4,5-Bis(arylethynyl)-1,2,3-triazoles—A New Class of Fluorescent Labels: Synthesis and Applications

Abstract

Cu-catalyzed 1,3-dipolar cycloaddition of ethyl 2-azidoacetate to iodobuta-1,3-diynes and subsequent Sonogashira cross-coupling were used to synthesize a large series of new triazole-based push–pull chromophores: 4,5-bis(arylethynyl)-1H-1,2,3-triazoles. The study of their optical properties revealed that all molecules have fluorescence properties, the Stokes shift values of which exceed 150 nm. The fluorescent properties of triazoles are easily adjustable depending on the nature of the substituents attached to aryl rings of the arylethynyl moieties at the C4 and C5 atoms of the triazole core. The possibility of 4,5-bis(arylethynyl)-1,2,3-triazoles’ application for labeling was demonstrated using proteins and the HEK293 cell line. The results of an MTT test on two distinct cell lines, HEK293 and HeLa, revealed the low cytotoxicity of 4,5-bis(arylethynyl)triazoles, which makes them promising fluorescent tags for labeling and tracking biomolecules.

Cu-catalyzed cycloaddition of aryl azides to 1-iodobuta-1,3-diynes: an experimental and quantum chemical study of unusual regiochemistry

“…Here we continue the study of 1-iodobuta-1,3-diynes with organic azides 47–49 (Fig. 1E) and report that the catalytic formation of nontrivial 4-iodotriazoles, along with conventional 5-iodotriazoles under CuAAC conditions is possible, but only in the case of aryl azides and 1-iodobuta-1,3-diynes (Fig.…”

“…The nature of the Cu(I) catalyst, the amount of 2,6-lutidine, and the temperature were varied (Table 1). We found that the initially used CuI(PPh 3 ) 3 catalyst introduced originally by Diez-Gonzalez 30 and found by us as the best catalyst for iododiacetylenes [47][48][49] is the optimal one for the shift of 5-iodo-/4-iodotriazoles ratio in favor of 4-iodotriazole (entries 1-3). Despite the fact that two other Cu(I) catalysts -TC (entry 2) and Et (entry 3) -gave approximately the same or slightly higher yields of triazoles, the ratio of 4-iodo-to 5-iodotriazoles was noticeably worse.…”

“…Taking into account that alkyl azides react with 1-iodobuta-1,3-diynes to form only 5-iodo-1,4-disubstituted triazoles, [47][48][49] we assumed that in the case of aryl azides the mechanism of 4-iodotriazole formation could involve a 6-membered TS with aryl azide coordinated to Cu(I) through the N3 atom that competes with the usual coordination through N1 because of the conjugation of the N1 lone pair with the aryl ring. The observed tendency towards the formation of 4-iodoisomeres in the case of aryl azides bearing stronger EWG can be considered as the confirmation for this hypothesis, since in this case the lone pair of the N1 atom becomes more conjugated and, therefore, less accessible for complexation with Cu(I), and Cu-N coordination can proceed through the N3 atom.…”

Synthesis and Photophysical Evaluation of Dialkynyl‐N‐(het)arylpyrroles: Promising Key Compounds in Fluorescence Chemistry

“…[6] Despite the extensive knowledge of various fluorophores, [7] over the past decade, chemists have shown interest in developing novel fluorescent compounds derived from small nitrogenous organic molecules. [8][9][10] Since the presence of heteroaromatic rings frequently imparts interesting properties to the overall system, including elevated polarizability, intense charge transfer upon electronic excitation, chemical inertness, and thermal stability, these rings also serve as donor or acceptor moieties due to the presence of one or more heteroatoms. [11] Moreover, the triple carbon-carbon bond can function as an efficient π-spacer unit, extending the conjugation by minimizing steric hindrance between the two (hetero)aromatic rings.…”

“…Continuing to explore the photophysical properties of these compounds, Govdi and coworkers described the synthesis and application of alkynyltriazoles with promising fluorescent tags for labeling and tracking biomolecules (Figure 1, compound III). [10] In these studies, the authors employed these molecules in labeling assays with proteins and the HEK293 cell line. These triazole dyes, featuring an ester group, can permeate cells, emitting a blue glow, and do not exhibit toxicity.…”