Quantum yields in the photolytic oxidation of some sulphur compounds

1981 ◽  
Vol 59 (18) ◽  
pp. 2750-2754 ◽  
Author(s):  
D. F. Sheraton ◽  
F. E. Murray
Keyword(s):  
Quantum Yield ◽  
Atmospheric Pressure ◽  
Photon Absorption ◽  
Quantum Yields ◽  
Methyl Mercaptan ◽  
Dimethyl Sulphide ◽  
Sulphur Compounds ◽  
Photo Oxidation ◽  
Dimethyl Disulphide ◽  
Oxidation In Air

The photolytic oxidation of methyl mercaptan, dimethyl sulphide, and dimethyl disulphide was studied in a batch photolysis apparatus. Short wavelength ultraviolet light was provided by a deuterium discharge lamp and monitored by a monochromator equipped with an extended response photomultiplyer tube. Sulphide concentrations were determined using a gas chromatograph equipped with a flame photometric detector having a sulphur response at 365 nm.The rate of photo-oxidation of methyl mercaptan was found to be a linear function of the photon absorption rate and exhibited a quantum yield of 12. The methyl mercaptan photo-oxidation rate was found to be unaffected by increased oxygen concentration, decreased atmospheric pressure, or the presence of sulphur dioxide.The quantum yield of dimethyl sulphide photo-oxidation was found to be dependent upon air pressure; the quantum yield of 4 at 1 atm pressure increased to 8 at 1/4 atm.The quantum yield of dimethyl disulphide photo-oxidation in air was found to be 1.9 at atmospheric pressure and a disulphide concentration of 7.04 × 10−5M.

Chemiluminescence from the reactions of ozone with sulphur compounds

1984 ◽  
Vol 62 (3) ◽  
pp. 417-423 ◽  
Author(s):  
P. K. Arora ◽  
J. P. S. Chatha
Keyword(s):  
Gas Phase ◽  
Singlet State ◽  
Carbon Disulphide ◽  
Emission Spectra ◽  
Reaction Pathways ◽  
Ozone Molecule ◽  
Dimethyl Sulphide ◽  
Sulphur Compounds ◽  
Remarkable Similarity ◽  
Dimethyl Disulphide

Emissions from excited SO2 in its singlet state (1B1, and/or 1A2) and triplet state (3B1) have been observed in gas-phase chemiluminescent reactions of ozone with a number of sulphur compounds. The compounds studied are carbon disulphide, thiophene, diallyl sulphide, diallyl disulphide, dimethyl sulphide, dimethyl disulphide, and thiophenol. The reaction pathways responsible for the formation of excited molecules are discussed. The remarkable similarity between the emission spectra of the reactions and the chemiluminescence from the SO + O3 reaction confirms that SO is a precursor for the observed chemiluminescence. Disulphides are found to be more chemiluminescent than monosulphides. The absence of chemiluminescence from HCHO* in the reactions of ozone with allyl sulphide and disulphide indicates that the attack of ozone molecule is on the C—S bond in organic sulphides.

Computational design of ratiometric two-photon fluorescent Zn2+ probes based on quinoline and di-2-picolylamine moieties

2021 ◽  
Author(s):  
Zhe Shao ◽  
Wen-Ying Zhang ◽  
Ke Zhao
Keyword(s):  
Quantum Yield ◽  
Cross Sections ◽  
Fluorescence Quantum Yield ◽  
Density Functional ◽  
Computational Design ◽  
Photon Absorption ◽  
Quantum Yields ◽  
Fluorescence Quantum Yields ◽  
Two Photon ◽  
Before And After

Abstract To improve two-photon absorption (TPA) response of a newly synthesized probe, a series of ratiometric two-photon fluorescent Zn2+ sensors based on quinoline and DPA moieties have been designed. The one-photon absorption, TPA and emission properties of the experimental and designed probes before and after coordination with Zn2+ are investigated employing the density functional theory in combination with response functions. The design consists of two levels. In the first level of design, five probes are constructed through using several electron acceptors or donors to increase accepting or donating ability of the fluorophores. It shows that all the designed probes have stronger TPA intensities at longer wavelengths with respect to the experimental probe because of the increased intra-molecular charge transfer. Moreover, it is found that the probe 4 built by adding an acyl unit has the largest TPA cross section among the designed strictures due to the form of longer conjugated length and more linear backbone. One dimethylamino terminal attached along the skeleton can improve TPA intensity more efficiently than two side amino groups. Therefore, in the second level of design, a new probe 7 is formed by both an acyl unit and a dimethylamino terminal. It exhibits that the TPA cross sections of probe 7 and its zinc complex increase dramatically. Furthermore, the fluorescence quantum yields of the designed probes 4 and 7 are calculated in a new way, which makes use of the relation between the computed difference of dipole moment and the measured fluorescence quantum yield. The result shows that our design also improves the fluorescence quantum yield considerably. All in all, the designed probes 4 and 7 not only possess enhanced TPA intensities but also have large differences of emission wavelength upon Zn2+ coordination and strong fluorescence intensity, which demonstrates that they are potential ratiometric two-photon fluorescent probes.

