Multi-functional Photoelectric Sensor Based on a Three-fold Interpenetrated Cd(II) Coordination Polymer for Sensitively Detecting Different Ions

Athree-fold interpenetrated cadmium coordination polymer[Cd₃(BTC)₂(H₂O)₉]·2H₂O(CP 1)(H₃BTC=1,3,5-benzenetricar-boxylic acid) was selected and synthesized to investigate its photoelectric properties. CP 1 showed excellent sensitivity for Cr₂O₇^2- and Fe³⁺, low limit of detection(LOD:0.39 µmol/L for Cr₂O₇^2- and 1.72 µmol/L for Fe³⁺) and stability as electrochemical sensor. More importantly, fluorescence sensing studies indicated that CP 1 exhibits sensing activity for Fe³⁺, Fe²⁺, and MnO₄^- with good cyclic stability and selectivity. Low LOD and high-sensitivity capability of CP 1 make it a potential multifunctional photoelectric sensor.     

Novel Oxidative Coupling of 2-Naphthols to 1,1'-Bi-2-naphthols Catalysed by Solid Lewis Acids Using Atmospheric Oxygen as Oxidant

l,l'-Bi-2-naphthol derivatives have wide applications as chiral inducing agents for asymmetric synthesis.¹ There are many good methods for resolution of racemic binaphthols to give enantiomeric binaphthols.² Therefore, it is essential to established simple, convenient, economically and environmental-friendly methods for preparation of racemic l,l'-binaphthol derivatives. A number of methods have been developed for the oxidative coupling of 2-naphthols usually by using Fe³⁺, Cu²⁺ or Mn³⁺ as oxidants. The reaction were carried out in organic solvent,^3a in solid state^3b and in aqueous Fe³⁺ solution.^3c However, all those cases by employing excess, usually 2 equivalents of oxidant. The excess Fe³⁺, Cu²⁺ and the resulted Fe²⁺, Cu⁺ and HCl were not acceptable from a view point of environmental protection. Recently, Sakamoto et at⁴ and Kantam et at⁵ independently reported two catalytic oxidative coupling procedure for preparation of l,l'-binaphthols using aerial oxygen as oxidant and Cu²⁺-exchanged montmorillonite as catalysts. However, both procedures were by using some toxic chlorobenzene as solvent and long reaction time (>2 h) and high temperature(>140℃) were needed. Consquently, there is still a great demand for catalytic oxidative coupling 2-naphthols to generate binaphthols under mild conditions, environmentally friendly procedure and rapid process. Herein we report novel oxidative coupling of to 1,1-bi-2-naphthols (2a, 2b) catalysed by a number of supported reagents using aerial oxygen as oxidant. The results are listed in Table 1.     

Assembly of Two Isostructural Metal-organic Frameworks Based on Hetero-N,O Donor Ligand for Detecting Nitro Explosives

Two isostructural metal-organic frameworks,[NO3][M3(H2O)3O(TBA)3]-2DMF-6H2O(1 and 2)[M=In and Fe, H2TBA=4-(1H-tetrazol-5-yl)-benzoic acid], have been successfully synthesized. Compounds 1 and 2 have three-dimensional structures bridged via the typical 6-connected tri-nuclear cluster units M3O(COO)6 and linear linker H2TBA. The whole 3D framework possesses a 6-connected acs topology. Notably, by the fluorescence technique, compound 1 can detect nitro explosives through fluorescence quenching effect, especially for 2,4,6-trinitrophenol(TNP, Ksv=3.64×10^4 L/mol). Furthermore, the fluorescence spectrum red shifts as the number of NO2 group increases. Based on the aforementioned consideration, compound 1 can be considered as a potential luminescent probe for the detection of TNP.     

