Sm0.5Sr0.5Co1−xNixO3−δ—A Novel Bifunctional Electrocatalyst for Oxygen Reduction/Evolution Reactions

The development of non-precious metal catalysts with excellent bifunctional activities is significant for air–metal batteries. ABO₃-type perovskite oxides can improve their catalytic activity and electronic conductivity by doping transition metal elements at B sites. Here, we develop a novel Sm_0.5Sr_0.5Co_1−xNi_xO_3−δ (SSCN) nanofiber-structured electrocatalyst. In 0.1 M KOH electrolyte solution, Sm_0.5Sr_0.5Co_0.8Ni_0.2O_3−δ (SSCN82) with the optimal Co: Ni molar ratio exhibits good electrocatalytic activity for OER/ORR, affording a low onset potential of 1.39 V, a slight Tafel slope of 123.8 mV dec⁻¹, and a current density of 6.01 mA cm⁻² at 1.8 V, and the ORR reaction process was four-electron reaction pathway. Combining the morphological characteristic of SSCN nanofibers with the synergistic effect of cobalt and nickel with a suitable molar ratio is beneficial to improving the catalytic activity of SSCN perovskite oxides. SSCN82 exhibits good bi-functional catalytic performance and electrochemical double-layer capacitance.     

Silver Catalyzed Site-Selective C(sp3)−H Bond Amination of Secondary over Primary C(sp3)−H Bonds

Sulfamates are widespread in numerous pharmacologically active molecules. In this paper, Silver/Bathophenanthroline catalyzed the intramolecular selective amination of primary C(sp³)−H bonds and secondary C(sp³)−H bonds of sulfamate esters, to produce cyclic sulfamates in good yields and with a high site-selectivity. DFT calculations revealed that the interaction between sulfamates and L10 makes the molecule more firmly attached to the catalyst, benefiting the catalysis reaction. The in vitro anticancer activity of the final products was evaluated in MCF-7 breast cancer cells.     

Unravelling the 2e− ORR Activity Induced by Distance Effect on Main-Group Metal InN4 Surface Based on First Principles

The p-electron-dominated main-group metals (Sb, Se, In, etc.) have recently been reported to possess excellent oxygen reduction reaction (ORR) activity by means of heteroatom doping into graphene. However, on these main group metal surfaces, other approaches especially the distance effect to modulate catalytic activity are rarely involved. In this work, the origin of excellent 2e⁻ ORR catalytic activity of graphene-supported InN₄ moiety by tuning the distance between metallic In atoms is thoroughly investigated by employing the first-principles calculations. Our DFT calculations show that the 2e⁻ ORR catalytic activity strongly depends on the crystal orbital Hamilton population (COHP) between In and O atoms. This work is useful for the rational design of main group metal single atom electrocatalysts.     

High-Quality Conjugated Polymers Achieving Ultra-Trace Detection of Cr2O72− in Agricultural Products

In view of that conjugated polymers (CPs) are an attractive option for constructing high-sensitive Cr₂O₇²⁻ sensors but suffer from lacking a general design strategy, we first proposed a rational structure design of CPs to tailor their sensing properties while validating the structure-to-performance correlation. Short side chains decorated with N and O atoms as recognition groups were instructed into fluorene to obtain monomers Fmoc-Ala-OH and Fmoc-Thr-OH. Additionally, their polymers P(Fmoc-Ala-OH) and P(Fmoc-Thr-OH) were obtained through electrochemical polymerization. P(Fmoc-Ala-OH) and P(Fmoc-Thr-OH) with high polymerization degrees have an excellent selectivity towards Cr₂O₇²⁻ in comparison to other cations and anions. Additionally, their limit of detection could achieve 1.98 fM and 3.72 fM, respectively. Especially, they could realize the trace detection of Cr₂O₇²⁻ in agricultural products (red bean, black bean, and millet). All these results indicate that short side chains decorated with N and O atoms functionalizing polyfluorene enables the ultra-trace detection of Cr₂O₇²⁻. Additionally, the design strategy will spark new ideas for the construction of highly selective and sensitive Cr₂O₇²⁻ sensors.     

一种新型Zn2＋近红外荧光探针的研究

Zn^2＋是多种酶和转录因子的必要成分, 在生物体内起着重要的作用, 检测Zn²⁺具有十分重要的生物学意义. 我们合成了一种新型近红外荧光探针TAEA-IR-780, 该探针通过配位作用与Zn^2＋结合后, 荧光显著增强. 通过质谱和氢谱对该探针进行了表征, 并探讨了pH值、其它金属离子对Zn^2＋检测的影响. 该探针的激发波长为683 nm, 发射波长为750 nm, 可避免对生物活体的损伤, 同时生物体内常见的金属离子对其干扰较小. 该探针对Zn^2＋的检测下限达1.0× 10^－9 mol•L^－1, 具有较高的检测灵敏度.     

