对Zn2+及S2-连续响应的罗丹明B酰肼类荧光探针的研究

该文采用简单的两步反应合成了一种新型N-(2-羟基-5-氯苯)基罗丹明B酰肼(HCPRH)分子探针,并对其进行了结构表征及荧光性能研究。结果显示,在含HCPRH分子探针的N,N-二甲基甲酰胺(DMF)溶液中加入Zn~(2+),会使其荧光显著增强,可在365 nm紫外灯下肉眼观察到体系颜色迅速由无色变为亮黄色,表明该分子探针可用于Zn~(2+)的快速、灵敏和裸眼识别,且其对Zn~(2+)具有良好的识别选择性,其它金属离子几乎不干扰HCPRH探针对Zn~(2+)的响应。采用Benesi-Hildebrand方程计算得HCPRH分子探针与Zn~(2+)之间形成了稳定的配合物,以Job?s法确定两者之间摩尔比为1∶1。根据荧光滴定的实验结果,发现HCPRH分子探针在512 nm处荧光发射峰强度变化值与Zn~(2+)浓度在10～250μmol/L之间呈良好的线性关系,对Zn~(2+)的检出限达3.6μmol/L,可用于其微量检测。另外,实验研究还表明该分子HCPRH探针可成功用于对Zn~(2+)与S~(2-)的连续荧光响应。     

新型香豆素席夫碱化合物的合成及对锌离子的荧光传感研究

以3-氨基-6-氯香豆素为荧光发光基团,设计合成了3-[(2-羟基-苯亚甲基)-氨基]-6-氯香豆素(CHS)并研究其作为肉眼可视化荧光识别Zn2+的分子探针。采用元素分析和物理化学仪器如FTIR、1HNM R、紫外可见吸收和荧光光谱等手段表征了分子探针CHS的结构特征和理化性能。在CHS的二甲基甲酰胺溶液(DMF)中加入Zn2+后均会使溶液荧光显著增强,而溶液颜色由无色迅速转变为黄色,而且其它的金属离子对分子探针CHS识别Z n2+的影响不明显。通过Job图可以计算得出分子探针CHS与Z n2+之间形成1:1的稳定化合物,由Benesi-Hildebrand方程(采用吸收光谱计算)计算出分子探针CHS与Zn2+之间形成配合物的稳定常数为9.97×102mol/L。螯合荧光增强效应(CHEF)是导致分子探针CHS和CHD与Z n2+作用后荧光强度增强和吸收光谱红移的主要原因。在分子探针CHS的DMF溶液中加入Zn2+之后,荧光强度增强值与Zn2+的浓度在0~60μmol/L之间呈良好的线性关系,检出限为1.92μmol/L(r=0.9907,信噪比为3),表明分子探针CHS可用于定量检测微量Zn2+。     

一种香豆素类锌离子荧光探针的合成及性能

通过Pechmann法使间苯二酚和乙酰乙酸乙酯发生脱水缩合反应,合成了4-甲基-7-羟基香豆素,再与六次甲基四胺反应,生成7-羟基-4-甲基-8-甲酰基香豆素,最终与吲哚酰肼发生席夫碱反应合成一种香豆素类荧光探针L。通过核磁共振波谱仪(NMR)、质谱(MS)、傅里叶变换红外光谱仪(FTIR)、荧光发射光谱仪和紫外可见分光光度计等技术手段研究该探针L的结构及其荧光性能。结果表明,探针L与Zn~(2+)的配合比为1∶1,对Zn~(2+)的检测限达到3.6×10~(-8)mol/L,降低了对Zn~(2+)的检测浓度,同时探针L对锌离子具有高选择性,可应用于在生物体内Zn~(2+)的检测。     

新型双功能席夫碱荧光探针分别识别检测Zn~(2+)和CN~-

合成了一种新的席夫碱荧光探针4'-羟基-3'-((2-吡啶亚甲基亚氨基)甲基)-4-氰基联苯(HPBC),用于对Zn~(2+)和CN~-的选择性识别检测。在Et OH-H_2O(2∶3,V/V,HEPES,p H=7.4)体系中,HPBC与Zn~(2+)按摩尔比1∶1络合,使探针在468 nm处的荧光明显增强,且最大发射峰发生15 nm的蓝移,而在加入其它金属离子后不产生明显的荧光增强现象,由此可以选择性识别检测水体系中的Zn~(2+)。本方法检测Zn~(2+)的线性范围为0.4~4.0μmol/L,检出限为36.5 nmol/L,比WHO规定的饮用水中Zn~(2+)限量水平(76μmol/L)约低1000倍。向HPBC中交替加入Zn~(2+)和EDTA,探针表现出"ON-OFF-ON"模式的荧光变化,且在4次循环后,体系荧光效率损失较小,表明HPBC对Zn~(2+)的识别具有良好的可逆性。荧光成像实验表明,HPBC可用于检测活细胞中的Zn~(2+)。而在DMSO-H2O(3∶7,V/V)介质中,由于与其它阴离子尤其是F~-与AcO~-相比,CN~-具有较强的碱性及较弱的氢键结合力,因此CN~-可使探针HPBC中的酚羟基去质子化,产生强的绿色荧光,且溶液颜色由无色变为淡黄色。由此可以选择性识别检测水溶液中的CN~-,且不受其它阴离子的干扰。HPBC对CN~-的检出限0.575μmol/L。HPBC还可制成试纸条,通过检测试纸条颜色及紫外灯下荧光的改变,方便快捷地检测水样中的CN~-。     

