We carried out Raman characterization of a highly folded individual serpentine (7,5) single-walled carbon nanotube (SWNT). Twenty five Raman peaks were observed, which included a radial breathing mode (RBMband), an overtone of RBM(2RBMband), an immediate-frequency band (IMF band), a disorder-induced band (Dband), a tangential band (Gband), an M band (1700-1900 cm-1), a combination mode of G and RBM (G+RBMband), a combination mode of in-plane transverse optic (iTO) phonon and longitudinal acoustic (LA) phonon (iTOLA band), an overtone of the D band (G'or 2D band), an overtone of the G band (2G band) and some other bands with unknown assignments. Further Raman measurements at different laser excitation wavelengths and different excitation polarization show that these Raman peaks are highly dependent on the excitation energy and the excitation polarization.

We used β-cyclodextrin (β-CD) to control the radiolytic reduction of Cu2+ in aqueous solution at a safe absorbed dose. With an increase in the concentration of β-CD, the reduction product of Cu(NO3)2 gradually changed from cuprous oxide to copper. At a β-CD concentration of 8.0 mmol·L-1, the main reduction product was composed of pure copper nanoparticles. Meanwhile, no cuprous oxide was generated during the course of irradiation. This is attributed to the regularity that β-CD is able to scavenge·OH, which suppresses the reaction between hydrated electrons (e-aq) and·OH, and increases the yield of e-aq. This favors the generation of copper. The adsorption of β-CDs on the surface of copper nanoparticles via hydroxyl groups promotes the stability of copper nanoparticles in the aqueous solution. The reduction products were characterized by UV-Vis absorption spectroscopy, powder X-ray diffraction (XRD), and selected area electron diffraction (SAED).

The solubility of americiumin Yuci groundwater was analyzed using a newly developed geochemical code CHEMSPEC and the influence of pH, groundwater composition, and temperature on its solubility was also investigated. The results indicate that the pH, the total carbonate concentration, and the temperature have obvious influences on solubility while the sulfate and chloride concentrations do not. The solubility of americiumin Yuci groundwater is 1.4×10^-10-6.3×10 ^-3 mol·L^-1. The maximum solubility was obtained at 25 ℃, pH=6.0, and a total carbonate concentration of 1×10^-5 mol·L^-1. These data can be used to predict the diffusion and migration behavior of americiumin the aquifer.

Phase transitions and structures of the monomer of side-chain liquid crystalline polyacetylene containing biphenyl mesogen, namely, 5-{[(4'-pentyloxy-4-biphenylyl)carbonyl]oxy}-1-pentyne (A3EO5) were investigated by differential scanning calorimetry (DSC), one dimensional (1D) wide angle X-ray diffraction (WAXD), and polarized light microscopy equipped with hot-stage (PLM-hot stage). DSC and 1D-WAXD results show that A3EO5 forms an enantiotropic liquid crystal and displays four transitions during the cooling and subsequent heating processes. Upon cooling fromisotropic phase to roomtemperature, the sample forms smectic A phase and then leads to smectic B phase with pseudo long-range orientation within the layer structure, further lowering the temperature, A3EO5 forms smectic E phase with orthorhombic packing within the smectic layer and enters crystal phase. PLM results show that the sample forms spherulitic texture, focal conic texture and concentric arcs texture during the cooling process.

In this paper, the photolysis kinetics of conjugate 4-(2-(4'-pyridinyl)ethynyl)benzene diazonium salt in acetonitrile and in solid-phase films was investigated by UV-Vis absorption spectroscopy after exposure to ultra-violet light (250 W, 245 nm). Results show that the photolysis kinetics follows first order reaction kinetics and the polar acetonitrile solvent causes the diazonium group to photodecompose more easily. In addition, X-ray photoelectron spectroscopy (XPS) and electrochemical analysis were used to confirm the formation of 4-(2-(4'-pyridinyl)ethynyl) benzene monolayer films which were anchored onto the surface of quartz and indium-tin-oxide (ITO) glass slides by covalent bonds. This method sets the stage for the successful design of organic-metal containing ultrathin films based on a layer-by-layer self-assembly technique.

Co-pressing and direct forming process has been developed for the preparation of a single-chamber solid oxide fuel cell (SC-SOFC), which consists of 8%(x) Y2O3-stabilized ZrO2 (YSZ) electrolyte, Ni-YSZ cermet anode and La0.7Sr0.3MnO3 (LSM) cathode. Scanning electron microscopy (SEM) showed tight integration between the cathode and electrolyte and od loading performance of LSMon the YSZ three-dimensional framework. The thickness of the YSZ electrolyte film, the anode and the cathode was about 50, 600 and 100 μm, respectively. The effects of temperature (T), number of catalyst loading layers (n) and the volume ratio of CH4 and O2 (Rmix=V(CH4)/V(O2)) on the SC-SOFC performance was studied. At T =800 C, n=2 and Rmix=2, the single cell performed the best, the open voltage was 0.95 V, the maximumcurrent density was 130 mA·cm-2 and the maximumpower density was 30 mW·cm-2.

The surface of an amorphous Mg45Ti3V2Ni50 alloy was modified with Ti, B, and a specific composite TiB by high energy ball-milling. Experimental results showed that after modification the electrochemical stability of the hydrogen storage alloy improved and the improvement for TiB was much more than that for Ti or B. The initial discharge capacity of the Mg45Ti3V2Ni50-TiB alloy electrode (mass ratio 2:1) was 529.4 mAh·g-1 and after 50 cycles the discharge capacity was 277.1 mAh·g-1. A synergistic effect between the metal and nonmetal was formed evidently not only between Ti and B in TiB but also between TiB and the Mg45Ti3V2Ni50 alloy. This synergistic effect enhanced the interaction between the modified layer and the Mg45Ti3V2Ni50 alloy. A new stereochemical pleats structure was formed by the synergistic effect between the metal and the nonmetal. The surface activity of the Mg45Ti3V2Ni50 alloy was increased and the electrochemical cycling stability improved greatly.