Flavour sulphides are produced from methionine by two different pathways by Geotrichum candidum

2000 ◽  
Vol 67 (3) ◽  
pp. 371-380 ◽  
Author(s):  
YANN DEMARIGNY ◽  
CÉLINE BERGER ◽  
NATHALIE DESMASURES ◽  
MICHELINE GUEGUEN ◽  
HENRY E. SPINNLER
Keyword(s):  
Mass Spectrometry ◽  
Gas Chromatography ◽  
Geotrichum Candidum ◽  
Gas Chromatography Mass Spectrometry ◽  
Specific Production ◽  
Dimethyl Sulphide ◽  
Sulphur Compounds ◽  
Nitrobenzoic Acid ◽  
Dimethyl Disulphide ◽  
Chromatography Mass Spectrometry

We have investigated the capacities of Geotrichum candidum strains to produce sulphides from methionine. This attribute is very important in cheese technology because of the flavouring potential of sulphur compounds. A spectrophotometric procedure using 5,5′-dithiobis(2-nitrobenzoic acid) to determine sulphides was tested on a collection of G. candidum strains, and confirmed by gas chromatography–mass spectrometry. The strains were distinguished on the basis of their ability to produce methanethiol. Gas chromatography–mass spectrometry also made it possible to identify other sulphides, such as dimethyl disulphide, dimethyl trisulphide and dimethyl sulphide. Using sonicated cells, the specific production of these four sulphides was studied in presence of L-[S-methyl-2H]methionine. Both methanethiol and dimethyl sulphide were produced from methionine, but two different pathways were used by G. candidum.

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

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.

The production of sulphur compounds in Cheddar cheese and their significance in flavour development

1976 ◽  
Vol 43 (2) ◽  
pp. 313-320 ◽  
Author(s):  
D. J. Manning ◽  
Helen R. Chapman ◽  
Zena D. Hosking
Keyword(s):  
Cheddar Cheese ◽  
Dimethyl Sulphide ◽  
Gas Chromatograph ◽  
Sulphur Compounds ◽  
Cheese Flavour ◽  
Photometric Detector

SummaryA method is described for determining H2S, methanethiol and dimethyl sulphide in Cheddar-cheese headspace. Cheeses ranging in age from 2 to 12 months were analysed using a gas chromatograph equipped with a photometric detector. These cheeses were presented to a trained flavour panel for the assessment of quality and intensity of Cheddar cheese flavour.An attempt is made to correlate the concentration of sulphur compounds in the headspace with the average flavour scores. The results suggest that the flavour intensity of the cheese is related to the concentration of methanethiol in the headspace.

New soluble 4-(4-formyl-2,6-dimethoxyphenoxy) substituted phthalocyanines: Synthesis, characterization, photophysical and photochemical properties

2021 ◽  
pp. 1-10
Author(s):  
Ibrahim Erden ◽  
Betül Karadoğan ◽  
Fatma Aytan Kılıçarslan ◽  
Göknur Yaşa Atmaca ◽  
Ali Erdoğmuş
Keyword(s):  
Quantum Yield ◽  
Singlet Oxygen ◽  
Fluorescence Quantum Yield ◽  
Metal Ion ◽  
Mass Spectra ◽  
Quantum Yields ◽  
Therapeutic Outcomes ◽  
Ft Ir ◽  
Photochemical Properties ◽  
New Compounds

This work describes the synthesis, spectral and fluorescence properties of bis 4-(4-formyl-2,6-dimethoxyphenoxy) substituted zinc (ZnPc) and magnesium (MgPc) phthalocyanines. The new compounds have been characterized by elemental analysis, UV-Vis, FT-IR, 1H-NMR and mass spectra. Afterward, the effects of including metal ion on the photophysicochemical properties of the complexes were studied in biocompatible solvent DMSO to analyze their potential to use as a photosensitizer in photodynamic therapy (PDT). The fluorescence and singlet oxygen quantum yields were calculated as 0.04–0.15 and 0.70–0.52 for ZnPc and MgPc, respectively. According to the results, MgPc has higher fluorescence quantum yield than ZnPc, while ZnPc has higher singlet oxygen quantum yield than MgPc. The results show that the synthesized complexes can have therapeutic outcomes for cancer treatment.

Quantum yields of CO2 and SO2 formation from 193 nm photo-oxidation of CO in a sulfuric acid aerosol

1996 ◽  
Vol 93 (2-3) ◽  
pp. 83-87 ◽  
Author(s):  
Clinton T. Mills ◽  
Glenn A. Rowland ◽  
Jan Westergren ◽  
Leon F. Phillips
Keyword(s):  
Sulfuric Acid ◽  
Quantum Yields ◽  
Oxidation Of Co ◽  
Photo Oxidation ◽  
193 Nm
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