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

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.

Diarylboryl-phenothiazine based multifunctional molecular siblings

Molecular siblings 1 and 2 are constructed from triarylboron and phenothiazine moieties and showed multifunctional characteristics such as AIE, mechanofluorochromism, triboluminescence and temperature sensing.

Boron clusters in luminescent materials

In recent times, luminescent materials with tunable emission properties have found applications in almost all aspects of modern material sciences. Any discussion on the recent developments in luminescent materials would be incomplete if one does not account for the versatile photophysical features of boron containing compounds. Apart from triarylboranes and tetra-coordinate borate dyes, luminescent materials consisting of boron clusters have also found immense interest in recent times. Recent studies have unveiled the opportunities hidden within boranes, carboranes and metalloboranes, etc. as active constituents of luminescent materials. From simple illustrations of luminescence, to advanced applications in LASERs, OLEDs and bioimaging, etc., the unique features of such compounds and their promising versatility have already been established. In this review, recent revelations about the excellent photophysical properties of such materials are discussed.

Multiple emissive triarylborane-A2H2 and triarylborane-Zn-A2H2 porphyrin conjugates

Triarylborane-A2H2 (1) and triarylborane-Zn-A2H2 porphyrins (2) have been synthesized by acid catalyzed condensation of 4-dimesitylboryl-benzaldehyde and dipyrromethane under ambient conditions. Compounds 1 and 2 showed multiple emission bands upon excitation at the triarylborane dominated absorption region (350 nm). Detailed experimental and computational studies show that the multiple emission features of 1 and 2 arise as a result of a partial energy transfer from the donor (triarylborane) to the acceptor (porphyrin) moieties. Compounds 1 and 2 showed very high selectivities towards fluoride ions compared to other competing anions.

White light emissive molecular siblings

White-light emission from boron based molecular siblings.

Triarylborane conjugated dicyanovinyl chromophores: intriguing optical properties and colorimetric anion discrimination

Three new triarylborane conjugated dicyanovinyl chromophores (Mes2B-π-donor-DCV); donor: N-methyldiphenylamine () and triphenylamine ( and [with two BMes2 substitutions]) of type A-D-A (acceptor-donor-acceptor) are reported. Compounds exhibit intense charge transfer (CT) absorption bands in the visible region. These absorption peaks are combination CT bands of the amine donor to both the BMes2 and DCV units. This inference was supported by theoretical studies. Compound shows weak fluorescence compared to and . The discrimination of fluoride and cyanide ions is essential in the case of triarylborane (TAB) based anion sensors as a similar response is given towards both the anions. Anion binding studies of , and showed that fluoride ions bind selectively to the boron centre and block the corresponding CT transition (donor to BMes2) leaving the other CT transition to be red shifted. On the other hand, cyanide ions bind with both the receptor sites and stop both the CT transition processes and hence a different colorimetric response was noted. The binding of F(-)/CN(-) induces colour changes in the visible region of the electronic spectra of and , which allows for the naked-eye detection of F(-) and CN(-) ions. The anion binding mechanisms are established using NMR titration experiments.

Recent advances in purely organic phosphorescent materials

A review of the recent advancement in the development of organic materials with efficient phosphorescent emission features is presented.

Effect of alkyl substituents in BODIPYs: a comparative DFT computational investigation

A detailed computational investigation encompassing the effects of alkyl groups on the structural and electronic properties of BODIPY dyes is presented.

A borane-bithiophene-BODIPY triad: intriguing tricolor emission and selective fluorescence response towards fluoride ions

The structure and photophysical properties of a new triad (borane–bithiophene–BODIPY) 1 have been investigated. Triad 1 exhibits unprecedented tricolour emission when excited at the borane centred high energy absorption band and also acts as a selective fluorescent and colorimetric sensor for fluoride ions with ratiometric response. The experimental results are supported by computational studies.