NDLI: Photochemical reactions of halogenated aromatic 1,3-diketones in solution studied by steady state, one- and two-color laser flash photolyses.

Please wait, while we are loading the content...

Optical and electron paramagnetic resonance studies of the excited triplet states of UV-B absorbers: 2-ethylhexyl salicylate and homomenthyl salicylate.

Optimizing optogenetic constructs for control over signaling and cell behaviours.

Atomic and molecular analysis highlights the biophysics of unprotonated and protonated retinal in UV and scotopic vision.

Characterizing rhodopsin signaling by EPR spectroscopy: from structure to dynamics.

Photochemical reactions of halogenated aromatic 1,3-diketones in solution studied by steady state, one- and two-color laser flash photolyses.

Pyrimidinone: versatile Trojan horse in DNA photodamage?

Nanostructured anatase $TiO_{2}$ densified at high pressure as advanced visible light photocatalysts

Characterization of photo-intermediates in the photo-reaction pathways of a bacteriorhodopsin Y185F mutant using in situ photo-irradiation solid-state NMR spectroscopy.

Spectral fine tuning of cyanine dyes: electron donor-acceptor substituted analogues of thiazole orange.

Current concept of photocarcinogenesis.

Influence of a chromophore analogue in the protein cage of a photoactive yellow protein.

Photo-damage, photo-protection and age-related macular degeneration.

Photo-control of DNA binding by an engrailed homeodomain-photoactive yellow protein hybrid.

Light, lipids and photoreceptor survival: live or let die?

Year: 2015 Volume: 14 Issue: 8

Year: 2015 Volume: 14 Issue: 7

Year: 2015 Volume: 14 Issue: 6

Year: 2015 Volume: 14 Issue: 5

Year: 2015 Volume: 14 Issue: 4

Year: 2015 Volume: 14 Issue: 3

Year: 2015 Volume: 14 Issue: 2

Year: 2015 Volume: 14 Issue: 1

Year: 2014 Volume: 13

Year: 2013 Volume: 12

Year: 2012 Volume: 11

Year: 2011 Volume: 10

Photochemical reactions of halogenated aromatic 1,3-diketones in solution studied by steady state, one- and two-color laser flash photolyses.

Content Provider	World Health Organization (WHO)-Global Index Medicus
Author	Yamaji, Minoru Suwa, Yurie Shimokawa, Rieko Paris, Cecilia Miranda, Miguel Ángel
Description	Country affiliation: Japan Author Affiliation: Yamaji M ( Division of Molecular Science, Graduate School of Science and Engineering, Gunma University, Kiryu, Gunma 376-8515, Japan. yamaji@gunma-u.ac.jp.)
Abstract	Photochemical processes of 4-tert-butyl-4'-methoxydibenzoylmethane (Avobenzone, AB), 4-phenylbenzoylbenzoyl-, 4-phenylbenzoyl-2'-furanyl- and 4-phenylbenzoyl-2'-thenoylmethanes (PB@Ph, PB@F and PB@T, respectively) substituted with Br and Cl at the C2 position were studied by stationary and laser flash photolyses in solution. The absorption spectral features showed that the molecular structures of the halogenated diketones are in the keto forms while those of halogen-free diketones are in the enol forms. The excited singlet and triplet state energies were determined from the absorption and emission spectra. From the absorption spectral changes upon steady state photolysis of brominated diketones in ethanol, the corresponding halogen-free diketones were formed due to Br elimination being the major photochemical process. The determined quantum yields for the formation of the halogen-free diketones were independent of the amount of dissolved oxygen, indicating that the elimination process is an event in the excited singlet (S1) states. In contrast, from the observed absorption spectra obtained upon photolysis of chlorinated AB and PB@Ph, it was inferred that Norrish type I is the major photochemical reaction in the S1 states in acetonitrile. Chlorinated PB@F and PB@T were found to undergo Cl elimination in the S1 states in cyclohexane to form the corresponding halogen-free diketones. Laser photolysis studies of brominated AB in acetonitrile and ethanol provided a transient absorption spectrum ascribable to the Avobenzone radical (ABR) produced by debromination as the initial intermediate, followed by the AB formation in ethanol. The quenching rate constant of ABR by ethanol and the quantum yield of the AB formation via ABR were determined. These observations provided evidence that H-atom abstraction of ABR from ethanol is responsible for the AB formation. Conversely, laser flash photolysis of brominated and chlorinated PB@Ph, PB@F and PB@T demonstrated the formation of the triplet-triplet absorption spectra. No chemical reactions were found to occur in the triplet (T1) states. Two-color two-laser photolysis studies were carried out on the T1 state of chlorinated PB@Ph, PB@F and PB@T, resulting in the formation of the corresponding halogen-free diketones. These observations confirmed the occurrence of Cl elimination in the highly excited triplet (Tn, n≥ 2) states. Based on the computed bond dissociation energies for the C-halogen and C-C bonds, switching mechanisms of dehalogenation and -cleavage were discussed.
File Format	HTM / HTML
ISSN	1474905X
Issue Number	9
Volume Number	14
e-ISSN	14749092
Journal	Photochemical & Photobiological Sciences
Language	English
Publisher	Royal Society of Chemistry
Publisher Date	2015-09-26
Publisher Place	Great Britain (UK)
Access Restriction	One Nation One Subscription (ONOS)
Subject Keyword	Discipline Chemistry Discipline Biology Ketones Chemistry Photolysis Acetonitriles Bromine Chlorine Ethanol Halogenation Lasers Models, Chemical Molecular Structure Oxygen Solutions Solvents Spectrum Analysis Journal Article Research Support, Non-u.s. Gov't
Content Type	Text
Resource Type	Article
Subject	Physical and Theoretical Chemistry

