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A series of metal‐free imidazole‐benzimidazole catalysts (ImBenz‐H, ImBenz‐NO2, ImBenz‐OCH3) for oxygen reduction reaction (ORR) were prepared. We demonstrate that the electrocatalytic O2 reduction by ImBenz‐NO2 with the electron‐withdrawing group showed high selectivity toward H2O with the number of electrons transferred (n=3.7) in a neutral aqueous solution. The highest ORR selectivity toward H2O2 was achieved using ImBenz‐H (n=2.4) in an alkaline solution. Electrochemical studies of reaction kinetics disclosed that the highest turnover frequencies were obtained from ImBenz‐H in both neutral and alkaline aqueous solutions. The results prove that the ORR selectivity is tunable by modulating the substituent of the ImBenz catalysts. Furthermore, DFT calculations suggested that the ORR mechanism of ImBenz‐H involves the electron transfer from imidazole‐benzimidazole to O2 resulting in the formation of H2O2 which supports the redox active properties of the catalysts ImBenz. [ABSTRACT FROM AUTHOR]

A highly sensitive and selective off–on bis-BODIPY fluorescent sensor, BODIPY-NN, could be used to detect Cu2+ ions in aqueous solutions and to image intracellular Cu2+ ions in living cells. Upon addition of Cu2+ ions, BODIPY-NN showed a turn-on fluorescence response with 4-fold enhancement at 529 nm, indicating the inhibition of photo-induced electron transfer (PET) from the phenylenediamine–triazole unit to the BODIPY skeleton. This was triggered by oxidative C–N cyclization of phenylenediamine–triazole to in situ form a benzimidazole–triazole receptor providing an appropriate coordination environment that enhances metal ion binding efficiency. A mechanistic study revealed that Cu2+ acts as both a catalyst for oxidative C–N cyclization and a coordination center. The detection limit was determined to be 85 nM. Importantly, BODIPY-NN has been successfully utilized for fluorescence imaging of Cu2+ ions in MCF-7 cells and showed no toxicity toward MCF-7 cells. The non-cytotoxic nature and high sensitivity of BODIPY-NN pave a way for its use in in vivo studies as a promising fluorescent probe for high-performance sensing and bioimaging. [ABSTRACT FROM AUTHOR]

Abstract: Oscillations in redox potential and chemiluminescence of the H2O2–KSCN–CuSO4–NaOH system in the presence of luminol were examined. Parts of the mechanism proposed in the previous studies were evaluated by substitution of SCN− with CN−. The amplitude of the chemiluminescent oscillations was found to be strongly dependent on the initial luminol concentrations. In addition, the time-series ARMA (2;1)-analysis with Box–Jenkins algorithm were used to simulate the system and the result is well in accordance with the observed oscillations. [ABSTRACT FROM AUTHOR]

A series of metal-free imidazole-benzimidazole catalysts (ImBenz-H, ImBenz-NO 2 , ImBenz-OCH 3 ) for oxygen reduction reaction (ORR) were prepared. We demonstrate that the electrocatalytic O 2 reduction by ImBenz-NO 2 with the electron-withdrawing group showed high selectivity toward H 2 O with the number of electrons transferred (n=3.7) in a neutral aqueous solution. The highest ORR selectivity toward H 2 O 2 was achieved using ImBenz-H (n=2.4) in an alkaline solution. Electrochemical studies of reaction kinetics disclosed that the highest turnover frequencies were obtained from ImBenz-H in both neutral and alkaline aqueous solutions. The results prove that the ORR selectivity is tunable by modulating the substituent of the ImBenz catalysts. Furthermore, DFT calculations suggested that the ORR mechanism of ImBenz-H involves the electron transfer from imidazole-benzimidazole to O 2 resulting in the formation of H 2 O 2 which supports the redox active properties of the catalysts ImBenz., (© 2023 The Authors. Chemistry - A European Journal published by Wiley-VCH GmbH.)

Ensuring continuous and sustainable lithium supply requires the development of highly efficient separation processes such as LLE (liquid-liquid extraction) for both primary sources and certain waste streams. In this work, 4-phosphoryl pyrazolones are used in an efficient pH-controlled stepwise separation of Li + from Ca 2+ , Mg 2+ , Na + and K + . The factors affecting LLE process, such as the substitution pattern of the extractant, diluent/water distribution, co-ligand, pH, and speciation of the metal complexes involved, were systematically investigated. The maximum extraction efficiency of Li + at pH 6.0 was 94 % when Mg 2+ and Ca 2+ were previously separated at pH<5.0, proving that the separation of these ions is possible by simply modulating the pH of the aqueous phase. Our study points a way to separation of lithium from acid brine or from spent lithium ion battery leaching solutions, which supports the future supply of lithium in a more environmentally friendly and sustainable manner., (© 2023 The Authors. Angewandte Chemie International Edition published by Wiley-VCH GmbH.)

Herein, we introduced a new chemosensor, bis-BODIPY linked-triazole based on catechol (BODIPY-OO) prepared by bridging two units of BODIPY fluorophore/triazole binding group with a catechol unit. A solution of this compound displayed 4- and 2-fold enhancements in fluorescence intensity after adding a mole equivalent amount of Ag + and Hg 2+ ions in methanol media, respectively. 1 H NMR titrations of BODIPY-OO with Ag + and Hg 2+ suggested that the triazole was involved in the recognition process. BODIPY-OO showed high sensitivity toward Ag + and Hg 2+ over other metal ions with detection limits of 0.45 μM and 1 μM, respectively. It can also distinguish Hg 2+ from Ag + by addition of an EDTA. This compound can therefore be employed as practical fluorescent probe for monitoring the presence of Ag + and Hg 2+ ions., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)