单-(6-巯基)-β-环糊精修饰的CdTe量子点的合成及与中性红的相互作用

以巯基乙酸(TGA)和单-(6-巯基)-β-环糊精(mono-6-thio-β-CD)作混合稳定剂,通过优化TGA/mono-6-thio-β-CD比例及回流时间,合成出了粒径分布均匀、荧光量子产率高达81.3%的mono-6-thio-β-CD修饰的CdTe量子点(QDs),建立了一种在水相中直接合成β-CD修饰的CdTe的新方法.利用荧光光谱、紫外-可见吸收光谱、共振瑞利散射光谱(RRS)研究了mono-6-thio-β-CD-CdTeQDs与中性红的相互作用,同时通过对比单独使用TGA为稳定剂合成的TGA-CdTeQDs与中性红的相互作用并结合透射电子显微镜(TEM)对反应机理进行了讨论并提出了相应的反应模型.在pH6.1的BR缓冲溶液中,当中性红浓度为7.5×10-6mol/L时,中性红的离子型体HNR+和分子型体NR分别与mono-6-thio-β-CD-CdTeQDs表面的-SCH2COO-和mono-6-thio-β-CD结合达饱和,当中性红浓度大于7.5×10-6mol/L时,中性红开始在mono-6-thio-β-CD-CdTeQDs表面聚集,导致mono-6-thio-β-CD-CdTeQDs粒径增大、荧光急剧猝灭、RRS显著增强.     

Carboranylpyrroles: a synthetic investigation

The unusual reactivity of carborane mono- and dialdehydes with pyrroles in the presence of acid catalysts leads to the formation of a new class of carboranyl mono- and dipyrro derivatives.     

The synthesis of mono-6-thio-β-cyclodextrin capped CdTe QDs and its interaction with neutral red

This paper presents a novel method for the synthesis of CdTe quantum dots (QDs) capped with β-cyclodextrin in aqueous solution using both TGA and mono-6-thio-β-CD as stabilizers. The interaction between mono-6-thio-β-CD-CdTe QDs and neutral red (NR) was studied with fluorescence, UV-absorption and the resonance Rayleigh scattering spectrum. When its concentration was over 7.5 × 10^?6 mol/L, the neutral red began to aggregate on the surface of the mono-6-thio-β-CD-CdTe QDs, which resulted in the mono-6-thio-β-CD-CdTe QDs particle size increasing, the sharply quenched fluorescence, and the marked increase of RRS intensity.     

A tellura-Baeyer–Villiger oxidation: one-step transformation of tellurophene into chiral tellurinate lactone

Baeyer–Villiger (BV) oxidation is a fundamental organic reaction, whereas the hetero-BV oxidation is uncharted. Herein, a tellura-BV oxidation is discovered. By oxidizing a tellurophene-embedded and electron-rich polycycle (1) with mCPBA or Oxone, an oxygen atom is inserted into the Te–C bond of the tellurophene to form tellurinate lactone mono-2. This reaction proceeds as follows: (i) 1 is oxidized to the tellurophene Te-oxide form (IM-1); (ii) IM-1 undergoes tellura-BV oxidation to give mono-2. Moreover, the hybrid trichalcogenasumanenes 7 and 8 are, respectively, converted to tellurinate lactones mono-9 and mono-10 under the same conditions, indicating that tellura-BV oxidation shows high chemoselectivity. Due to the strong secondary bonding interactions between the Te O groups on tellurinate lactones, mono-2, mono-9, and mono-10 are dimerized to form U-shaped polycycles 2, 9, and 10, respectively. Notably, mono-2, mono-9, mono-10, and their dimers show chirality. This work enables one-step transformation of tellurophene into tellurinate lactone and construction of intricate polycycles.

A tellura-Baeyer–Villiger oxidation is discovered, which enables one-step transformation of tellurophene into chiral tellurinate lactones. The resulting tellurinate lactones are dimerized in the solid state to form U-shaped polycycles.     

Evaluation of magnetically recyclable nano-Fe3O4 as a green catalyst for the synthesis of mono- and bis-tetrahydro-4H-chromene and mono and bis 1,4-dihydropyridine derivatives

Research on Chemical Intermediates - Magnetically separable Fe3O4 nanoparticles were used as an environmental friendly catalyst for the synthesis of mono- and bis-tetrahydro-4H-chromene and mono-...     

2,4,6-trichloropyrimidine. Reaction with 4-substituted phenolate ions

A systematic investigation of the reactivity of 2,4,6-trichloropyrimidine with phenoxide nucleophiles has been conducted. Conditions have been described which lead to mono-, di-, and trisubstituted-pyrimidines. Unexpected product distributions for mono- and disubstituted products were observed and explanations for these results are offered.     

Ruthenium-catalyzed cross-metathesis between diallylsilanes and electron-deficient olefins

Diallysilanes can be selectively coupled with electron-deficient olefins under cross-metathesis (CM) conditions using the Hoveyda-Grubbs catalyst to produce mono- and/or bis-CM compounds in good yield. The formation of the mono- and the bis-CM compounds depends on the nature of the electron-deficient olefin.     