Two New Borates Built by Different Types of {B9} Cluster Units

Two new belt-like borates Na₄[B₉O₁₄(OH)₃]·0.5H₂O(1) and Na₅[B₉O₁₄(OH)₄](2) have been synthesized under solvothermal conditions. Both compounds contain unprecedented B₉O₁₆(OH)_n^(n+5)-[n=3(1), 4(2)] clusters, which are constructed from four B₃O₃ rings via three BO₄ tetrahedra. Compound 1 exhibits a rare 1D belt with two types of 8-membered ring(MR) windows based on B₉O₁₆(OH)₃^8- clusters. Compound 2 features two different 1D belts built by different B₉O₁₆(OH)₄^9- units, which is first discovered in borate family. UV-Vis diffuse reflectance spectra reveal that compounds 1 and 2 have the cut-off edges below 190 nm, indicating that they may have potential application in deep UV(DUV) region.     

Synthesis of 6-aryl-3-cinchophenyl-1,2,4-triazolo[3,4-b]-1,3,4-thiadiazoles

In recent years, fused heterocycles have been found to possess many unique properties in synthesis and pharmacology. Especially, 1,2,4-triazolo[3,4-b]-1,3,4-thiadiazoles derivatives have been attracting much attention of chemists and pharmacologists because of their broad-spectrum biological activities such as antibacterial¹, hypotensive and CNS depressant² activities. We have prepared some 3,6-substituted 1,2,4-triazolo[3,4-b]-1,3,4-thiadiazoles and found that these compounds exhibited antimacrobial, insecticidal and promote plant growth.^3-5 Cinchophen had been used widely as medicine in clinic,but has been obsolete in recent years due to its by-effect. In order to seek for other uses of cinchophen, as a continuation of our preceeding studies, we used cinchophen as the starting material to synthesize ten new 6-aryl-3-cinchophenyl-l,2,4-triazolo[3,4-b]-l,3,4-thiadiazoles 5a-j. Compound 1 was prepared by the reaction of cinchophen and ethanol in the presence of sulfuric acid. 1 then reacted with hydrazine hydrate in absolute ethanol to give 2 which yielded 3 on treatment with CS₂ and KOH. On refluxing of 3 with excess hydrazine hydrate, 4 was obtained. 4 reacted with various substituted benzoic acids in the presence of POCl₃ to afifort 5a-j.     

Rational Design of Ratiometric Fe3+ Fluorescent Probes Based on FRET Mechanism

As the most abundant transition metal element in mammals, iron(Fe) plays a vital role in life activities. It is of great significance to study the variation of Fe³⁺ level in living organisms. In virtue of the advantages of high sensitivity, good selectivity and low damage to living systems, the fluorescence detection of Fe³⁺ has attracted much attention. Compared with the intensity-based fluorescent probe, the ratiometric fluorescent probe has less interference of environmental and can realize quantitative detection. In this study, four ratiometric Fe³⁺ fluorescent probes, R1, R2, R3 and R4_, were designed and synthesized using fluorescence resonance energy transfer(FRET) mechanism to achieve quantitative detection of Fe³⁺. In the FRET systems, 1,8-naphthalimide fluorophore derivatives were adopted as donors while rhodamine B derivatives were selected as receptors. The connection sites of the donor and acceptor in R3 and R4 are different from those in R1 and R2. All the four probes showed good response and selectivity to Fe³⁺. The energy transfer efficiencies of R3 and R4 were obviously higher than those of R1 and R2. This work provided a promising strategy for the development of fluorescent ratiometic Fe³⁺sensors.     

一种罗丹明衍生物的合成及其对三价金属离子(Fe~(3+)、Cr~(3+)和Al~(3+))的识别

三价金属离子(Cr~(3+)、Fe~(3+)和Al~(3+))与人体健康密切相关。目前,检测Cr~(3+)、Fe~(3+)和Al~(3+)需要采用不同的荧光探针,增加了检测成本和检测时间。发展能够同时检测Cr~(3+)、Fe~(3+)和Al~(3+)的高灵敏度和强抗干扰能力的荧光探针具有非常重要的意义。本文以罗丹明B为原料,合成和表征了一种罗丹明类荧光增强型探针(P),并研究了其光谱性质。研究表明,在V(甲醇)∶V(水)=9∶1体系中对三价金属离子Fe~(3+)、Cr~(3+)和Al~(3+)具有较高的选择性,不受其它二价金属离子及一价金属离子的影响,抗干扰能力强。同时,探针P对三价金属离子具有较高的灵敏度,对Cr~(3+)、Al~(3+)和Fe~(3+)的检测限分别为3.0×10~(-4)、2.7×10~(-4)和1.0×10~(-4)mol/L,表明其可用于Cr~(3+)、Al~(3+)和Fe~(3+)的检测。     

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.     