一种席夫碱Al3+荧光探针的制备及细胞成像应用

以4-（二乙氨基）水杨醛与奥肼缩合制备了一例席夫碱类荧光探针1,通过¹H NMR、¹³C NMR和电喷雾电离质谱表征了1的结构。光谱分析实验结果显示,探针1可选择性与Al³⁺作用,在495 nm处荧光发射峰显著增强。探针对Al³⁺的检测灵敏度高,检测限低至1.44 μmol·L^-1。结合理论计算,证实探针以三齿配位的模式,与Al³⁺形成1∶1型稳定配合物。此外,该探针还可用于活细胞中Al³⁺的检测。     

Enantioselective Recognition of Lysine and Phenylalanine Using an Imidazole Salt-Type Fluorescent Probe Based on H8-BINOL

An imidazole bromide fluorescent probe (R)-1 based on chiral H₈-BINOL was synthesized with a high yield; it was found to have good enantioselective recognition of lysine and phenylalanine using fluorescence analysis. When L-lysine was recognized, the enantioselective fluorescence enhancement ratio was 2.7 (ef = I_L − I₀/I_D − I₀, ef = 2.7, 20 eq Lys); as the amount of L-Lys increased, a distinct red shift was observed (the wavelength varied by 55.6 nm, 0–100 eq L-Lys), whereas D-Lys had a minimal red shift. The generation of this red shift phenomenon was probably due to the ICT effect; the probe’s intramolecular charge transfer was affected after (R)-1 bound to L-Lys, and this charge transfer was enhanced, leading to a red shift in fluorescence. In addition to the enantioselective recognition of lysine, phenylalanine was also recognized; the enantioselective fluorescence enhancement ratio was 5.1 (ef = I_L − I₀/I_D − I₀, ef = 5.1, 20 eq Phe).     

基于牛血清白蛋白功能化金纳米棒的荧光探针测定Hg2+

建立了一种以牛血清白蛋白功能化的金纳米棒(BSA-Cys-GNRs)为荧光探针检测Hg²⁺的新方法。以半胱氨酸作为连接臂成功将牛血清白蛋白修饰在金纳米棒表面,通过紫外可见吸收光谱、荧光光谱、红外光谱和荧光倒置显微镜等多种分析方法对材料进行表征。研究发现,在295nm波长光激发下,BSA-Cys-GNRs探针在338nm显示强荧光,而Hg²⁺能够有效地猝灭BSA-Cys-GNRs的荧光。对一系列影响猝灭效果的因素进行考察,得出pH 4.0、孵育时间5.0min为最佳检测条件。Mn²⁺、K⁺、Ni²⁺、Na⁺、Cr³⁺、Cd²⁺、Mg²⁺、Cu²⁺、Ca²⁺、Al³⁺和Zn²⁺对BSA-Cys-GNRs的荧光信号没有明显的影响。当Hg²⁺的浓度为0.04444~8.888μmol·L^-1时,荧光猝灭效率与Hg²⁺的浓度之间存在良好的线性关系,检测限为8.08nmol·L^-1。将该方法用于环境水样中Hg²⁺的检测,回收率为98.9%~105.0%。     

A Galactosidase-Activatable Fluorescent Probe for Detection of Bacteria Based on BODIPY

Pathogenic E. coli infection is one of the most widespread foodborne diseases, so the development of sensitive, reliable and easy operating detection tests is a key issue for food safety. Identifying bacteria with a fluorescent medium is more sensitive and faster than using chromogenic media. This study designed and synthesized a β-galactosidase-activatable fluorescent probe BOD-Gal for the sensitive detection of E. coli. It employed a biocompatible and photostable 4,4-difluoro-3a,4a-diaza-s-indancene (BODIPY) as the fluorophore to form a β-O-glycosidic bond with galactose, allowing the BOD-Gal to show significant on-off fluorescent signals for in vitro and in vivo bacterial detection. This work shows the potential for the use of a BODIPY based enzyme substrate for pathogen detection.     