In this paper, we review the application of fluorescent probe technology in self-assembly systems of amphiphile aqueous solutions. Fluorescence technology, especially fluorescence probe technology has been extensively employed to explore local information about various molecular assemblies. The following contents are covered: (1) The critical aggregate concentration, microviscosity, and micropolarity may be obtained fromfluorescence parameters such as emission maxima, fluorescence intensity, and lifetime etc. (2) Probe quenching, especially, time-resolved fluorescence quenching (TRFQ) can give information about aggregation number and surface charge density which can be used as the indication on aggregate transition. (3) Fluorophore-labeled amphiphiles which can take part in the formation of aggregates reveal more precise information, so that an in situ investigation of local environments is possible. Moreover, fluorescence resonance energy transfer (FRET) and excited state proton transfer (ESPT) are also useful in this field. Therefore, fluorescence probe technology provides us with a simple and effective method to study organized amphiphiles systems.

In this review, a summary of recent research progress on the assembly structures of amyloid peptides related to protein conformational diseases is presented. Various characterization methods have been introduced to study the peptide assembly structures in solid-state, in solution, and at interfaces. Recent work on the structural analysis of peptide assemblies at solid-liquid interfaces has been undertaken using scanning tunneling microscopy, and these include the determination of the fine structures of peptide as-semblies at solid/liquid interfaces, surface-induced protein conformational changes and interactions between peptides and modulator or labeling molecules.

Static and dynamic light scattering were employed to monitor the temperature-induced aggregation and fusion processes of liposomes consisting of 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC) and palmitic acid (PA) in a molar ratio of 1:2. From 25 to 41 ℃, the size and the relative molecular mass of the liposome increased with increasing temperature indicating the occurrence of aggregation or fusion. Meanwhile, the size showed strong angular dependence, suggesting that the vesicle structure was at least partially destroyed upon aggregation. During the subsequent cooling process, the size and relative molecular mass continued to increase. On the basis of these results, we propose that the aggregation is caused by the adhesion of liposomes in the palmitic acid rich zones. The formed aggregate had a structure between that of bilayers and inverted hexa nal (HII) packing. Upon aggregation, the ratio of fusion was small. Our results also indicated that the vesicle was kinetically stable. Once the transition from the gel state to semi-inverted hexa nal (HII) packing was triggered, the aggregation or fusion of the liposome proceeded automatically.

In this review, we will provide a brief review of our recent theoretical and experimental studies of bimetallic surfaces and catalysts for the low-temperature hydrogenation of unsaturated C=C and C=O bonds. We will first use the hydrogenation of cyclohexene as a probe reaction to demonstrate the importance of using several parallel approaches, including fundamental surface science and density functional theory (DFT) studies on single crystal surfaces, synthesis, and characterization of polycrystalline surfaces and supported catalysts, and reactor evaluation of supported catalysts. We will then provide a summary of applications of bimetallic catalysts for other hydrogenation reactions, including the selective hydrogenation of the C=O bond in acrolein, the low-temperature hydrogenation of benzene, and the selective hydrogenation of acetylene in the presence of ethylene. Finally, we will discuss the possibility of replacing the platinum(Pt) component with metal carbides to reduce the loading of Pt in bimetallic catalysts.

Benzene has severe health and environmental consequences because of its high toxicity and carcinogenicity. Although TiO2-based photocatalytic oxidation (PCO) has been established as one of the most promising technologies for environmental remediation and has been successful in treating a wide variety of volatile organic compounds (VOCs), PCO has only limited success in the treatment of aromatic compounds like benzene because of the deactivation of TiO2. The development of high performance photocatalysts for benzene degradation is indispensable for benzene treatment. Recently a series of wide bandgap p-block metal oxides/hydroxides with superior performance for the photocatalytic degradation of benzene have been developed in our institute. These wide bandgap p-block metal oxides/hydroxides are a series of promising photocatalysts for benzene degradation. In this article, the preparations of these p-block metal oxides/hydroxides, their photocatalytic activity and mechanism for benzene degradation as well as the structure-activity relationship are summarized.

Catalytic combustion is one of the most effective techniques for the removal of volatile organic compounds (VOCs). In this review, the recent developments in catalytic combustion of VOCs with regard to active species such as noble metal catalysts, mixed metal oxides, perovskite and spinel metal oxide phases were examined. The effects of particle sizes of active species, catalyst supports, the water vapor effect and the coking effect on catalytic combustion were evaluated. It is found that the research on noble metal catalysts mainly focuses on developing new supports and bi-elemental noble metal catalysts; while the research on non-noble metal catalysts focuses on developing new mixed metal oxides, perovskites and spinel catalysts, as well as investigating the effects of particle sizes and various supports on the combustion activity. Additionally, as far as practical application is concerned, the effect of water vapor and coking deactivation on the catalytic combustion process are discussed. This review will be helpful in choosing an appropriate technique for the removal of VOCs by catalytic combustion with high activity and high stability.

It is of great importance to study the selective oxidation of light alkanes on metal oxide catalysts from a fundamental and industrial point of view. Clarification of the relationship between the structure of the oxide catalysts and their catalytic properties is vital for the design of efficient catalysts and for the realization of efficient oxidative conversion of light alkanes. In this review, we summarize some recent progress in the understanding of the structures and catalytic properties of several catalysts including V-P-O, V-Sb-O, Mo-V-Te-Nb-O, and V-Mg-O metal oxides. These oxides as well as the Re-Sb-O catalysts developed by us have been extensively studied for the selective oxidation of light alkanes. We then revisit several key aspects including multi-functionality, site isolation, and phase cooperation. These aspects are required for catalysts that are efficient in the selective oxidation of light alkanes and will provide insights into the design and synthesis of metal oxide catalysts and their efficient application to the oxidative conversion of light alkanes.

