Mechanistic Investigation of a Dual Bicyclic Photoinitiating System for Synthesis of Organic-Inorganic Hybrid Materials.
One-pot synthesis of organic-inorganic hybrid materials under light requires specific photoinitiating systems which are able to release several different initiating species after light absorption. In this paper, the reaction mechanism of a photocyclic three-component initiating system based on isopropylthioxanthone as photoinitiator and an iodonium salt and a thiol as co-initiators was studied. It is shown that this system enables simultaneous release of both radicals and protons which are able to initiate a free radical photopolymerization and the hydrolysis-condensation of a sol-gel network, respectively. Time-resolved investigations by laser flash photolysis show that the initiating species are produced within two concomitant cyclic reaction mechanisms depending on the relative quantities of the co-initiators. Protons resulting from the secondary dark reaction of the photocyclic systems are detected at the microsecond scale by means of a proton-sensitive molecular probe, and corresponding quantum yields are measured. Finally, synthesis of organic, inorganic, and hybrid materials under LED light at 395 nm is evaluated with respect to the mechanistic considerations demonstrating the dual initiating character of the system.
Laboratory of Macromolecular Photochemistry and Engineering, University of Haute-Alsace , 3b rue Alfred Werner, 68093 Mulhouse, France.
Julien
J
Christmann
Key Laboratory of Synthetic and Natural Functional Molecule Chemistry of Ministry of Education and College of Chemistry & Material Science, Northwest University , Xi'an 710069, PR China.
Suqing
S
Shi
Laboratory of Macromolecular Photochemistry and Engineering, University of Haute-Alsace , 3b rue Alfred Werner, 68093 Mulhouse, France.
Ahmad
A
Ibrahim
Laboratory of Macromolecular Photochemistry and Engineering, University of Haute-Alsace , 3b rue Alfred Werner, 68093 Mulhouse, France.
Christian
C
Ley
Laboratory of Macromolecular Photochemistry and Engineering, University of Haute-Alsace , 3b rue Alfred Werner, 68093 Mulhouse, France.
Céline
C
Croutxé-Barghorn
Laboratory of Macromolecular Photochemistry and Engineering, University of Haute-Alsace , 3b rue Alfred Werner, 68093 Mulhouse, France.
Marjolaine
M
Bessières
Laboratory of Macromolecular Photochemistry and Engineering, University of Haute-Alsace , 3b rue Alfred Werner, 68093 Mulhouse, France.
Xavier
0000-0003-2194-939X
X
Allonas