Note on the Influence of External Heavy-Atom Perturbers on the Phosphorescence Spectrum of Triphenylene

1984 ◽  
Vol 39 (11) ◽  
pp. 1145-1146 ◽  
Author(s):  
M. Zander
Keyword(s):  
Complex Formation ◽  
Methyl Iodide ◽  
Ground State ◽  
Chemical Nature ◽  
Heavy Atom ◽  
Phosphorescence Spectrum ◽  
Symmetry Reduction ◽  
Spectral Changes ◽  
Silver Perchlorate ◽  
Phosphorescence Spectra

Spectral changes in symmetry-forbidden phosphorescence spectra observed in the presence of external heavyatom perturbers may have quite different causes depending on the chemical nature of the perturber. This is exemplified using triphenylene as the phosphorescent compound and methyl iodide and silver Perchlorate respectively as the perturber. Intensification of the 0-0 band of the symmetry-forbidden phosphorescence spectrum of triphenylene by silver Perchlorate is assumed to result from symmetry-reduction of the hydrocarbon by ground-state complex formation with silver Perchlorate.

Photoluminescence of [22]Paracyclophane and p-Xylene in the Presence of Silver Ions

1984 ◽  
Vol 39 (10) ◽  
pp. 1009-1010 ◽  
Author(s):  
M. Zander
Keyword(s):  
Fluorescence Quenching ◽  
Ground State ◽  
Room Temperature ◽  
Silver Ions ◽  
Ethyl Bromide ◽  
Silver Ion ◽  
Fluid Solution ◽  
Silver Perchlorate ◽  
Phosphorescence Spectra

Abstract Phosphorescence spectra and phosphorescence lifetimes of [22]paracyclophane (I) and p-xylene have been measured in ethanol glass at 77 K in the presence of silver Perchlorate at various concentrations. From the results it is concluded that the ground state complex formed with AgClO4 is much more stable in the case of the cyclophane than with p-xylene. The results would indicate that under the conditions used [22]paracyclophane forms a 1:1 complex with AgClO4 with the silver ion being located within the cyclophane cage. Fluorescence quenching measurements in fluid solution at room temperature using ethyl bromide and AgClO4 as quenchers support this assumption.

Zur Photolumineszenz von Benzologen des Thiophens

1985 ◽  
Vol 40 (5) ◽  
pp. 497-502 ◽  
Author(s):  
Maximilian Zander
Keyword(s):  
Energy Gap ◽  
Heavy Atom ◽  
Phosphorescence Spectrum ◽  
Quantum Yields ◽  
Triplet States ◽  
Fluorescence And Phosphorescence Spectra ◽  
Atom Effect ◽  
Fluorescence And Phosphorescence ◽  
Phosphorescence Spectra ◽  
Hydrocarbon Fragment

Fluorescence and phosphorescence spectra, fluorescence and phosphorescence quantum yields and phosphorescence lifetimes of the benzologues I -V of thiophene have been measured in ethanol at 77 K. By comparing the energies of the lowest triplet states of the molecules with those of corresponding hydrocarbons it is concluded that the sulphur atoms act like substituents and are not equivalent to aromatic double bonds. The rate of the radiationless deactivation of the lowest triplet state depends on the energy gap Δ E(T1 - S0) in accordance with the Siebrand relation. An unexpected small intraannullar heavy-atom effect of the sulphur is observed in 2,2′-bis-benzo[b]thienyl (II), a strongly fluorescing compound. As the most likely explanation it is concluded from experiments that in II the interaction between the heavy-atom and the π-MO’s of the hydrocarbon fragment (1,4-biphenylbutadiene) is much smaller compared to that in other structurally related benzologues of thiophene. External heavy-atom perturbers (AgClO4, CH3J) have a strong influence on the vibronic structure of the phosphorescence spectrum of IV.

Distorted forms of metalloporphyrins probed by methods of highly resolved spectroscopy

2009 ◽  
Vol 13 (08n09) ◽  
pp. 957-963 ◽  
Author(s):  
Aleksander Starukhin ◽  
Mikalai Kruk
Keyword(s):  
Ground State ◽  
Heavy Atom ◽  
Rare Gas ◽  
Cryogenic Temperatures ◽  
Out Of Plane ◽  
Saddle Type ◽  
Fluorescence And Phosphorescence Spectra ◽  
Atom Effect ◽  
Fluorescence And Phosphorescence ◽  
Phosphorescence Spectra

The spectral manifestations of the distorted forms of sterically unconstrained metallocomplexes of porphyrin in rare gas and Shpol'skii matrices at cryogenic temperatures were detected. The planar and two kinds of distorted conformations of the Mg - and Zn -porphyrins in rare gas matrices have been measured simultaneously in the fluorescence and phosphorescence spectra due to external heavy atom effect. The distinctly different frequencies of the vibronic transitions have been revealed for planar and distorted forms. In the phosphorescence spectra of the Pd -porphyrin the manifestation of the two forms in the ground state has been proven also, with one of them being planar and the other being saddle-type distorted. The ratio of the planar and non-planar forms was shown to depend on the deuteration of both meso-positions of the porphyrin and n-alkane matrix. The appearance of the out-of-plane modes in the phosphorescence spectra of the Pd - and Pt -porphyrin has been demonstrated.