Transition metal nanoparticles (MNP) stabilized in green solvents, i.e., ionic liquids (ILs) and water, have great potential for use in catalysis. These new catalytic systems are more efficient and greener while easy segregation of substances depends on a two-phase design. By an appropriate design of the metal nanoparticle, the stabilizer and the functional solvent, nanoparticle catalytic systems have been used in different reactions and processes. In this review, we discuss this green catalytic family by considering the development of nanoparticle-stabilizer-green solvent catalytic systems in our laboratory.

A chlorine doped titaniumdioxide photocatalyst was synthesized by a hydrothermal process using silica gel as a carrier, Ti(SO4)2 as a Ti source, and NaCl as a Cl source.We discuss factors such as the doping ratio of chlorine to titanium, the calcination temperature, and the ratio of titanium to silicon, all of which influence the photocatalytic activity of the sample.We found that the best chlorine to titaniumratio (nCl/nTi) was 15%, the best calcination temperature was 750 ℃, and the best ratio of titaniumto silicon (nTi/nSi) was 3:1. The BET surface area of the chlorine doped titanium dioxide supported on SiO2 (CTS) was 60.8 m2 ·g-1. No rutile phase of TiO2 was formed in the CTS after calcination at high temperature indicating that the presence of silica inhibited the phase transformation of TiO2 from anatase phase to rutile phase. It also influences the structural and textural properties of the chlorine doped titanium dioxide (CT). A phenol degradation test showed that the photocatalytic activity of the CTS was better than that of the CT although the TiO2 concentration in the CTS was 0.7740 g·g-1, which was less than that of the CT.

The surface modification of Mg-Al hydrotalcite mixed oxides (MgAlO) with K was investigated using X-ray powder diffraction (XRD), X-ray photoelectron spectroscopy (XPS), in situ infrared (in situ IR) spectroscopy, and temperature-programmed desorption of CO2 (CO2-TPD).We found thatKwas highly dispersed on the surface of MgAlO when the loading amount was less than 8% (w). New Lewis base sites were formed through the interaction between K and MgAlO. The weakly basic Mg(Al)-O-K resulted from the proton substitution of Mg(Al)-OH with K. Mg-O-K was obtained by combination with strongly basic O2- sites. At a K loading between 5% (w) and 8% (w), the quasi free KOx species that interacted weakly with the support and showed stronger basicity than Mg-O-K was formed. The increase in basicity of K/MgAlO can be attributed to charge transfer from K to the surface oxygen anions, which increases the negative charge of the strongly basic sites.

Dibenzo-18-crown-6 (DBC) was immobilized on cross-linked polyvinyl alcohol (CPVA) microspheres to prepare the triphase-transfer catalyst DBC-CPVA. The phase transfer catalytic behavior of DBC-CPVA was mainly studied using the esterification reaction of 1-bromobutane in the organic phase and potassium benzoate in the water phase as a model system. We examined the effects of the main factors on the phase transfer catalytic esterification reaction. The experimental results show that after the benzoic acid in the water phase reacts with KOH to form potassium benzoate, complex cations form between the immobilized DBC and K+ ions. The complex cations will effectively carry negative benzoate ions from the water phase into the organic phase and this enables the esterification reaction between benzoate ion and 1-bromobutane to be favorably carried out. Solvent polarity is advantageous to the esterification reaction. When the volume ratio of the organic phase to the water phase is 1:4, a maximum conversion of about 70%for 1-bromobutane is obtained. The catalyst DBC-CPVA has excellent recycle and reuse properties and the catalytic activity remains stable after eight cycles.

Self-assembled monolayer (SAM) of oxovanadium phthalocyanine (VOPc), an organic semiconductor compound, was prepared at room temperature on a highly oriented pyrolytic graphite (HOPG) substrate by immersing the substrate in a 1,2-dichloroethane (C2H4Cl2) colloidal solution containing both VOPc nanoparticles (2-20 nm) and dissolved VOPc molecules (ca 10-3 g·L^-1). The VOPc nanoparticles further assembled on the VOPc SAM. The nanoparticle-assembling in the experimental conditions exhibited a high size-selectivity to VOPc nanoparticles of (4.60±0.47) nm with a standard deviation of 10%. As revealed by scanning tunneling microscopy (STM) measurements, with increasing VOPc concentration of the colloidal solution from 2.5 ×10^-2 to 2.5 ×10 ^-1 g·L^-1, the amount of VOPc nanoparticles assembled on the molecular layer increased gradually, and a dense VOPc nanoparticle monolayer formed in the end. The found assembly structures and method are promising for the development of photoelectric or electric functional systems.

Metal organic frameworks (MOFs) are a new class of materials that are formed by the copolymerization of organic ligands with transition metals. Because of their properties such as high surface areas, microporosity, and the ability to tune pore size, many applications have recently been developed in catalysis, separation, and gas storage. We prepared MOFs by three different methods and characterized them with scanning electron microscopy (SEM), X-ray diffraction (XRD), and infrared (IR) spectroscopy. MOFs prepared via the three methods are completely different in morphology and microstructure. We demonstrate that the MOFs prepared via the “direct mixing”method are very effective heterogeneous catalyst for the transesterification of diethyl carbonate with alcohols to prepare organic carbonates. We studied the effects of the amount of MOFs, the reaction time, and the reaction temperature on product yield. Asymmetric organic carbonates can be produced with moderate to high yields and 100% selectivity via the reaction of diethyl carbonate with aromatic, cyclic, heterocyclic, or aliphatic alcohols. The solid catalyst can be recovered simply by centrifugation and reused for at least two cycles.

