Effect of a heavy atom on photophysical deactivation of triplet states of tetrachloro-substituted derivatives of dibenzo-p-dioxine of symmetry D2h and C2h

2000 ◽  
Vol 89 (1) ◽  
pp. 42-49
Author(s):  
V. G. Klimenko ◽  
R. N. Nurmukhametov ◽  
S. A. Serov ◽  
E. A. Gastilovich
Keyword(s):  
Heavy Atom ◽  
Triplet States ◽  
Derivatives Of

Solvent Effects on the Phosphorescent State of Some Aromatic Carbonyls

1972 ◽  
Vol 50 (22) ◽  
pp. 3601-3606 ◽  
Author(s):  
James B. Gallivan
Keyword(s):  
Heavy Atom ◽  
Solvent Polarity ◽  
Triplet States ◽  
Absorption Bands ◽  
Fundamental Properties ◽  
Relative Contribution ◽  
Alkyl Derivatives ◽  
Solvent Environment ◽  
Derivatives Of ◽  
Phosphorescent State

Triplet state properties of chromone, 4-chromanone, acetophenone, and several alkyl derivatives of acetophenone were studied in a variety of solvent systems. The phosphorescence excitation method was used to monitor the energies and relative intensities of singlet–triplet absorption bands in the presence and absence of heavy atom solvents. The results, combined with earlier optical and magnetic resonance studies of such systems, illustrate the importance of solvent environment in determining fundamental properties of these excited states. Observed trends are interpreted in terms of contrasting effects of changing solvent polarity on proximate n,π* and π.π* triplet states. To describe the relative contribution of each orbital type to the phosphorescent state, the coefficients of each wavefunction must change with solvent. Correspondingly, the solvent environment should be specified whenever orbital designations are made.

Depletion of singlet and triplet states of 1-amino-5, 6, 7, 8-tetrahydronaphthalene due to external heavy-atom perturbation

1986 ◽  
Vol 8 (5) ◽  
pp. 541-552 ◽  
Author(s):  
K. Chatterjee ◽  
S. Chakravorti ◽  
T. Ganguly ◽  
S. B. Banerjee
Keyword(s):  
Heavy Atom ◽  
Triplet States ◽  
Singlet And Triplet States

scholarly journals Фотофизические процессы в молекулах галогенпроизводных флуоресцеина в анионных обратных мицеллах

2020 ◽  
Vol 128 (12) ◽  
pp. 1842
Author(s):  
О.И. Волкова ◽  
А.А. Кулешова ◽  
Б.Н. Корватовский ◽  
А.М. Салецкий
Keyword(s):  
Reverse Micelles ◽  
Heavy Atom ◽  
Rotational Correlation Time ◽  
Dye Molecules ◽  
Time Resolved Fluorescence ◽  
Time Resolved ◽  
Micellar Systems ◽  
Aqueous Micellar Solutions ◽  
Derivatives Of ◽  
Rotational Correlation

Studies of photophysical processes in aqueous micellar solutions of halogen derivatives of fluorescein: Eosin( E), Erythrosin (ER) and Bengal Rose (BR) by methods of dynamic light scattering, stationary and time-resolved fluorescence spectroscopy were carried out. It was found that the introduction of dye molecules into reverse AOT micelles causes an increase in their hydrodynamic radii Rh. The time-resolved fluorescence of the studied dye molecules in reverse micelles was measured. A decrease in the average time of the excited state with an increase in Rh for E, ER, and BR was found, which is associated with an increase in the mobility of water molecules and a decrease in the effect of geometric restriction of dye molecules. The degrees of anisotropy of the fluorescence r of dye molecules in reverse micelles were measured. It was shown that in micellar systems r is greater than in aqueous solutions and decreases with increasing Rh. The rotational correlation time for the studied dye molecules in micellar systems is determined, which decreases for all the studied dyes with an increase in Rh, indicating a decrease in the microviscosity of the confined aqueous medium inside the micelle. In this case , i.e., the value of the time of the rotational correlation is affected by the "heavy atom effect".

Perchlorate and difluorophosphate coordination derivatives of rhenium carbonyl

1980 ◽  
Vol 33 (11) ◽  
pp. 2369 ◽  
Author(s):  
E Horn ◽  
MR Snow
Keyword(s):  
Heavy Atom ◽  
Coordination Geometry ◽  
X Ray Diffraction ◽  
Metal Centre ◽  
Triclinic Space Group ◽  
Full Matrix ◽  
X Ray ◽  
Rhenium Carbonyl ◽  
Hydrolysis Of ◽  
Derivatives Of

The complexes Re(CO)5ClO4, Re(CO)5PO2F2, L2(CO)3Re(OClO3) and L2(CO)3Re(PO2F2), where L2 = 2,2?-bipyridyl (bpy), have been synthesized by bromide abstraction reactions from the respective rhenium carbonyl bromide precursors. The complexes were characterized by infrared and mass spectroscopy. The crystal structure of (bpy)(CO)3Re(PO2F2) has been determined from X-ray diffraction data by the heavy-atom technique. The crystals are triclinic, space group Pī with a 8.620(3), b 15.912(5), c 6.466(3) Ǻ, α 102.08(8), β 83.29(8), γ 95.08(4) and Z 2. The structure has been refined by full-matrix least-squares from 2829 reflections to R = 0.084, Rw = 0.088. The coordination geometry about rhenium is that of a distorted octahedron. Difluorophosphate coordinates to the metal centre by one of its oxygen atoms. Formation of the difluorophosphate by hydrolysis of hexafluorophosphate was shown by 31P n.m.r. spectra.

