间羧基氯磺酚的合成及其光度法测定钢中铌

报道了间羧基氯磺酚(SCPmK)的合成及其与铌的显色反应,在1．8-3．0mol·L-1的盐酸介质中,铌与SCPmK形成1∶1的深蓝色配合物,最大吸收波长在640nm处,其摩尔吸光系数为1． 08×10５L·mol-1·cm-1(乙醇溶液),铌含量在0-60μg／50ml符合比耳定律,运用此法可直接测定钢中微量铌。     

偶氮胂Ⅲ分光光度法测定人血清中蛋白质

偶氮胂Ⅲ是测定无机离子的灵敏显色剂 ,研究发现该试剂能在pH 2 1的缓冲介质中 ,与牛血清白蛋白形成复合物 ,最大吸收波长 60 2nm ,比试剂本身红移 5 9nm ,表观摩尔吸光系数 5 6× 1 0 5L·mol- 1·cm- 1,线性范围 0～ 45 0 μg/mL。方法用于人血清样品中蛋白质的测定 ,结果可靠     

水溶苯胺蓝吸光光度法测定人血清蛋白

用吸光光度法研究了水溶苯胺蓝(AnB)与牛血清白蛋白(BSA)在Britton-Robinson广泛pH缓冲介质中的结合反应,在最佳试验条件下,以试剂空白为参比,AnB-BSA复合物在600nm波长处的吸光度,与BSA的浓度呈良好的线性关系,BSA的线性范围为1.6×10-8～2.4×107mol.L-1,摩尔吸光系数ε=1.34×106L·mol-1·cm-1,Sandell灵敏度为0.051μg·cm-2,BSA的检出限为1.0×10-8mol·L-1,方法具有灵敏度较高、选择性好等特点,用于人血清样品中蛋白质的测定,与溴甲酚绿方法结果一致。     

酸性铬蓝K与卵白蛋白相互作用的分光光度研究及应用

在pH1.30的氯乙酸缓冲溶液中,在TritonX-100存在下,卵白蛋白与酸性铬蓝K可形成有色复合物,其最大吸收波长为585nm。卵白蛋白浓度在0～2.85mg/L和3.14～11.40mg/L范围呈线性,摩尔吸光系数分别为4.76×105L·mol-1·cm-1、5.46×104L·mol-1·cm-1。相对标准偏差在1.18%～1.27%,回收率在98.8%～101.7%之间。提出的方法已用于豆粕浸提液中蛋白质的测定,分析结果满意。探讨了卵白蛋白与酸性铬蓝K形成复合物的反应机理。     

蛋白质的铬偶氮KS分光光度法测定

在 pH1.4的克拉克 -鲁布斯(Clark -Lubs)缓冲介质中 ,红色的铬偶氮KS能与蛋白质作用形成紫色的复合物 ,其最大吸收波长为588nm ,比铬偶氮KS本身红移68nm ,测定的表观摩尔吸光系数ε588 达2.971×105 L/(mol·cm)(牛血清白蛋白) ,线性范围为10～140mg/L;所拟方法用于人血清中总蛋白的测定 ,结果与考马斯亮蓝G_250法一致     

7-苯基偶氮-变色酸与蛋白质的显色反应研究

研究了蛋白质与 7-苯基偶氮 -1 ,8-二羟萘 -3 ,6-二磺酸的显色反应。在 p H2 .7的缓冲溶液中 ,7-苯基偶氮 -1 ,8-二羟萘 -3 ,6-二磺酸与蛋白质形成红紫色复合物 ,λmax为 564 nm,ε为 1 .3× 1 0 5L· mol- 1· cm- 1,线性范围为 6.6～ 1 3 2 mg/ L。实验证实7-苯基偶氮 -1 ,8-二羟萘 -3 ,6-二磺酸与蛋白质的作用符合 Pesavento模式。所提出的方法不经任何预处理可直接测定血清和花生中的蛋白质     

亮黄共振光散射法测定微量蛋白质

基于蛋白质对生物染色剂亮黄的共振光散射的增强效应,拟定了一种测定蛋白质的共振光散射法。在pH 2.5的Britton Robison缓冲溶液中,亮黄在510 nm处的共振光散射增强与蛋白质浓度呈线性关系。对牛血清白蛋白,线性范围为0.25~11.5 mg·L-1,检出限48μg·L-1。方法用于合成样品和人尿样品中蛋白质的测定,结果满意。     

借对乙酰基偶氮羧p-铕(Ⅲ)络合物作光度探针测定生物样品中蛋白质

在pH 3.0的Britton-Robinson缓冲介质中,蛋白质能与铕(Ⅲ)-对乙酰基偶氮羧p形成复合物,最大吸收峰波长为695 nm,比络合物探针本身红移145 nm。可用于生物样品中蛋白质的测定,牛血清白蛋白(BSA)的线性范围为0.010~0.030 g.L-1,相关系数为0.995 4;人血清白蛋白(HAS)的线性范围为0.005~0.025 g.L-1,相关系数为0.994 7,应用于测定生物试样中的总蛋白质,RSD小于6.5%,回收率在98.4%~103.7%。     

灿烂甲酚蓝二聚体作为荧光探针测定人血清白蛋白

阳离子染料灿烂甲酚蓝(BCB)在适宜浓度的阴离子表面活性剂十二烷基硫酸钠(SDS)或十二烷基磺酸钠(SLS)存在时形成二聚体。研究了以此形成的现场二聚体作为荧光探针测定蛋白质的可能性。结果表明,二聚体具有弱荧光,其荧光强度的回升与体系中蛋白质的量呈线性关系,线性范围为0～7.8μg·ml-1,检出限为3.89×10-3μg·ml-1。用于人血清白蛋白的测定,结果满意。     

水溶苯胺蓝与蛋白质结合反应的研究及应用

在pH 2.36的Britton-Robinson(B-R)缓冲介质中,水溶苯胺蓝与蛋白质形成显色化合物,其最大吸收波长为688nm,比试剂本身红移88nm,表观摩尔吸光系数达4.25×105L·mol-1·cm-1(牛血清白蛋白)。制定了四种蛋白质的标准工作曲线,用于人血清样品中总蛋白的测定,结果与溴甲酚绿法一致。     

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.