Can Plasmon Change Reaction Path? Decomposition of Unsymmetrical Iodonium Salts as an Organic Probe

Abstract

Plasmon-assisted transformations of organic compounds represent a novel opportunity for conversion of light to chemical energy at room temperature. However, the mechanistic insights of interaction between plasmon energy and organic molecules is still under debate. Herein, we proposed a comprehensive study of the plasmon-assisted reaction mechanism using unsymmetric iodonium salts (ISs) as an organic probe. The experimental and theoretical analysis allow to exclude the possible thermal effect or hot electron transfer. We found that plasmon interaction with unsymmetrical ISs led to the intramolecular excitation of electron followed by the regioselective cleavage of C-I bond with the formation of electron-rich radical species, which cannot be explained by the hot electron excitation or thermal effects. The high regioselectivity is explained by the direct excitation of electron to LUMO with the formation of dissociative excited state according to quantum-chemical modeling, which provide a novel opportunities to the fine control of reactivity using plasmon energy.

Copper‐Catalyzed Selective N‐Arylation of Oxadiazolones by Diaryliodonium Salts

“…The main drawback of unsymmetrical iodonium salts is connected with regioselectivity issues controlled by steric or electronic effects in iodonium salts [64] or external physical triggers such as plasmon resonance. [65] However, the application of unsymmetrical iodonium salts can access arylation products, which are difficult to prepare using symmetrical iodonium salts due to synthetic limitations. For instance, preparation of symmetrical iodonium salts bearing electron-withdrawing groups proceed in low yields and often required expensive reagents as corresponding boronic acid.…”

Spatial Separation of Plasmonic Hot Electron Generation and a Hydrodehalogenation Reaction Center Using a DNA Wire

“…The laser power affects a plasmon-induced reaction in two different ways: on the one hand a higher laser power results in generation of more hot-electrons increasing the reaction rate by increasing the number of reactants hot-electrons, on the other hand it can be converted to heat due to the thermalization of the hot-carriers and the reaction is faster due to the thermal contribution. 1,4,54 Disentangling both contributions is very hard principally because both processes happen at the same time (at least in the time scales discussed here in this work). The time traces for the sample containing 8BrdA far from the AgNP surface (i.e., ~5.5 nm) at different laser powers is given in Figure 5C.…”

“…1,2 Anyway, for both cases there is the necessity of close contact of the reagent molecule with the nanoparticle surface, i.e., covalent bonding or adsorption, to activate it to further undergo the reaction. 3,4 This interaction can be problematic leading principally to the inactivation of the nanoparticle surface due to surface poisoning or undesired product generation , such as amorphous carbon. [5][6][7][8] So far, many molecules were already shown to react on the surface of illuminated plasmonic nanoparticles, like CO2, H2, 4-nitrothiophenol and other organic molecules which were recently reviewed by Gellé et al 9 The case of the dimerization of 4-nitrothiophenol is the most studied since the reaction can be directly tracked using surface enhanced Raman spectroscopy (SERS), which can also be used to study the reaction mechanism.…”

The New Method of Surface-Assisted COF Synthesis for Optical Sensor Modification

“…However, the manufacture of COF requires difficult experimental conditions and is quite expensive [4,5]. In addition, the formation of COF layer on functional materil or devices surface still remain a challenging task [6,7]. So, the development of a technology for producing COFs on the solid surface(s) is urgently required.…”