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In nature, enantiomers are pairs of chiral compounds, and have semblable chemical and physical properties but mostly show opposite biological effects when they enter an organism. Therefore, chiral recognition has a crucial research value in the fields of medicine, food, biochemistry, etc. Cyclodextrins (CDs) are produced by cyclodextrin glucosyltransferase in some species of bacillus on starch and include three main members α-, β-, and γ-CD with six, seven and eight units of glucose, respectively. With a hydrophilic external cavity and a hydrophobic internal cavity, β-CD can also combine with a variety of materials (e.g., graphene, nanoparticles, COFs, and OFETs) to enhance the chiral recognition of guest molecules in a chiral sensor. This review presents the progress of β-CD modification with different materials for chiral recognition and describes in detail how different materials assist β-CD in chiral recognition and improve the effect of β-CD chiral discrimination. [ABSTRACT FROM AUTHOR]

A series of lanthanide-based metal–organic frameworks (Ln-MOFs) with significantly improved and tunable upconversion emissions were prepared. Y-MOFs co-doped with Yb3+/Er3+ ions have exhibited characteristic upconversion emissions at 520, 545, and 658 nm under 980 nm laser excitation, the intensities of which vary with Yb3+/Er3+ concentrations. In addition, experimental results have indicated that an excited state absorption mechanism is responsible for the upconversion process of Y-MOF:Yb/Er materials. This study has provided a novel design principle and experimental basis for the preparation of luminescent Ln-MOF materials. [ABSTRACT FROM AUTHOR]

Two macrocyclic ferrocenophanes containing a coumarin fluorophore, Se2N[7]ferrocenophane (fc1), and Se4N2[7,7]ferrocenophane (fc2), construct an assembly of fc1-H+…ClO4…[Eu(C10H21COO)2(H2O)2(ClO4)] (fc1⌒Eu) and fc2-2H+…{ClO4…[Eu(C10H21COO)2(H2O)2(ClO4)]}2 (fc2⌒Eu) via a N–H…O hydrogen bond and a coordinate bond between EuIII and ClO4−. In fc1⌒Eu, UV light irradiation triggers non-covalent bond cleavage to release a ferrocenium and EuII complex, accompanying chromism and luminescence signals. Investigations through the steady-state UV-vis absorption, fluorescence, time-resolved fluorescence, femtosecond transient absorption spectra and electrochemical characterization elucidate a stepwise mechanism: firstly, an effective electron transfer occurs from a ferrocene unit to the singlet state of a coumarin unit; the following proton-coupled electron transfer (PCET) reduces EuIII and results in a non-covalent interaction cleavage. Further in vitro exploration of fc1⌒Eu in HepG2 cells demonstrated phototriggered integrated cell cytotoxicity and fluorescent modality imaging. [ABSTRACT FROM AUTHOR]