New Series of Red-Light Phosphor Ca9−xZnxGd0.9(PO4)7:0.1Eu3+ (x = 0–1)

In this study, a new series of phosphors, Ca_9−xZn_xGd_0.9(PO₄)₇:0.1Eu³⁺ (x = 0.00–1.00, step dx 0.05), was synthesized, consisting of centro- and non-centrosymmetric phases with β-Ca₃(PO₄)₂-type structure. Crystal structures with space groups R3c (0.00 ≤ x < 0.35) and R3¯c (x > 0.8) were determined using X-ray powder diffraction and the method of optical second harmonic generation. In the region 0.35 ≤ x ≤ 0.75, phases R3c and R3¯c were present simultaneously. Refinement of the Ca₈ZnGd(PO₄)₇ crystal structure with the Rietveld method showed that 71% of Gd³⁺ ions are in M3 sites and 29% are in M1 sites. A luminescent spectroscopy study of Ca_9−xZn_xGd_0.9(PO₄)₇:0.1Eu³⁺ indicated the energy transfer from the crystalline host to the Gd³⁺ and Eu³⁺ luminescent centers. The maximum Eu³⁺ luminescence intensity corresponds to the composition with x = 1.     

一种检测亚硫酸氢根的苯并咪唑类荧光增强型探针及其实际应用

合成和表征了一种用于检测HSO3^-的苯并咪唑类荧光增强型探针(FP1)。结果表明:FP1对HSO3^-表现出了明显的荧光关-开响应,具有高的选择性和灵敏度,且抗干扰能力强,响应时间短(2 min)。FP1的荧光强度与HSO3^-的浓度在1.2~8.1μmol·L^-1的范围内呈线性关系,其对HSO3^-的检出限为0.14μmol·L^-1。此外,FP1能用于实际样品中HSO3^-的检测,回收率良好,它还可应用于HeLa活细胞中对HSO3&-进行荧光成像。     

一种基于分子内电荷转移的亚硫酸氢盐比率测量荧光探针

2-甲基苯并噻唑与对苯二甲醛一步反应制得含有苯甲醛结构的半菁染料HCy,通过1H NMR与MS对目标染料HCy进行了表征。考察了HCy在水溶液及DMSO溶液中对HSO3-的识别性能以及不同环境对HCy光谱的影响,并测试了HCy对肝细胞(HL-7702)与肝癌细胞(Hep G2)的毒性。结果显示,荧光探针HCy对亚硫酸氢盐显示出优异的选择性及高灵敏度,在水溶液中及DMSO溶液中均可快速响应,适宜于作为HSO3-的比率测量荧光探针;此外,HCy对GSH有特异性响应,细胞实验表明,HCy具有优异的生物相容性。     

A Quinoxaline−Naphthaldehyde Conjugate for Colorimetric Determination of Copper Ion

This work facilitates detection of bivalent copper ion by a simple Schiff base probe QNH based on a quinoxaline−naphthaldehyde framework. The detailed study in absorption spectroscopy and theoretical aspects and crystal study of the probe and probe−copper complex has been discussed. The detection limit of the probe in the presence of Cu²⁺ is 0.45 µM in HEPES−buffer/acetonitrile (3/7, v/v) medium for absorption study. The reversibility of the probe−copper complex has been investigated by EDTA. The selective visual detection of copper has been established also in gel form.     

High-Affinity Ratiometric Fluorescence Probe Based on 6-Amino-2,2′-Bipyridine Scaffold for Endogenous Zn2+ and Its Application to Living Cells

Zinc is an essential trace element involved in many biological activities; however, its functions are not fully understood. To elucidate the role of endogenous labile Zn²⁺, we developed a novel ratiometric fluorescence probe, 5-(4-methoxyphenyl)-4-(methylsulfanyl)-[2,2′-bipyridin]-6-amine (6 (rBpyZ)) based on the 6-amino-2,2′-bipyridine scaffold, which acts as both the chelating agent for Zn²⁺ and the fluorescent moiety. The methoxy group acted as an electron donor, enabling the intramolecular charge transfer state of 6 (rBpyZ), and a ratiometric fluorescence response consisting of a decrease at the emission wavelength of 438 nm and a corresponding increase at the emission wavelength of 465 nm was observed. The ratiometric probe 6 (rBpyZ) exhibited a nanomolar-level dissociation constant (K_d = 0.77 nM), a large Stokes shift (139 nm), and an excellent detection limit (0.10 nM) under physiological conditions. Moreover, fluorescence imaging using A549 human lung adenocarcinoma cells revealed that 6 (rBpyZ) had good cell membrane permeability and could clearly visualize endogenous labile Zn²⁺. These results suggest that the ratiometric fluorescence probe 6 (rBpyZ) has considerable potential as a valuable tool for understanding the role of Zn²⁺ in living systems.     

