A hydrogen peroxide (H2O2) electrode and electron spin resonance (ESR) methods were used to continuously monitor and analyze the autoxidation and prooxidation of Danshensu in aqueous solutions with various pH values. We found that Danshensu exhibited obvious autoxidative activity in alkalescence buffer solutions (pH=8.5) and the presence of Cu2+ evidently accelerated the generation of H2O2. The primary product of the autoxidation was a superoxide anion radical (O2-·) and then it could be converted into H2O2. The autoxidation of Danshensu was totally inhibited under weak acidic conditions (pH=6.5) and a partial prooxidation of Danshensu occurred in the presence of cupric ion. However, under physiological conditions (pH=7.4), the autoxidation of Danshensu was very slow and its prooxidation, initiated by Cu2+, was very limited. Consequently, the autoxidation and prooxidation of Danshensu cannot be completely ignored when used in clinical practice especially under alkaline body fluid conditions.

Octanol-water partition coefficient and water solubility are two important physicochemical properties of organic compounds in medicinal chemistry and environmental chemistry studies. They are used as critical parameters in quantitative structure-activity relationship (QSAR) studies to model the adsorption, distribution and metabolism of drugs in the living body and the distribution of organic compounds in naturenvironment. The most widely applied approaches to calculating octanol-water partition coefficients and water solubility can be roughly divided into two cate ries: fragment-addition models and descriptor-based models. This article provides a comprehensive review on these approaches, discusses their strengths and shortcomings, and provides an outlook for possible future developments in this area.

Mixed quantum-classical methods are of great interest in simulating dynamic processes of complex molecular systems. We investigated the application of the Ehrenfest method, the surface hopping method, and the mixed quantum classical Liouville equation method to calculate charge transfer rates in the nonadiabatic limit. The three methods were applied to realistic problems of charge transfer in organic semiconductor materials. We found that both the Ehrenfest and surface hopping methods may deviate significantly from the correct result. This deviation is due to an incorrect treatment of the coherence term, and is more severe when high frequency modes are involved.

Reactions between transition metal oxide clusters and hydrocarbon molecules were extensively studied to reveal the mechanisms of the related catalytic processes at a molecular level. Compared with transition metal oxide cluster cations, anions are usually much less reactive toward some hydrocarbon molecules and thus much less studied. In this work, vanadium oxide cluster anions (VxOy) were prepared by laser ablation and reacted with alkanes (C2H6 and C4H10) and alkenes (C2H4 and C3H6) in a fast flow reactor under near thermal collision conditions. A time of flight mass spectrometer was used to detect the cluster distribution before and after the reactions. Hydrogen atom-pickup products V2O6H- and V4O11H- were observed in the reactions of VxOy with alkanes while the association products V2O6X- and V4O11X- (X=C2H4 or C3H6) were produced in the cluster reactions with alkenes. Density functional theory calculations predict that V2O-6 reacts with C2H6 and C4H10 by C—H activation and with C2H4 and C3H6 by 3+2 cycloaddition to form a five-membered ring structure (-V-O-C-C-O-) with surmountable reaction barriers. This is in agreement with the experiments. Both the V2O-6 and V4O-11 clusters have the bonding characteristics of oxygen-centered radicals (O·or O-) and these were also identified over the surface of the vanadium oxide based catalysts. This study provides a molecular level mechanismfor the reaction between surface O- species and hydrocarbon molecules.

Kinetics of the reactions of ozone with diethylamine (DEA) and triethylamine (TEA) were investigated in a self-made Teflon chamber. Experiments were conducted under pseudo-first-order decay conditions using excess DEAand TEA. Cyclohexane was added to the reactor to quench OHradicals. At (298±1)Kand 1.01×105 Pa, the measured absolute rate constants were (1.33±0.15)×10^-17 cm³·molecule^-1·s^-1 for DEA and (8.20±1.01)×10^-17 cm³·molecule^-1·s^-1 for TEA. Comparing our results with data for the reactions of analo us amines with ozone, we propose that the amines react with ozone probably through an electrophilic reaction mechanism. In addition, the reactions of trialkylamines with ozone are all much faster than those of dialkylamines with ozone, which may explain the intriguing finding in several field studies where higher concentrations of dialkylammoniumwere detected in aerosol samples. The atmospheric lifetimes of DEA and TEA were also estimated based on the measured rate constants and the ambient tropospheric concentration of ozone, which indicates that the reaction with ozone is an important loss pathway for these amines in the atmosphere, especially in polluted areas.

