On-Surface Azide-Alkyne Cycloaddition Reaction: Does It Click with Ruthenium Catalysts?

0557363 - ÚOCHB 2023 RIV US eng J - Journal Article
Li, T. - Dief, E. M. - Kalužná, Z. - MacGregor, M. - Foroutan-Nejad, Cina - Darwish, N.
On-Surface Azide-Alkyne Cycloaddition Reaction: Does It Click with Ruthenium Catalysts?
Langmuir. Roč. 38, č. 18 (2022), s. 5532-5541. ISSN 0743-7463
R&D Projects: GA ČR(CZ) GA21-17806S
Institutional support: RVO:61388963
Keywords : electrostatic catalysis * molecular rulers * silicon surfaces
OECD category: Physical chemistry
Impact factor: 3.9, year: 2022
Method of publishing: Open access
https://doi.org/10.1021/acs.langmuir.2c00100

Owing to its simplicity, selectivity, high yield, and the absence of byproducts, the „clic“kazide-alkyne reaction is widely used in many areas. The reaction is usually catalyzed by copper(I), which selectively produces the 1,4-disubstituted 1,2,3-triazole regioisomer. Ruthenium-based catalysts were later developed to selectively produce the opposite regioselectivity-the 1,5-disubstituted 1,2,3-triazole isomer. Ruthenium-based catalysis, however, remains only tested for click reactions in solution, and the suitability of ruthenium catalysts for surface-based click reactions remains unknown. Also unknown are the electrical properties of the 1,4- and 1,5-regioisomers, and to measure them, both isomers need to be assembled on the electrode surface. Here, we test whether ruthenium catalysts can be used to catalyze surface azide-alkyne reactions to produce 1,5-disubstituted 1,2,3-triazole, and compare their electrochemical properties, in terms of surface coverages and electron transfer kinetics, to those of the compound formed by copper catalysis, 1,4-disubstituted 1,2,3-triazole isomer. Results show that ruthenium(II) complexes catalyze the click reaction on surfaces yielding the 1,5-disubstituted isomer, but the rate of the reaction is remarkably slower than that of the copper-catalyzed reaction, and this is related to the size of the catalyst involved as an intermediate in the reaction. The electron transfer rate constant (ket) for the ruthenium-catalyzed reaction is 30% of that measured for the copper-catalyzed 1,4-isomer. The lower conductivity of the 1,5-isomer is confirmed by performing nonequilibrium Green's function computations on relevant model systems. These findings demonstrate the feasibility of ruthenium-based catalysis of surface click reactions and point toward an electrical method for detecting the isomers of click reactions.
Permanent Link: http://hdl.handle.net/11104/0331404