Synthesis and application of mono-2A-azido-2A-deoxyperphenylcarbamoylated beta-cyclodextrin and mono-2A-azido-2A-deoxyperacetylated beta-cyclodextrin as chiral stationary phases for high-performance liquid chromatography

Two novel chiral stationary phases (CSPs) were prepared based upon the regioselective immobilizations of beta-cyclodextrin (beta-CD) at its C2 position to the silica support. The mono-2A-azido-2A-deoxyperphenylcarbamoylated beta-cyclodextrin and mono-2A-azido-2A-deoxyperacetylated beta-cyclodextrin were synthesized by selective tosylation and azidolysis followed by perfunctionalisation. The derivatised cyclodextrins were then immobilized onto the aminised silica gel via the Staudinger reaction to provide new chiral stationary phases. Their application to high-performance liquid chromatography (HPLC) enantioseparation of racemic compounds was demonstrated using beta-adrenergic blockers, flavonone compounds, benzodiazepinones, antihistamines and weakly protolytic compounds, of which good separations were achieved for some racemic compounds, for instance, bendroflumethiazide (Rs 6.26), oxazepam (Rs 5.99), temazepam (Rs 2.85) and althiazide (Rs 1.13) when compared with the corresponding CSPs where the beta-CD molecule was regioselectively immobilized at the C6 position. The enantiodiscriminatory properties of these CSPs were found to be affected by the orientation of the CD cavity under reversed-phase conditions, and also by the derivitising groups of the CD. The HPLC results inferred that the mono-6A-azido-6A-deoxyperphenylcarbamoylated CD CSP (CD bonded at C6 position to silica) exhibited slightly better chiral recognition ability than mono-2A-azido-2A-deoxyperphenylcarbamoylated CD CSP under the normal-phase and reversed-phase modes on the separation of 31 different racemic compounds and drugs. On the contrary, higher chiral recognition abilities were observed on the mono-2(A)-azido-2A-deoxyperacetylated CD CSP compared to mono-6A-azido-6A-deoxyperacetylated CD CSP.     

The more gold--the more enantioselective: cyclohydroaminations of γ-allenyl sulfonamides with mono-, bis-, and trisphospholane gold(I) catalysts

A series of chiral mono-, di-, and trinuclear gold(I) complexes have been prepared and used as precatalysts in the asymmetric cyclohydroamination of N-protected γ-allenyl sulfonamides. The stereodirecting ligands were mono-, di-, and tridentate 2,5-diphenylphospholanes, which possessed C(1), C(2), and C(3) symmetry, respectively, thereby rendering the catalytic sites in the di- and trinuclear complexes symmetry equivalent. The C(3)-symmetric trinuclear complex displayed the highest activity and enantioselectivity (up to 95?% ee), whilst its mono- and dinuclear counterparts exhibited considerably lower enantioselectivities and activities. A similar trend was observed in a series of mono-, di-, and trinuclear 2,5-dimethylphospholane gold(I) complexes. Aurophilic interactions were established from the solid-state structures of the trinuclear gold(I) complexes, thereby raising the question as to whether these secondary forces were responsible for the different catalytic behavior observed.     

Electron paramagnetic resonance studies on copper(II)-cyclodextrin systems

Three copper(II) complexes containing beta-cyclodextrin (betaCD) derivatives as ligands [mono-6-methylamino-6-deoxy-betaCD dithiocarbamate (CDTC), mono-6-histamino-6-deoxy-betaCD (CDHM) and mono-6-Nalpha-arginyl-6-deoxy-betaCD (CDARG)] have been studied by electron paramagnetic resonance. The spectra have been recorded at X- and S-bands and different temperatures and simulated to obtain the best set of magnetic parameters. In particular, the 300 K spectra are typical of the slow motion regime, as expected considering the high molecular weight of the ligands. Some structural characteristics of the complexes are proposed on the basis of dynamic and covalency parameters obtained from simulation.     

Phospha-carba-oligo-enes,Synthesis and Reactivity

Abstract

The synthesis of various mono-, di- and mphosphabutadienes, of two hiphosphapentadienes and of several mono-, di- and tetraphospha-hexadienes is being reported. Their chemistry demonstrates an astonishing relationship to the corresponding olefinic compounds.     

Synthesis of new dithiocarbamate-based organosilanes for grafting on silica

A new and mild method was developed for the chemoselective conversion of mono-, bis- and tris-aminosiloxanes into their corresponding mono-, bis- and tris-dithiocarbamates, using alkaline hydrides and carbon disulfide in THF. Enhanced scavenging capacity towards mercury ions was observed when these compounds were grafted on silica compared to amine-functionalized silicas or to commercial resins bearing dithiocarbamate moieties.     

Reaction of fullerene with benzocyclobutene homologs

Fullerene was easily converted to its derivatives by the treatment with benzocyclobutene homologs for 20 h at 140 °C. The spectroscopic analyses clearly indicate mono-[4+2]-cycloadduct structures of its derivatives. Isolated yields of mono- and di-adducts were from 4.4 to 15.6% and from 8.1 to 5.3%, respectively.     

