玛卡荧光碳点的合成及用于苦味酸的荧光检测

以玛卡为碳源,采用水热法制备荧光碳点。碳点水溶液在激发波长为315 nm时,最大荧光发射波长为425 nm。在玛卡荧光碳点的磷酸盐缓冲液(0.2 mol/L,pH 5.8)中,加入苦味酸,其荧光被猝灭,基于此建立了以玛卡荧光碳点为荧光探针测定苦味酸的方法。本方法检测苦味酸的线性范围为0.4~80 mmol/L,相关系数为0.9978,检出限为110 nmol/L(S/N=3),本方法线性范围宽、灵敏度高、响应快(2 min内),选择性和抗干扰能力良好。用于实际水样中苦味酸的检测,加标回收率为92.0%~110.0%,结果令人满意。     

苯丙烯酸桥联的双核镉配合物[Cd(cinnamato)2(Phen)]2的水热合成和晶体结构

A cadmium complex [Cd(cinnamato)₂(Phen)]₂ was synthesized by the reaction of cinnamic acid, phenanth-roline (phen), and Cd(ClO₄)₂·6H₂O. It crystallizes in triclinic, space group P1, with a=1.142 1(13) nm, b=1.157 6(13) nm, c=2.106 1(2) nm, α=80.307(2)°, β=77.334(2)°, γ=71.630(2)°, V=2.563 4(5) nm³, D_c=1.521 g·cm^-3, Z=2, M_r=586.90, μ=0.891 mm^-1, F(000)=1 184, the final R=0.031 7, wR=0.067 5. The crystal structure shows that the cadmium ion is coordinated with two nitrogen atoms from one phen molecule and five oxygen atoms respectively from three cinnamic acids, giving a pentagonal bipyramid coordination geometry. CCDC: 687380.     

3,4-二甲氧基苯乙酸邻菲啰啉镱(III)配合物的合成、晶体结构及荧光光谱

合成了3,4-二甲氧基苯乙酸邻菲啰啉镱(III)配合物(C84H82Yb2N4O24): [Yb2(DMPA)6(phen)2](HDMPA=3,4-二甲氧基苯乙酸(C12H12O4), phen=1,10-邻菲啰啉)(CCDC: 757541), 并通过元素分析、红外(IR)光谱、热重分析(TG-DTG)对其进行了表征, 用单晶X射线衍射测定了配合物的晶体结构. 配合物C84H82Yb2N4O24属三斜晶系, 空间群P1, 晶胞参数: a = 1.22877(14) nm, b=1.23235(16) nm, c=1.45234(19) nm, α=91.726(7)°, β=103.321(7)°, γ=113.885(6)°, 晶胞体积: V=1.9379(4) nm3, 晶胞内分子数Z=1, 相对分子质量Mr=1877.62, 电子数F(000)=946, 密度Dc=1.609 g·cm-3, 吸收系数μ(Mo Kα)=2.481 mm-1. 测定了铕和铽掺杂(2.5%, 5.0%, 10.0%, 摩尔分数)的配合物的荧光光谱, 结果表明, 单独的配体没有荧光, 在形成配合物后, 依然显示铕(III)离子和铽(III)离子的特征发射峰, 这表明配体将吸收的能量有效地转移给了中心离子, 配体起到了很好的敏化作用.     

Azomethine-H as a Highly Selective Fluorescent Probe for Fe3+ Detection in 100％ Aqueous Solution and Its Application in Living Cell Imaging

