Synthesis of a ball-chain system C_(60) aza-derivative

Nitrenes generated by thermolysis of alkyl azides were found to add to C60 in chloroben-zene solvent. The product was isolated by means of silica gel chromatography and identified by field desorption mass spectroscopy and 13C NMR spectroscopy.     

Investigation of nitroxoline-human serum albumin interactions by spectroscopic methods

Nitroxoline is a wide spectrum antibacterial and is one of the most important urinary antiseptics.The interaction between nitroxoline and human serum albumin(HSA)has been investigated systematically by fluorescence spectroscopy,synchronous fluorescence,three-dimensional fluorescence,CD spectroscopy and UV-Vis absorption spectroscopy.The results indicated that the quenching of HSA by nitroxoline was static.The corresponding thermodynamic parameters △H,△S and △G calculated according to van’t Hoff equation revealed that the intermolecular forces acting between nitroxoline and HSA were mainly hydrogen bonding and van der Waals forces.The conformational changes in the interaction were studied by synchronous fluorescence,CD spectroscopy and three-dimensional fluorescence spectra which showed changes in the microenvironment and conformation of HSA.     

一种新型含三苯胺的喹啉衍生物及其金属配合物的合成与表征

A new 8-hydroxyquinoline derivative(5)was synthesized and characterized by ESI-MS,~1H NMR spectroscopy,elemental analysis and IR spectroscopy.The photophysical properties of compounds 5,6 and 7 were also deteminedby UV-vis and FL spectroscopy.The vibrational frequency of ligand 5 predicted by using B3LYP method is in goodagreement with experimentally determined values.The compositions of the corresponding copper(Ⅱ)and zinc(Ⅱ)complexes were confirmed to be Cu(C_(29)H_(21)N_2O)_2·H_2O(6)and Zn(C_(29)H_(21)N_2O)_2·H_2O(7)by elementary analysis,thermogravimetry analysis and IR spectroscopy.     

Oxygen Atom Exchange Mechanism in Reaction of OH Radical with AsO

IntroductionNitrous acid,HONO,has been extensivelystudied by means of experimental[1,2 ] andtheoretical methods due to its importance inatomspheric chemistry[3 ] . Those studies includedits experimental spectroscopy[1,2 ] and potentialenergy surface with the aid of density functionaltheory[3 ] . Its phosphorus analogue,HOPO,hasbeen studied by virtue of theoreticalcomputations[4] ,and detected in the gas by infraredlaser spectroscopy in2 0 0 0 by Bell and coworkers[5]and matrix isolation in…     

Study on the Interaction of Colloidal Gold with Taq DNA Polymerase

The interaction of colloidal gold with Taq DNA polymerase （Taq） was investigated in this study. Taq-gold conjugate was formed by adding the enzyme to the colloidal gold solution, as evidenced by UV-Vis spectroscopy, X-ray photoelectron spectroscopy, and photon cross correlation spectroscopy measurements. The conjugate was further characterized by transmission electron microscopy. It was found that the Taq-gold conjugate particles were still spherical and well-dispersed. The influence of gold nanoparticles on the bioactivity of Taq was studied by analyzing the yield of the polymerase chain reaction amplification. Results indicated that the enzymatic activity of Taq decreased after interaction with the colloidal gold.     

Modulating the Electronic Structures of Single-walled Carbon Nanotubes by Filling with Electron Acceptors and the Effect on Their Reactivity with Aryl Diazonium Salts

The electronic structures of single-walled carbon nanotubes （SWCNTs） were modulated by filling with tetracyanoquinodimethane （TCNQ）, a strong electron acceptor. The structures of TCNQ-filled SWCNTs were checked by X-ray diffraction analysis, high-resolution transmission electron microscopy and Raman spectroscopy. Optical absorption spectroscopy demonstrated an enhanced reactivity between aryl diazonium and semiconducting SWCNTs.     

The Synthesis of Single Crystals of Manganese Aluminophosphate Molecular Sieve and Studies on Their Properties

Single crystals of the molecular sieve, MnAPO-5, were synthesized by hydrothermal synthesis in the presence of fluoride ions. It was shown by X-ray diffraction, infrared spectroscopy, electron paramagnetic resonance spectroscopy, electron probe analysis and chemical composition analysis that the structure of MnAPO-5 is of the A1PO-5 type, and manganese(Ⅱ) is incorporated into the framework. Adsorption properties, thermal stability and surface acidity were also investigated.     