Study on the α-Thiocarbonylthioformamide Ⅰ-Comparison with α-carbonylthioformamide

α-Carbonylthioformamide 1 and α-thiocarbonylthioformamide 1 were synthesized by Adiwidjaja in 1980¹. However, there is no report of these compounds related their properties and reaction activities². Compound 1 has two possible sites for nucleophilic attack. In our previous works., it was used to synthesize a lot of heterocyclic compounds (Scheme l)^3-6.     

Pyrazolo[1, 2-a]pyrazoliumolates as novel structure elements in liquid crystals [1]

A series of pyrazolo[1, 2-a]pyrazoliumolates of type 3, 4, and 5 was prepared. Compound 4(R³ = CH₃) shows liquid crystalline properties (C 158.5 N 162 I).     

First Total Synthesis of (-)-4-O-(6'-Hydroxy-7'(9')-Dehydro-6',7,-Dihydrogeranyl)-Coniferyl Alcohol

Some Ligularia species have long used as folk remedies due to their antibiotic, antiphlogistic and antitumor activities.¹ Compound 1,² a novel coniferyl alcohol, was isolated from ligularia duciformis(Compoitae). The geometrical structure of 1,determined by spectroscopic techniques, was corresponded to 4-o-(6,-hydroxy-7'(9')-dehydro-6',7'-dihydrogeranyl)-coniferyl alcohol. But its absolute configuration at C-₆,has not yet been determined. Herein, we report the total synthesis of (6'S)-(-)-1 from Geraniol 2 through 9 steps (Scheme 1).     

A Novel Cyclization of Squalene Initiated by Radical Cation

Squalene 1 is recognized as the precursor of sterols and polycyclic triterpenoids that play important roles in numerous life processes¹. In view of the fact that the cyclization of hexa-1, 5-diene by γ-irradiation² and some isoprenoid polyenes by photochemical method³ through radical cation intermediates have been reported and that tris (p-bromophenyl)ammoniumyl hexachloroantimonate (TBPA⁺SbCl₆, 2) could oxidize olfines to the corresponding radical cations that underwent pericyclic reactions⁴, we thought it might be worthwhile to try the biomimetic cyclization of squalene initiated by radical cations. Previously we⁵ have reported the cyclization of geraniol and nerol to cis-p-mentha-2,8-dien-l-ol by reaction with 2. Herein, we report the cyclization of 1 initiated by 2 in dry dichloromethane to give 20-R-protosta-5,24-diene 3a and 20-S-protosta-5,24-diene 3b in the ratio of 1:1 with the total yield of 20%(Scheme 1).     

Chemo-and regioselective hydroboration of △^14,15 in certain cephalostatin analogue

The symmetrical diketone Ⅱ, which can be synthesized in gram scale using a well established method, was used as a starting material to prepare the 11α-methoxy ketomethylene Ⅵ. This is in continuation of our study aiming at the synthesis of multihydroxylated cephalostatin analogues, as for example cephalostatin 1Ⅰ, a potent anti-tumor natural product. Compound Ⅵ underwent chemo- and regioselective hydroboration reaction at only one of △14.15 double bonds furnishing compound Ⅸ as a major product in a fair yield.     

