Truxene-cored π-expanded triarylborane dyes as single- and two-photon fluorescent probes for fluoride?

Analyst Pub Date: 2014-01-03 DOI: 10.1039/C3AN02179C

Abstract

Fluoride anion (F?) significantly affects chemical, biological, and environmental processes. Fluoride recognition and detection have received increasing attention. Convenient, effective, and sensitive fluorescent probes for F? should urgently be designed and synthesized. In this study, we describe a strategy for constructing two triarylborane-based fluoride fluorescent probes: 2,7,12-tri(2-(5-(dimesitylboryl)thiophen-2-yl)ethynyl)-5,5′,10,10′,15,15′-hexaethyltruxene (C3B3) with π–3A (acceptor) configuration and 2,7-di(N,N-diphenylamino)-12-(5-(dimesitylboryl)thiophen-2-yl)-5,5′,10,10′,15,15′-hexaethyltruxene (N2SB) with 2D (donor)–π–A configuration. The loss of color of the tetrahydrofuran solution of these probes from greenish yellow suggests that they can conveniently monitor F? at a low concentration (10 μM) free of apparatus. The different structural features of these probes varied their fluorescent responses to F?. The single-photon fluorescence intensity of C3B3 declined to 90% upon the addition of 4.5 equivalents of F? to its tetrahydrofuran solution. However, the single-photon fluorescence intensity of N2SB was enhanced six-fold upon addition of 2.5 equivalents of the F?. Under the experimental conditions, the detection limits of the two probes for F? can reach 12–13 μM (C3B3) and 3–5 μM (N2SB). The ability of the two probes in detecting F? in their toluene solutions in the two-photon mode was also investigated. The sensitive two-photon fluorescence responses of both probes make them excellent two-photon fluorescence probes.

Graphical abstract: Truxene-cored π-expanded triarylborane dyes as single- and two-photon fluorescent probes for fluoride
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