A Highly Efficient and Recyclable Solid Acid Catalyst for Synthesis of Spiro-oxindole Dihydroquinazolinones Under Ultrasound Irradiation

A simple,efficient and green procedure for the synthesis of spiro-oxindole dihyfroquinazolinones was developed by multi-component condensation of isatoic anhydride,aniline and isatin in the presence of a novel solid acid catalyst under ultrasound irradiation.The present environmentally benign protocol offers several advantages, such as shorter reaction time,a wide range of fimctional group tolerance,the use of an inexpensive heterogeneous catalyst,and a high yield of products via a simple experimental and work-up procedure.The mesoporous solid acid catalyst was directly prepared from phytic acid by microwave-sulfonation method without template.The phytic acid based solid acid was fully characterized by means of Fourier transform infrared spectroscopy(FTIR),Raman spectroscopy,X-ray diffraction(XRD),X-ray photoelectron spectroscopy(XPS),and transmission electron imcroscopy(TEM).The catalyst can be recovered and reused for at least five runs without significant impact on the product yields.     

Synthesis and Pyrolysis of Soluble Cyclic Hf-Schiff Base Polymers

Soluble Hf-containing polymers are significant processable precursors for the fabrication of ultra-high temperature ceramics. In this work, cyclic Hf-Schiff base polymers were synthesized via direct polymerization of hafnium alkoxide and bis-salen monomers. The defined structure and molecular weight of the polymers were characterized by NMR spectroscopy, gel permeation chromatography and MALDI-TOF mass spectroscopy. The feed ratio of monomers regulated the molecular weight and solubility of the polymers. This synthetic strategy features simple operation under ambient conditions, efficient reaction with high yield and cyclic polymers as the main products. The Hf-Schiff base polymers were converted to HfC/C materials after pyrolysis under argon at 1600 °C, which was identified by XRD measurements, elemental analyses and Raman spectroscopy. This work will inspire more precise and efficient synthesis and applications of metallopolymers.     

Azide-functionalization of carbon nanotubes by electrochemical oxidation of N3- in situ

Azide-functionalization of single-walled carbon nanotubes （SWCNTs） was achieved by electrochemical oxidation of N3 in situ. The functionalized nanotubes were characterized in details by single internal reflection infrared spectroscopy （ATR-FTIR） and thermogravimetic analysis （TGA/MS）. The results revealed that a covalent C-N bond had formed and this might provide an effective method for the preparation of azide-functionalized materials, especially carbon materials. The degree of functionaliza- tion was measured by X-ray photoelectron spectroscopy （XPS）.     

3-Mercaptopropionic Acid Capped Gold Nanoclusters: Quantized Capacitance in Aqueous Media

IntroductionAnextensiveresearchinterest1,2 inmonolayerprotectedgoldclusters (MPCs)hasariseneversincethemilestonere portofBrustetal.3TheparticularlyinterestingpropertyoftheMPCscoreisitssmallcapacitance (sub attofarad ,aF) ,whichcausesthatsingleelectrontransfersto/fromthecoreleadingtoreadilymeasurablechangesinitselectronicpoten tial.Thatis ,theelectrochemicalchargingoftheMPCscorebecomesaquantizedprocess .However,usualalkanethiolateMPCsarenotwater soluble,resultinginthelimitationoftheirpote…     

Preparation, characterization, and chemical stability of gold nanoparticles coated with mono-, bis-, and tris-chelating alkanethiols

A systematically varying series of monolayer-protected clusters (MPCs) was prepared by exposing small gold nanoparticles ( approximately 2 nm in diameter) to the following four adsorbates: n-octadecanethiol ( n - C18), 2-hexadecylpropane-1,3-dithiol ( C18C2), 2-hexadecyl-2-methylpropane-1,3-dithiol ( C18C3), and 1,1,1-tris(mercaptomethyl)heptadecane ( t - C18). The resultant MPCs were characterized by solubility studies, UV-vis spectroscopy, transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), and Fourier-transform infrared spectroscopy (FT-IR). All of the MPCs were soluble in common organic solvents; moreover, analysis by TEM showed that the core dimensions were unaffected by exposure to any of the adsorbates. Separate studies by XPS revealed that the sulfur atoms in all MPCs were predominantly bound to the surface of gold (i.e., approximately 85% or better). Analysis by FT-IR showed that MPCs functionalized with n - C18 possessed alkyl chains having the greatest conformational order in both the solid-state and dispersed in solution; in contrast, those generated from the other three adsorbates were more liquid-like with reduced conformational order (or crystallinity). The rate of nanoparticle decomposition induced by cyanide ions was monitored by UV-vis spectroscopy. While MPCs functionalized with n - C18 showed the fastest rate of decomposition, those functionalized with C18C3 were the most resistant to decomposition. Overall, the following trend in chemical stability was observed, C18C3 > C18C2 > t - C18 > n - C18.     