The physical and chemical properties of organic semiconductors play key roles in the performance of optoelectronic devices. The manipulation of these properties offers research opportunities and challenges in physical chemistry. The spectral stability and the origin of the low-energy emission band (LEEB) in polyfluorenes-based blue light-emitting diodes have received much attention over the past few decades. In this review, we cate rized various LEEB phenomena according to characterization and related mechanisms, including inter-chain aggregates and/or excimers, on-chain ketone defect emissions, interchain ketone-based excimers, and hydroxy-terminated oxidation on the interface of devices. Recent advances in highly stable blue light-emitting polyfluorenes are cate rically summarized. This review highlighted the contributions of the steric hindrance effects of various nonplanar bulky groups, molecular conformations and topologies of chains and antioxidant hindered amine light stabilizers (HALS), together with physical blending as well as interface engineering.

The low frequency vibrational spectrum that reflects the intermolecular interaction of an imidazolium cation ionic liquid 1-butyl-3-methyl imidazolium hexafluorophosphate ([bmim][PF6]) was studied by femtosecond optically heterodyne-detected optical Kerr effect (OHD-OKE) spectroscopy. Several explicit time correlation functions of the Brownian oscillator were used to simulate the kinetic nuclear contribution of the femtosecond OHD-OKE data. The time evolution behavior of each individual oscillator in the time domain was obtained. We obtained the frequency spectrum for each oscillator in the frequency domain by the fast Fourier transform theorem. In addition, we also measured the low frequency vibrational spectrum of [bmim][PF6] by low frequency Raman spectroscopy. These low frequency spectra obtained by low frequency Raman spectroscopy and by femtosecond OHD-OKE spectroscopy show very similar characteristics. These results demonstrate that the explicit time correlation function of the Brownian oscillator can be used to resolve the time evolution behavior of the low frequency vibration mode in ionic liquids.

A novel liquid crystalline (LC) polythiophene bearing cyanoterphenyl mesogenic pendants with a long flexible spacer {—[thiophene—CH2—COO—(CH2)6—O—terphenyl—CN]n—, PT(6)TPhCN}was designedandsynthesized. Structures of the monomer and the polymer were characterized by nuclear magnetic resonance (NMR) and Fourier transform infrared (FT-IR) spectroscopy while the liquid crystalline and other properties were evaluated with thermo- gravimetry, differential scanning calorimetry (DSC), polarized optical microscopy (POM), ultraviolet visible (UV-Vis) spectroscopy, and photoluminescence (PL). The monomer shows enantiotropic smectic phases during the heating and cooling processes. Because of the long flexible spacer, the polymer PT(6)TPhCN exhibits a colorful SmAd mesogenic phase texture. The cyanoterphenyl group results in the polymer having od photoluminescence. The spacer length also greatly influences the UV absorption and photoluminescence behavior of the polymers. A longer spacer may better segregate the backbone, which effectively enhances the stronger photoluminescence emission. More interestingly, without introducing any chiral groups, the polymer exhibits an obvious Cotton effect on the circular dichroism (CD) spectra, which results from the predominant screw sense of the backbone. This is probably due to the heavy bulky mesogenic pendant rotating around the polythiophene backbone and producing a backbone with a helical conformation in the long wavelength region.

The application of room-temperature ionic liquids (RTILs) to the separation of high level radioactive nuclides from waste water demands a comprehensive knowledge of the radiation effects on the RTILs. Herein, we report a systematic study on the influence of γ-irradiation on the phase behavior and fluorescence properties of the widely used hydrophobic room-temperature ionic liquids [C4mim]X, where [C4mim]+ is 1-butyl-3-methylimidazolium and X- is hexafluorophosphate (PF-6) and bis(trifluoromethylsulfonyl)imide (NTf-2), respectively. It was found that the relaxation time of crystallization in the ILs increased during γ-irradiation leading to a delay before crystallization. The irradiated ILs showed an obvious“red edge effect”similar to that in unirradiated ILs. The whole spectrum, however, shifted to a longer wavelength with increasing the dose and the maximum variation was ca 150 nm. Furthermore, the “red edge effect”was unexpectedly observed in an acetonitrile solution of irradiated ILs and the whole spectrum shifted towards a shorter wavelength with increasing the dilution. All the above-mentioned observations relating to the phase behavior and fluorescence properties are attributed to a change in the spatial correlation between cations and anions in the ILs after γ-irradiation.

1-Octanol is a promising solvent for the extraction of high-level radioactive waste from nuclear fuel reprocessing and a study of radiation effects on 1-octanol is necessary before its industrial application in high-radiation environments. In this work, UV-Vis spectroscopy and Fourier transform infrared (FTIR) spectroscopy were used to investigate the radiation stability of 1-octanol in nitrogen for the first time. Results indicate that 1-octanol is chemically stable at a dose of 100 kGy and that compounds containing a carboxyl group are formed at a dose of more than 300 kGy. The major radiolysis products of irradiated 1-octanol at 600 kGy were analyzed using gas chromatography(GC) and gas chromatography-mass spectrometry(GC-MS). Hydrogen was formed as a major gaseous product and small amounts of carbon dioxide and methane were also found. The dominant liquid product was 1-octanal and its mass percent was less than 1% in the 1-octanol solution. Small amounts of heptane and 8-pentadecanol were also produced. Analysis of the chemical structure and radiolysis products of the irradiated 1-octanol suggests that during gamma irradiation in nitrogen, C—H bond breakage at the α-carbon in 1-octanol is the dominant reaction and the C—C bond at the β-carbon can break as well. Additionally, hydrogen abstraction reactions occur between the primary H-atom radical produced during irradiation and 1-octanol.