A simple assay for the detection of Fe³⁺ in water by means of fluorescence spectroscopy was developed based on a commercially available reagent, Azomethine-H(A-H), allowing sensing trace levels of Fe³⁺ with high selectivity over other cations. A significant fluorescence quenching of A-H at 424 nm was found after its binding with Fe³⁺ in 100% aqueous solution at pH=7.0, while other physiologically relevant metal ions posed little interference. The fluorescence responses can be well described by the modified Stern-Volmer equation. A good linear relationship(R²=0.9904) was observed up to 1.6×10^-5 mol/L Fe³⁺ ions. The detection limit, calculated via the 3σ IUPAC(international union of pure and applied chemistry) criteria, was 1.95×10^-7 mol/L. Moreover, the colorimetric and fluorescent response of A-H to Fe³⁺ can be conveniently detected by the naked eye, providing a facile method for visual detection of Fe³⁺. The proposed method was used to determine Fe³⁺ in water samples. Moreover, inverted fluorescence microscopy imaging using human umbilical vein endothelial cells shows that A-H can be used as an effective fluorescent probe for detecting Fe³⁺ in living cells.     

A Water Stable CdII‐based Metal‐Organic Framework as a Multifunctional Sensor for Selective Detection of Cu2+ and Cr2O72– Ions

A water stable tetrazolate‐containing metal‐organic framework, [Cd₂(L)(OH)(H₂O)₂]_n ( 1 ) [H₃L = 5‐(4‐(tetrazol‐5‐yl)phenyl)isophthalic acid], was synthesized under solvothermal conditions and structurally characterized. Compound 1 displays a three dimensional porous network with one dimensional tubular channels based on trinuclear cluster [Cd₃(μ₃‐OH)N₄C] units. Notably, 1 exhibits highly sensitive response to Cu²⁺ and Cr₂O₇^2– through luminescence quenching effects with the detection limit of 0.666 ppm for Cu²⁺ and 0.846 ppm for Cr₂O₇^2–, respectively. The possible mechanism of the luminescence quenching was discussed in detail.     

Synthesis,Crystal Structure,and Properties of a Cadmium(II) Complex with the Flexible Ligand (1′H‐[2, 2′]Biimidazoly‐1‐yl)‐acetic Acid

A novel coordination polymer {[Cd(BDAC)]₂ · H₂O}_n ( 1 ) [HBDAC = (1′H‐[2, 2′]biimidazoly‐1‐yl)‐acetic acid] was synthesized under hydrothermal conditions and characterized by elemental analysis and single‐crystal X‐ray diffraction. Complex 1 crystallizes in the acentric orthorhombic space group Ccc2. The Cd1 atoms and BDAC^2– ligands construct [Cd1(BDAC)] rhomboid grid (4, 4)‐topology layer motifs, whereas the Cd2 atoms and BDAC^2– ligands form [Cd2(BDAC)] 1D coordination polymer ribbons. Furthermore, adjacent lay motifs are linked into 3D net structures by 1D coordination polymer ribbons with 4‐connected 3D trinodal {4²8²10²}{4⁴6²}{4³6²8}₂ topology. The measurement of electric hysteresis loops indicated that complex 1 displays a ferroelectric characteristic.     

Electrosynthesis of 1,3,5-Trimethylpyrazole-4-Carboxylic Acid through Oxidation of 1,3,5-Trimethyl-4-Formylpyrazoles on a Nickel Anode in Aqueous Alkaline Medium

Electrosynthesis of 1,3,5-trimethylpyrazole-4-carboxylic acid is realized through electrocatalytic oxidation of 1,3,5-trimethyl-4-formylpyrazole in a diaphragmless cell on an NiOOH electrode in an aqueous alkaline medium. The synthesis conditions are optimized and a preparative method of producing the desired product with a yield of 78% as calculated per charged 4-formylpyrazole is developed.     

