scholarly journals New core-pyrene π structure organophotocatalysts usable as highly efficient photoinitiators

2013 ◽  
Vol 9 ◽  
pp. 877-890 ◽  
Author(s):  
Sofia Telitel ◽  
Frédéric Dumur ◽  
Thomas Faury ◽  
Bernadette Graff ◽  
Mohamad-Ali Tehfe ◽  
...  
Keyword(s):  
Free Radicals ◽  
Dft Calculations ◽  
Flash Photolysis ◽  
Laser Flash Photolysis ◽  
Alkyl Halide ◽  
Laser Flash ◽  
Absorption Property ◽  
Sulfonium Salts ◽  
The Core ◽  
Initiation Step

Eleven di- and trifunctional compounds based on a core-pyrene π structure (Co_Py) were synthesized and investigated for the formation of free radicals. The application of two- and three-component photoinitiating systems (different Co_Pys with the addition of iodonium or sulfonium salts, alkyl halide or amine) was investigated in detail for cationic and radical photopolymerization reactions under near-UV–vis light. The proposed compounds can behave as new photocatalysts. Successful results in terms of rates of polymerization and final conversions were obtained. The strong MO coupling between the six different cores and the pyrene moiety was studied by DFT calculations. The different chemical intermediates are characterized by ESR and laser flash photolysis experiments. The mechanisms involved in the initiation step are discussed, and relationships between the core structure, the Co_Py absorption property, and the polymerization ability are tentatively proposed.

Decay Kinetics of Benzophenone Triplets and Corresponding Free Radicals in Soft and Rigid Polymers Studied by Laser Flash Photolysis

2013 ◽  
Vol 90 (2) ◽  
pp. 369-373 ◽  
Author(s):  
Peter P. Levin ◽  
Alexei F. Efremkin ◽  
Natalie B. Sultimova ◽  
Valery V. Kasparov ◽  
Igor V. Khudyakov
Keyword(s):  
Free Radicals ◽  
Flash Photolysis ◽  
Laser Flash Photolysis ◽  
Laser Flash ◽  
Decay Kinetics ◽  
Rigid Polymers ◽  
Kinetics Of

Optical Absorption Spectra of Phosphonyl Radicals

1984 ◽  
Vol 39 (5) ◽  
pp. 434-436 ◽  
Author(s):  
T. Sumiyoshi ◽  
A. Henne ◽  
P. Lechtken ◽  
W. Schnabel
Keyword(s):  
Free Radicals ◽  
Absorption Band ◽  
Flash Photolysis ◽  
Laser Flash Photolysis ◽  
General Structure ◽  
Laser Flash ◽  
Type I ◽  
Phosphine Oxides ◽  
Optical Absorption Spectra ◽  
Strong Absorption Band

Upon UV-irradiation, various phosphine oxides of the general structure I were found to be fragmented readily into free radicals I′ and I″ Laser flash photolysis studies revealed that radicals of type I" with R2 and/or R3 being phenyl groups possess a strong absorption band with a maximum around 330 nm. ε335nm= 1.9×104 1/mol cm was estimated for diphenyl phosphonyl radicals (Ph2P = O).

Kinetics of benzophenone ketyl free radicals recombination in a polymer: reactivity in the polymer cage vs. reactivity in the polymer bulk

2015 ◽  
Vol 14 (5) ◽  
pp. 891-896 ◽  
Author(s):  
Peter P. Levin ◽  
Alexei F. Efremkin ◽  
Igor V. Khudyakov
Keyword(s):  
Free Radicals ◽  
Flash Photolysis ◽  
Laser Flash Photolysis ◽  
Laser Flash ◽  
Decay Kinetics ◽  
Temperature Range ◽  
Polymer Bulk ◽  
Poly Ethylene ◽  
Kinetics Of ◽  
Soft Rubber

The decay kinetics of intermediates produced under photolysis of benzophenone (B) dissolved in soft rubber poly(ethylene-co-butylene) films (abbreviated asE) was studied by ns laser flash photolysis in the temperature range of 263–313 K.

The absolute kinetics for radical addition and electronic energy transfer to [1.1.1]propellane

1998 ◽  
Vol 76 (10) ◽  
pp. 1474-1489 ◽  
Author(s):  
P F McGarry ◽  
J C Scaiano
Keyword(s):  
Free Radicals ◽  
Rate Constants ◽  
Flash Photolysis ◽  
Laser Flash Photolysis ◽  
Laser Flash ◽  
Electronic Energy ◽  
Triplet States ◽  
Quenching Rate ◽  
Electronic Energy Transfer ◽  
Diffusion Controlled

Free radicals react more readily with [1.1.1]propellane, 1, than with styrene. For example Et3Si· reacts with 1 and styrene with rate constants of 6 × 108 M-1 s-1 and 2 × 108 M-1 s-1, respectively. Fluorenone, phenanthrene, triphenylene, benzophenone, and pyrene transfer electronic energy to 1 with rate constants well below the diffusion-controlled limit. For example, triplet benzophenone is quenched by 1 with a bimolecular rate constant of 9.9 × 106 M-1 s-1. A linear dependence of the log of the quenching rate constants, log kq, upon the excited-state energy of the donors is found.Key words: propellane, laser flash photolysis, free radicals, triplet states.

Photoinduced Bond Dissociation of 4-Methylcoumarin Derivatives in Solution Studied by Laser Flash Photolysis and DFT Calculations

2009 ◽  
Vol 113 (20) ◽  
pp. 5815-5822 ◽  
Author(s):  
Minoru Yamaji ◽  
Koichi Nozaki ◽  
Xavier Allonas ◽  
Satoru Nakajima ◽  
Shozo Tero-Kubota ◽  
...  
Keyword(s):  
Dft Calculations ◽  
Flash Photolysis ◽  
Laser Flash Photolysis ◽  
Laser Flash ◽  
Bond Dissociation

Effect of Aggregation on Bacteriochlorin a Triplet-state Formation: A Laser Flash Photolysis Study¶

2002 ◽  
Vol 76 (5) ◽  
pp. 480 ◽  
Author(s):  
Xavier Damoiseau ◽  
Francis Tfibel ◽  
Maryse Hoebeke ◽  
Marie-Pierre Fontaine-Aupart
Keyword(s):  
Triplet State ◽  
State Formation ◽  
Flash Photolysis ◽  
Laser Flash Photolysis ◽  
Laser Flash

A Laser Flash Photolysis and Pulse Radiolysis Study of Primary Photochemical Processes of Flumequine¶

2000 ◽  
Vol 72 (4) ◽  
pp. 451 ◽  
Author(s):  
M. Bazin ◽  
F. Bosca ◽  
M. L. Marin ◽  
M. A. Miranda ◽  
L. K. Patterson ◽  
...  
Keyword(s):  
Pulse Radiolysis ◽  
Flash Photolysis ◽  
Laser Flash Photolysis ◽  
Laser Flash ◽  
Photochemical Processes
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