The Photolysis in Acidic Aqueous Solutions of the Monooxalato-bisethylenediamine Chromium(III) Cation and the Bisoxalatomonoethylenediamine Chromate(III) Anion: Photolysis Modes and Quantum Yields

1971 ◽  
Vol 49 (3) ◽  
pp. 375-383 ◽  
Author(s):  
A. D. Kirk ◽  
K. C. Moss ◽  
J. G. Valentin
Keyword(s):  
Quantum Yield ◽  
Aqueous Solutions ◽  
Quantum Yields ◽  
Ligand Field ◽  
Intersystem Crossing ◽  
Empirical Correlations ◽  
Complex Ions ◽  
Ethylenediamine Complex ◽  
Ethylenediamine Ligand ◽  
Ph Range

The photolysis reactions of the complex ions [Cr(en)2ox]+ and [Cren(ox)2]− have been studied in the pH range 1 → 3 and at temperatures from 0 to 25 °C. It has been found that both ions photoaquate to a monodentate protonated ethylenediamine complex which then undergoes further aquation thermally with loss of the ethylenediamine ligand. Quantum yields for these aquations were measured for irradiation into the ligand field bands, the values obtained being 0.18 and 0.02, respectively. The results are discussed in terms of known empirical correlations for Cr(III) complexes. Assuming these reactions may occur from the 4T2g state as precursor, arguments are presented that the correlation between quantum yield and ΔE may depend on mixing of the 4T2g and 2Eg states, and its effect on the intersystem crossing rate constant.

Photochemistry of the cis- and trans-Dichlorobisethylenediamine Chromium(III) Cations in Acidic Aqueous Solutions. Observation of a Stereochemical Change in Photoaquation

1971 ◽  
Vol 49 (9) ◽  
pp. 1524-1528 ◽  
Author(s):  
A. D. Kirk ◽  
K. C. Moss ◽  
J. G. Valentin
Keyword(s):  
Aqueous Solution ◽  
Quantum Yield ◽  
Aqueous Solutions ◽  
Trans Isomer ◽  
Ligand Field ◽  
Acidic Aqueous Solution ◽  
Ethylenediamine Complex ◽  
Cis And Trans ◽  
Cis Isomer

The photoreactions of cis- and trans-[CrCl2(en)2]+ have been investigated in acidic aqueous solution at pH 3 and 0 °C. On photolysis in the ligand field bands the cis isomer was found to undergo mainly ethylenediamine aquation, apparently to a thermally unstable monodentate protonated ethylenediamine complex, with a quantum yield of 0.13. In addition chloride aquation occurred with[Formula: see text]. In contrast, the trans isomer underwent exclusive chloride aquation with quantum yield 0.32. The results are qualitatively, but not quantitatively, in agreement with predictions of Adamson's empirical rules. It was found that for trans-[CrCl2(en)2]+ photolysis, the reaction product [CrCl(H2O)(en)2]2+ was produced at least 70% in the cis configuration.

scholarly journals Estimation of quantum yields of weak fluorescence from eosin Y dimers formed in aqueous solutions

2018 ◽  
Vol 17 (6) ◽  
pp. 793-799 ◽  
Author(s):  
Masami Enoki ◽  
Ryuzi Katoh
Keyword(s):  
Quantum Yield ◽  
Aqueous Solutions ◽  
Fluorescence Quantum Yield ◽  
Quantum Yields ◽  
Eosin Y

A weak fluorescence from eosin Y dimers can be observed. The fluorescence quantum yield was estimated to be 0.005.

Photolysis of polychlorinated benzenes in cyclohexane solution

1983 ◽  
Vol 61 (6) ◽  
pp. 1103-1104 ◽  
Author(s):  
Nigel J. Bunce ◽  
Patrick J. Hayes ◽  
Mary E. Lemke
Keyword(s):  
Excited State ◽  
Quantum Yield ◽  
Concentration Dependence ◽  
Quantum Yields ◽  
Intersystem Crossing ◽  
Triplet Excited State ◽  
Chlorinated Benzenes ◽  
Polychlorinated Benzenes

Quantum yields of dechlorination and of intersystem crossing have been measured in cyclohexane for a series of chlorinated benzenes. The results are compatible with the reactions occurring predominantly from the triplet excited state. The quantum yield of reaction shows a concentration dependence on [Formula: see text], but the dependence is less for the more heavily chlorinated members of the scries.