Synthesis,Characterization, and Electrocatalytic Behavior for Hydrogen Evolution of a Dinuclear Copper(II) Complex of 1-[(2-Carboxymethyl) benzene]-3-[2-carboxybenzene] triazene

A dinuclear copper(II) complex, [Cu^II₂(L)₂] is afforded by the reaction of CuCl₂ · 2H₂O with a triazenido ligand, 1-[(2-carboxymethyl) benzene]-3-[2-carboxybenzene] triazene (H₂L). Structural investigation shows that the copper-copper distance [2.3985(7) Å] is significantly shorter than the sum of the van der Waals radii of Cu (1.40 Å), suggesting that there are metal-metal bonds in [Cu^II₂(L)₂]. In solid, there is a strong antiferromagnetic interaction between copper(II) ions (J = –135.6 cm^–1). In homogeneous environment, [Cu^II₂(L)₂] shows electrocatalytic activities for hydrogen generation both from acetic acid with a turnover frequency (TOF) of 32 mol of hydrogen per mole of catalyst per hour [mol(H₂) · mol^–1(catalyst) · h^–1] at an overpotential (OP) of 941.6 mV, and neutral buffer with a TOF of 512 mol(H₂) · mol^–1(catalyst) · h^–1 at an OP of 836.7 mV.     

双核铜(Ⅱ)配合物在H2O2存在下对DNA的氧化切割活性

A novel dinuclear copper(Ⅱ) complex, [Cu₂(phen)(dipic)₂(H₂O)₂]·2H₂O (phen=1,10-phenanthroline, dipicH₂=2,6-pyridinedicarboxylic acid), has been prepared and structurally characterized. The complex crystallizes in the triclinic system, space group P1 with cell parameters a=0.846 0(17) nm, b=1.289 5(3) nm, c=1.452 7(3) nm, α=77.42(3)°, β=79.11(3)°, γ=87.08(3)°, and V=1.518 8(6) nm³. The dinuclear complex shows potential DNA cleavage activity at micromolar concentration in the presence of H₂O₂ and exhibits higher nuclease efficiency than mononuclear complex [Cu(dipic)(H₂dipic)]·H₂O. Without external reductants, the added H₂O₂ may contribute to the generation of hydroxyl radicals that result in DNA strand scission.CCDC:291786.     

Cleavage of a PN Bond in a Urea‐Containing (Ph2P(R)PPh2)‐Bridged Dinuclear Gold(I) Thiolate Complex by Fluoride and a Mechanistic Insight

A urea‐containing, (Ph₂P(R)PPh₂)‐bridged, dinuclear, gold(I) thiolate complex, [Au₂{Ph₂PN(C₆H₄OMe‐4)PPh₂}(SC₆H₄NHCONHC₆H₅)₂] ( 1 ) was designed and synthesized and its photophysical and anion recognition properties studied. The results show that 1 has a high selectivity toward F^?. Upon addition of F^?, the yellow solution was decolorized, and drastic changes of emission and ¹H and ³¹P{¹H} NMR signals were observed. Interestingly, these changes are attributed to fluoride‐assisted P?N bond hydrolysis, instead of the expected hydrogen‐bonding interactions with the urea receptor. Similar changes were observed for two other basic anions, AcO^? and H₂PO₄^?, but to a much lesser extent; and these anions were found to bind to the urea receptor at the same time. On the other hand, Cl^? was found to only bind to the urea moiety through hydrogen‐bonding interactions. Further studies with the control complex [Au₂{Ph₂PN(C₆H₄OMe‐4)PPh₂}Cl₂] ( 2 ) indicate that F^? assists the hydrolysis process via cleavage of the P?N bond. DFT calculations were performed to study the reaction mechanism for the fluoride‐assisted P?N bond hydrolysis of 2 ; these provide a better insight into the role of fluoride in the hydrolysis.     

Induced Circular‐Dichroism Chirality Probes for Selective Amino Acid Detection through Screening of a Dynamic Combinatorial Library of Lanthanide Complexes

A dynamic combinatorial library of lanthanide complexes was prepared to develop induced‐circular‐dichroism (CD) chirality probes. It totaled 168 combinations of coordinative N‐aromatic chromophores, trivalent lanthanide centers, and guest amino acids. Eu³⁺ and Tb³⁺ complexes prepared with quinolinecarboxylic acid were particularly effective as induced‐CD chirality probes for selective alanine detection, whereas a Yb³⁺ complex with terpyridine exhibited glutamine selectivity. The former two complexes highly preferred alanine to the corresponding amine, ester, amino alcohol, and carboxylic acid derivatives. As such, the present combinatorial screening of a dynamic lanthanide complex library has led to a new series of induced‐CD chirality probes for specific amino acids.     