Spirobifluorene (SPF)-based soluble copolymers containing different chain lengths of alkoxy-benzene units in the main chain were synthesized via a chemical oxidative method using FeCl3 as the catalyst. The copolymers are soluble in common organic solvents such as methylene chloride, tetrahydrofuran (THF), and chloroform. The chemical structure and luminescence properties of the as-prepared copolymers were investigated by Fourier transform infrared (FT-IR) spectroscopy, proton nuclear magnetic resonance spectroscopy (1HNMR), ultraviolet-visible (UV-Vis) spectroscopy, and photoluminescence (PL) spectroscopy. With dimethylsulfoxide (DMSO) as solvent, the copolymers emit a strong blue light. The absorption and PL emission peaks appear at 356 and 413 nm, respectively. Using quinine sulfate as the reference, the fluorescence quantum yields of the copolymers were found to be 0.69 and 0.77. Cyclic voltammetry (CV) tests indicated that the highest occupied molecular orbital (HOMO) energy levels of the copolymers are located between -5.85 and -5.69 eV.

This is an exciting time for studying thiolated ld nanoclusters. Single crystal structures of Au₁₀₂(SR)₄₄ and Au₂₅(SR)₁₈^- (—SR being an organothiolate group) bring both surprises and excitement in this field. First principles density functional theory (DFT) simulations turn out to be an important tool to understand and predict thiolated ld nanoclusters. In this review, I summarize the progresses made by us and others in applying first principles DFT to thiolated ld nanoclusters, as inspired by the recent experiments. First, I will give some experimental background on synthesis of thiolated ld nanoclusters, followed by a description of the recent experimental breakthroughs. Then I will introduce the superatom complex concept as a way to understand the electronic structure of thiolated ld nanoclusters or smaller nanoparticles. Next, I will describe in detail how first principles DFT is used to understand the Au-thiolate interface, predict structures for Au₃₈(SR)₂₄, screen od dopants for the Au₂₅(SR)₁₈^- cluster, design the smallest magic thiolated ld cluster, and demonstrate the need for the trimer protecting motif. I will conclude with a grand challenge: the real time monitoring of nucleation of thiolated ld nanoclusters.

The many-body perturbation theory based on the Green's function provides a ri rous conceptual framework to describe ground-state and excited-state properties of materials. The Green's function depends on the exchange-correlation self-energy, which is the solution of a set of complicated integro-differential equations, named Hedin's equations. The method, which approximates the self-energy by its first-order term in terms of the screened Coulomb interaction (W), is currently the most accurate first-principles approach to describe quasi-particle electronic band structure properties of extended systems. In this review, we first give an overview of the many-body perturbation theory for quasi-particle excitations based on the Green's function and screened Coulomb interaction. The latest methodological developments are reviewed with an attempt to put different newly proposed schemes in a unified framework. The current status of the method, in particular for d/f-electron systems, is illustrated by a few prototypical examples.

Density functional theory (DFT)-Tao-Perdew-Staroverov-Scuseria (TPSS) functional calculations on dizinc complex-mediated phosphodiester cleavage indicate a general base catalytic mechanism. 2-hydroxylpropyl-4-nitrophenyl phosphate (HPNP) favors the bridging of two Zn ions by the formation of two coordination bonds between terminal phosphate oxygens and Zn ions. The Zn-bound hydroxide deprotonates the hydroxyl on the side chain of HPNP and consequently the alkoxide is stabilized by coordination to a Zn ion and a hydrogen-bond to Zn-bound water. A water molecule is tightly bound to two amino protons in the bis(1,4,7-triazacyclononane) ligand and this determines the orientation of HPNP during a nucleophilic attack to form a tri nal bipyramidal PO5 intermediate and it also weakens the bond between phosphorus and the phenolate, which makes the leaving of the latter easier. The phenolate formed after the collapse of the five-coordinated phosphorus intermediate easily coordinates to a Zn ion. Surprisingly, the stabilizing solvent effect for the transition state after the formation of the PO5 intermediate is much stronger (at least 42 kJ·mol-1) than that of all other species as they have solvation energies that fluctuate around 12.6 kJ·mol-1. Thus, the overall free energy barrier for this reaction after reactant-binding and before product release is about 17.0 kJ·mol -1, which is too low to be rate-determining. The rate-determining step is very likely part of the release process of the products. Based on various calculations, we discuss possible reasons for the different catalytic efficiencies of the dizinc complex and the enzymes.

The parallelism and convergence of the approximate and analytical integration methods on solvation effect calculation were investigated by simulating the solute cavity with polyhedrons. We find that these two methods have excellent parallelismfor the 40 neutral molecules studied. The parallelismis poor for the 27 anions and 20 cations studied as the cavity is the 0.001 and 0.002 a.u. isodensity contours. The accuracy of the approximation method is, therefore, not guaranteed. We also find that despite the type of polyhedron used to simulate the cavity, the ground state electronic energies of the solute molecules calculated by the above two methods converge to nearly the same limit as the faces of the polyhedrons approach infinity.

Group-14 metalloles possess interesting optical properties and are promising molecules for light-emitting materials. We present a theoretical study of the electronic structures and the optical spectra from silole to stannole to gain insight into their optical properties. The optimized equilibrium geometries and the electronic and vibrational structures for the ground state (S0) and the first singlet excited state (S1) were calculated using density functional theory (DFT) and time-dependent density functional theory (TD-DFT), respectively. The optical absorption and emission spectra were calculated using the thermal vibration correlation function formalism. The lineshapes of the calculated optical absorption and emission spectra, especially the full width at half maximum for all the compounds at room temperature, were found to be in od agreement with the available experimental data. Low-frequency modes that are assigned to the rotation motion of free aromatic rings and the high-frequency modes related to the stretching vibration of carbon-carbon bonds contribute greatly to the optical features such as the bandwidth of the optical line-shapes.