Large-scale core-shell SiO2/Pt particles were synthesized via layer-by-layer assembly. The platinum shell was found to be about 26 nmthick and consisted of Pt nanoparticle aggregates. Cyclic voltammetry (CV) was employed to evaluate the electrocatalytic activity of the as-prepared core-shell SiO2/Pt particles for CO detection. Compared with the bulk Pt catalyst, the main oxidation potential was more negative at about 0.49 V (vs SCE). Moreover, COadsorption behavior was also examined using in-situ electrochemical Fourier transform infrared (FTIR) spectrum. Interestingly, the FTIR spectra showed inverted IR bands of linearly bonded CO and each IR band was split into two bands with an interval of ca 14 cm-1, which was difficult to discern at saturation coverage of CO on the Pt metal surface. Those anomalous phenomena can most probably be attributed to the structural effects of core-shell SiO2/Pt particles.

In this paper we demonstrated a novel type of electrochemical Hg2+ biosensor based on a DNA-modified electrode. Ferrocenyl-modified T-rich DNA (DNA-Fc) molecules were synthesized for use as electrochemical probes. We then fixed these DNA-Fc probes onto a ld electrode surface by self-assembly. In the presence of Hg2+, the single strand DNA on the electrode surface turned to a thymine-Hg2+-thymine (T-Hg2+-T) hairpin structure. The ferrocenyl groups were kept away from the surface of the electrode, and this could be measured sensitively by differential pulse voltammetry (DPV). The results showa reduction peak of ferrocene at 0.26 V (vs saturated calomel electrode (SCE)) and the peak current of DPV decreased with increasing the concentration of Hg2+. The rate of current change is linear with regards to lgcHg2+ over a concentration range from0.1 nmol·L-1 to 1 μmol·L-1 and with a detection limit of 0.1 nmol·L-1. A test for interference metal ions showed that this electrochemical biosensor based on a DNA modified electrode is highly sensitive and selective, and it can be widely used for trace Hg2+ detection.

Organic semiconductors are charge carrier-transporting molecular solids with π-orbital channels. Organic semiconductors are π-systems that can be created via the molecular engineering of π-orbitals. In this review, we present a pattern in physical organic chemistry by summarizing four fundamental elements of organic/polymeric π-semiconductors according to our previous work. These include electronic structure, steric hindrance, conformation and topology, and supramolecular interactions. Advances in the field of organic/polymeric π-semiconductors with respect to these four elements are highlighted to demonstrate the impact on device functionality and performance. We also provide an outlook of the four-element principle as a basic thinking pattern in scientific research.

Significant data sets of crystallographic van der Waals radii for the noble gases, the non-metal elements, and the metal elements that have appeared within the last seven decades are summarized and examined systematically. From the most useful sets all the reliable data are recommended. Certain remaining problems are identified and the need for further studies in this area is suggested.

Recent advances in hybrid molecular materials based organoimido-substituted polyoxometalates (POMs) are reviewed. Related imidoylation and C-C coupling reactions developed in our group are highlighted.

In this review, we summarize a newly discovered one-pot process for the synthesis of aromatic oli amide and oli hydrazide macrocycles. A mechanism for these highly efficient one-pot macrocyclization reactions is presented and discussed. The unprecedented high efficiencies of these one-pot macrocyclization reactions are rationalized based on the folding of uncyclized oli meric precursors, which is enforced by intramolecular hydrogen bonds. These one-pot macrocyclization reactions, with their unusually high efficiencies and novel mechanism, afford several new classes of shape-persistent macrocycles that are otherwise difficult to obtain using traditional methods. It has been already demonstrated that these macrocycles possess unique properties in the specific recognition of guest species and the formation of highly conducting transmembrane pores.

Two new compounds, Sr6Sb4Co3O14(OH)10 (SSC) and Sr6Sb4Mn3O14(OH)10 (SSM), were synthesized under hydrothermal conditions in an alkaline medium. Their structures were determined by powder X-ray diffraction using Rietveld analysis, and the topology of the metal cation network was discussed. These two isostructural compounds crystallize in a garnet-related or hydrogarnet-related structure with the space group I43d and the lattice parameters (a) are 1.30634(2) nm(SSC) and 1.31367(1) nm(SSM). The SbO6 octahedron and MO4 (M=Co, Mn) tetrahedron share corners with each other to formthe backbone of the structure. The topology of the Sb5+ andM2+ (M=Co,Mn) network is ctn, which is the C3N4network. The Sb5+ node is three-connected and that of M2+ (M=Co, Mn) is four-connected. The distribution of the M2+ (M=Co, Mn) cations in the structure is in a fanlike mode with a thp topology, i.e., a network of Th atoms in Th3P4. These two compounds are antiferromagnetic. Sr6Sb4Co3O14(OH)10 exhibits a net magnetic moment, which may be related to the canting ordering of Co2+ ions below 10 K. Sr6Sb4Co3O14(OH)10 and Sr6Sb4Mn3O14(OH)10 decompose above 300 ℃ and give rise to the perovskite-type compounds Sr2(Sb, M)2O6(M=Co, Mn) as the main phases in the products after treatment at 900 ℃ under atmospheric conditions.

