Next Article in Journal
Comparative Evaluation of Essential Oils from Medicinal-Aromatic Plants of Greece: Chemical Composition, Antioxidant Capacity and Antimicrobial Activity against Bacterial Fish Pathogens
Next Article in Special Issue
New Donor-Acceptor Stenhouse Adducts as Visible and Near Infrared Light Polymerization Photoinitiators
Previous Article in Journal
Identifying Ortholog Selective Fragment Molecules for Bacterial Glutaredoxins by NMR and Affinity Enhancement by Modification with an Acrylamide Warhead
Open AccessFeature PaperArticle

Design of Iodonium Salts for UV or Near-UV LEDs for Photoacid Generator and Polymerization Purposes

1
Aix Marseille Univ, CNRS, ICR UMR 7273, 13397 Marseille, France
2
Université de Haute-Alsace, CNRS, IS2M UMR 7361, F-68100 Mulhouse, France
3
Université de Strasbourg, 67000 Strasbourg, France
*
Authors to whom correspondence should be addressed.
Academic Editors: Frédéric Dumur and Guillaume Noirbent
Molecules 2020, 25(1), 149; https://doi.org/10.3390/molecules25010149
Received: 16 December 2019 / Accepted: 27 December 2019 / Published: 30 December 2019
(This article belongs to the Special Issue Recent Advances in Photocatalysts for Polymerization Reaction)
Iodonium salts are well established photoacid generators, cationic photoinitiators, as well as additives commonly used in photoredox catalytic cycles. However, as a strong limitation, iodonium salts are characterized by low light absorption properties for λ > 300 nm so that these latter cannot be activated with cheap, safe, and eco-friendly near UV or even visible light emitting diodes (LEDs). To overcome this drawback, the covalent linkage of an iodonium salt to a chromophore absorbing at longer wavelength is actively researched. With aim at red-shifting the absorption spectrum of the iodonium salt, the synthesis of new compounds combining within a unique chemical structure both the chromophore (here the naphthalimide scaffold) and the iodonium salt is presented. By mean of this strategy, a polymerization could be initiated at 365 nm with the modified iodonium salts whereas no polymerization could be induced with the benchmark iodonium salt i.e., Speedcure 938 at this specific wavelength. To examine the effect of the counter-anion on the photoinitiating ability of these different salts, five different counter-anions were used. Comparison between the different anions revealed the bis(trifluoromethane)sulfonimide salt to exhibit the best photoinitiating ability in both the free radical polymerization of acrylates and the cationic polymerization of epoxides. To support the experimental results, molecular orbital calculations have been carried out. By theoretical calculations, the initiating species resulting from the photocleavage of the iodonium salts could be determined. The cleavage selectivity and the photochemical reactivity of the new iodoniums are also discussed. View Full-Text
Keywords: iodonium salt; photoacid; photopolymerization; cationic initiator; LED iodonium salt; photoacid; photopolymerization; cationic initiator; LED
Show Figures

Graphical abstract

MDPI and ACS Style

Villotte, S.; Gigmes, D.; Dumur, F.; Lalevée, J. Design of Iodonium Salts for UV or Near-UV LEDs for Photoacid Generator and Polymerization Purposes. Molecules 2020, 25, 149.

Show more citation formats Show less citations formats
Note that from the first issue of 2016, MDPI journals use article numbers instead of page numbers. See further details here.

Article Access Map by Country/Region

1
Search more from Scilit
 
Search
Back to TopTop