Jean Pierre Fouassier

Bio: Jean Pierre Fouassier is an academic researcher from University of Upper Alsace. The author has contributed to research in topics: Photopolymer & Polymerization. The author has an hindex of 53, co-authored 231 publications receiving 8191 citations. Previous affiliations of Jean Pierre Fouassier include Centre national de la recherche scientifique & École Normale Supérieure.

Toward Nitroxide-Mediated Photopolymerization

Abstract: A new alkoxyamine (methyl 2-((4-benzoylphenyl)((1-methoxy-2-methyl-1-oxopropan-2-yl)oxy)amino)-2-methylpropanoate 4) bearing a chromophore group directly linked to the aminoxyl function is proposed...

Subtle ligand effects in oxidative photocatalysis with iridium complexes: application to photopolymerization.

Abstract: Iridium(III) complexes were designed and evaluated as efficient photoinitiators of polymerization reactions in combination with iodonium salts and silanes. Mechanistically, these reactions were shown to proceed through oxidative photoredox catalysis, generating aryl and silyl radicals under very soft irradiation conditions (blue LED, xenon lamp, and even sunlight). These radicals can initiate the free radical polymerization of acrylates or can be oxidized during the catalytic cycle to promote the ring-opening polymerization of epoxy monomers. Remarkably, both the (photo)chemical reactivity and the practical efficiency are dramatically affected by the ligands. In addition, the central role played by the oxidation ability of the excited state of the photocatalyst is discussed.

Visible Light Photoredox Catalysis with Transition Metal Complexes: Applications in Organic Synthesis

Abstract: A fundamental aim in the field of catalysis is the development of new modes of small molecule activation. One approach toward the catalytic activation of organic molecules that has received much attention recently is visible light photoredox catalysis. In a general sense, this approach relies on the ability of metal complexes and organic dyes to engage in single-electron-transfer (SET) processes with organic substrates upon photoexcitation with visible light. Many of the most commonly employed visible light photocatalysts are polypyridyl complexes of ruthenium and iridium, and are typified by the complex tris(2,2′-bipyridine) ruthenium(II), or Ru(bpy)32+ (Figure 1). These complexes absorb light in the visible region of the electromagnetic spectrum to give stable, long-lived photoexcited states.1,2 The lifetime of the excited species is sufficiently long (1100 ns for Ru(bpy)32+) that it may engage in bimolecular electron-transfer reactions in competition with deactivation pathways.3 Although these species are poor single-electron oxidants and reductants in the ground state, excitation of an electron affords excited states that are very potent single-electron-transfer reagents. Importantly, the conversion of these bench stable, benign catalysts to redox-active species upon irradiation with simple household lightbulbs represents a remarkably chemoselective trigger to induce unique and valuable catalytic processes. Open in a separate window Figure 1 Ruthenium polypyridyl complexes: versatile visible light photocatalysts.

Organic Photoredox Catalysis

Abstract: In this review, we highlight the use of organic photoredox catalysts in a myriad of synthetic transformations with a range of applications. This overview is arranged by catalyst class where the photophysics and electrochemical characteristics of each is discussed to underscore the differences and advantages to each type of single electron redox agent. We highlight both net reductive and oxidative as well as redox neutral transformations that can be accomplished using purely organic photoredox-active catalysts. An overview of the basic photophysics and electron transfer theory is presented in order to provide a comprehensive guide for employing this class of catalysts in photoredox manifolds.

Two-photon polymerization initiators for three-dimensional optical data storage and microfabrication

Abstract: Two-photon excitation provides a means of activating chemical or physical processes with high spatial resolution in three dimensions and has made possible the development of three-dimensional fluorescence imaging, optical data storage, and lithographic microfabrication. These applications take advantage of the fact that the two-photon absorption probability depends quadratically on intensity, so under tight-focusing conditions, the absorption is confined at the focus to a volume of order λ3 (where λ is the laser wavelength). Any subsequent process, such as fluorescence or a photoinduced chemical reaction, is also localized in this small volume. Although three-dimensional data storage and microfabrication have been illustrated using two-photon-initiated polymerization of resins incorporating conventional ultraviolet-absorbing initiators, such photopolymer systems exhibit low photosensitivity as the initiators have small two-photon absorption cross-sections (δ). Consequently, this approach requires high laser power, and its widespread use remains impractical. Here we report on a class of π;-conjugated compounds that exhibit large δ (as high as 1, 250 × 10−50 cm4 s per photon) and enhanced two-photon sensitivity relative to ultraviolet initiators. Two-photon excitable resins based on these new initiators have been developed and used to demonstrate a scheme for three-dimensional data storage which permits fluorescent and refractive read-out, and the fabrication of three-dimensional micro-optical and micromechanical structures, including photonic-bandgap-type structures.

Photoremovable Protecting Groups in Chemistry and Biology: Reaction Mechanisms and Efficacy

Abstract: The review covers the knowledge on photoremovable protecting groups and includes all relevant chromophores studied in the time period of 2000–2012; the most relevant earlier works are also discussed.