Density functional theory (DFT) calculations were carried out to study the charge transfer properties of N,N'-bisperylene-3,4,9,10-tetracarboxylic diimide (1), N,N'-bis(3-chlorobenzyl)perylene-3,4,9,10-tetracarboxylic diimide (2), N,N'-bis(3-fluorobenzyl)perylene-3,4,9,10-tetracarboxylic diimide (3), and N,N'-bis(3,3-difluorobenzyl)perylene-3,4,9,10-tetracarboxylic diimide (4) for use as organic field effect transistors (OFETs). The highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO) energies, ionization energy (IE), electron affinity (EA), and reorganization energy (λ) were investigated for these compounds. Corresponding to energy changes in the HOMO and LUMO for 2-4, the introduction of chlorobenzyl or fluorobenzyl groups leads to high adiabatic electron affinity (EAa) values for 2-4. The transfer integral (V) and field effect transistor (FET) properties for the four compounds with known crystal structures were calculated based on Marcus electron transfer theory. The calculated results reveal that a very small injection barrier exists relative to the Au source-drain electrode of 1-4 for electrons, producing od potential n-type semiconductors. Intrinsic electron transfer mobilities (μ-) of 5.39, 0.59, 0.023, and 0.17 cm2·V-1·s-1 were calculated for compounds 1-4, respectively. The high intrinsic electron mobilities for 1-4 were rationalized by examining  the changes in geometric structure upon reduction and charge transfer integral for the different transfer modes in crystal 3.

We studied the quantitative structure-activity relationships (QSAR) of macrolactone derivatives. Statistical results fromthe established comparative molecular field analysis (CoMFA), the comparative molecular similarity indices analysis (CoMSIA), and the hologram quantitative structure-activity relationship (HQSAR) models showed believable predictability based on the cross-validated value (r2cv>0.5) and the non cross-validated value (r2>0.8). A contour maps analysis of the CoMFA and CoMSIA models showed that the hydrophobic and hydrogen-bond acceptor fields are important factors that affect the herbicidal activity of macrolactone compounds except for the steric and electrostatic fields. The structural modification information from the different atom contributions in the HQSAR model is in agreement with those of the 3D-QSAR models. According to the results from the CoMFA and CoMSIA models, the structure of compound B1-3 with the best herbicidal activity was modified and some designed compounds were predicted to have higher activity.

9,9'-Spirobifluorene oli mers ((SBF)n(n=1-4)) were fully optimized using density functional theory (DFT) at the B3LYP/6-31G(d) level. We obtained the highest occupied molecular orbital (HOMO), the lowest unoccupied molecular orbital (LUMO) energies, and HOMO-LUMO energy gap from these DFT calculations. All molecules have od π conjugation structures. Fromthe optimized geometries of the cationic and anionic charged states, we calculated the ionization potential (IP), electron affinity (EA), hole extraction potential (HEP), electron extraction potential (EEP), and the reorganization energy. The singlet excited geometry of 9,9'-spirobifluorene was calculated using the single-excitation configuration interaction (CIS)/3-21G method. Absorption and emission spectra were obtained by employing time-dependent (TD)-DFTcalculations. Results showthat as the lengths of oli mers increase, the HOMO-LUMOenergy gaps become narrower, the hole injection and the electron transport properties improve, the lowest excitation energies decrease, the oscillator strength (f) increases, and the maximum absorption wavelengths (λmax) show a red shift. The electronic and electrochemical properties of the polymer were predicted by extrapolating the properties of the oli mers with an infinite reciprocal chain length. To investigate the influence of substituting the 9 position of the fluorene, some parameters of the parent fluorene ((FL)n(n=1-4)) were calculated for comparison. Fromthis comparison, it is obvious that spiro-functionalization at the fluorene C-9 bridge position can greatly improve the electron and hole transport properties and the excellent emission spectral quality of the fluorene is maintained.

Electrospray ionization mass spectrometry (ESI-MS) was used to investigate the non-covalent interaction of human telomeric G-quadruplex (G4) DNA with 12 natural product molecules. We found that Fangchinoline, a new ligand of the human telomeric G-quadruplex, had the highest binding affinity among these molecules. The stabilities of the G-quadruplex and the complexes of the G-quadruplex with small molecules were investigated using a mass spectrometry heating experiment. By Fangchinoline binding, the dissociation temperature (T1/2) value of the complex of G-quadruplex with the ligand increased to 200 ℃. We studied the binding mode and stability of the G-quadruplex with the small molecules using Autodock. Possible binding sites were found and the binding energy was about -31.5 kJ·mol -1. Unlike the typical binding molecules with a planar structure, Fangchinoline is a new kind of G-quadruplex ligand and it gives us a different insight for the design of new G-quadruplex ligands.

It has been a challenge to accurately extract dynamic information from experimental fluorescence correlation spectroscopy (FCS) data. In this paper, we compare three major fitting methods: the model-dependent multiple exponential function (MultiExp), the empirical stretched exponential function (StreExp), and the exponential function based on the model-free maximumentropy method (MemExp). MultiExp has straight forward physical significance but it is difficult to implement and interpret in a complex system. StreExp has simple form and is easy to use but its physical picture is obscure. MultiExp is model free but its results are sensitive to experimental noise. A od choice seems to be a combination of MemExp and MultiExp. In our example, we have unraveled that two independent processes exist in the intra-chain collision of a single-stranded DNA when base pair formation is possible, which has not been observed by previous investigators. MemExp is recommended for the FCS data analysis, although caution should be exercised in the practice.

