Squarylium‐Triazine Dyad as a Highly Sensitive Photoradical Generator for Red Light

Abstract

New dyads, based on squarylium dye and substituted-triazine, were synthesized that exhibit an intramolecular photodissociative electron-transfer reaction. The compounds were used as a red-light photoradical generator. The photochemical activity of the dyad was compared to the corresponding unlinked systems (S+T) by determining the rate constant of electron transfer. The efficiency of the radical generation from the dyad compared to the unlinked system was demonstrated by measuring the maximum rate of free radical polymerization of acrylates in film. An excellent relationship between the rate of electron transfer and the rate of polymerization was found, evidencing the interest of this new approach to efficiently produce radicals under red light.

Tailoring of organic dyes with oxidoreductive compounds to obtain photocyclic radical generator systems exhibiting photocatalytic behavior

“…In practice BET reduce the overall radical generation quantum yields. Some new approaches allow to trigger this reaction [57–58]. …”

“…The measurements were performed in acetonitrile solutions under argon bubbling at room temperature. The quenching rate constants k q of the excited states were obtained according to the Stern–Volmer analysis where the reciprocal lifetime is plotted as a function of quencher concentration: [57]. …”

Visible light sensitive photoinitiating systems: Recent progress in cationic and radical photopolymerization reactions under soft conditions

“…), have been mentioned for red light or near-IR induced radical polymerizations [66,67,[221][222][223][224][225][226][227]. However, to the best of our knowledge, [129,213] ε623nm ∼ 28,000 M −1 cm −1 Laser diode (635 nm) Cationic photopolymerization [200] ε638nm ∼ 23,800 M −1 cm −1 LED bulb (630 nm) Cationic photopolymerization [15] ε635nm ∼ 14,400 M −1 cm −1 Laser diode (635 nm) Radical and cationic photopolymerization [150] cationic polymerization under red light (above 600 nm) has not been reported until recently (see Table 11).…”

N‐alkoxypyridinium salts as coinitiators in radical polymerization: Synthesis and Photochemical Properties

“…Among the different ways used to generation efficiently different radicals, photochemistry appears as very popular, affording a good, and pure control of the release process, with high yields and without thermal heating. Therefore, searching for new photoradical generators is still a topic that finds attractive applications in many different fields, such as microelectronics, photoresist, and photopolymerization . The free radical polymerization among various polymer synthesis approaches, is a fast and efficient method for the production of polymeric materials under light irradiation.…”