A highly efficient and environmentally friendly method for the resolution of racemic 1,1'-bi-2-naphthol (BINOL) was developed by inclusion complexation with the cheap and readily accessible (R)/(S)-N,N,N-trimethyl-1-hydroxyl-3-methyl-2-butanaminiumiodide resolving agents, which were prepared by a simple two-step reaction starting with D/L-valinol. The X-ray structural analysis was carried out for the inclusion complex of the (R)-quaternary ammoniumsalt with (R)-BINOL in CH3OH. This showed that the O—H…I- hydrogen bonds among the bridged iodide anions with the alcoholic hydroxyl of the host (resolving agent) and the phenolic hydroxyls of the guests (BINOL) together with the C—H…O hydrogen-bond interactions between the host and guest molecules from the adjacent layers are responsible for the chiral recognition in the inclusion complex formation. In addition, the solution and solid-state circular dichiroism(CD) spectra of a pair of inclusion complexes were also carefully investigated.

The molecule-ion interaction between a sugar and a salt is important and significant in biophysics and biochemistry. In this paper, powder X-ray diffraction (PXRD) technology was used to examine the molecule-ion adducts of a series of inorganic salts with β-cyclodextrin (β-CD). Our results indicate that there are considerable differences in the spectral properties of the PXRDs for adducts formed by similar inorganic salts and β-CD. Since their PXRD patterns are mainly dominated by β-CD, the large difference in spectral behavior reflects the diversity and complexity of molecule-ion interactions. The spectral differences were carefully compared by considering several factors such as the formation conditions of crystal adducts, the nature of the anions or cations and ionic charges. The diversity and complexity in adduct behaviors between sugars and salts in the crystal state should be very useful for scientific research and for the practical application of carbohydrates in biophysical chemistry, molecular biology, clinical medicine, nanoscience, and technology.

We investigated the self-assembly behavior of bolaamphiphilic tetraethyl ester-di-L-glutamic acid-N,N'-hexadecanedioic amide (L-HDGE) and its enantiomer D-HDGE at the air/water interface. The self-assembled structures of the HDGE (L-HDGE or D-HDGE) molecule at the air/water interface and some other factors that affect the assembled structures, such as the chirality of the hydrophilic head group, surface tension, and ionic liquid subphase were studied. Atomic force microscopy (AFM) and Fourier transform infrared (FTIR) spectroscopy were employed to investigate the morphology and assembly mechanism of the transferred film. The HDGE molecule was found to form parallel nanowires on the surface of water with widths from 50 to 120 nm and heights from 1 to 5 nm while only a thin film was obtained when the racemic mixture was used under the same conditions. The FTIR spectra show that the heterochiral interaction of the HDGE molecule is stronger than the homochiral interaction. With an increase in surface tension, the parallel nanowires aggregate. Trace amounts of ionic liquid added to the subphase remarkably accelerated the aggregation of the nanowires to yield nanostrips, and some helical structures were observed when the surface tension was increased. The handedness of the helical structures was determined by the molecular chirality of the head group.

The interaction between [1,1'-binaphthalene]-2,2'-diols (BINOL) and a solid supported bilayer lipid membrane (s-BLM) was studied by cyclic voltammetry and alternating current (AC) impedance measurements. Results indicate that BINOL interacts with s-BLMthrough hydrogen bonding and hydrophobic interaction. The oxidation peak current of the BINOL/s-BLMsystem increases initially and then decreases with an increase in time. This suggests that BINOL gradually destroys the integrity of s-BLM and induces the formation of microchannels within the membrane. The infiltration time of BINOL through the s-BLM decreases as the BINOL concentration increases. With an increase in lecithin and cholesterol content, the membrane resistance of s-BLM increases and the infiltration rate of BINOL through the membrane decreases, which results in a reduction of the infiltration capacity of BINOL towards s-BLM.