Ionic dissociation in complexes of iodine with triphenylarsine and triphenylstibine

1991 ◽  
Vol 69 (4) ◽  
pp. 606-610 ◽  
Author(s):  
Ying Ru Zhang ◽  
Ira Solomon ◽  
Seymour Aronson
Keyword(s):  
Complex Formation ◽  
Chemical Nature ◽  
Equilibrium Constants ◽  
Electrochemical Technique ◽  
High Iodine ◽  
Ionic Complex ◽  
Ionization Mechanisms ◽  
Iodine Complex ◽  
Ionic Dissociation ◽  
Iodine Complexes

An electrochemical technique has been employed to study the ionization of the iodine complexes of (C6H5)3As, (C6H5)3Sb, and pyridine. Several different ionization mechanisms are proposed depending on the chemical nature and concentration of the reactants. A new ionic complex, (C6H5)3MI22+ is postulated for the interaction of iodine with (C6H5)3As and (C6H5)3Sb at high iodine concentrations. Equilibrium constants have been calculated from the emf data for the various ionization steps. Key words: triphenylarsine, triphenylstibine, iodine, complex formation, ionization.

scholarly journals THE CHEMICAL NATURE OF MACROPHAGE RNA-ANTIGEN COMPLEXES AND THEIR RELEVANCE TO IMMUNE INDUCTION

1969 ◽  
Vol 130 (3) ◽  
pp. 557-574 ◽  
Author(s):  
Georges E. Roelants ◽  
Joel W. Goodman
Keyword(s):  
Amino Acids ◽  
Complex Formation ◽  
Chemical Nature ◽  
Divalent Cations ◽  
Chelating Agent ◽  
Total Absence ◽  
Synthetic Polypeptides ◽  
Antigen Complex ◽  
Anionic Groups ◽  
Do So

10 different compounds, including natural and synthetic polypeptides, proteins, polysaccharides, amino acids, and steroid hormones, were assayed for their capacity to form complexes with peritoneal exudate cell RNA. Only molecules carrying negatively charged groups were able to do so. The formation of RNA-antigen complexes was unrelated to the immuno-potency of the "antigen," was not an enzyme-dependent reaction, did not require the synthesis of RNA following introduction of the antigen, did not seem to involve antigen-specific RNAs, was not specific for macrophages, since HeLa cells could be used as effectively, and occurred when purified RNA was mixed with antigen only in the presence of divalent cations. The complexes were very stable, once formed, but could be dissociated by exhaustive dialysis against buffers containing a chelating agent. The macrophage RNA-antigen complex therefore appears to be a chelate between anionic groups on the two components. Based on the total absence of a relationship between immunogenicity and the capacity to form such complexes, as well as the nonspecific nature of complex formation at every level examined, it appears unlikely that RNA-antigen complexes play a physiologically significant role in immune induction.

Ground-state charge-transfer complex formation in hybrid poly(3-hexyl thiophene):titanium dioxide solar cells

2008 ◽  
Vol 93 (22) ◽  
pp. 223302 ◽  
Author(s):  
I. Haeldermans ◽  
K. Vandewal ◽  
W. D. Oosterbaan ◽  
A. Gadisa ◽  
J. D’Haen ◽  
...  
Keyword(s):  
Titanium Dioxide ◽  
Solar Cells ◽  
Charge Transfer ◽  
Complex Formation ◽  
Ground State ◽  
Charge Transfer Complex ◽  
State Charge

scholarly journals Complex formation in a liquid-liquid extraction-chromogenic system for vanadium(IV)

2019 ◽  
Vol 17 (1) ◽  
pp. 599-608 ◽  
Author(s):  
Kiril B. Gavazov ◽  
Vassil B. Delchev ◽  
Nikolina P. Milcheva ◽  
Galya K. Toncheva
Keyword(s):  
Complex Formation ◽  
Ground State ◽  
Experimental Spectrum ◽  
Molar Absorptivity ◽  
Equilibrium Geometry ◽  
Ortho Position ◽  
Unusual Structure ◽  
Tetrazolium Chloride ◽  
State Equilibrium ◽  
Equilibrium Geometries

AbstractThe azo dye 4-(2-thiazolylazo)orcinol (TAO) and the cationic ion-pair reagent 2,3,5-triphenyl-2H-tetrazolium chloride (TTC) were examined as constituents of a water-chloroform extraction-chromogenic system for vanadium(IV). The effects of TAO concentration, TTC concentration, pH and extraction time were examined. Under the optimum conditions the extracted complex has a composition of 1:2:1 (V:TAO:TTC). The absorption maximum, molar absorptivity and constant of extraction were determined to be λmax=544 nm, ε544=1.75×104 dm3 mol–1 cm–1 and Log Kex=4.1. The ground state equilibrium geometries of the possible monoanionic VIV-TAO 1:2 species were optimized by the HF method using 3-21G* basis functions. Their theoretical time dependent electronic spectra were simulated and compared with the experimental spectrum. The best fit was obtained for the structure in which one of the TAO ligands is tridentate, but the other is monodentate (bound to VIV through the oxygen which is in the ortho-position to the azo group) and forms a hydrogen bond N–H...O=V through its protonated heterocyclic nitrogen. Based on this unusual structure, which can explain some peculiarities of the complex formation between VIV and commonly used azo dyes, the ground state equilibrium geometry of the whole ternary 1:2:1 complex was computed at the HF and BLYP levels.

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