The 3C-like proteinase (3CLpro) of severe acute respiratory syndrome (SARS) coronavirus has been proposed to be a key target for anti-SARS drug discovery. It has been proposed and verified that the dimer was the active form of 3CLpro and only one protomer is active. In our previous work, we measured the dissociation constant (Kd) of the purified SARS 3CLpro using analytical ultracentrifugation at around 14.0 μmol·L-1. Using this Kd value, most of the SARS 3CLpro in the in vitro activity assay (1-3 μmol·L-1) might be in the monomer formand inactive. To explain this dilemma, we measured the enzyme activity change together with the enzyme concentration. By fitting the concentration dependent activity profile, the apparent dissociation constant was found to be 0.94 μmol·L-1, indicating a clear tendency toward substrate enhanced dimerization. This also explains why SARS 3CLpro was still active in the in vitro activity assay under a relatively low enzyme concentration. To further verify the substrate induced dimerization phenomenon, we selected a previously reported SARS 3CLpro isatin inhibitor, 1-(2-naphthlmethyl) isatin-5-carboxamide (5f), which has similar binding interactions with the substrate and we studied its influence on SARS 3CLpro dimer formation using analytical ultracentrifugation. 5f showed a strong ability to induce SARS 3CLpro dimer formation. By measuring the dimer and monomer distribution under different 5f concentrations, the EC50 of dimer induction was found to be about 1.0 μmol·L-1 under an enzyme concentration of 3.0 μmol·L-1. This implies that only one protomer in the SARS 3CLpro dimer binds to the inhibitor or the substrate. As the apparent association constant and thus the enzyme activity of SARS 3CLpro increases with the concentration of the substrate, this may be a smart way to allosterically regulate the hydrolysis of the SARS viral polyproteins and the correct assembly of virons.

DNA G-quadruplexes (G4s) are believed to be involved in many biological processes, including the gene expression regulation and the maintenance of telomere. However, the kinetics of G4, in particular how G4 forms in the double-stranded genomic DNA is an underexplored issue. We found that a very stable G4 can form in the promoter of human myocyte enhancer factor 2D (MEF2D), the gene encodes a transcription factor belonging to the MEF2 (myocyte enhancer factor-2) family which regulates the response of heart to cardiac stress signals. Biophysical characterizations, in particular single molecule fluorescence resonance energy transfer (smFRET) measurements, suggest that this G4 is more stable than its duplex form in near physiological conditions. Two major G4 structures were identified based on single molecule conformational analysis on the end and internal labeled DNA systems. A free energy landscape for the G4 hybridization was established in light of the smFRET G4/duplex competition assay. In addition, the G4 hybridization and unfolding rate constants were obtained.

The binding mode of metal ions with proteins is usually different in different systems. Yeast alcohol dehydrogenase (YADH) is a zinc containing metalloenzyme that catalyzes the fermentation reaction of alcohol to acetaldehyde. UV-Vis spectroscopy, fluorescence spectroscopy, and differential scanning calorimetry (DSC) were used to investigate the interaction of nickel(II) with Yeast alcohol dehydrogenase. The binding of Ni(II) to Yeast alcohol dehydrogenase shows a 320 nm UV absorbance band and the enzyme conformational change is reflected in the fluorescence data. Both UV-Vis and fluorescence spectra exhibit biphasic kinetics for the binding process. The interaction of Ni(II) with Yeast alcohol dehydrogenase causes the enzyme to transform from a tetramer to a dimer. The conformational change of the Yeast alcohol dehydrogenase results in an increase in the denaturation temperature and in a molar enthalpy change during the DSC process. This study reveals a complex but deep-seated mechanism for the interaction of Ni(II) with YADH.

The immobilization of four different proteases on a series of molecular sieves, including microporous HY, NaY, NH4Y, MCM-22, Hβ zeolites, modified Y zeolites HDAY, HNH4DAY, and mesoporous MCM-41, by adsorption was systematically investigated. The four proteases were α-chymotrypsin, papain, subtilisin, and thermoase (or its pure form thermolysin). The results showed that the enzyme loading amount and the activity of immobilized enzyme were significantly affected not only by the structures and textures of molecular sieves and the enzyme properties, but also by the adsorptive conditions such as buffer pH values and enzyme concentration. In most cases, the amount of protease loading on molecular sieves was relatively higher at pH 6.0, but declined with further increasing of pH values. The nature of the interaction between protease and molecular sieves is discussed. As for α-chymotrypsin, its loading amount on Hβ zeolites was found to be the highest, whereas the activity of α-chymotrypsin immobilized on MCM-22 was the highest, which is probably due to different adsorption states.

The base pair stack within a DNA duplex can transport charge over long distances. The π-stacked base pairs provide an effective medium for long distance charge transport in DNA molecules. The DNA-mediated charge transport is extremely sensitive to the DNA sequence. This sensitivity can be used to fabricate electrochemical DNA biosensors for single base mismatch sensing. Polyamides are DNA recognition molecules which can bind to the minor groove in DNA to form a DNA/polyamide complex with high affinity and specificity. Polyamide molecules with the nitro group are used as an electrochemically active probe for DNA biosensors. The electrochemical properties of the nitro-polyamide was investigated on a DNA self-assembly electrode. The results indicated that the electrochemical response was enhanced intensitively, and the polyamide can be used as a probe to detect a single base pair mismatch in DNA.

Discotic liquid crystal (LC) molecules readily form columnar supramolecular structures. Because of molecular mobility in the LC state these columnar assemblies can self-heal structural defects to a certain extent. Therefore, conjugated aromatic molecules of the discotic LC state may exhibit exceptional charge carrier transport properties, and thus are potential active materials for use in optoelectronic devices. In this review, a number of discotic LC materials including benzene, triphenylene, hexabenzocoronene, perylene, and phthalocyanine derivatives are reviewed. The emphases are on the correlation between chemical structure and LC properties and some recent developments in the application of these materials in optoelectronic devices such as organic light-emitting diodes (OLED), organic field-effect transistors (OFET), and photovoltaic cells. In addition, studies related to the dynamics of some discotic LC materials are briefly discussed.

The breath figure technique is one of the most promising strategies for the fabrication of large-sized patterns containing an ordered two-dimensional array of holes. In this review, particular emphasis is placed on the static breath figure technique, which is a robust methodology suitable for various polymers including linear polystyrene (PS), amphiphilic diblock copolymers and polymer/inorganic precursor hybrid films. The resultant highly ordered microporous polymer films can be used as a mask for lithography. Moreover, the microporous polymer films can be surface modified and cross-linked by UV irradiation. The surface modified films can potentially be applied as a cell scaffold and the cross-linked polymer/hybrid films can be used as templates for the growth of nanomaterial arrays.

