双-(2,4-二羟基苯乙酮)缩肼的合成及其与锶的荧光猝灭反应

合成了一种新的双席夫碱荧光试剂——双-(2,4-二羟基苯乙酮)缩肼。该试剂在491．2nm处有强荧光峰,当有锶离子存在时,可形成稳定的络合物而使试剂的荧光猝灭。利用此反应建立了一个荧光测定痕量锶的新方法,其线性范围为0．10—50．0μg/L,检出限0．056μg/L,方法成功地应用于矿泉水中痕量锶的测定。     

DNA荧光探针—荧光素-中性红体系的研究

基于DNA对荧光素(FL)-中性红(NR)分子间荧光能量转移的抑制作用，以荧光素-中性红为荧光探针，考察该探针与DNA的结合反应，建立了准确测定DNA的新方法，在pH＝6.5条件下，hsDNA、ctDNA和smDNA的浓度与荧光素-中性红体系的荧光比值变化量Δ(Fd／Fa)成线性关系，响应线性范围分别为0．25-6．25μg／mL、0．10-5．00μg／mL、0．10-4．00μg／mL，0.025μg/mL和0．023μg／mL；分析测定了DNA合成样品，回收率91．3％-101．4％，相对标准偏差小于4．2％．     

2，3，4-兰羟基苯乙酮缩-2-羧基苯胺与铜的高灵敏度荧光反应及其应用

合成了新荧光试剂2,3，4-三羟基苯乙酮缩-2-羧基苯胺(TAFA)。详细研究了试剂与铜的荧光反应新体系的最佳适宜条件。在pH9．0的乙醇／水(3．5：6．5，V/V)溶液中，该试剂与铜离子形成稳定的络合物，组成比为1：1(金属：试剂)，λex/em=422．4／561．6nm。所建立的铜的荧光分析方法的线性范围为0.5～120.0μg／L；检出限为0．26μg／L。方法成功地应用于矿泉水和水中痕量铜的测定。     

硫酸喹啉荧光猝灭法测定脱氧核糖核酸

基于DNA在pH2～4的范围内对硫酸喹啉的荧光具有较强的猝灭作用，建立了一种测定DNA的新方法。当DNA的浓度为10～700μg／L时，荧光猝灭程度与DNA浓度呈线性关系，其线性回归方程为：△IF=1．52118 0．11038G(μg／L)；相关系数r=0．9985；检出限为5．9μg／L。本方法用于大肠杆菌提取的质粒DNA的测定，获得满意结果。     

新试剂3-对氟苯基-5-（2＇-羧基苯偶氮）若丹宁的合成及荧光法测定铋

合成了新型试剂3-对氟苯基-5．(2’-羧基苯偶氮)若丹宁，并经元素分析、IR确证了其结构。研究发现在pH=5．2时该试剂与痕量铋锄形成的螯合物可使试剂的荧光强度大大减弱，在λex／λem=305nm/404nm处有最大峰；其荧光猝灭值与铋的浓度在1．0-12μg/L范围内呈线性关系，检出限达0．26μ／L。建立了荧光光度法测定痕量铋的新方法。     

联吡啶-铜(Ⅱ)络合物荧光增强法测定核酸

利用联吡啶-Cu(Ⅱ)络合物作为荧光探针测定脱氧核糖核酸(DNA),实验发现加入天然和变性DNA均能使联吡啶-Cu(n)络合物(Cu(bpy)2^2 )体系的荧光强度大幅度增强。测定体系的最大激发和发射波长分别为304和334nm。在最佳实验条件下,测定的线性范围分别为：小牛胸腺(CT-DNA)0．09—9mg／L;鱼精DNA(FS—DNA)0．01—12.5mg／L;酵母DNA(yeastDNA)0．30—35mg／L。检出限分别为0.003、0．002和0．02mg／L。实验结果推测该络合物与DNA之间通过静电作用结合。     

锆—7—（1—苯偶氮）—8—羟基喹啉—5—磺酸—Triton X—100荧光熄灭法测定锆

基于在pH＝4．5～5.5、TritonX－100存在下、锆同7－（1-苯偶氮）－8-羟基喹啉-5-磺酸形成组成比为1：3的黄色络合物使荧光熄灭，建立了荧光熄灭测定锆的新方法。该方法的线性范围为0～28μgZrO2／L，检测限为0．5μg／L，体系稳定，灵敏度高，用于α-βAl2O3及瓷釉中锆的测定，结果满意。     

