide. The water was glass redistilled, and quantitative technique was used throughout. Absorption spectra were measured on a Cary Model 14 MR spectro...

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Section: Resultsmentioning

confidence: 99%

Spectra of Molecular Complexes of Porphyrins in Aqueous Solution^*

Mauzerall¹

1965

Biochemistry

105

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“…Total energies Etotal , and Erest, are obtained by .adding to the corresponding 7r-electronic energies the core repulsion energy (5) where 2 , and ZQ denote the number of 7r-electrons contributed by the atoms p and q respectively. According to the usual description of the core, y, in Equation (5) should be the same as the Coulomb repulsion integral of the corresponding 7r-electrons when p and q are far apart.…”

Section: And (3)mentioning

confidence: 99%

Theoretical study of a 1 : 1 complex between quinone and hydroquinone

Sundaram

Purcell

1971

Int J of Quantum Chemistry

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AbstractsThe Variable Electronegativity Pariser-Parr-Pople method has been successfully applied to calculate the potential energy curve for the formation of a 1 : 1 complex between quinone and hydroquinone. A consistent evaluation of core and electronic repulsion integrals is important to obtain a meaningful curve. A computationally simple procedure has been suggested for separating interactions due to electron exchange between the components from other intermolecular interactions. In agreement with experimental deductions the preferred configuration for the quinone-hydroquinone complex is found to be one in which the molecules are in parallel planes with their C-0 bonds parallel. The equilibrium separation between the molecular planes is found to be 2.3 A and the stabilization energy in this position is 1.2 eV. In this equilibrium position forces due to electron exchange constitute the major contributing factor to the stability of the complex.

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“…It is important to note that the actual values of the slopes are much smaller than unity. It is well known that unit slopes are characterizing weak molecular interactions (22,23). On the other hand, it has been suggested that the smaller the value of the slope, the stronger is the interaction between the donoracceptor partners (24).…”

Section: Resultsmentioning

confidence: 99%

Interpretation of n-donor specific solvent effect on electronic spectra of copper acetate and chloride complexes by intermolecular perturbation theory

Szpakowska¹,

Nagy²

1988

Can. J. Chem.

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MARIOLA SZPAKOWSKA and O T T~ B.NAGY. Can. J. Chem. 66, 2250Chem. 66, (1988. A simple second order intermolecular perturbation theory is proposed in the Fukui approximation to account for the electronic spectral behavior of electron acceptor solutes dissolved in pure n-donor solvents. This double perturbation theory considers explicitly both the solvating and complexing effects of the solvent. Using the electronic spectral data of mono-and binuclear copper acetate and chloride complexes obtained in pure pyridine derivatives it is shown that the predicted shifts brought about by increasing n-donor ability of solvent are fully corroborated by experiment. The sensitivity of mononuclear copper complexes to steric effects is also confirmed and it is shown that binuclear ones are not sensitive to this effect. New ionization potential values have also been determined using a simple interpolation-standardization procedure.MARIOLA SZPAKOWSKA et O T T~ B.NAGY. Can. J. Chem. 66,2250Chem. 66, (1988. Une thtorie simple de perturbation intermoltculaire d'ordre deux est proposte dans I'approximation de Fukui afin d'interprtter le comportement spectroscopique de solutts accepteurs d'tlectrons dissouts dans des solvants purs n-donneurs. Cette thtorie de double perturbation considtre explicitement les effets solvatants et complexants du solvant. En utilisant les donntes de la spectroscopie tlectronique de complexes d'acttate et de chlorure de cuivre mono-et binucltaires obtenues dans des dtrivts purs de pyridine, il est dtmontrt que les dtplacements prtdits, provoquts par le pourvoir n-donneur croissant du solvant, sont complttement corroborts par l'exptrience. La sensibilitt de complexes de cuivre mononucltaires aux effets sttriques est aussi confirmte et il est dtmontrt que les complexes binucltaires ne sont pas sensibles a ces effets. De nouvelles valeurs de potentiel d'ionisation ont t t t aussi dttermintes en utilisant une simple proctdure d'interpolation et de standardisation.

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Konfiguration der Elektronen-Donator-Acceptor-Komplexe

Cited by 80 publications

References 65 publications

Spectra of Molecular Complexes of Porphyrins in Aqueous Solution^*

Spectra of Molecular Complexes of Porphyrins in Aqueous Solution^*

Theoretical study of a 1 : 1 complex between quinone and hydroquinone

Interpretation of n-donor specific solvent effect on electronic spectra of copper acetate and chloride complexes by intermolecular perturbation theory

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Konfiguration der Elektronen-Donator-Acceptor-Komplexe

Cited by 80 publications

References 65 publications

Spectra of Molecular Complexes of Porphyrins in Aqueous Solution*

Spectra of Molecular Complexes of Porphyrins in Aqueous Solution*

Theoretical study of a 1 : 1 complex between quinone and hydroquinone

Interpretation of n-donor specific solvent effect on electronic spectra of copper acetate and chloride complexes by intermolecular perturbation theory

Contact Info

Product

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Spectra of Molecular Complexes of Porphyrins in Aqueous Solution^*

Spectra of Molecular Complexes of Porphyrins in Aqueous Solution^*