Recent Progress in the Synthetic Applications of Substituted Furans and Pyrroles

In this lecture, I would like to present efficient synthetic routes towards the total synthesis of syringolide 1 (2)^1,2 and secosyrin 1 (3),¹ employing 2,4-disubstituted furan 1 as a common precursor. A modified total synthesis of prehispanolone (6)³ from (S)-(+)-Wieland-Miescher ketone (4) via hispanolone (5) will also be discussed. Our methodology for the synthesis of 3,4-disubstituted-lH-pyrroles⁴ and for the generation of 3,4-didehydrothiophene⁵ has also guided us to the successful identification of 1-tert-butoxycarbonyl-3,4-didehydro-1H-pyrrole (7),which is presumably the most strained heterocyclic cumulene ever recorded.     

以9-蒽醛为荧光基团的吡唑啉衍生物荧光探针对Fe3+和Cu2+的检测

以9-蒽醛为荧光基团,吗啉环和吡唑环为识别基团,合成了一种新型荧光探针1,5-二苯基-3-(10-(吗啉甲基)蒽-2-基)吡唑啉(PMAP),利用1H NMR、13C NMR和单晶衍射表征其结构,通过荧光发射光谱和紫外可见吸收光谱研究其离子识别性能。结果表明,探针PMAP对Fe³⁺、Cu²⁺具有良好的识别效果,荧光量子产率分别从0.14降到0.05和0.04,溶液颜色从淡黄色变为蓝色。PMAP与Fe³⁺/Cu²⁺以1∶1的化学计量比形成配合物,检测限约为1μmol·L^-1。同时,干扰实验表明PMAP具有良好的抗干扰性能。在实际样品中的应用表明,PMAP传感器能有效地检测实际水样中的Cu²⁺和Fe³⁺。另外,根据Fe³⁺、Cu²⁺和H+不同组合时PMAP的量子产率构建了分子水平上的三输入NOR逻辑门电路。     

A Multifunctional {P2Mo5}-based Hybrid Applying to Catalysis,Electrocatalysis and Dye Adsorption

As a common environmental pollutant, thioether can cause serious environmental pollution, so selective oxidation of thioether has become one of the current research hotspots. In this paper, an inorganic-organic hybrid based on a Standberg-type polyoxometalate,[Hbiz]₅[HP₂Mo₅O₂₃]·5H₂O(1)(biz=benzimidazole), was obtained by adjusting pH under hydrothermal conditions. The structure was characterized by infrared spectroscopy, thermogravimetric analysis, and single-crystal X-ray diffraction. Compound 1 can be used as an excellent catalyst for the oxidation of thioanisole. The experimental results showed that thioanisole could be catalytically oxidized to methyl phenyl sulfoxide by compound 1 as a catalyst within 40 min. The conversion rate and selectivity reached 99%. Compound 1 had good cycling stability as a heterogeneous catalyst. In addition, the electrocatalytic reduction of H₂O₂ and Cr₂O₇^2‒ for hybrid 1 was preliminarily investigated. In addition, the adsorption performance of hybrid 1 on cationic dye crystal violet and methylene blue was tested, and the adsorption efficiencies can reach 98.5% and 86.3%, respectively.     

Metal-organic framework as a multi-component sensor for detection of Fe3+, ascorbic acid and acid phosphatase

In this research,a hydroxyl group functionalized metal-organic framework(MOF),UiO-66-(OH)₂,was synthesized as a "on-off-on" fluore scent switching nanoprobe for highly sensitive and selective detection of Fe³⁺,ascorbic acid(AA) and acid phosphatase(ACP).UiO-66-(OH)₂ emits yellow-green light under ultraviolet light,when Fe³⁺ was added,Fe³⁺ was chelated with hydroxyl group,the electrons in the excited state S_1 of the MOF transferred to the half-filled 3 d orbits of Fe³⁺,resulting in fluorescence quenching because of the nonradiative electron/hole recombination annihilation.AA could reduce Fe³⁺ to Fe²⁺,which can destroy the electron transfer between UiO-66-(OH)₂ and Fe³⁺ after AA adding,resulted in nonoccurrence of the nonradiative electron transfer,leading to the recovery of UiO-66-(OH)₂ fluorescence intensity.The probe can also be used to detect ACP based on the enzymolysis of 2-phospho-L-ascorbic acid(AAP) to produce AA.Benefitting from the hydroxyl group and the characteristics of UiO-66,including the high porosity and large surface area,the developed UiO-66-(OH)₂ showed extensive advantages as a fluorescent probe for detection of multi-component,such as high sensitivity and selectivity,colorimetric detection,fast response kinetics and easy to operate,economical and secure.This is the first time to use active group functionalized MOFs as a multicomponent sensor for these three substances detection.     