On the Size Evolution of Monolayer‐Protected Gold Clusters during Ligand Place‐Exchange Reactions: The Effect of Solvents

Ligand place‐exchange (LPE) reactions are extensively applied for the post‐functionalization of monolayer‐protected gold clusters (MPCs) by using excessive incoming ligands to displace initial ones. However, the modified MPCs are often enlarged or degraded; this results in ill‐defined size‐dependent properties. The growth of MPCs essentially involves an unprotected surface that is subsequently has gold atoms added or is fused with other gold cores owing to collision. Reported herein is a guideline for the selection of solvents to suppress unwanted MPC growth. Favorable solvents are those with significant affinity to gold or with low solubility for desorbed ligands because these properties retard LPE reactions and minimize the time available for unprotected gold cores. This finding provides a general and convenient approach to regulate the size of functionalized MPCs.     

Mercaptocarborane-capped gold nanoparticles: electron pools and ion traps with switchable hydrophilicity

A simple single-phase method for the preparation of ca. 2 nm gold nanoparticles capped with mercaptocarborane ligands is introduced. The resultant monolayer protected clusters (MPCs) exhibit redox-dependent solubility and readily phase transfer between water and nonpolar solvents depending on the electronic and ionic charge stored in the metal core and in the ligand shell, respectively. The particles and their properties have been characterized by high angle annular dark field imaging in a scanning transmission electron microscope, elemental analysis, centrifugal particle sizing, UV-vis and FTIR spectroscopy, and thermogravimetric analysis and by (1)H, (11)B, and (7)Li NMR spectroscopy. Cellular uptake of the MPCs by HeLa cells has been studied by TEM, and the subsequent generation of reactive oxygen species inside the cells has been evaluated by confocal fluorescence microscopy. These MPCs qualitatively showed significant toxicity and the ability to penetrate into most cell compartments with a strong tendency of finally residing inside membranes. Applications in catalysis, electrocatalysis, and biomedicine are envisaged.     

Water-soluble nitric oxide-releasing gold nanoparticles

The synthesis and characterization of water-soluble nitric oxide (NO)-releasing monolayer-protected gold clusters (MPCs) are reported. Tiopronin-protected MPCs ( approximately 3 nm) were functionalized with amine ligands and subsequently exposed to 5 atm of NO to form diazeniumdiolate NO donors covalently bound to the gold MPC. Diazeniumdiolate formation conditions, NO-release, and nanoparticle stability were examined as a function of the structure of the protecting ligand, pH, and storage time. Despite their aqueous solubility, proton-initiated decomposition of the diazeniumdiolate-modified Tio-MPCs resulted in only modest NO-release (<0.023 micromol/mg) for short durations (<1.5 h). To increase the NO storage capacity of gold nanoparticles, polyamine-stabilized MPCs ( approximately 5 nm) were synthesized with significantly enhanced NO-release properties (0.386 micromol/mg) and durations (up to 16 h). Transmission electron microscopy, thermogravimetric analysis, nuclear magnetic resonance spectroscopy, elemental analysis, and UV-vis spectroscopy were used to characterize both nanoparticle systems before and after NO exposure. The MPCs represent the smallest water-soluble NO-release nanoparticles to date (3-5 nm).     

Arylthiolate-protected silver quantum dots

This paper describes a new, organic-soluble 4-tert-butylbenzyl mercaptan (BBT) monolayer-protected silver cluster (AgBBT MPC) as the first example of a dissolved silver nanoparticle that exhibits quantized one-electron double layer charging (QDL) voltammetry. Polydisperse AgBBT MPCs made by two different synthetic protocols, but with similar average core diameters (2.1 nm), exhibit sharply differing electrochemistry and optical absorbance spectra. A two-phase procedure (organic/aqueous, termed Prep A-AgBBT) produced MPCs exhibiting a 475 nm surface plasmon absorbance and QDL voltammetry. Neither property was seen for MPCs made by a single-phase procedure, termed Prep B-AgBBT. The difference is thought to reflect poor passivation to oxide formation in the latter Prep B procedure, which is supported by X-ray photoelectron spectroscopy results. Thermogravimetry, mass spectra, and electrochemistry results suggest an average stoichiometric formula of Ag140BBT53, but transmission electron microscopy shows that the products are also polydisperse and include polycrystalline aggregates. Dry, cast films of both Ag MPC preparations on interdigitated array electrodes exhibit low electron hopping conductivity, compared to Au MPCs.     

