A novel coumarin hydrozone compound which exhibits piezochromic luminescence upon grinding was prepared. The piezofluorochromic properties were reversible upon fuming or heating. The intermolecular hydrogen bonds have been observed by single-crystal X-ray structural analysis, which are believed to make a major contribution to the piezofluorochromic properties.

•A novel water-soluble coumarin derivative was synthesized.•Compound I was used to detect lipopolysaccharides selectively.•The detection process was studied upon UV–vis and fluorescence spectrum.•The bioimaging application of I in bacteria was studied.A novel fluorescent compound 7-diethylamino-3-[4׳-N-((2-ethoxy)ethanol)methyl aminobenzoylhydrazone]methyl coumarin (I) was synthesized and employed as a fluorescent probe for detecting lipopolysaccharides (LPS). This coumarin-based probe exhibited high fluorescence in aqueous environment, which could be quenched in the presence of Cu2+ ion due to the complexation between I and Cu2+. However, the fluorescence of I can be recovered upon addition of LPS, because the binding between LPS and Cu2+ ion is stronger than that between I and Cu2+ ion, which disassociates the complexation of I and Cu2+ ion and releases the fluorescence of I. Therefore, this three-component sensing system can be used to detect lipopolysaccharides in a facile manner. In addition, biological imaging studies have demonstrated that the probe can be used to evaluate the biosorptive capacity for Cu2+ ion in living bacteria.

Three novel fluorescent compounds were synthesized and employed as fluorescent probes for detecting different metal ions selectively. The naphthol-based probe (I) exhibited weak fluorescence in water, which was enhanced in the presence of Al3+ ions due to the complexation between I and Al3+. In addition, the coumarin-based probe (II) and quinolone-based probe (III) could selectively detect Cu2+ ions and Zn2+ ions, respectively. Unlike the changes in the fluorescence spectra of I and III upon Al3+ ion and Zn2+ ion addition, the fluorescence intensity of II decreased dramatically after Cu2+ ions were added into the aqueous solution. This is due to the fact that different mechanisms occurred in the recognition process for metal ions. Colorimetric monitoring of these processes was also feasible.

A novel fluorescent compound, 4-(trimethyl ammonium chloride)acetamide-2-(1H-naphtho[2,3-d]imidazol-2-yl)phenol (TMACA-NIP), was synthesized and used as a fluorescent probe for detecting glutathione reduced (GSH). The new NIP-based probe exhibited high fluorescence in water, which was quenched during the presence of copper (II) due to the complexation between TMACA-NIP and Cu2+. But after adding GSH into the TMACA-NIP and Cu2+ system, the fluorescence of TMACA-NIP was recovered because the binding force between GSH and Cu2+ is stronger than that between TMACA-NIP and Cu2+, which destroys the equilibrium between NIP and copper (II) ions and releases the fluorescence probe of TMACA-NIP. This three-component competing system of NIP/Cu2+/GSH can be used to detect GSH simply and rapidly.Highlights► A novel fluorescence probe was developed to detect GSH that operates in aqueous solution. ► TMACA-NIP was synthesized and employed as “read-out” units of NIP/Cu2+/GSH. ► NIP-based probe shows high selectivity over other sulfhydryl compounds.

Three novel fluorescent compounds were synthesized and employed as fluorescent probes for detecting different metal ions selectively. The naphthol-based probe (I) exhibited weak fluorescence in water, which was enhanced in the presence of Al3+ ions due to the complexation between I and Al3+. In addition, the coumarin-based probe (II) and quinolone-based probe (III) could selectively detect Cu2+ ions and Zn2+ ions, respectively. Unlike the changes in the fluorescence spectra of I and III upon Al3+ ion and Zn2+ ion addition, the fluorescence intensity of II decreased dramatically after Cu2+ ions were added into the aqueous solution. This is due to the fact that different mechanisms occurred in the recognition process for metal ions. Colorimetric monitoring of these processes was also feasible.

A novel coumarin hydrozone compound which exhibits piezochromic luminescence upon grinding was prepared. The piezofluorochromic properties were reversible upon fuming or heating. The intermolecular hydrogen bonds have been observed by single-crystal X-ray structural analysis, which are believed to make a major contribution to the piezofluorochromic properties.