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Your search keyword '"Thioxanthenes radiation effects"' showing total 3 results
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3 results on '"Thioxanthenes radiation effects"'

1. Synthesis of Xanthones, Thioxanthones and Acridones by a Metal-Free Photocatalytic Oxidation Using Visible Light and Molecular Oxygen.

Author

Torregrosa-Chinillach A and Chinchilla R

Subjects
Acridones chemistry, Acridones radiation effects, Light, Metals chemistry, Oxidants, Photochemical chemistry, Oxidants, Photochemical pharmacology, Oxidation-Reduction radiation effects, Thioxanthenes chemistry, Thioxanthenes radiation effects, Xanthones chemistry, Xanthones radiation effects, Acridones chemical synthesis, Oxygen chemistry, Thioxanthenes chemical synthesis, Xanthones chemical synthesis
Abstract

9 H -Xanthenes, 9 H -thioxanthenes and 9,10-dihydroacridines can be easily oxidized to the corresponding xanthones, thioxanthones and acridones, respectively, by a simple photo-oxidation procedure carried out using molecular oxygen as oxidant under the irradiation of visible blue light and in the presence of riboflavin tetraacetate as a metal-free photocatalyst. The obtained yields are high or quantitative.

Published
2021
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2. Polymerization kinetics and reactivity of alternative initiators systems for use in light-activated dental resins.

Author

Ely C, Schneider LF, Ogliari FA, Schmitt CC, Corrêa IC, Lima Gda S, Samuel SM, and Piva E

Subjects
Absorptiometry, Photon, Biphenyl Compounds chemistry, Biphenyl Compounds radiation effects, Bisphenol A-Glycidyl Methacrylate chemistry, Bisphenol A-Glycidyl Methacrylate radiation effects, Camphor analogs & derivatives, Camphor chemistry, Camphor radiation effects, Composite Resins radiation effects, Dental Materials radiation effects, Humans, Light-Curing of Dental Adhesives, Methacrylates chemistry, Methacrylates radiation effects, Onium Compounds chemistry, Onium Compounds radiation effects, Photoinitiators, Dental radiation effects, Polyethylene Glycols chemistry, Polyethylene Glycols radiation effects, Polymerization, Polymethacrylic Acids chemistry, Polymethacrylic Acids radiation effects, Solubility, Spectrophotometry, Ultraviolet, Spectroscopy, Fourier Transform Infrared, Thiobarbiturates chemistry, Thiobarbiturates radiation effects, Thioxanthenes chemistry, Thioxanthenes radiation effects, Toluene analogs & derivatives, Toluene chemistry, Toluene radiation effects, Water chemistry, Xanthones chemistry, Xanthones radiation effects, para-Aminobenzoates chemistry, para-Aminobenzoates radiation effects, Composite Resins chemistry, Dental Materials chemistry, Photoinitiators, Dental chemistry
Abstract

Objectives: The purpose of this study was to evaluate the reactivity and polymerization kinetics behavior of a model dental adhesive resin with water-soluble initiator systems., Methods: A monomer blend based on Bis-GMA, TEGDMA and HEMA was used as a model dental adhesive resin, which was polymerized using a thioxanthone type (QTX) as a photoinitiator. Binary and ternary photoinitiator systems were formulated using 1mol% of each initiator. The co-initiators used in this study were ethyl 4-dimethylaminobenzoate (EDAB), diphenyliodonium hexafluorophosphate (DPIHFP), 1,3-diethyl-2-thiobarbituric acid (BARB), p-toluenesulfinic acid and sodium salt hydrate (SULF). Absorption spectra of the initiators were measured using a UV-Vis spectrophotometer, and the photon absorption energy (PAE) was calculated. The binary system camphorquinone (CQ)/amine was used as a reference group (control). Twelve groups were tested in triplicate. Fourier-transform infrared spectroscopy (FTIR) was used to investigate the polymerization reaction during the photoactivation period to obtain the degree of conversion (DC) and maximum polymerization rate (R(p)(max)) profile of the model resin., Results: In the analyzed absorption profiles, the absorption spectrum of QTX is almost entirely localized in the UV region, whereas that of CQ is in the visible range. With respect to binary systems, CQ+EDAB exhibited higher DC and R(p)(max) values. In formulations that contained ternary initiator systems, the group CQ+QTX+EDAB was the only one of the investigated experimental groups that exhibited an R(p)(max) value greater than that of CQ+EDAB. The groups QTX+EDAB+DPIHFP and QTX+DPIHFP+SULF exhibited values similar to those of CQ+EDAB with respect to the final DC; however, they also exhibited lower reactivity., Significance: Water-soluble initiator systems should be considered as alternatives to the widely used CQ/amine system in dentin adhesive formulations., (Copyright © 2012 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.)

Published
2012
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3. [Molecular origin of the effects of light on nucleic acid metabolism].

Subjects
Animals, Bacteria drug effects, Bacteriophages drug effects, Cytosine metabolism, DNA radiation effects, Humans, Methylene Blue radiation effects, Mice, Nucleic Acid Renaturation, Nucleic Acids metabolism, Orotic Acid metabolism, Photochemistry, Protein Conformation, Pyrimidines radiation effects, Quaternary Ammonium Compounds radiation effects, RNA radiation effects, Skin Neoplasms radiotherapy, Thioxanthenes radiation effects, Thymine metabolism, Uracil metabolism, Viruses drug effects, Nucleic Acids radiation effects, Radiation Effects, Ultraviolet Rays adverse effects
Published
1974

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