Kinetic Model under Light-Limited Condition for Photoinitiated Thiol–Ene Coupling Reactions

Abstract

Thiol–ene click chemistry has become a powerful paradigm in synthesis, materials science, and surface modification in the past decade. In the photoinitiated thiol–ene reaction, an induction period is often observed before the major change in its kinetic curve, for which a possible mechanism is proposed in this report. Briefly, light soaking generates radicals following the zeroth-order reaction kinetics. The radical is the reactant that initializes the chain reaction of thiol–ene coupling, which is a first-order reaction. Combining both and under the light-limited conditions, a surprising kinetics represented by a Gaussian-like model evolves that is different from the exponential model used to describe the first-order reaction of the final product. The experimental data are fitted well with the new model, and the reaction kinetic constants can be pulled out from the fitting.

Reusable Chemically-Micropatterned Substrates via Sequential Photoinitiated Thiol-Ene Reactions as Template for Perovskite Thin-Film Microarrays

“…We have reported the reaction kinetics of these reactions in the bulk solution under the same conditions very recently. 32 We characterized these patterned samples using XPS and fluorescence microscope by selectively labeling the surfaces. Then we used the patterned substrate to fabricated perovskite microarrays using the simple spin-coating method.…”

“…We rationalize that simple benchtop surface patterning method, such as thiol-ene click chemistry, 32,33 may provide a chemically-patterned substrate for the spin-coating of perovskite precursors. The excellent quality of thin films from the spin-coating process has been demonstrated in the literature.…”

“…37 The photo-initiated thiol-ene click reaction produces high yields even in the presence of water and oxygen, which greatly simplifies the process. 38 In our previous work, 32 we have studied the photochemical kinetics of the reaction between vinyltrimethoxysilane (VTMS) with either thioglycolic acid (TGA) or cysteamine hydrochloride (CAH) under sunlight. This reaction can be directly adapted in the surface functionalization of oxides surfaces such as glass and fluorine-doped tin oxide (FTO) substrates.…”

Depolymerization of supramolecular polymers by a covalent reaction; transforming an intercalator into a sequestrator

“…Furthermore, we assume that thus the chain transfer step (movement of the radical from the formed sulde to a new thiol group) can be considered as the rate-limiting step. 38,39 When the reaction is performed with low light intensity (365 nm, $7 mW cm À2 ), and followed by IR, the kinetics of thiol conversion and polymers disappearance overlap with approximately 50% conversion of the thiol aer 23 minutes of irradiation corresponding to 50 mol% of the polymer disappearance (Fig. S17 †).…”

Mechanistic Investigations of Nickamine- catalyzed Hydrosilylation of Alkenes: Nickel Nanoparticles Are the Active Species

“…An induction period like this could be an indication of catalyst activation, [22] autocatalysis, [23] or a radical chain reaction with slow initiation. [24] A radical chain reaction could be excluded by the hydrosilylation reaction of trans-(2-vinylcyclopropyl)benzene (1c). The reaction leads to the anti-markovnikov hydrosilylation product 3e with a 57% yield (Scheme 3).…”