How do ligands influence the quantum yields of cyclometalated platinum(ii) complexes, a theoretical research study

2017 ◽  
Vol 19 (34) ◽  
pp. 23454-23460 ◽  
Author(s):  
Baozhu Yang ◽  
Shuang Huang ◽  
Jianhao Wang
Keyword(s):  
Quantum Yield ◽  
Field Strength ◽  
Research Study ◽  
Theoretical Research ◽  
Quantum Yields ◽  
Ligand Field ◽  
Molecular Rigidity ◽  
Cyclometalated Ligand

Quantum yield differences were explained by the cyclometalated ligand, molecular rigidity and ligand-field strength.

scholarly journals Studying the intersystem crossing rate and triplet quantum yield of meso-substituted porphyrins by means of pulse train fluorescence technique

2016 ◽  
Vol 20 (01n04) ◽  
pp. 282-291 ◽  
Author(s):  
Tiago Gualberto Bezera de Souza ◽  
Marcelo Gonçalves Vivas ◽  
Cleber Renato Mendonça ◽  
Shane Plunkett ◽  
Mikhail A. Filatov ◽  
...  
Keyword(s):  
Quantum Yield ◽  
Pulse Train ◽  
Quantum Yields ◽  
Intersystem Crossing ◽  
Fluorescence Technique ◽  
Substitution Pattern ◽  
Donor And Acceptor ◽  
Yield Values ◽  
Electron Donor And Acceptor ◽  
Triplet Quantum Yields

Excited state dynamics, particularly intersystem crossing, of a set of meso-substituted porphyrins bearing different electron–donor and acceptor groups was studied by pulse train fluorescence technique. Triplet quantum yield was found to be critically dependent on the nature of meso-substituents in the porphyrin system. Porphyrins with meso methoxyphenyl groups were found to show high triplet quantum yields ([Formula: see text] between 0.70 and 0.81). Moreover, the quantity of methoxyphenyl groups and the substitution pattern directly influence [Formula: see text]. Alternatively, porphyrins attached to nitrophenyl group possess low triplet quantum yield values (~0.3). The observed structure-properties relationships suggest new ways for tuning the optical properties of porphyrins via chemical modification.

scholarly journals Ruthenium-based PACT agents based on bisquinoline chelates: synthesis, photochemistry, and cytotoxicity

2021 ◽  
Author(s):  
Anja Busemann ◽  
Ingrid Flaspohler ◽  
Xue-Quan Zhou ◽  
Claudia Schmidt ◽  
Sina K. Goetzfried ◽  
...  
Keyword(s):  
Quantum Yield ◽  
Singlet Oxygen ◽  
Cancer Cells ◽  
Cellular Uptake ◽  
Ruthenium Complex ◽  
Human Cancer ◽  
Light Irradiation ◽  
Quantum Yields ◽  
Light Activation ◽  
Human Cancer Cells

AbstractThe known ruthenium complex [Ru(tpy)(bpy)(Hmte)](PF6)2 ([1](PF6)2, where tpy = 2,2’:6’,2″-terpyridine, bpy = 2,2’-bipyridine, Hmte = 2-(methylthio)ethanol) is photosubstitutionally active but non-toxic to cancer cells even upon light irradiation. In this work, the two analogs complexes [Ru(tpy)(NN)(Hmte)](PF6)2, where NN = 3,3'-biisoquinoline (i-biq, [2](PF6)2) and di(isoquinolin-3-yl)amine (i-Hdiqa, [3](PF6)2), were synthesized and their photochemistry and phototoxicity evaluated to assess their suitability as photoactivated chemotherapy (PACT) agents. The increase of the aromatic surface of [2](PF6)2 and [3](PF6)2, compared to [1](PF6)2, leads to higher lipophilicity and higher cellular uptake for the former complexes. Such improved uptake is directly correlated to the cytotoxicity of these compounds in the dark: while [2](PF6)2 and [3](PF6)2 showed low EC50 values in human cancer cells, [1](PF6)2 is not cytotoxic due to poor cellular uptake. While stable in the dark, all complexes substituted the protecting thioether ligand upon light irradiation (520 nm), with the highest photosubstitution quantum yield found for [3](PF6)2 (Φ[3] = 0.070). Compounds [2](PF6)2 and [3](PF6)2 were found both more cytotoxic after light activation than in the dark, with a photo index of 4. Considering the very low singlet oxygen quantum yields of these compounds, and the lack of cytotoxicity of the photoreleased Hmte thioether ligand, it can be concluded that the toxicity observed after light activation is due to the photoreleased aqua complexes [Ru(tpy)(NN)(OH2)]2+, and thus that [2](PF6)2 and [3](PF6)2 are promising PACT candidates. Graphic abstract