一种2-乙酰基吡嗪-罗丹明B衍生物的合成及其对Ni~(2+)的识别

分子光谱法具有灵敏度高、操作简单等优点,发展简便、快捷、对镍离子(Ni~(2+))具有高度选择性的探针具有非常重要的意义。本文以金属离子诱导罗丹明酰胺衍生物反应开环的策略,设计并合成了对Ni~(2+)检测具有单一选择性识别的紫外吸收探针。同时,该探针可对水溶液中的Ni~(2+)实现"裸眼"识别。此外,该探针对Ni~(2+)具有较高的灵敏度,其对水溶液中Ni~(2+)的检测限为0.5μmol/L,表明该探针可用于Ni~(2+)的检测分析。     

中性或弱酸性体系下锌基水系电池负极材料研究进展

锌具有原料丰富、质量轻便、金属导电性与延展性好以及理论比容量高等优势,可以作为绿色可充电电池的理想电极材料。其中,以中性或弱酸性水溶液为电解质、锌为负极的锌基水系电池具有安全性高、电池材料廉价无毒、制备工艺简单、环境友好等特点,在储能和动力电池领域具有极高的应用价值和发展前景。但电池充放电过程中伴随的锌枝晶、析氢、腐蚀、钝化等问题限制了其实际应用。本文综述了锌基水系电池负极存在的问题及当前的解决策略,并对其负极研究发展方向进行了展望。     

Mechanistic Studies on the Oxidation of Glyoxylic and Pyruvic Acid by a [Mn4O6]4+ Core in Aqueous Media: Kinetics of Oxo‐Bridge Protonation

In aqueous media (pH 2.5–6.0), the Mn^IV tetramer [Mn₄(μ‐O)₆(bipy)₆]⁴⁺ ( 1 ⁴⁺; bipy = 2,2′‐bipyridine) oxidizes both glyoxylic and pyruvic acid to formic and acetic acid, respectively, under formation of CO₂. Kinetics studies suggest that the species 1 ⁴⁺, its oxo‐bridge protonated form [ 1 H]⁵⁺, i.e., [Mn₄(μ‐O)₅(μ‐OH)(bipy)₆]⁵⁺, the reducing acids (RH) and their conjugate bases (R^?) all take part in the reaction. The oxo‐bridge protonated oxidant [ 1 H]⁵⁺ was found to react much faster than 1 ⁴⁺. Thereby, the gem‐diol forms of the α‐oxo acids (especially in the case of glyoxylic acid) are the possible reductants. A one‐electron/one‐proton electroprotic mechanism operates in the rate‐determining step.     

Complete Transmetalation in a Metal–Organic Framework by Metal Ion Metathesis in a Single Crystal for Selective Sensing of Phosphate Ions in Aqueous Media

A complete transmetalation has been achieved on a barium metal–organic framework (MOF), leading to the isolation of a new Tb‐MOF in a single‐crystal (SC) to single‐crystal (SC) fashion. It leads to the transformation of an anionic framework with cations in the pore to one that is neutral. The mechanistic studies proposed a core–shell metal exchange through dissociation of metal–ligand bonds. This Tb‐MOF exhibits enhanced photoluminescence and acts as a selective sensor for phosphate anion in aqueous medium. Thus, this work not only provides a method to functionalize a MOF that can have potential application in sensing but also elucidates the formation mechanism of the resulting MOF.     

