Charge Transfer Interactions in the Generation of Singlet Oxygen O2(1Δg) by Strong Electron Donors

1999 ◽  
Vol 103 (15) ◽  
pp. 2705-2711 ◽  
Author(s):  
Alexander P. Darmanyan ◽  
Woojae Lee ◽  
William S. Jenks
Keyword(s):  
Charge Transfer ◽  
Singlet Oxygen ◽  
Electron Donors ◽  
Strong Electron

The ionization energies of some phenothiazine tranquillizers and molecules of similar structure

1968 ◽  
Vol 21 (4) ◽  
pp. 873 ◽  
Author(s):  
A Fulton ◽  
LE Lyons
Keyword(s):  
Charge Transfer ◽  
Complex Formation ◽  
Molecular Orbital ◽  
Equilibrium Constants ◽  
Electron Donors ◽  
Molecular Orbital Calculations ◽  
Strong Electron ◽  
Ionization Energies ◽  
Physiological Action ◽  
The Difference

Charge-transfer spectroscopy was used to determine the ionization energies of ten phenothiazine tranquillizers and similar molecules which are stimulants, in order to throw light on the proposed relation between physiological action and electron-donating power, and to compare the ionization energies of the phenothiazines with molecular orbital calculations. All the ionization energies obtained lie in the range 7.0-8.4 eV. The phenothiazines are thus strong electron donors, in agreement with calculations. There is little difference in ionization energies and equilibrium constants of complex formation between tranquillizers and either non-tranquillizers or stimulants. The difference in physiological action of the drugs therefore cannot be dependent on electron-donating power alone.

scholarly journals Heterophenes revisited

2008 ◽  
Vol 80 (3) ◽  
pp. 475-484 ◽  
Author(s):  
Tien-Yau Luh ◽  
Hsin-Chieh Lin ◽  
Chih-Ming Chou
Keyword(s):  
Charge Transfer ◽  
Double Bond ◽  
Absorption Spectra ◽  
Nonlinear Optical ◽  
Emission Spectra ◽  
Electron Donors ◽  
Significant Enhancement ◽  
Strong Electron ◽  
Nlo Properties ◽  
Stokes Shifts

By employing the furan annulation protocol, a new series of furan-containing teraryl [n.2]cyclophenes (n = 2-6 and 12) are prepared. These cyclophenes exhibit charge-transfer character in the absorption spectra and unusually large Stokes shifts in the emission spectra. They have neither particularly strong electron-donating moieties nor electron-withdrawing groups, but exhibit unusual second-order nonlinear optical (NLO) properties. The π-systems in teraryl system and in the bridging double bond are highly twisted. Interaction between these twisted π-systems may account for the significant enhancement in hyperpolarizability. Thiophene analog behaved similarly. The five-membered heteroaromatic rings may not only serve as electron donors, but also may accommodate the appropriate geometry to enable the interactions between the oligoaryl systems and the double bond leading to unusual photophysical and NLO properties.

New asymmetric π-electron donors yielding metallic charge transfer salts

1999 ◽  
Vol 103 (1-3) ◽  
pp. 2224-2227 ◽  
Author(s):  
C. Rovira ◽  
E. Ribera ◽  
J. Veciana ◽  
V.N. Laukhin ◽  
E. Molinh ◽  
...  
Keyword(s):  
Charge Transfer ◽  
Electron Donors ◽  
Metallic Charge ◽  
Charge Transfer Salts

Lifetime of Singlet Oxygen and Quenching by NaN3 in Mixed Solvents

1982 ◽  
Vol 37 (5) ◽  
pp. 649-652 ◽  
Author(s):  
N. Miyoshi ◽  
M. Ueda ◽  
K. Fuke ◽  
Y. Tanimoto ◽  
M. Itoh ◽  
...  
Keyword(s):  
Activation Energy ◽  
Charge Transfer ◽  
Singlet Oxygen ◽  
Mixed Solvents ◽  
Solvent Polarity ◽  
Thermal Lensing ◽  
Partial Charge ◽  
Partial Charge Transfer ◽  
Quenching Rate ◽  
Quenching Rate Constant

Singlet oxygen was generated by the photosensitization of erythrosine. The lifetime of singlet oxygen and the quenching rate constant for singlet oxygen by NaN3 were measured by a thermal lensing method in MeOH-H2O mixed solvents. The reciprocal of the lifetime increased linearly with the increase of the H2O mole fraction. Semi-log plot of the quenching constant against the reciprocal of the solvent polarity exhibited a linear relation. The quenching of the singlet oxygen by NaN3 may proceed through a partial charge-transfer intermediate. The activation energy for the quenching reaction of N3- + 1O2 →[N3·1O2-] increased with the increase of the solvent polarity. The lifetime was also measured in MeOH-ethyleneglycol mixed solvents, and its relation with viscosity was obtained

The photocycloaddition of dibenzoylmethanatoboron difluoride (DBMBF2) with conjugated enones and en-esters