First Total Synthesis of (±)-Ponganone Ⅲ

In recent years, the synthesis and pharmacology of pyranoflavanoids have been extensively investigated due to their wide range of pharmacological properties^[1-3]. Ponganone Ⅲ^[4],a new natural pyranoflavanone isolated from the Pongamia pinnala, was identified as (2S)-3',4'-dimethoxy-6',6"-dimethylpyrano-[2",3":7,8]-flavanone (2) on the basis of spectra data. Its precursor,3,4-dimethoxy-2'-hydroxy-6",6"-dimethylchromeno-[2",3":4',3']-chalcone (1) is also a new natural product^[5] isolated from the roots of Lonchocarpus subglaucescent. Their total synthesis have not been reported. Herein, we wish to report the first total synthesis of compounds 1 and 2 in order to confirm the proposed structure and further more to evaluate its biological activities.     

A Novel Coumarin-based Fluorescence Chemosensor for Fe^3＋

A novel coumarin derivative[7-diethylamino-2-oxo-2H-chromene-3-carboxylic acid（6-amino-pyridin2-yl）-amide,CFe1] has been synthesized and its potential application as a chemosensor for the detection of metal ions has been further investigated.The responses of CFe1 to Fe^3＋ were studied by fluorescence emission spectrometry in the presence of other metal ions such as Al^3＋,Ba^2＋,Ca^2＋,Co^3＋,Cr^3＋,Cu^2＋,Fe^2＋,Hg^2＋,Mg^2＋,Mn^2＋,Na^＋,Ni^＋,Pb^2＋,Zn^2＋,K^＋,and Ag^＋.CFe1 showed a good selectivity for Fe^3＋ with fast response,a wide pH span of 3.3-9.18,and a large Stocks shift.CFe1 in the presence of Fe^3＋ and ethylene diamine tetraacetic acid（EDTA） makes the blue solution fade to colorless,which is due to the formation of CFe1-Fe^3＋ complex instead of any catalytic action of Fe^3＋.Furthermore,the imaging of Fe^3＋ in cultured single mice microglia cells was realized with the aid of CFe1,indicating that CFe1 has a great potential to be used as promising models for the future design of novel and robust chemosensor for metal ion detection in the field of biomedical and environmental analyses.     

单分散键合型含铕聚苯乙烯微球的制备与荧光传感性能

制备了一种可定性定量检测水溶液中三价铁离子的含铕聚苯乙烯微球, 分别用固体核磁碳谱(¹³C CP/MAS NMR)、 傅里叶变换红外光谱(FTIR)、 X射线光电子能谱(XPS)、 扫描电子显微镜(SEM)、 透射电子显微镜(TEM)、 元素分析、 粒度分析和ζ电位分析等对其化学组成和结构形貌进行表征. 当铕配合物单体用量低于2.5%时, 可以得到稳定的单分散键合型含铕聚苯乙烯微球. 用紫外光激发时, 该含铕聚苯乙烯微球发射铕离子的特征红光. Fe³⁺能猝灭该微球的荧光, 酸根离子和其它金属离子对其干扰较少; 猝灭效率与Fe³⁺浓度在0~300 μmol/L浓度范围内均呈线性关系; 随着铕配合物单体用量的增加, 微球的荧光增强, 其在检测Fe³⁺的荧光时, 猝灭常数(K_SV)增加, 检测限(LOD)下降. 调节铕配合物单体的用量, 可获得热性能优异、 红光发射强度高且稳定性好的单分散聚苯乙烯荧光微球, 对Fe³⁺荧光检测显示出较高的选择性, 在生物检测和环境保护等领域具有较高的应用价值.