The hydrothermal synthesis of ordered mesoporous materials with high stability at high temperatures is currently a hot topic in the materials field. This review covers recent developments in the synthesis of ordered mesoporous silicas, titanosilicates and polymer materials with high hydrothermal stability at high temperatures. The uses of fluorocarbon and hydrocarbon surfactant mixtures and solo hydrocarbon surfactants are also discussed.

A mesoporous SiO2@Fe3O4 nanocomposite was prepared by the sol-gel method. The nanocomposite was modified with a thiol and then a long carbon chain oxime carbapalladacycle complex as grafted by a—SCH2— linkage. The catalyst was characterized by transmission electron microscopy (TEM), high resolution transmission electron microscopy (HRTEM), Fourier transform infrared (FT-IR) spectroscopy, N2 adsorption-desorption isotherms, X-ray photoelectron spectroscopy (XPS), and vibration samplemagnetometry (VSM). Its catalytic activity for the Heck coupling reaction was measured. The BET surface area of the support with a diameter of 150 nm was about 287.0 m2·g-1 and the average pore size was about 3.5 nm. The catalyst had superparamagnetic properties. In the Heck reaction of iodobenzene with ethyl acrylate, a high conversation of 99%was obtained after 2.5 h. The catalyst was reused 6 times without significant loss of activity (95%after the sixth run). The catalyst was easily dispersed in the reaction mixture and was separated swiftly by an added magnetic field.

A series of Al2O3-doped (0.5%-3.0%, molar fraction) sulfated tin oxide catalysts were prepared by a co-precipitation method. The structures and textural properties of these catalysts were characterized by N2 adsorption, thermogravimetric (TG) analysis, X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), diffuse reflectance infrared Fourier transformspectroscopy (DRIFTS), Raman spectroscopy, and 27Al magic-angle spinning nuclearmagnetic resonance (MAS NMR). The number of acid sites on the catalysts was measured by the potentiometric titration of n-butylamine. Their catalytic performance for the esterification of lauric acid with methanol and the transesterification of triacetin with methanol was also investigated. The results showed that the addition of Al2O3 to sulfated tin oxide improved the catalytic activity markedly. The remarkable activities of the Al2O3-doped catalysts are caused by the larger number of acid sites. The SO2-4/SnO2 catalyst doped with a 1.0% molar fraction of Al2O3 exhibited the highest activity. The lauric acid conversion was 92.7%after esterification for 6 h, and the triacetin conversion was 91.1% after transesterification for 8 h on this catalyst.

Magnetic sulfonated carbon-based solid acid catalysts (Fe/C-SO3H) were prepared by the pyrolysis of cellulose and subsequent sulfonation. The catalyst samples were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Fourier transforminfrared (FT-IR) spectroscopy, and vibrating sample magnetometry (VSM). Their catalytic properties for the hydrolysis of cellulose were investigated. Results show that Fe exists in the carbon body in the form of γ-Fe2O3 and the Fe/C-SO3H catalyst has superparamagnetic properties. In the hydrolysis reaction, cellulose conversion reached 40.6% over Fe/C-SO3H under optimal conditions. Furthermore, the catalyst could be steadily dispersed in the reaction mixture and be separated using an externally applied magnetic field. However, the catalytic performance dropped after the first run. The reason for deactivation is deduced to be a reduction in the amount of sulfonic acid groups on the surface of the catalyst.

MoOx supported on pure monoclinic zirconia (m-ZrO2) and tetra nal zirconia (t-ZrO2) with different Mo surface densities were prepared and their structures were characterized by X-ray diffraction, Raman spectroscopy and temperature-programmed reduction in H2. At Mo surface densities lower than the theoretical monolayer coverage (~5 nm-2), isolated MoOx and two-dimensional polymolybdates were dominant on the m-ZrO2 surface while MoO3 crystallites were still present on the t-ZrO2 surface indicating a favorable dispersion of MoOx on m-ZrO2. As the Mo surface densities increased to more than monolayer coverage, MoOx tended to form ZrMo2O8 on the ZrO2 surface by a solid reaction at 600 ℃, which was more prevalent on m-ZrO2 than on t-ZrO2. The acidity of the MoOx/ZrO2 catalysts increased with an increase in the Mo surface density indicating that ZrMo2O8 is more acidic than dispersed MoOx. Catalysts prepared using t-ZrO2 resulted in more acidic MoOx/ZrO2 and consequently higher selectivity for dimethyl ether during the selective oxidation of methanol was achieved. The MoOx structures were more reducible on the m-ZrO2 surface leading to improved activity for the oxidation of methanol to formaldehyde, dimethoxymethane and methylformate. An understanding of the effect of ZrO2 crystallite phase on the structures of the MoOx species and their catalytic properties for the selective oxidation of methanol provides useful information for the study of other metal oxides such as VOx, and the design of catalysts that are bifunctional in terms of acidity and redox activity.