We herein reported on novel phosphatidylserine-functionalized Fe3O4@SiO2 NPs (nanoparticles) and enzyme-encapsulated liposomes for the visual detection of Cu2+ by employing phosphatidylserine for Cu2+ recognition and the enzymatic catalysis/oxidation of 3,3′,5,5′-tetramethylbenzidine sulfate (TMB) as a signal generator. Phosphatidylserine (1,2-dioleoyl-sn-glycero-3-phospho-l-serine, DOPS) was covalently assembled on the Fe3O4@SiO2 NP surface to obtain DOPS-functionalized Fe3O4@SiO2 NPs, and was used to encapsulate horseradish peroxidase (HRP) to form HRP-encapsulated DOPS liposomes. It was demonstrated that DOPS-functionalized Fe3O4@SiO2 NPs can specifically bind HRP-encapsulated DOPS liposomes in the presence of Cu2+ at basic pH. The HRP-encapsulated DOPS liposome bound on the DOPS-functionalized Fe3O4@SiO2 NPs was then separated from solution with a magnet. Upon the addition of TMB–H2O2 solution, the HRP-encapsulated DOPS liposome bound on the DOPS-functionalized Fe3O4@SiO2 NPs was broken to release HRP, and the released HRP catalyzes the H2O2-mediated oxidation of TMB, which gives rise to a change from colourless to blue in solution colour and a new absorption peak at 652 nm. This provided a sensing platform for the sensitive, specific and field-portable colorimetric detection of Cu2+. By using the sensing platform, a selective and sensitive visual sensor for the detection of Cu2+ was developed. The proposed method has outstanding advantages including adequate sensitivity (the sensitivity can be improved by using a greater volume of the water sample), shorter analysis time, relatively low cost, operation at room temperature and stronger resistibility to the matrix. It can be used to detect as little as 0.1–0.5 μM of Cu2+ in river water using naked-eye observation and 0.05 μM of Cu2+ in river water using UV-visible spectrophotometry when 2 mL of the water sample was used for detection, within 15 min and with a recovery of 95–101% and a RSD ＜ 5% (n = 5). A visual detection limit of 0.1–0.5 μM is much lower than the maximum allowable level of Cu2+ (∼20 μM) in drinking water defined by the USA EPA. The above features make our sensor a promising approach for the rapid and on-site detection of trace free copper ions in aqueous environments by only naked-eye observation. [ABSTRACT FROM AUTHOR]

The development of aqueous ammonium-ion batteries (AAIBs) is currently attracting great attention because of the interesting electrochemical features induced by the charge carrier NH 4 + . One possible way to improve the performance of AAIBs is increasing the salt concentration in the electrolyte. Yet, few studies focus on the complex electrode-electrolyte interface behaviors in highly concentrated electrolytes, which affect the electrochemical performance of AAIBs significantly. Herein, we aim to understand the impact of CH 3 COONH 4 electrolyte concentration on the NH 4 + storage performance of a bimetallic hydroxide material. Experimental and theoretical simulation results indicate that the acetate anion will participate in the construction of the solvated NH 4 + in a highly concentrated electrolyte, facilitating the adsorption of the solvated NH 4 + cluster on the electrode surface. Besides, a new partial de-solvation model is also proposed, demonstrating an energy favorable de-solvation process. Finally, an ammonium-ion hybrid battery is designed, which provides a high average discharge voltage of 1.7 V and good energy density of 368 W h kg (cathode) -1 , outperforming most of the state-of-the-art aqueous batteries. This work provides new understanding about the electrode's interfacial chemistry in different concentrated CH 3 COONH 4 electrolytes, establishes a correlation between the electrolyte concentration and the electrode's performances, and demonstrates the superiority of the hybrid ammonium-ion battery design., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)

Two macrocyclic ferrocenophanes containing a coumarin fluorophore, Se 2 N[7]ferrocenophane (fc1), and Se 4 N 2 [7,7]ferrocenophane (fc2), construct an assembly of fc1-H + ClO 4 [Eu(C 10 H 21 COO) 2 (H 2 O) 2 (ClO 4 )] (fc1∩Eu) and fc2-2H + {ClO 4 [Eu(C 10 H 21 COO) 2 (H 2 O) 2 (ClO 4 )]} 2 (fc2∩Eu) via a N-HO hydrogen bond and a coordinate bond between Eu III and ClO 4 - . In fc1∩Eu, UV light irradiation triggers non-covalent bond cleavage to release a ferrocenium and Eu II complex, accompanying chromism and luminescence signals. Investigations through the steady-state UV-vis absorption, fluorescence, time-resolved fluorescence, femtosecond transient absorption spectra and electrochemical characterization elucidate a stepwise mechanism: firstly, an effective electron transfer occurs from a ferrocene unit to the singlet state of a coumarin unit; the following proton-coupled electron transfer (PCET) reduces Eu III and results in a non-covalent interaction cleavage. Further in vitro exploration of fc1∩Eu in HepG2 cells demonstrated phototriggered integrated cell cytotoxicity and fluorescent modality imaging.