Hydrogen reactivity of palladium nanoparticles coated with mixed monolayers of alkyl thiols and alkyl amines for sensing and catalysis applications

Palladium monolayer-protected clusters (MPCs) coated with octylamines (C8NH(2)), hexanethiolates (C6S), and mixed monolayers of C8NH(2) and C6S exhibit significantly different reactivities with hydrogen gas, depending on the relative amounts of the two ligands coating the Pd nanoparticle surface, as determined by UV-vis spectroscopy of Pd MPCs in solution and electronic measurements of films of Pd MPCs as a function of exposure time to hydrogen. The average estimated composition of the ~3.0 nm diameter Pd MPCs was Pd(919)(C6S)(192) or Pd(919)(C8NH(2))(177-x)(C6S)(x), where x was varied to be 0, 3, 10, 16, 32, or 81 by the synthesis of pure C8NH(2) Pd MPCs and subsequent liquid-phase place exchange with a varied amount of C6SH. When x = 0-10, the Pd MPCs react strongly with H(2), leading to aggregated particles in solution and large irreversible changes in the morphology of films accompanied by an increase in film conductivity by 2-5 orders of magnitude. Pd(919)(C6S)(192) MPCs are stable against significant aggregation in solution and do not exhibit large film morphology changes, but they are also not highly reactive to H(2), as determined by minimal changes in the optical properties of solutions and the small, irreversible changes in the conductivity of films in the presence of H(2). Finally, when x is 32 and 81, the Pd MPCs are fairly stable, exhibit minimal aggregation or morphology changes, and readily react with H(2) based on the significant, reversible changes in film conductivity in the presence of H(2). Pd MPCs with mixed monolayers have the benefit of high H(2) reactivity while maintaining the structural stability necessary for sensing and catalysis applications.     

Effect of chloride anion on the electrochemical charging of gold nanoparticle films

Reactivity of halide anion (Cl^?) with monolayer-protected gold nanoclusters (MPCs) of 1.8 nm in diameter has been studied. Typically, thin films of MPCs were prepared on an electrode surface and immersed in aqueous solutions containing Cl^?. It was observed that Cl^? inevitably resulted in the destruction of electrochemical charging of MPC films, which was studied and analyzed in details by cyclic voltammetry, electrochemical quartz crystal microbalance, and X-ray photoelectron spectroscopy measurements. The destruction is most likely due to the strong affinity of Cl^? for the surface of MPCs, leading to a significant variation of the surface structure and thereby quenching the electrochemical charging property.     

Mixed Polyanionic Compounds as Positive Electrodes for Low‐Cost Electrochemical Energy Storage

Low‐cost electrochemical energy storage systems (EESSs) are urgently needed to promote the application of renewable energy sources such as wind and solar energy. In analogy to lithium‐ion batteries, the cost of EESSs depends mainly on charge‐carrier ions and redox centers in electrodes, and their performance is limited by positive electrodes. In this context, this Minireview evaluates several EESS candidates and summarizes the known mixed polyanionic compounds (MPCs)—a family with robust frameworks and large channels for ion storage and migration. After comprehensive analysis, it is pointed out that a deeper exploration of MPCs may generate numerous novel crystallographically interesting compounds and excellent cathode materials for low‐cost energy storage applications.     

Synthesis and characterization of phosphido-monolayer-protected gold nanoclusters

Gold-phosphido-monolayer-protected clusters (MPCs) of 1-2-nm diameter, Au(x)(PR2)y, analogues of the well-known thiolate materials Au(x)(SR)y, were prepared by NaBH4 reduction of a mixture of HAuCl4.3H2O and a secondary phosphine PHR2 in tetrahydrofuran/water. In comparison to the Au-thiolate MPCs, fewer of the larger phosphido groups are required to cover the surface, and the Au-P bond is not cleaved as readily in reactions with small molecules as is its Au-S counterpart. 31P NMR spectroscopy provides a direct method to study cluster formation and the interaction of the phosphido ligand with the gold surface.