Sl.	Authority	Responsibilities	Communication Details
1	Ministry of Education (GoI), Department of Higher Education	Sanctioning Authority	https://www.education.gov.in/ict-initiatives
2	Indian Institute of Technology Kharagpur	Host Institute of the Project: The host institute of the project is responsible for providing infrastructure support and hosting the project	https://www.iitkgp.ac.in
3	National Digital Library of India Office, Indian Institute of Technology Kharagpur	The administrative and infrastructural headquarters of the project	Dr. B. Sutradhar bsutra@ndl.gov.in
4	Project PI / Joint PI	Principal Investigator and Joint Principal Investigators of the project	Dr. B. Sutradhar bsutra@ndl.gov.in Prof. Saswat Chakrabarti will be added soon
5	Website/Portal (Helpdesk)	Queries regarding NDLI and its services	support@ndl.gov.in
6	Contents and Copyright Issues	Queries related to content curation and copyright issues	content@ndl.gov.in
7	National Digital Library of India Club (NDLI Club)	Queries related to NDLI Club formation, support, user awareness program, seminar/symposium, collaboration, social media, promotion, and outreach	clubsupport@ndl.gov.in
8	Digital Preservation Centre (DPC)	Assistance with digitizing and archiving copyright-free printed books	dpc@ndl.gov.in
9	IDR Setup or Support	Queries related to establishment and support of Institutional Digital Repository (IDR) and IDR workshops	idr@ndl.gov.in

Photophysical and Photochemical Processes of Excited Singlet and Triplet $[3_{n}]Cyclophanes$ (n = 2–6) Studied by Emission Measurements and Steady-State and Laser Flash Photolyses

Photoreactions of 1,4-naphthoquinone with lysozyme studied by laser flash photolysis and steady-state analysis.

Photosensitized oxidation of tryptophan and tyrosine by aromatic ketones: A laser flash photolysis study

Free-radical reactions of halogenated bridged polycyclic compounds. Part X. Addition of bromine and chlorine to hexachloronorbornadiene

Singlet oxygen production by pyrano and furano 1,4-naphthoquinones in non-aqueous medium.

Aromatic aldols and 1,5-diketones as optimized fragrance photocages.

Direct Photoreduction and Ketone-Sensitized Reduction of Nitrospirobenzopyranindolines by Aliphatic Amines

(CF3CO)2O/CF3SO3H-mediated synthesis of 1,3-diketones from carboxylic acids and aromatic ketones

Photoinduced electron transfer reactions in the 10-methylacridinium cation–benzyltrimethylsilane system: steady-state and flash photolysis studies

Photochemical reactions of halogenated aromatic 1,3-diketones in solution studied by steady state, one- and two-color laser flash photolyses.

Similar Documents

Photophysical and Photochemical Processes of Excited Singlet and Triplet $[3_{n}]Cyclophanes$ (n = 2–6) Studied by Emission Measurements and Steady-State and Laser Flash Photolyses

Photoreactions of 1,4-naphthoquinone with lysozyme studied by laser flash photolysis and steady-state analysis.

Photosensitized oxidation of tryptophan and tyrosine by aromatic ketones: A laser flash photolysis study

Free-radical reactions of halogenated bridged polycyclic compounds. Part X. Addition of bromine and chlorine to hexachloronorbornadiene

Singlet oxygen production by pyrano and furano 1,4-naphthoquinones in non-aqueous medium.

Aromatic aldols and 1,5-diketones as optimized fragrance photocages.

Direct Photoreduction and Ketone-Sensitized Reduction of Nitrospirobenzopyranindolines by Aliphatic Amines

(CF3CO)2O/CF3SO3H-mediated synthesis of 1,3-diketones from carboxylic acids and aromatic ketones

Photoinduced electron transfer reactions in the 10-methylacridinium cation–benzyltrimethylsilane system: steady-state and flash photolysis studies

Photochemical reactions of halogenated aromatic 1,3-diketones in solution studied by steady state, one- and two-color laser flash photolyses.