Chemosensor C1, namely, 3-acetoacetyl-7-hydroxycoumarin, was synthesized and exhibited highly selective and sensitive fluorescence sensing ability for Cu2+ over other metal ions under physiological conditions. The fluorescence quenching response of C1 for Cu2+ indicated that C1 can be used as an on-off fluorescent chemosensor to selectively detect Cu2+. The binding process was confirmed by UV–vis absorption, fluorescence measurement, mass spectroscopy, IR spectra and DFT calculation. To test the practical use of the probe, the determination of Cu2+ in real water samples was evaluated. The application of the fluorescent probe in monitoring intracellular Cu2+ in HeLa cells has also been demonstrated.

•Five copper(II) complexes with different number of metal centers have been synthesized and characterized.•The results indicate that the five copper(II) complexes show good cytotoxicity.•The flow cytometry and western blotting show that complex 5 can bring about apoptosis of tumor cells.Five complexes, [Cu(L)2]·4.5H2O (1), [Cu(HL)2](NO3)2·CH3OH (2) {[Cu2(L)2(NO3)(H2O)2]·(NO3)}n (3), [Cu2(HL)2(SO4)2]·2CH3OH (4) and [Cu4(L)4Cl4]·5H2O (5) based on HL (where HL = 2-acetylpyrazine isonicotinoyl hydrazone) have been synthesized and characterized by X-ray diffraction analyses. The counter anion and organic base during the synthesis procedure influence the structures of the complexes efficiently, which generate five complexes as mono-, bi-, tetra-nuclear and one-dimensional structures. The antitumor activities of the complexes 1–5 (except for complex 3 with the poor solubility) against the Patu8988 human pancreatic cancer, ECA109 human esophagus cancer and SGC7901 human gastric cancer cell lines are screened by MTT assay. The results indicate that the chelation of Cu(II) with the ligand is responsible for the observed high cytotoxicity of the copper(II) complexes and the 1:2 copper species 1 and 2 demonstrate lower antitumor activities than that of the 1:1 copper species 4 and 5. In addition, the in vitro apoptosis inducing activity of the copper(II) complex 5 against SGC7901 cell line is determined. And the results show that the complex can bring about apoptosis of the cancerous cells in vitro.

•A new rhodamine-based fluorescent probe for Fe3+ has been developed.•Response of probe to Fe3+ is a coordination reaction.•The probe has been used for imaging of Fe3+ in living cells.•Crystal structure of the possible intermediate of R1 with Ag+ and Hg2+ ions were reported.A rhodamine-2-thioxoquinazolin-4-one derivative (R1) has been synthesized by an addition-elimination reaction of rhodamine 6G ethylenediamine with methyl 2-isothiocyanatobenzoate, which exhibits high selectivity and sensitivity as a fluorescent sensor toward Fe3+ under physiological conditions. Moreover, R1 could sense Fe3+ by “naked eye” with a color change from colorless to yellow. To test the practical use of the probe, the determination of Fe3+ in real water samples was evaluated. The application of the fluorescent sensor in monitoring intracellular Fe3+ in glioma cell line U251 has also been demonstrated. In addition, single crystal structures of R1·1·5H2O·0·5CH3CN, as well as the possible intermediate of R1 with Ag+ and Hg2+ ions were reported.

A rhodamine derivative was synthesised via the hydrazone formation of rhodamine 6G hydrazide with 7-diethylamino-3-(1-hydroxy-3-oxobut-1-enyl)-2H-chromen-2-one. As a colourimetric and ratiometric fluorescent probe, the derivative exhibited high selectivity towards Cu2+ in neutral aqueous media. Moreover, the probe sensed Hg2+ with fluorescence enhancement at pH 10. The binding process was confirmed via UV-vis absorption, fluorescence measurements, 1H NMR, mass spectroscopy and density functional theory calculation. To validate the applicability of the probe, the probe was used to detect Cu2+ and Hg2+ ions in actual water samples. The application of the fluorescent sensor in monitoring intracellular Cu2+ in Hela cells has also been demonstrated.

•A new rhodamine-based off-on fluorescent probe for Cu2+ has been developed.•Response of probe to Cu2+ is a coordination reaction.•The application of the fluorescent sensor in monitoring intracellular Cu2+ was demonstrated.A rhodamine derivative (R1) has been synthesized by an additive reaction of rhodamine 6G hydrazide with methyl 2-isothiocyanatobenzoate, which exhibits high selectivity and sensitivity as a fluorescent sensor toward Cu2+ under physiological conditions. The detection limit of Cu2+ ion is 47.2 nM. Moreover, R1 could sense Cu2+ by “naked eye” with a color change from colorless to pink. This selective signaling behavior is not affected by other canions that might be present in the environmental samples. The application of the fluorescent sensor in monitoring intracellular Cu2+ in HeLa cells was also demonstrated.

•A new 1,8-naphthalimide-based ratiometric fluorescent probe for Cu2+ has been developed.•Response of probe to Cu2+ is an electrophilic substitution reaction.•The probe has been used for imaging of Cu2+ in living cells.A 1,8-naphthalimide hydrazone derivative bearing a pyrrole unit is a highly selective ratiometric fluorescent Cu2+ probe used to monitor intracellular Cu2+ in HeLa cells. This probe functions via a unique hydrolysis mechanism through Cu2+-promoted electrophilic substitution. Binding is confirmed through UV–vis absorption, fluorescence measurements, mass spectroscopy, IR, X-ray single crystal diffraction, and DFT calculation.Download high-res image (117KB)Download full-size image

•Fe2O3/reduced graphene oxide composite was fabricated by a facile colloidal electrostatic assembly method.•The flower-like Fe2O3 NPs were decorated with visible micro-cracks.•The high performance of FFGC indicated its usage in the application of energy issues.Fe2O3/reduced graphene oxide composite (FFGC) was fabricated by a hydrothermal method for the exploration of electrochemical energy storage, where the Fe2O3 nanoparticles (NPs) loaded onto the surface of reduced graphene oxide (rGO) sheet uniformly. Interestingly, the TEM image showed that visible micro-cracks were appeared on the surface of flower-like Fe2O3 NP, which did not interfere with its stably crystalline structure. Herein, FFGC was investigated as anode material for lithium-ion battery (LIB) as well as electrode material for supercapacitor (SC). For instance, the specific discharge capacity was of 1366 mAh g−1 at 0.1 A g−1 in LIB case, while the specific capacitance of 318.9 F g−1 at 0.1 A g−1 in SC experiment. On the other hand, FFGC exhibited the excellently steady performance in either LIB or SC experiment. Those results suggest the roseate future of FFGC in the application of energy issues.The high performance of LIBs and SC highlight the potential applications of FFGC for energy storage.

•A new rhodamine-based off-on fluorescent probe for Cu2+ has been developed.•The probe shows fluorescence enhancement toward Cd2+ by a typical ICT response.•Response of probe to Cu2+/Cd2+ are based on coordination reaction.•Probe-Cd2+ complex could act as ratiometric fluorescent sensor for Cu2+.•The probe has been used for imaging of Cu2+ in living cells.A new rhodamine-based derivative bearing pyrrole unit, R1 was synthesized as a dual-mode Cu2+-selective sensor via the rhodamine ring-opening approach and ratiometric displacement. A colorimetric and “off-on” signal for Cu2+ through rhodamine ring opening in R1 and ratiometric fluorescent signal output when Cu2+ displaces the bound Cd2+ in the R1-Cd2+ complex can be observed. The application of fluorescent R1 to biological imaging was also demonstrated.