Colorimetric and fluorometric detection of copper ion (Cu2+) has attracted much attention due to the biological, environmental and medical significance of the Cu2+ ion. Colorimetric and fluorescent detection of metal ions have proven to be powerful methods due to their simplicity, cost effectiveness, high detection limit and applicability to bioimaging. This review will consolidate selective and sensitive Cu2+ ion detection achieved by various receptor types in the years between 2013 to 2015.

Colorimetric and fluorescent chemosensors for Cu2+. A comprehensive review from the years 2013–15

Reaction-based fluorescent probes for SO2 derivatives and their biological applications

An effective colorimetric and ratiometric fluorescent probe for bisulfite in aqueous solution

A ratiometric fluorescent probe, 2-(7-diethylamino-2-oxo-2H-1-benzopyran-3-yl)-7-hydroxyl-1-benzopyrylium (1), has been developed for sulfite sensing. The method employs the nucleophilic addition of sulfite to the electrically positive benzopyrylium moiety of 1 to block the π-conjugated system of the whole molecule, which in turn results in significant blue shifts in the absorption and emission spectra of the sensing system. The fluorescence intensity ratio at 485 and 640 nm (I485/I640) increases linearly with sulfite concentration in the range of 0.05–10 μM. The proposed probe shows excellent selectivity toward sulfite over other common anions and biothiols. The bioimaging experiment demonstrates the potential of probe 1 for the ratiometric fluorescent imaging of sulfite in living cells.

Development of a ratiometric fluorescent probe for sulfite based on a coumarin–benzopyrylium platform

Single atomic cobalt catalyst for efficient oxygen reduction reaction

Tuning Zn2+ coordination tunnel by hierarchical gel electrolyte for dendrite-free zinc anode.

Aqueous Mn2+/MnO2 based-batteries have attracted enormous attentions in aqueous energy storage fields, owing to their high working voltage and theoretical capacity (616 mAh g-1) brought by the two-electron reaction (Mn2+/Mn4+). However, there are currently several tricky challenges facing Mn2+/MnO2-based batteries of their complicated working mechanisms, existing issues, and optimization strategies. In this review, we aim to provide a mechanistic understanding and an overview of the insufficiency, the optimization, and the future development for Mn2+/MnO2-based batteries. The existing issues and deficiency in Mn2+/MnO2 based-batteries have been systematically analyzed, of which the optimization strategies have also been rationally summarized, and discussed with deep insights. Also, the often-overlooked optimized objects and aspects have been highlighted with unique perspectives. The proposals of testing methods and performance assessment are presented, containing different degradation mechanisms. Based on the above points, this review would provide guidance and contribute to the further development of aqueous Mn2+/MnO2 based-batteries.

Issues and Opportunities Facing Aqueous Mn2+/MnO2-based batteries.

Simultaneous regulation of cations and anions in an electrolyte for high-capacity, high-stability aqueous zinc–vanadium batteries

A coumarin-based dye, Fluorescent Red GK, was developed for the detection of bisulfite anions. The probe has exhibited high selectivity and sensitivity against other anions at room temperature. Upon addition of HSO 3 − , the strong fluorescence of Fluorescent Red GK was severely quenched and its color changed significantly from orange to colorless under illumination with a UV lamp. The color of the solution was also changed from pink to colorless. As a result, it can be used as a specific colorimetric and fluorescent probe for bisulfite anions. In addition, the detection limit was as low as 1.76 μM. The results showed that the Fluorescent Red GK could be used in the design of the fluorescent probe for detecting HSO 3 − in aqueous solution. Furthermore, the probe has been used for determination of bisulfite in sugar samples with satisfactory results.

Fluorescent Red GK as a fluorescent probe for selective detection of bisulfite anions

The solid–liquid transition reaction lays the foundation of electrochemical energy storage systems with high capacity, but realizing high efficiency remains a challenge. Herein, in terms of thermodynamics and dynamics, this work demonstrates the significant role of both interfacial H+ concentration and Mn2+ migration steric hindrance for the high‐efficiency deposition/dissolution chemistry of zinc–manganese batteries. Specially, the introduction of formate anions can buffer the generated interfacial H+ to stabilize interfacial potential according to the Nernst equation, which stimulates high capacity. Compared with acetate and propionate anions, the formate anion also provides high adsorption density on the cathode surface to shield the electrostatic repulsion due to the small spatial hindrance. Particularly for the solvated Mn2+, the formate‐anion‐induced lower energy barrier of the rate‐determining step during the step‐by‐step desolvation process results in lower polarization and higher electrochemical reversibility. In situ tests and theoretical calculations verify that the electrolyte with formate anions achieve a good balance between ion concentration and ion‐migration steric hindrance. It exhibits both the high energy density of 531.26 W h kg‐1 and long cycle life of more than 300 cycles without obvious decay.

Liping Qin

Papers

Tuning Zn2+ coordination tunnel by hierarchical gel electrolyte for dendrite-free zinc anode.

Issues and Opportunities Facing Aqueous Mn2+/MnO2-based batteries.

Simultaneous regulation of cations and anions in an electrolyte for high-capacity, high-stability aqueous zinc–vanadium batteries

Fluorescent Red GK as a fluorescent probe for selective detection of bisulfite anions

Balanced Interfacial Ion Concentration and Migration Steric Hindrance Promoting High‐Efficiency Deposition/Dissolution Battery Chemistry