A new coumarin-based fluorescent probe CMOH was easily synthesized for detection of Cu2+ and S2- in aqueous media and living cells. CMOH displayed high sensitivity (detection limit = 3.2 nM) and selectivity to Cu2+ with a non-fluorescence complex CMOH-Cu2+ formation via a 1:1 binding mode. According to displacement approach, the fluorescence of CMOH-Cu2+ was recovered in the presence of S2- and acted as a sensitive sensor with a low detection limit of 11.4 nM. This "on-off-on" process can be accomplished within 1 min and repeated at least 5 times. What's more, CMOH exhibited good permeability, low cytotoxicity and can be used as a suitable tool to detect changes of Cu2+ and S2- in biosystem. (C) 2019 Elsevier Ltd. All rights reserved.

Conformational control is of importance for compounds to implement their properties and functions. In this work, a pyrrole-based amide pentamer 1 was synthesized. NOESY NMR experiments show it adopts two main conformations, one of which can be sorted out and stabilized via binding of a dihydrogen phosphate anion.

Herein, a novel quinoline-based fluorescent probe DQPH has been developed for ratiometric detection of subtle pH fluctuation in biosystem. Upon altering the pH from 4.50 to 9.00, the emission spectra exhibit a large hypsochromic shift (57 nm) and the ratio of fluorescence intensity (F-531 nm/F-588 nm) changes from 0.30 to 1.36 with an ideal pK(a) value of 7.18 and a linear pH variation range of 6.35-8.00. The ratiometric response is attributed to the protonation-activable resonance charge transfer (PARCT) process, which has been proved by H-1 NMR and NOESY experiment. This probe displayed good solubility, low cytotoxicity, anti-interference capability and reversible pH sensing. Furthermore, DQPH was successfully applied for monitoring pH changes in living cells.

A new on-off-on fluorescent probe, CMOS, based on coumarin was developed to detect the process of hypochlorous acid (HOCl) oxidative stress and cysteine/homocysteine (Cys/Hcy) reduction. The probe exhibited a fast response, good sensitivity and selectivity. Moreover, it was applied for monitoring the redox process in living cells.