Triarylboron Anchored Luminescent Probes: Selective Detection and Imaging of Thiophenols in the Intracellular Environment

Abstract

The advances in boron incorporated organics have captured overwhelming interest on account of their outstanding properties and promising applications in various fields. Mostly, triarylborane compounds (TAB) are exploited as sensors of F and CN anions at the expense of the intrinsic Lewis acidic nature of boron. New molecular probes 1 and 2 for detection of toxic thiophenol were designed by conjugating highly fluorescent borylanilines with the luminescent quencher 2,4-dinitrobenzene based sulfonamides (DNBS), wherein the electrophilicity of the DNBS moiety has been modulated by fine-tuning the intrinsic Lewis acidity of boron. The interplay between PET (photoinduced electron transfer) and ICT have been employed for developing the TAB tethered turn-on fluorescent sensor for thiophenol with high selectivity for the first time. The newly developed probes showed very fast response toward thiophenol (within ∼5 min) with limits of detection (LOD) lying in the micromolar range, clearly pointing to their potential. Further, compounds 1 and 2 were explored for detecting thiophenol in the intracellular environment by discriminating biothiols. DFT and TD-DFT calculations were performed to support the sensing mechanism.

Tuning the π-bridge of quadrupolar triarylborane chromophores for one- and two-photon excited fluorescence imaging of lysosomes in live cells

“…By loading them into nanogels, they became cell membrane permeable, stained the cytoplasm and could be applied as temperature, viscosity, pH, H 2 O 2 and biothiol sensors 111–115. Another intracellular “turn-on”-sensor for thiophenol, based on a triarylborane moiety, was very recently published by Thilagar and co-workers 116. In 2016, our group reported the only water-soluble quadrupolar three-coordinate boron compound for imaging ( 2TM ), which exhibited a very reasonable two-photon brightness of 285 GM in MeCN (Scheme 2).…”

Fluorescent probes based on nucleophilic aromatic substitution reactions for reactive sulfur and selenium species: Recent progress, applications, and design strategies

“…Benzenesulfonamide and benzenesulfonate are the main reactive groups of benzenesulfonic acid [20] , [112] , [113] , [114] , [115] , [116] , [117] , [118] , [119] , [120] . RSS and RSeS can break the benzenesulfonamide or benzenesulfonate bond and become bound to the aromatic part of the detection group with the concomitant release of SO 2 .…”

Recent Progress in the Development of Fluorescent Probes for Thiophenol

“…Based on an amino phenothiazine boranil dye, Chen and Sheng et al developed a highly sensitive fluorescent probe ( 8 ) (Figure 4) for sensing PhSH [62]. Recently, Thilagar et al synthesized two triarylborane-derived fluorescent PhSH probes ( 9 and 10 ) (Figure 4), which displayed high sensitivity and selectivity, as well as applicability for intracellular imaging [63].…”