Alternative Method for Forensic Determination of Lysergic Acid Diethylamide and Related Compounds in Body Fluids by Liquid–Liquid Extraction and HPLC with Fluorescence Detection

An alternative and practical method is described for simultaneous detection and quantification of the potent hallucinogen lysergic acid diethylamide (LSD) and related compounds in urine and serum samples. The procedure is based on liquid–liquid re-extraction with ethyl acetate and reversed-phase liquid chromatography coupled with fluorescence detection (HPLC–FLD). With detection limits in urine and serum samples of ca 0.07 ng mL^–1 for LSD, nor-LSD, and iso-LSD, respectively, the method is well suited to forensic investigations. Application of the method to clinical samples and autopsy material enable selective identification and accurate quantification of LSD and related compounds. Comparison of results with those obtained from an LSD immunoassay (EMIT II) emphasize the need for chromatographic confirmation.Revised: 1 December 2003 and 9 February 2004     

Catalytic Polymerizations of Hydrophobic,Substituted, Acetylene Monomers in an Aqueous Medium by Using a Monomer/Hydroxypropyl‐β‐cyclodextrin Inclusion Complex

Ten hydrophobic, substituted, acetylene monomers were examined as to their abilities to form an inclusion complex with hydroxypropyl‐β‐cyclodextrin (HPCD). Only the monomers with suitable substitutents were found to form the monomer/HPCD complex, which was identified by NMR, FTIR, and UV‐vis spectroscopy. Polymerizations of the monomers were successfully carried out in aqueous solution by using the prepared monomer/HPCD inclusion complex and by using a water‐soluble Rh‐based catalyst, [Rh(cod)₂BF₄] or [Rh(nbd)(H₂O)OTs]. Such polymerizations provided high‐yield (>90%) polymers with a cis content of approximately 100%. The as‐prepared polymers could take an ordered helical conformation, just like their counterparts obtained in organic solvents.

     

Electochemiluminescence of CdTe/CdS Quantum Dots with Triproprylamine as Coreactant in Aqueous Solution at a Lower Potential and Its Application for Highly Sensitive and Selective Detection of Cu2+

Anodic electrochemiluminescence (ECL) of 3‐mercaptopropionic acid (MPA)‐ capped CdTe/CdS core‐shell quantum dots (QDs) with tripropylamine (TPrA) as the co‐reactant were studied in aqueous (Tris buffer) solution for the first time. The results suggest that the oxidation of TPrA at a glassy carbon electrode (GCE) surface participated in the ECL of QDs, and the onset potential and the intensity of ECL of CdTe/CdS QDs were affected seriously by TPrA, as the co‐reactant, in Tris buffer solution. The onset potential of ECL in this new system was about +0.5 V (vs. Ag/AgCl) and the ECL intensity greatly enhanced when TPrA was present. Various influencing factors, such as the electrolyte, pH, QDs concentration, potential range and scan rates on the ECL were studied. Based on the selective quenching by Cu²⁺ to the light emission from CdTe/CdS QDs/TPrA system, a highly sensitive and selective method for the determination of Cu²⁺ was developed. At the optimal conditions, the relative ECL intensity, I₀/I, was proportional to the concentration of Cu²⁺ from 14 nM to 0.21 μM with the detection limit of 6.1 nM based on the signal‐to‐noise ratio of 3. The possible ECL mechanism of QDs and the quenching mechanism of ECL were proposed.     

Amplification of a FRET Probe by Lipid–Water Partition for the Detection of Acid Sphingomyelinase in Live Cells

Real‐time monitoring of acid sphingomyelinase (ASM) activity is crucial for investigating its role in lipid‐mediated signaling processes. In this study, we synthesized fluorescent phosphosphingolipids capable of FRET by phosphorodichloridate chemistry. These sphingomyelin analogues are substrates for recombinant human ASM and can be used to monitor ASM activity by fluorescence spectroscopy. Incubation with cell lysates from wild‐type and knock‐out mice further confirmed probe cleavage to be exclusive to ASM. We also systematically exploited the environmental sensitivity of the fluorophores to achieve significant increases in responsiveness. This concept may be transferred to other lipid probes in the future. The ASM activity in live cells was imaged by two‐photon‐excitation microscopy.