EVIDENCE OF THE INTRAMOLECULAR VIBRATIONAL EFFECT IN p-BENZOQUINONE

Bagli, Jehanbux F.

doi:10.1021/j100824a506

Cited by 9 publications

(2 citation statements)

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“…The broad peak is assigned to the C=O stretch vibration. No specific assignments have been made for individual components of this band, for which Fermi resonance effects are believed to be responsible (Bagli, 1961). The absorbances in this region are characterized by a splitting of the peak in the higher-intensity region into peaks at 1651.9 and 1649.5 cm-'.…”

Section: Spectral Features Associated With Polar Groupsmentioning

confidence: 99%

A difference infrared-spectroscopic study of the interaction of ubiquinone-10 with phospholipid bilayers

Ondarroa¹,

Quinn²

1986

Biochemical Journal

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The interaction between 1,2-dipalmitoyl phosphatidylcholine and ubiquinone-10 in aqueous systems was studied by difference i.r. spectroscopy. Binary mixtures of the two lipids in proportions of 2, 5 and 15 mol% were investigated in the spectral regions reporting on the hydrocarbon chains of the phospholipid and the polar phosphate group. No spectral shifts or significant broadening of any absorbances due to the phospholipid were detected at temperatures of 20 or 54 degrees C. Changes in the frequency of the maximum of the CH2 antisymmetric C-H stretching vibration with temperature indicated that the gel-to-liquid-crystal-line phase-transition temperature of the phospholipid was lowered by about 2 degrees C in the presence of between 2 and 15 mol% ubiquinone-10. Absorbance by the benzoquinone substituent of ubiquinone-10 was detected by spectral subtraction of dispersions of phospholipid alone. Bands due to C = O stretching and ester group vibrations of ubiquinone-10 in co-dispersion with phospholipid were compared with the same spectral region when ubiquinone-10 was dissolved in solvents or as a crystalline solid. Spectral changes could be detected when ubiquinone-10 in phospholipid was compared with solution in dodecane and chloroform. These may indicate that the benzoquinone ring system is located within a hydrocarbon domain in dispersions with dipalmitoyl phosphatidylcholine. It was concluded from the study that when ubiquinone-10 is co-dispersed with dipalmitoyl phosphatidylcholine in water the two lipids phase-separate. There is no evidence that ubiquinone-10 intercalates between phospholipid molecules, which undergo a gel-liquid-crystalline phase transition in only a slightly modified form. The data suggest that the benzoquinone substituent resides in a hydrophobic domain and that aggregates spanning the bilayer are a possible arrangement of the ubiquinone in the structure.

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Section: Spectral Features Associated With Polar Groupsmentioning

confidence: 99%

A difference infrared-spectroscopic study of the interaction of ubiquinone-10 with phospholipid bilayers

Ondarroa¹,

Quinn²

1986

Biochemical Journal

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“…The vibrational spectrum of the most basic of the p- quinones, 1,4-benzoquinone, has been investigated by many methods. Many early experimental studies ,− concluded that the CO stretching band of quinones, which is highly influenced by reduction , and therefore the most widely monitored in experimental studies, was seen as a doublet because of a Fermi resonance or some intermolecular interaction. Some work concluded that NQ exhibits only one CO stretching frequency .…”

Section: Introductionmentioning

confidence: 99%

A Comparison of the Properties of Various Fused-Ring Quinones and Their Radical Anions Using Hartree−Fock and Hybrid Hartree−Fock/Density Functional Methods

Grafton

Wheeler

1997

J. Phys. Chem. A

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The hybrid Hartree−Fock/density functional B3LYP has been used to predict a variety of properties of 1,4-naphthoquinone, 2-methyl-1,4-naphthoquinone, 2,3-dimethyl-1,4-naphthoquinone, and 9,10-anthraquinone, as well as their radical anions. Geometries and spin properties show good agreement with experiment. The calculated adiabatic electron affinities show excellent agreement with previously determined experimental values, where available. An electron affinity of 1.63 eV is predicted for 2,3-dimethyl-1,4-naphthoquinone. A complete analysis of the vibrational spectra of each neutral molecule is provided and compared with available experimental and previous theoretical results. In each case, the CO antisymmetric stretching vibration is found to be slightly higher in frequency than the CO symmetric stretch. The first full analysis of the vibrational spectra of each of the radical anions is presented, and a comparison is made with the spectra of the neutral molecules. It is found that B3LYP/6-31G(d) theory consistently overestimates vibrational frequencies by 4−5%, in agreement with previous tests, but also does an excellent job of predicting the correct relative ordering of vibrational modes. Unrestricted Hartree−Fock geometries and frequencies are also provided for comparison.

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Notiz über Octafluoranthrachinon

Pavláth

1963

Chem. Ber.

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EVIDENCE OF THE INTRAMOLECULAR VIBRATIONAL EFFECT IN p-BENZOQUINONE

Cited by 9 publications

References 0 publications

A difference infrared-spectroscopic study of the interaction of ubiquinone-10 with phospholipid bilayers

A difference infrared-spectroscopic study of the interaction of ubiquinone-10 with phospholipid bilayers

A Comparison of the Properties of Various Fused-Ring Quinones and Their Radical Anions Using Hartree−Fock and Hybrid Hartree−Fock/Density Functional Methods

Notiz über Octafluoranthrachinon

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