scholarly journals The binding of platinum hexahalides (Cl, Br and I) to hen egg-white lysozyme and the chemical transformation of the PtI6octahedral complex to a PtI3moiety bound to His15

2014 ◽  
Vol 70 (9) ◽  
pp. 1132-1134 ◽  
Author(s):  
Simon W. M. Tanley ◽  
Laurina-Victoria Starkey ◽  
Lucinda Lamplough ◽  
Surasek Kaenket ◽  
John R. Helliwell
Keyword(s):  
Heavy Atom ◽  
Egg White ◽  
Hen Egg White Lysozyme ◽  
Egg White Lysozyme ◽  
Density Maps ◽  
Square Planar ◽  
Chemical Behaviour ◽  
Hen Egg White ◽  
Derivatives Of ◽  
Hen Egg

This study examines the binding and chemical stability of the platinum hexahalides K2PtCl6, K2PtBr6and K2PtI6when soaked into pre-grown hen egg-white lysozyme (HEWL) crystals as the protein host. Direct comparison of the iodo complex with the chloro and bromo complexes shows that the iodo complex is partly chemically transformed to a square-planar PtI3complex bound to the Nδatom of His15, a chemical behaviour that is not exhibited by the chloro or bromo complexes. Each complex does, however, bind to HEWL in its octahedral form either at one site (PtI6) or at two sites (PtBr6and PtCl6). As heavy-atom derivatives of a protein, the octahedral shape of the hexahalides could be helpful in cases of difficult-to-interpret electron-density maps as they would be recognisable `objects'.

Triplet state quantum yields for some arom atic hydrocarbons and xanthene dyes in dilute solution

1967 ◽  
Vol 299 (1458) ◽  
pp. 348-353 ◽  
Keyword(s):  
Triplet State ◽  
State Formation ◽  
Heavy Atom ◽  
Quantum Yields ◽  
Triplet States ◽  
Dilute Solution ◽  
Perturbation Techniques ◽  
Excited Singlet ◽  
Xanthene Dyes ◽  
Extinction Coefficients

Quantum yields of triplet state formation and extinction coefficients of the triplet states have been determined by direct depletion methods for solutions of anthracene, phenanthrene, 1,2,5,6-dibenzanthracene, fluorescein, dibromofluorescein, eosin and erythrosin. The values obtained for the hydrocarbons are in reasonable agreement with those obtained by other workers using energy transfer and heavy atom perturbation techniques. In all cases which we have studied, the sum of the quantum yields of fluorescence and triplet state formation is equal to unity within the limits of experimental error, showing that radiationless transfer from the excited singlet to the ground state is negligible.

scholarly journals HAD, a Data Bank of Heavy-Atom Binding Sites in Protein Crystals: a Resource for Use in Multiple Isomorphous Replacement and Anomalous Scattering

1998 ◽  
Vol 54 (6) ◽  
pp. 1199-1206 ◽  
Author(s):  
Suhail A. Islam ◽  
David Carvin ◽  
Michael J. E. Sternberg ◽  
Tom L. Blundell
Keyword(s):  
Binding Sites ◽  
Heavy Atom ◽  
Data Bank ◽  
Protein Crystals ◽  
Anomalous Scattering ◽  
Isomorphous Replacement ◽  
Crystallization Conditions ◽  
Derivatives Of ◽  
Coordinate Data

Information on the preparation and characterization of heavy-atom derivatives of protein crystals has been collected, either from the literature or directly from protein crystallographers, and assembled in the form of a heavy-atom data bank (HAD). The data bank contains coordinate data for the heavy-atom positions in a form that is compatible with the crystallographic data in the Brookhaven Protein Data Bank, together with a wealth of information on the crystallization conditions, the nature of the heavy-atom reagent and references to relevant publications. Some statistical information derived from the data bank, such as the most popular heavy-atom derivatives, is also included. The information can be directly accessed and should be useful to protein crystallographers seeking to improve their success in preparing heavy-atom derivatives for the methods of isomorphous replacement and anomalous dispersion. The World Wide Web address of HAD is http://www.icnet.uk/bmm/had.

scholarly journals Phosphoreszenzeigensch aften von Methyl-, Chlor- und Brom-Derivaten des [2.2] Paracyclophans

1987 ◽  
Vol 42 (9) ◽  
pp. 1041-1042 ◽  
Author(s):  
H. Hopf ◽  
E. Hermann
Keyword(s):  
Triplet State ◽  
Fluorescence Spectra ◽  
Heavy Atom ◽  
The Other ◽  
Quantum Yields ◽  
Heavy Atom Effect ◽  
Chloro Derivatives ◽  
Derivatives Of ◽  
Atom Effect

Phosphorescence and fluorescence spectra, quantum yields of phosphorescence and fluorescence as well as phosphorescence lifetimes have been measured of six methyl-, chloro- and bromo-derivatives of [2.2] paracyclophane in ethanol at 77 K. While the chloro-derivatives as well as dibromo-paracyclophane exhibit a normal internal heavy-atom effect behaviour the momobromo-compound shows anomalies. These possibly indicate that in the monobromo-compound an additional pathway of the radiationless deactivation of the lowest triplet state is effective which does not occur with the other compounds.

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