Aminolysis of diphenyldichlorosilane and heterocyclic chlorosilanes

Reaction of diphenyldichlorosilane, dichlorosila fluorene, and dichlorosiloxarophenanthrene with amines in mono- or disubstituted organoaminosilanes gave mono- or disubstituted organoaminosilanes.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 6, pp. 754–756, June, 1976.     

Enantiomer separation of miconazole by capillary electrophoresis with dual cyclodextrin systems.

A cyclodextrin-modified micellar capillary electrophoretic method (MECC) was developed using mixtures of beta, cyclodextrins (beta-CD) and mono-3-O-phenylcarbamoyl-beta-CD as chiral additives for the chiral separation of miconazole with the dual CDs systems. The enantiomers were resolved using a running buffer of 50 mmol/L borate pH 9.5 containing 15 mmol/L beta-CD and 15 mmol/L mono-3-O-phenylcarbamoyl-beta-CD containing 50 mmol/L sodium dodecyl sulfate and 1 mol/L urea. A study of the respective influence of the beta-CD and the mono-3-O-phenylcarbamoyl-beta-CD concentration was performed to determine the optimal conditions with respect to the resolution. Good repeatability of the method was obtained.     

Synthesis of mono- and dihydroxylated furanoses, pyranoses, and an oxepanose for the preparation of natural product analogue libraries

[structures: see text] Numerous biologically active natural products contain furanoses and pyranoses with mono- and dihydroxylated substituents. However, much of the structure-activity studies on such molecules is gathered on the aglycons without attention to the corresponding carbohydrate components. Consequently, there are few synthetic procedures that enable the rapid preparation of mono- and dihydroxyfuranoses and mono- and dihydroxypyranoses and no report for a 3,4-dihydroxyoxepanose. In this article we report the practical synthesis of orthogonally protected five-, six-, and seven-membered carbohydrate derivatives. The succinct manner in which these molecules were synthesized allows the rapid preparation of analogues aimed at discovering the role of ring size and individual hydroxyl moieties on the pyranose skeleton.     

Synthesis of Polycyclic Functionally-substituted Triazole- and Tetrazole-containing Systems

Cycloaddition of organic mono- and diazides to the triple bond of propargyl esters of mono- and dicarboxylic acids gave rise to polycyclic 1,2,3-triazole-substituted carboxylates. Dipropargyl dicarboxylates with diazides afforded oligomeric products with alternating triazole and carboxylate fragments. Reaction of a dipropargyl ester with 5-azidomethyltetrazole furnished a tetracyclic system with alternating triazole and tetrazole rings.     

Quinoline-annulated porphyrins

Porphyrin-2,3-dione mono- and dioximes were used as starting materials for the efficient syntheses of mono- and bis-quinoline-annulated porphyrins and their corresponding N-oxides. Owing to an extended π-system, these novel porphyrinoid chromophores show significantly red-shifted UV-vis spectra compared to the parent porphyrins. A crystal structure exemplifies the nonplanar conformation of the macrocycle.     

The use of approximation formulae in calculations of acid-base equilibria-IV Mixtures of acid and base and titration of acid with base

The pH of mixtures of mono- or diprotic acids and a strong base is calculated by use of approximation formulae and the theoretically exact equations. The regions for useful application of the approximation formulae (error < 0.02 pH) have been identified. The results obtained are used to calculate the curves for titration of mono- or diprotic acids with a strong base.     

Synthesis of cationic beta-cyclodextrin derivatives and their applications as chiral stationary phases for high-performance liquid chromatography and supercritical fluid chromatography

Four cationic beta-cyclodextrin derivatives, namely mono-6-(3-methylimidazolium)-6-deoxy-perphenylcarbamoyl-beta-cyclodextrin chloride (MPCCD), mono-6-(3-methylimidazolium)-6-deoxyper(3,5-dimethylphenylcarbamoyl)-beta-cyclodextrin chloride (MDPCCD), mono-6-(3-octylimidazolium)-6-deoxyperphenylcarbamoyl-beta-cyclodextrin chloride (OPCCD) and mono-6-(3-octylimidazolium)-6-deoxyper(3,5-dimethylphenylcarbamoyl)-beta-cyclodextrin chloride (ODPCCD), have been synthesized and physically coated onto porous spherical silica gel to obtain novel chiral stationary phases (CSPs). The performances of these CSPs are studied on high-performance liquid chromatography (HPLC) and supercritical fluid chromatography (SFC) using 18 racemic aryl alcohols as test analytes. Among these four CSPs, OPCCD shows the best separation results for all analytes on both HPLC and SFC analyses. Chromatographic studies reveal that the CSPs consisting of an n-octyl group on the imidazolium moiety and phenylcarbamoyl groups on the cyclodextrin ring provide enhancement of analyte-chiral substrate interactions over CSPs bearing the methyl group on the imidazolium moiety and 3,5-dimethylphenylcarbamoyl groups on the cyclodextrin ring.