基于苯并吡喃腈的激活型半胱氨酸荧光探针

设计并合成了基于苯并吡喃腈为母体单元的近红外激活型荧光探针(E)-2-(苯并吡喃腈基)乙烯基-5-(二乙氨基)丙烯酸苯酯(DCM-AC),其结构中的丙烯酰酯键作为氨基酸激活反应的响应基团。 研究结果表明,探针分子DCM-AC对半胱氨酸具有高灵敏、选择性光谱响应,不仅能观察到明显的颜色变化,而且探针在710 nm处的荧光发射强度显著增强,相应的荧光增强比值与半胱氨酸的浓度(1.0~8.0 μmol/L)呈现良好的线性关系。 探针DCM-AC对半胱氨酸的检出限为2.8×10^-7 mol/L,能选择性检测半胱氨酸区别于结构类似的高半胱氨酸和谷胱甘肽,且不受其它氨基酸物质干扰。 通过质谱、核磁和紫外吸收光谱研究了DCM-AC检测半胱氨酸的反应激活机理:半胱氨酸先通过巯基与DCM-AC上的丙烯酰酯双键发生亲核加成,然后环化脱除内酰胺环状化合物。     

基于氟硼二吡咯染料的汞离子荧光分子探针的合成与光谱性质

合成了一种中位-苯甲酸基取代的氟硼二吡咯类染料衍生物(1)并研究了它的金属离子传感性能。在甲醇溶液中,染料1显示出显著的对汞离子具有选择性的"开-关"型亲离子荧光团响应,而对其他一些代表性碱金属、碱土金属、过渡金属及重金属离子等都没有明显的荧光响应;同时染料1在对所检测的金属离子中,通过其溶液颜色的改变对汞离子显示出明显的选择性显色行为,以便实现对汞离子的"裸眼检测"。     

A Highly Selective and Sensitive Fluorescent Probe Recognition for Co2+ in Aqueous Media Based on 8‐Hydroxyquinolin‐2‐carbaldehyde‐2‐pyridylformylhydrazone Derivative

A new (8‐hydroxyquinolin‐2‐yl)methylene picolinohydrazide derivative ( L ) has been successfully synthesized and characterized. The probe L displays high selectivity to Co²⁺ in CH₃CN/HEPES (1:1, Ｖ/Ｖ, 10 mmol·L^?1, pH=7.4) with a fluorescence "ON‐OFF" response. The Co²⁺ ion recognition event possesses some distinct features including rapid response, high selectivity and sensitivity, good anti‐interference ability and being applicable within a wide pH range. Based on job's plot and ESI‐MS studies, the 1:1 binding mode was proposed. The binding constant of L and Co²⁺ is 1.63×10⁸ L·mol^?1 and the detection limit is 1.15 µmol·L^?1. Natural water samples experiments revealed that probe L can be potentially applied to the detection of Co²⁺ in real environment.     

一个基于苯并噻唑的铜离子荧光探针的合成、晶体结构和光谱性质

合成和表征了一个苯并噻唑类的荧光探针N-(4-(苯并噻唑-2-基)苯基)-2-((2-羟乙基)(吡啶-2-甲基)氨基)乙酰胺(FL),用光谱法研究了它与各种金属离子的识别特性。结果表明:FL对Cu2+具有较高的选择性和灵敏度,并且对Cu2+的识别不受其它金属离子的干扰。FL与Cu2+形成配合物的结合比为1∶1,其荧光强度与Cu2+浓度(3.8~9.6μmol·L-1)呈现较好的线性关系,而且它还可应用于自来水和湖水等水体样品中Cu2+的检测。     

Fe(HSO4)3 and Fe(HSO4)3/DMSO as Efficient,Heterogeneous, and Reusable Catalyst Systems for the Oxidative Coupling of Thiols

Fe(HSO₄)₃ has been used as a heterogeneous, efficient, and recyclable catalyst in ethanol for the selective oxidation of thiols to their corresponding disulfides. The same results were obtained under identical conditions using catalytic amounts of Fe(HSO₄)₃ in the presence of DMSO. Different types of aliphatic, aromatic, and heteroaromatic thiols have been used in the reaction, and in all cases the products were obtained in good to excellent yields.     

Characterization of a Hg2+-Selective Fluorescent Probe Based on Rhodamine B and Its Imaging in Living Cells

A small organic molecule P was synthesized and characterized as a fluorometric and colorimetric dual-modal probe for Hg²⁺. The sensing characteristics of the proposed probe for Hg²⁺ were studied in detail. A fluorescent enhancing property at 583 nm (>30 fold) accompanied with a visible colorimetric change, from colorless to pink, was observed with the addition of Hg²⁺ to P in an ethanol-water solution (8:2, v/v, 20 mM HEPES, pH 7.0), which would be helpful to fabricate Hg²⁺-selective probes with “naked-eye” and fluorescent detection. Meanwhile, cellular experimental results demonstrated its low cytotoxicity and good biocompatibility, and the application of P for imaging of Hg²⁺ in living cells was satisfactory.