Bioactivities of Triazolium‐Based N‐Heterocyclic Carbene Salts

Abstract

1,2,4-Triazolium salts are precursors of N-heterocyclic carbenes (NHCs), which have been extensively used as effective catalysts and ligands for both asymmetric and nonenantioselective reactions. Nevertheless, they are also a kind of quaternary ammonium compounds (QACs) that possess amphipathic properties. The unique chemical and physical properties of 1,2,4-triazolium salts have received significant attention from scientists focusing on the development of novel bioactive molecules as pesticides and medicines. It is timely and meaningful to summarize the bioactivities of 1,2,4triazolium salt derivatives against various bacteria, fungi, cancer cells, and other pathogens in the past 30 years. Meanwhile, the structure-activity relationship (SAR) of 1,2,4triazolium salts was also summarized. Finally, our perspective on the future development and applications of triazolium salts as agrichemicals or human drugs is presented.

Impact of Ligand Modification on the Hydrogen Evolution Reaction of Highly Active Silver(I)- and Ruthenium(II)-N-Heterocyclic Carbene-Based Electrocatalysts: Comprehension from the Hydrogen Oxidation Reaction

“…In the proton NMR spectra of triazolium hexafluorophosphate salts 6 and 7 , a characteristic singlet peak was observed at δ 10.28 and 10.21 ppm, ascribed to the resonance of triazole C5 protons, while another distinct singlet peak with an integration value of one is observed at δ 9.38 and 9.32 ppm, corresponding to the resonance of C3 protons. Similarly, sec -butyl chain and benzocoumarin aromatic proton resonances were observed in the range δ 0.68–4.70 and 7.67–8.44 ppm, respectively, with appropriate proton integration values, which are in agreement with the analogous triazolium salts reported earlier . Interestingly, the coumaryl methylene linker and coumarin C3′ protons appear as singlets at δ 5.93 and 6.57 ppm, respectively, in the case of salt 6 , while these two were observed to be merged and centered at δ 6.43 ppm in the case of salt 7 .…”

“…Similarly, sec-butyl chain and benzocoumarin aromatic proton resonances were observed in the range δ 0.68−4.70 and 7.67− 8.44 ppm, respectively, with appropriate proton integration values, which are in agreement with the analogous triazolium salts reported earlier. 32 Interestingly, the coumaryl methylene linker and coumarin C3′ protons appear as singlets at δ 5.93 and 6.57 ppm, respectively, in the case of salt 6, while these two were observed to be merged and centered at δ 6.43 ppm in the case of salt 7. Alongside, their carbon NMR spectra evidenced characteristic peaks at ca.…”