一种具有ESIPT和AIEE荧光探针的合成及对Zn2+的识别

利用2-氨基苯并噻唑和5-甲基-2-羟基间苯二甲醛合成了一种具有聚集荧光增强性质的简单高效的荧光探针M,通过~1H-NMR、~(13)C-NMR表征了其结构。探针M在545 nm处有最大吸收峰,在甲醇∶水(7∶3)的体系下,向探针M中加入金属阳离子,发现只有加入Zn~(2+)时,表现出明显的荧光增强且发射波长发生明显的蓝移现象,在495 nm处出现最强吸收峰,检测限为9.638×10~(-6 )M,具有较高的灵敏度和良好的识别效果。     

基于香豆素的比色探针的合成及对Cu^(2+)的识别EI北大核心CSCD

合成了探针8-(2-肼基苯并噻唑)-4-甲基-7-羟基香豆素(L),通过紫外光谱法研究其识别Cu^(2+)性能,并通过Job’s曲线、红外光谱和质谱研究其对Cu^(2+)的识别机理。结果表明:在二甲基亚砜(DMSO)/水(V∶V=9∶1)溶液体系中,探针溶液中加入Cu^(2+)后,溶液颜色由无色变为浅黄色;探针溶液的紫外可见吸光度与Cu^(2+)浓度在0.125~5μmol/L范围内呈良好的线性关系,线性方程为A=0.037c+0.052,线性相关系数R^(2)=0.9881,检出限为0.02μmol/L,该探针可以定量检测水中的Cu^(2+)。     

甾体荧光探针的合成及对废水重金属离子的检测

本文利用3-氧代-5β-24-胆烷酸甲酯(4)与单缩二氨基硫脲(2)为原料,合成了一种新型甾体不对称双缩二氨基硫脲席夫碱荧光探针N′-(2-羟基亚苄基)-2-(3-基亚甲基-5β-24-胆烷酸甲酯)肼基-1-硫代碳酰肼(L)。在缓冲溶液(pH 6～9)中,探针L可以高选择性荧光识别Zn~(2+),检测限可达到0.21μM。在365 nm紫外灯照射下,溶液由无色变成亮绿色强荧光。生成1∶1型配合物(L-Zn~(2+))。实际应用研究表明,探针L可应用于实际水样中一定浓度范围内Zn~(2+)的检测。     

基于功能化萘二甲酰亚胺席夫碱的Fe~(3+)传感器分子的合成及性能

将功能化的1,8-萘二甲酰亚胺衍生物与羟基萘甲醛缩合,合成了一种新颖的传感器分子2-羟基-1-奈甲醛缩N-(4-氨基苯基)-1,8-奈二甲酰胺席夫碱(H1).通过核磁共振氢谱,碳谱和高分辨质谱等方法对H1进行了表征.测定了H1在二甲基亚砜(DMSO)/H_2O(V:V=7:3)溶液中的荧光光谱,其最大荧光发射波长为496nm.H1的溶液在365 nm紫外灯照射下显示黄绿色荧光.H1对Fe~(3+)具有荧光-比色双通道检测能力.当在H1的DMSO/H_2O溶液中分别加入Fe~(3+),Ag~+,Ca~(2+),Ba~(2+),CO~(2+),Ni~(2+),Cd~(2+),Pb~(2+),Zn~(2+),Cu~(2+),Mg~(2+)和Hg~(2+)等阳离子时,只有Fe~(3+)的加入使H1的荧光猝灭并且溶液颜色褪色.抗干扰实验结果表明,这一识别过程不受其它阳离子干扰.H1对Fe~(3+)具有较高的检测灵敏度,对Fe~(3+)的荧光光谱最低检测限和紫外-可见吸收光谱最低检测限分别为3.04×10~(-8)和2.71×10~(-6+mol·L~(-1).最后,制备了基于H1的检测试纸,该试纸可以方便快捷地检测水中的Fe~(3+).     

一种pH荧光探针的合成及光谱研究

设计合成了一种pH荧光分子探针2,5-双(4-羟基-苯亚甲基)环戊酮,并对其光谱性能进行了研究.pH滴定实验表明:探针的紫外吸收和荧光光谱对溶液的pH值有很强的依赖性.当体系溶液由酸性变为碱性时,探针紫外吸收光谱发生明显的红移,并伴有溶液颜色的显著变化.荧光光谱强度在酸性条件下随pH的变化不大,而在碱性条件下荧光强度则...     

基于香豆素的比率型荧光探针对溶液及气相中三氟化硼的检测

合成了一种以香豆素为主体的具有高选择性及灵敏性的比率型荧光探针3-对甲基苯基-7-二乙氨基香豆素(TDC), 并将其用于溶液及气相中三氟化硼(BF₃)的即时可视化检测, 检出限为5.5×10^-7 mol/L. 通过荧光光谱、 紫外-可见吸收光谱和核磁共振波谱(¹⁹F NMR)等方法证实, 该探针与BF₃之间发生的路易斯酸碱反应会对TDC分子内电荷转移(ICT)过程产生影响, 从而引起光谱和溶液颜色的明显变化. 基于TDC分子制成的试纸能够实现裸眼检测溶液和气相中的BF₃.     

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.