Blue light driven free-radical polymerization using arylazo sulfones as initiators

Abstract

The polymerization of a broad range of electron-poor olefins has been achieved under free-radical conditions by using arylazo sulfones as visible light photoinitiators. The process proceeds smoothly at room temperature...

“Clickable” Polymer Brush Interfaces: Tailoring Monovalent to Multivalent Ligand Display for Protein Immobilization and Sensing

“…RAFT polymerization in this context appears to be a suitable candidate since, apart from advantages like its metalfree nature, the chain end of polymers obtained using this method bears the thioester or trithio-carbonate groups, which can undergo a variety of chemical transformations. 38−40 Azo group containing molecules which decompose through either thermal or photochemical activation furnish radical intermediates which can act as polymerization initiators, 41 fragmentation units, 42 or chain-terminating agents for polymers obtained through RAFT polymerization. 43−46 Herein, we demonstrate that polymer brushes fabricated on a Si/SiO 2 glass-like surface using RAFT polymerization are amenable to the facile transformation of their thioester-based chain end group into a variety of monovalent or multivalent reactive clickable groups.…”

“…Thus, a facile methodology to install various reactive groups at the chain end of polymer brushes will enable one to readily obtain such functional interfaces. RAFT polymerization in this context appears to be a suitable candidate since, apart from advantages like its metal-free nature, the chain end of polymers obtained using this method bears the thioester or trithio-carbonate groups, which can undergo a variety of chemical transformations. − Azo group containing molecules which decompose through either thermal or photochemical activation furnish radical intermediates which can act as polymerization initiators, fragmentation units, or chain-terminating agents for polymers obtained through RAFT polymerization. − …”

Visible-Light-Driven Solventylation Strategy for Olefin Functionalization

“…Thanks to the presence of a dyedauxiliary group (N 2 SO 2 R), these derivatives absorb visible light in the 400–450 nm region (with e ranging 100–200 M –1 cm –1 ) and efficiently release an aryl/sulfonyl radical pair upon homolytic cleavage of the N–S bond followed by nitrogen loss from the so-obtained aryl diazenyl radical . Since their peculiar photoreactivity, such compounds find multifaced applications in synthesis as photoacid generators (PAGs) and as initiators in free-radical polymerization …”

“…11 Since their peculiar photoreactivity, such compounds find multifaced applications in synthesis 10 as photoacid generators (PAGs) 12 and as initiators in free-radical polymerization. 13 In view of such premises, we report herein an arylazo sulfone-mediated synthetic platform that allows the visible light solventylation of alkenes by a large variety of organic solvents. Since our former Ru(II)-catalyzed protocol 8 required an oxidative step (i.e., the turnover event of the photocatalytic cycle, with the renewal of the catalyst itself), we envisioned that such a step could either take place upon SET to the concomitantly generated sulfur-centered radical (that should be easily reduced to the corresponding sulfinate anion) or by means of an external oxidant.…”

Device for automated screening of irradiation wavelength and intensity – investigation of the wavelength dependence of photoreactions with an arylazo sulfone in continuous flow

“…Third, arylazo sulfones are versatile and enable a wide range of reactions through additives. [33][34][35][36][37][38][39] Through automated wavelength screening, supplemented by batch experiments, we investigate the wavelength dependence of the photoconversion of the arylazo sulfone 1 in aqueous acetonitrile under different reaction conditions, with and without a borylation additive (Fig. 1).…”