1993 ◽  
Vol 71 (6) ◽  
pp. 846-854 ◽  
Author(s):  
Yuan L. Chow ◽  
Shi-Sen Wang ◽  
Xian-En Cheng
Keyword(s):  
Excited State ◽  
Charge Transfer ◽  
Ring Opening ◽  
Electron Donors ◽  
Head Orientation ◽  
Singlet Excited State ◽  
Methyl Substitution ◽  
Unsaturated Ketones ◽  
Dibenzoylmethanatoboron Difluoride

Dibenzoylmethanatoboron difluoride (DBMBF2), the BF2 complex of dibenzoylmethane, reacted from its singlet excited state with α,β-unsaturated ketones and esters to give 1,5-diketones by a [2+2] cycloaddition and ring-opening sequence in an analogous pathway to that observed in the photocycloaddition to olefins and dienes. The present photoreaction is unexpected since conjugated enones and en-esters are poor electron donors to comply with the previously proposed charge transfer requirement in DBMBF2 photoreactions. The photocycloaddition to these substrates was highly regioselective and stereoselective, giving the head-to-head orientation, which could be enhanced by α-methyl substitution; β-methyl substitution increased the alternate head-to-tail orientation. The photolysis of a mixture of DBMBF2 and a cyclic enone also caused the latter to dimerize to give head-to-head and head-to-tail dimers in significant yields. These photodimerizations were apparently caused by DBMBF2 sensitization. The mechanism of the sensitization is discussed.

The Influence of Ordering on the Photoinduced Charge Transfer in Composites of Phenyl-type Substituted Polythiophenes with Methanofullerenes

1999 ◽  
Vol 598 ◽  
Author(s):  
Christoph J. Brabec ◽  
Christoph Winder ◽  
Markus C. Scharber ◽  
N. Serdar Sariciftci ◽  
Mats R. Andersson ◽  
...  
Keyword(s):  
Thin Films ◽  
Charge Transfer ◽  
Treatment Results ◽  
Generation Efficiency ◽  
Charge Generation ◽  
Photoinduced Charge Transfer ◽  
Strong Electron ◽  
Low Energies ◽  
Photoinduced Charge ◽  
Absorption Measurements

ABSTRACTRegioregular polythiophenes baring 3-(p-methoxyethoxyethoxy)-phenyl substituents (PEOPT) show high photoluminescence efficiencies. Exposing thin films of this polymer to vapors of chloroform or annealing them by heat treatment results in a red shift of the absorption maximum due to solvent or heat induced ordering which gives rise to more planar conformations. The fact, that annealed thin films of PEOPT exhibit absorption edges at relatively low energies and thus have an enhanced spectral range makes them suitable for use in photodiodes / solar cells. The photoinduced charge generation efficiency in PEOPT is significantly enhanced by the addition of a strong electron acceptor like fullerene, as observed by quenching of the luminescence and by photoinduced absorption measurements in the infrared and UV-Vis regime. The efficiency of the photoinduced charge transfer from PEOPT to a methanofullerene is found to depend on the ordering of PEOPT in thin films.

scholarly journals Spectrophotometric Determination of Three Anti-Ulcer Drugs Through Charge-Transfer Complexation

2002 ◽  
Vol 85 (5) ◽  
pp. 1003-1008 ◽  
Author(s):  
Sheikha Al-Ghannam ◽  
Fathalla Belal
Keyword(s):  
Free Energy ◽  
Charge Transfer ◽  
Stability Constants ◽  
Pharmaceutical Preparations ◽  
Correlation Coefficients ◽  
Spectrophotometric Assay ◽  
Electron Donors ◽  
Radical Anions ◽  
Charge Transfer Complexation

Abstract A simple charge-transfer complexation method is described for the spectrophotometric assay of nizatidine, ranitidine, and famotidine. This method is based on interaction of these drugs, as n-electron donors, with 7,7,8,8-tetracyanoquinodimethane, as the π-acceptor, in acetonitrile to give highly colored green radical anions that are measured at 840 nm. Calibration graphs for the 3 compounds are linear over the concentration ranges of 1–6 μg/mL for nizatidine and ranitidine and 1–7 μg/mL for famotidine, with correlation coefficients (n = 6) of >0.999. The conditioned stability constants and the free energy changes were measured; the values obtained were generally high and negative, respectively, suggesting highly stable complexes. The proposed method was successfully applied to the determination of the drugs in pharmaceutical preparations. The assay results were in accordance with those obtained by using reference methods.

scholarly journals Charge-transfer heptamethine dyes for NIR singlet oxygen generation

2019 ◽  
Vol 55 (38) ◽  
pp. 5511-5514 ◽  
Author(s):  
John B. Jarman ◽  
Dennis A. Dougherty
Keyword(s):  
Charge Transfer ◽  
Triplet State ◽  
Singlet Oxygen ◽  
State Formation ◽  
Charge Transfer State ◽  
Previous Evidence ◽  
Oxygen Generation ◽  
Singlet Oxygen Generation ◽  
A Charge ◽  
Transfer State

A heptamethine-based charge-transfer dye was designed based on previous evidence of triplet state formation in orthogonal charge-transfer partners and calculations suggesting the formation of a charge-transfer state in heptamethine dye derivatives.

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