用银-邻菲啰啉-邻氯苯基荧光酮离子缔合物体系荧光熄灭法测定银

在聚乙烯醇存在下，银与邻氯苯基荧光酮及邻菲啰啉形成离子缔合型异配位体络合物使邻氯苯基荧光酮的荧光熄灭。在pH6．4～7．2的HAc－NH4Ac或NH3·H2O－NH4Ac介质中，λex＝400nm，λem＝550nm，体系的相对荧光强度最大，线性范围为0～500μg／L，检出限为0．013mg／L，方法用于阳极泥中银的测定，结果满意。     

双席夫碱双-(2,4-二羟基苯乙酮)缩肼的合成及其与铜的荧光猝灭反应

报道了一种新的双席夫碱荧光试剂——双—(2，4—二羟基苯乙酮)缩肼的合成；试剂在492.8nm处有一强荧光峰，当有铜离子存在时，可与试剂形成稳定的配合物而使试剂的荧光猝灭；利用此反应建立了一个荧光测定痕量铜的新方法，测定铜的线性范围为0．0～180．0μg／L，检出限0．02μg／L，方法可应用于矿泉水和水中痕量铜的测定。     

环境水样中痕量肼的荧光分析

基于在硫酸介质中，肼与罗丹明6G反应，使其荧光增强，建立了一种荧光测定痕量肼的新方法。该方法线性范围2．0－14．0μg/L，检出限为0．62μg/L。可用于环境水样中肼含量的测定，并进行了回收实验，回收率为97％－107％。     

A carbanion induced synthesis of highly congested pyrazole and imidazole containing heterocycles

An efficient approach to the synthesis of highly congested di, penta and hexacyclic pyrazoles as well as imidazole fragment containing novel heterocyclic molecule has been developed through a carbanion induced transformation of suitably functionalized 2H-pyran-2-ones, benzo[h]chromene and thiochromeno[4,3-b]pyrans. Due to the presence of fluorescence, we report their prime application metal sensor as off/on switching in ferric ions.     

α-Amino acid derived enaminones and their application in the synthesis of N-protected methyl 5-substituted-4-hydroxypyrrole-3-carboxylates and other heterocycles

A new and simple synthesis of novel N-protected methyl 5-substituted-4-hydroxypyrrole-3-carboxylates, which exist in equilibrium with their 4-oxo tautomers, has been developed in two steps starting from N-protected α-amino acids. The key intermediates are enaminones, which can also be isolated, characterized, and used for the construction of other functionalized heterocycles, before they spontaneously decompose to pyrrole products. 4-Hydroxypyrroles are prone to partial aerial oxidation but can be efficiently alkylated or reduced to stable polysubstituted pyrrolidine derivatives.     

Specific intramolecular aromatic CH insertion of diazosulfonamides

The chemoselectivity in the intramolecular CH insertion of various diazosulfonamides has been experimentally studied. The results reveal that the aliphatic 1,4-, 1,5-, or 1,6-C(sp³)?H insertions of diazosulfonamides are not accessible, while the aromatic 1,5-C(sp²)?H insertion can be realized specifically by adjusting the diazo-adjacent group. In addition, the general chemoselectivities in the intramolecular CH insertions of diazosulfonyl compounds are summarized. Generally, diazosulfones undergo both aromatic 1,5-C(sp²)?H and aliphatic 1,5- and 1,6-C(sp³)?H insertions, while diazosulfonates undergo aliphatic 1,5- and 1,6-C(sp³)?H insertions. However, diazosulfonamides only undergo aromatic 1,5-C(sp²)?H insertion.     

N-Heterocyclic carbene-palladacyclic complexes: synthesis,characterization and their applications in the C-N coupling and α-arylation of ketones using aryl chlorides

N-Heterocyclic carbene-palladacyclic complexes 3 were successfully achieved in a one-pot procedure under mild conditions. The structure of 3a was unambiguously confirmed by X-ray single crystal diffraction and it was an active catalyst in the Buchwald-Hartwig amination and α-arylation of ketones even at very low catalyst loadings (0.01?mol%).     