We herein reported on novel phosphatidylserine-functionalized Fe 3 O 4 @SiO 2 NPs (nanoparticles) and enzyme-encapsulated liposomes for the visual detection of Cu 2+ by employing phosphatidylserine for Cu 2+ recognition and the enzymatic catalysis/oxidation of 3,3',5,5'-tetramethylbenzidine sulfate (TMB) as a signal generator. Phosphatidylserine (1,2-dioleoyl-sn-glycero-3-phospho-l-serine, DOPS) was covalently assembled on the Fe 3 O 4 @SiO 2 NP surface to obtain DOPS-functionalized Fe 3 O 4 @SiO 2 NPs, and was used to encapsulate horseradish peroxidase (HRP) to form HRP-encapsulated DOPS liposomes. It was demonstrated that DOPS-functionalized Fe 3 O 4 @SiO 2 NPs can specifically bind HRP-encapsulated DOPS liposomes in the presence of Cu 2+ at basic pH. The HRP-encapsulated DOPS liposome bound on the DOPS-functionalized Fe 3 O 4 @SiO 2 NPs was then separated from solution with a magnet. Upon the addition of TMB-H 2 O 2 solution, the HRP-encapsulated DOPS liposome bound on the DOPS-functionalized Fe 3 O 4 @SiO 2 NPs was broken to release HRP, and the released HRP catalyzes the H 2 O 2 -mediated oxidation of TMB, which gives rise to a change from colourless to blue in solution colour and a new absorption peak at 652 nm. This provided a sensing platform for the sensitive, specific and field-portable colorimetric detection of Cu 2+ . By using the sensing platform, a selective and sensitive visual sensor for the detection of Cu 2+ was developed. The proposed method has outstanding advantages including adequate sensitivity (the sensitivity can be improved by using a greater volume of the water sample), shorter analysis time, relatively low cost, operation at room temperature and stronger resistibility to the matrix. It can be used to detect as little as 0.1-0.5 μM of Cu 2+ in river water using naked-eye observation and 0.05 μM of Cu 2+ in river water using UV-visible spectrophotometry when 2 mL of the water sample was used for detection, within 15 min and with a recovery of 95-101% and a RSD < 5% (n = 5). A visual detection limit of 0.1-0.5 μM is much lower than the maximum allowable level of Cu 2+ (∼20 μM) in drinking water defined by the USA EPA. The above features make our sensor a promising approach for the rapid and on-site detection of trace free copper ions in aqueous environments by only naked-eye observation.

In this paper, we have reported on novel phosphatidylserine-functionalized AuNPs (gold nanoparticles) for the visual detection of Cu 2+ by employing phosphatidylserine for Cu 2+ recognition and AuNPs for signal generation. The phosphatidylserine (1,2-dioleoyl-sn-glycero-3-phospho-l-serine, DOPS) was covalently assembled on the AuNP surface to obtain DOPS-functionalized AuNPs. It was demonstrated that DOPS-functionalized AuNPs could specifically bind Cu 2+ and lead to the aggregation of AuNPs, which gave rise to a colour change from wine-red to blue and a new absorption band around 650 nm. This provides a sensing platform for the simple, rapid and field portable colorimetric detection of Cu 2+ . By using the sensing platform, a selective and sensitive visual biosensor for the detection of Cu 2+ was developed. The proposed biosensor has outstanding analytical advantages such as good stability, relatively high sensitivity, low cost and short analysis time. It can be used to detect concentrations of Cu 2+ as low as 30 μM in river water by observation with the naked eye and of 1.55 μM Cu 2+ in river water by UV-visible spectrophotometry, within 10 min and with a recovery of 98-103% and a relative standard deviation (RSD) < 4% (n = 6). The proposed biosensor is promising for on-site detection of trace Cu 2+ in clinical diagnosis or environmental monitoring.