scholarly journals Investigations of ternary complexes of Co(II) and Ni(II) with thiodiacetate anion and 1,10-phenanthroline or 2,2’-bipyridine in aqueous solutions

2014 ◽  
Vol 13 (1) ◽  
Author(s):  
Dariusz Wyrzykowski ◽  
Joanna Pranczk ◽  
Dagmara Jacewicz ◽  
Aleksandra Tesmar ◽  
Bogusław Pilarski ◽  
...  
Keyword(s):  
Aqueous Solutions ◽  
Substitution Reactions ◽  
Experimental Conditions ◽  
Kinetic Measurements ◽  
Hydroxo Complexes ◽  
Binary Complexes ◽  
Vis Spectroscopy ◽  
Potentiometric Titration Method ◽  
The Stability ◽  
Ph Range

AbstractA potentiometric titration method (PT) and a stopped-flow kinetic technique monitored by a UV−Vis spectroscopy have been used to characterize the stability of series of Co(II)- and Ni(II)-thiodiacetato complexes, M(TDA), in the presence of 1,10-phenanthroline (phen) or 2,2’-bipyridine (bipy) in aqueous solutions. The stability constants of the binary (1:1), ternary (1:1:1) as well as the resulting hydroxo complexes were evaluated and compared to the corresponding oxydiacetate complexes. Based on the species distribution as a function of pH the relative predominance of the species in the system over a pH range was discussed. Furthermore, the kinetic measurements of the substitution reactions of the aqua ligands to phen or bipy in the coordination sphere of the binary complexes M(TDA) were performed in the 288–303 K temperature range, at a constant concentration of phen or bipy and at seven different concentrations of the binary complexes (0.2–0.5 mM). The kinetic stability of the M(TDA) complexes was discussed in relation to the experimental conditions and the kind of the auxiliary ligands (phen/bipy). Moreover, the influence of the type of primary ligand (thiodiacetate/oxydiacetate) on the substitution rate of the auxiliary ligands was also compared.

Chemilumineszenz der SO2-Oxidation / Chemiluminescence of SO2-Oxidation

1978 ◽  
Vol 33 (3) ◽  
pp. 293-299 ◽  
Author(s):  
Joachim Stauff ◽  
Wolfgang Jaeschke
Keyword(s):  
Aqueous Solutions ◽  
Spectral Region ◽  
Time Course ◽  
Light Emission ◽  
Analog Computer ◽  
Reaction Scheme ◽  
So2 Oxidation ◽  
Recombination Product ◽  
Electronically Excited ◽  
Ph Range

Abstract The reactions of diluted aqueous solutions of SO2 resp. HSO3-ions with MnO4-or Ce4+ ions in the pH range 1-4 produce chemiluminescence in the spectral region of 450-600 nm. Measurements of the time course of the light emission and their simulation on an analog computer led to a reaction scheme in which a recombination product of primarily formed HSO3 radicals -of a lifetime of about 1 second -appears as precursor of electronically excited SO2 molecules. The participation of singlet oxygen can be excluded because at least the reaction with Ce4+ ions proceeds also in the absence of oxygen.

Quantum yield of solution photolysis of bicyclo[3.1.0]hexan-3-one and derivatives

1981 ◽  
Vol 59 (11) ◽  
pp. 1607-1609 ◽  
Author(s):  
Karl R. Kopecky ◽  
Rodrigo Rico Gomez
Keyword(s):  
Quantum Yield ◽  
Quantum Yields

The quantum yields for photolysis of 0.25 M solutions of bicyclo[3.1.0]hexan-3-one, 1,5-dimethylbicyclo[3.1.0]hexan-3-one, and tricyclo[4.3.1.0]decan-8-one in pentane or cyclohexane with 313 nm light are 0.44, 0.52, and 0.32, respectively.

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