Selective synthesis of 4,5-dihydroimidazo- and imidazo[1,5-a]quinoxalines via modified Pictet–Spengler reaction

An efficient tandem approach for the selective synthesis of 4,5-dihydroimidazo[1,5-a]quinoxalines 6a–g and imidazo[1,5-a]quinoxalines 7a–h by the reaction of 2-imidazolyl anilines 4a–c with aryl aldehydes 5a–k under mild reaction conditions is described. Introduction of electron releasing alkyl groups in substrates 4a–b was found to be instrumental for the success of the reaction.     

Understanding the Diels-Alder reactivity of 1,2-azaborine analogues

The Diels-Alder reactivity of 1,2-heteroborines (H₄C₄B(H)X, X?=?NH, PH, AsH; O, S, Se) has been computationally explored by means of Density Functional Theory (DFT) calculations. The influence of the HB?=?X fragment on the reactivity of the system has been quantitatively analyzed in detail by means of the so-called Activation Strain Model (ASM) of reactivity. It is found that the interaction between these species and the dienophile is significantly stronger than that computed for their all-carbon isoelectronic counterpart, benzene. In addition, the strain energy plays a key role in the observed reactivity trends. The role of the aromaticity strength of these heteroarenes on the reactivity is also assessed.     

Synthesis of N-substituted carbazolones from α-iodo enaminones via Pd(0)-catalyzed intramolecular coupling under microwave irradiation

A variety of N-aryl and N-alkyl carbazolones were conveniently achieved in good to high yields via Pd₂(dba)₃-mediated intramolecular coupling of N-substituted α-iodo enaminones under microwave irradiation. The Pd(0)-catalyzed cyclization was found to proceed favorably with the more electron-deficient phenyl ring during the reactions involving unsymmetrical N,N-diaryl α-iodo enaminones. This unique property enables the construction of carbazolone skeleton containing nitro substituted benzenoid ring.     

Iodine-mediated oxidative Pictet-Spengler reaction using terminal alkyne as the 2-oxoaldehyde surrogate for the synthesis of 1-aroyl-β-carbolines and fused-nitrogen heterocycles

An efficient iodine-mediated oxidative Pictet-Spengler reaction in dimethyl sulphoxide (DMSO) using terminal alkynes as the 2-oxoaldehyde surrogate for the synthesis of aryl (9H-pyrido[3,4-b]indol-1-yl)methanones is described. The scope of the protocol includes the total synthesis of Fascaplysin, Eudistomins Y₁ and Y₂. The methodology is extended for preparing pyrrolo[1,2-a]-quinoxaline and indolo[1,5-a]quinoxaline derivatives. The utility of 1-aroyl-β-carbolines was demonstrated by performing palladium-catalyzed β-carboline directed ortho-C(sp2)-H functionalization of the phenyl ring with thiomethyl (SMe) group using DMSO as source and for accessing 4-aryl-canthin-6-ones.     

Facile synthesis of bicyclic 1-arylpyrazol-5-ones

In this Letter, we described a facile method for constructing fused bicyclic 1-arylpyrazol-5-one ring system. We employed various methylene-containing carboxylic acids as the substrates and proved that the pyrazolone ring closure requires activated methylene group in intermediate II. Accordingly, a series of structurally diversified, fused bicyclic 1-arylpyrazol-5-ones was prepared in moderate to high yields using the requisite substrates.     

Synthesis of substituted 2,4,5,6-tetrahydrocyclopenta[c]pyrazoles and 2,4,5,6-tetrahydropyrrolo[3,4-c]pyrazoles by intramolecular nitrilimine cycloaddition

Both substituted 2,4,5,6-tetrahydrocyclopenta[c]pyrazoles and 2,4,5,6-tetrahydropyrrolo[3,4-c]pyrazoles have been synthesized by the 3+2 intramolecular dipolar cycloaddition of nitrilimines to alkynes. This cyclization has been extended to more versatile 3-bromo derivatives by the use of alkynylbromides as dipolarophiles.