We discuss recent developments in the preparation methods of high surface area silicon carbide, such as templated synthesis, sol-gel processing, and polycarbosilane pyrolysis. We provide an overview and an outlook for the applications of high surface area silicon carbide as catalyst support materials.

In this study, a nondestructive method to mass produce crossed nanotube-graphene junctions through twice polymer-mediated transfer techniques and selective oxygen plasma etching was developed. Raman and conductance measurements demonstrate that the quality and electrical properties of the single-layer graphene (SLG) sheets are uniform over a large area. Furthermore, SLG synthesis and device fabrication discussed here also provide a reproducible method to pattern graphene sheet arrays for making graphene-based microdevices over large areas and with high yield, which is compatible with standard thin film technologies and allows SLG to be integrated into large scale electronics circuitry within several simple steps that can be easily streamlined and automated. These results might offer grounds for the creation of a wide variety of molecular rectifiers and other functional nano/molecular devices.

Star-branched poly(ε-caprolactone) (PCL) including hexa-armed star-shaped PCL (HPCL), dendritic PCL (DPCL), and linear PCL (LPCL) were spin-coated onto mica substrates at room temperature. The effect of molecular structure on the wetting-dewetting behavior of ultrathin film(about 15 nm)was investigated with atomic force microscopy (AFM). During spin-coating, film formation is verned by competing dewetting and crystallization processes. According to differential scanning calorimetry (DSC), the crystallizability of DPCL is weaker than that of HPCL which is weaker than that of LPCL, when they have the same relative molecular mass. Depending on the molecular structure and the relative molecular mass of PCL, the competition between crystallization and dewetting results in ultrathin films of LPCL, HPCL, and DPCL with surface morphologies such as perfect spherulites, open spherulites, dendritic lamellae, and dispersed droplets of different sizes.

We prepared a novel plasma polyquinoline derivative thin film, plasma-polymerized 3-cyanoquinoline (PP3QCN). Fourier transform infrared spectroscopy (FT-IR), UV-visible (UV-Vis) absorption spectroscopy, X-ray photoelectron spectroscopy (XPS), and atomic force microscopy (AFM) characterization revealed that the plasma polymerization conditions affected the chemical structure, surface composition, morphology, and dielectric property of the plasma-deposited films. A smooth and homogenous PP3QCN film with a large π-conjugated system and a high retention of the aromatic ring structure of the monomer was obtained at a low discharge power of 10 W. At 25 W, more severe monomer molecular fragmentation was apparent during the plasma polymerization and thus the conjugation length of the PP3QCN films decreased because of the formation of a non-conjugated polymer. A low dielectric constant of 2.45 was obtained for the as-grown PP3QCN thin filmdeposited at 10 W.

Nano-alumina powders were prepared by vacuum freeze drying combined with reverse microemulsion method. The reverse microemulsion system consisted of cyclohexane/polyethylene glycol octylphenyl ether (Triton X-100)-hexadecyl trimethyl ammonium bromide (CTAB)/n-butylalcohol/water. The morphology, structure, specific surface area, pore volume, and pore size of the alumina nanoparticles were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), and specific surface area analysis. The specific surface area of the alumina nanoparticles was about 550.0 m2·g-1 (changed with different reaction parameters) and the crystal structure was γ-Al2O3. The particle size was very uniform and smaller than 10.0 nm. The influence of different drying methods (normal hot-gas drying, normal vacuumdrying, vacuumfreeze drying) and the main parameters of vacuum freeze drying on the physical properties of the product were studied. Results showed that the nano-alumina powders obtained by vacuum freeze drying had much higher specific surface area and pore volume than that obtained by the two other drying methods. The specific surface area and pore structure of the nano-alumina were affected by the freezing rate, pre-freezing time, and drying time in the vacuumfreeze drying process.

Triangular silver nanoplates were successfully prepared by a water-bath heating method. NaBH4 and sodium citrate were both used as reducing agents while polyvinylpyrrolidone (PVP) was used as a surfactant and protective agent. The product was characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), UV-Vis absorption spectroscopy, and surface-enhanced Raman scattering (SERS) spectrum. The product has a cubic face-centered Ag structure. The triangular silver nanoplates have a border size of (100±40) nmand a thickness of (10±5) nm. A growth mechanism is proposed to account for the formation of triangular nanoplates. The preferential absorption of citrate on different crystal planes of silver nuclei, the encapsulation function of PVP and the existence of lattice defects in silver crystals plays a significant role in the formation of products. Compared with spherical nanoparticles, the triangular silver nanoplates exhibit a different absorption spectrum and strong SERS activity for pyridine (Py) molecules.

We designed and synthesized a new pyrazine derivative containing the carbazyl moiety, 2,3-di(4-(9-carbazylmethyl)phenyl)-5-methylpyrazine(CzMPMP) and investigated its reaction with iridium(III) ion to form the iridium complex Ir(CzMPMP)2(acac) (acac: acetyl acetone). The complex was characterized by nuclear magnetic resonance (NMR) spectroscopy, mass spectrometry (MS) and elemental analysis (EA) and its photophysical properties were investigated by UV-Vis spectroscopy as well as solution and solid state photoluminescence (PL) techniques. By comparing Ir(CzMPMP)2(acac) with Ir(DPMP)2(acac) (DPMP: 2,3-diphenyl-5-methylpyrazine), we find that the carbazyl group greatly influences the photophysical properties of the complexes. Firstly, Ir(DPMP)2(acac) has a strong and broad excimer peak in its solid state PL spectrum, while Ir(CzMPMP)2(acac) has no such peak under the same conditions. Furthermore, the PL intensity of Ir(CzMPMP)2(acac) in solution increased significantly compared with Ir(DPMP)2(acac). These results suggest that steric hindrance from the carbazyl groups may play an important role in preventing excimer formation and thus resulting in the increased PL intensity.