Carbon/alumina (titania) composites have unique physicochemical properties and have been widely used in adsorption and catalysis. Carbon in these composites greatly influences the sintering and phase transformation behavior of the oxides. Calcining carbon/γ-Al2O3 in oxygen at high temperature results in a quick γ-to α-Al2O3 transformation. In nitrogen, X-ray diffraction (XRD) analysis showed that carbon inhibited the phase transformation significantly. This inhibition effect was found to be carbon content dependent. For the carbon/titania system, pure titania and carbon-protected-titania samples were calcined at different temperatures and analyzed by XRD, transmission electron microscopy (TEM), and Raman spectroscopy. Surface area and pore size analysis was performed by isothermal nitrogen adsorption-desorption. Results show that the carbon layer can improve the thermal stability of the TiO2 nanoparticles and hinder the phase transformation of anatase to rutile at up to 800 ℃ under nitrogen-protected heat treatment. On the other hand, carbon can be removed by controlling calcination in oxygen at 500 ℃ without affecting the phase composition and texture of titania. The carbon removal efficiency was examined by temperature-programmed oxidation (TPO) analysis. Therefore, carbon can be used as a special surface modifier which can inhibit the high temperature phase transformation of oxides without introducing alien elements effectively.

Fullerene has been extensively used in functional devices requiring electron transfer between fullerene and functional molecules. The investigation of multi-component assembly structures of fullerene and functional molecules on electrode surfaces will benefit the fabrication of fullerene based nanodevices as well as the study of their fundamental physical and chemical properties. The two dimensional (2D) self-assembly structure of C60 and the donor-π-acceptor molecule Z-β-(5-hexadecyloxy-1,3,3-trimethyl-2-indolium)-α-cyano-4-styryl dicyanomethanide (C16H33O-I3CNQ) on an Au(111) electrode surface was investigated by electrochemical scanning tunneling microscopy (ECSTM) in HClO4. The C16H33O-I3CNQ molecules self-organized into a short-ranged ordered structure on the Au(111) surface. C60 molecules formed band-like assembly structures templated by the C16H33O-I3CNQ adlayer. The orientation of the C60 band structure is controlled by the arrangement of the donor-π-acceptor moieties. π-π stacking interactions and charge transfer between C60 and C16H33O-I3CNQ may contribute to the formation of the C60 band-like assembly. The results reported here are expected to provide a new approach for the fabrication of fullerene films and functional devices.

We added 2,4,6-tris[bis(methoxymethyl)-amino]-1,3,5-triazine as a crosslinking agent and diphenyliodonium hexafluorophosphate as an acid generator to phenolic resin, which is a thermosensitive polymer. A topographically patterned polydimethylsiloxane (PDMS) stamp was used to obtain micro/nano structures by hot microcontact printing (hot μCP). The fine pattern was characterized using scanning electron microscopy (SEM) and a contact angle measurement. We found that hot μCP is a fast, simple, and inexpensive technique that can produce thermal cross-linking patterns and the obtained minimumsize is close to 100 nm.

Photodissociation dynamics of n-C3H7I and i-C3H7I at 266 nm were investigated using an ion imaging technique combined with resonance enhanced multiphoton ionization (REMPI). Information on energy disposal and a nonadiabatic transition between the dissociative electronic states involved in the photodissociation of both molecules were analyzed and compared. The fraction of internal energy in the I channel is greater than that in the I* channel for both molecules. As the alkyl group becomes more branched the energy distribution of the atom fragments (I and I*) becomes obviously wider suggesting that the alkyl radical at the α-carbon atomhas more complicated models of the ro-vibration models. On the other hand, the relative oscillator strengths of these molecules that were pumped using 266 nm photons show a small difference in the 3Q0←X transition. The probability of yielding an I* fragment decreases markedly from 0.72 for n-C3H7I to 0.46 for i-C3H7I. This is attributed to the greater contribution of the bending modes for I and I* during the photodissociation of i-C3H7I than that of n-C3H7I leading to an enhancement of the nonadiabatic transition between the 3Q0 and 1Q1 states. Additionally, the 3Q0←X transition is not a completely parallel transition for both molecules and the angle between the transition dipole moment and the bond axis is estimated to be about 15° for n-C3H7I and 18° for i-C3H7I, respectively.

To determine the origin of the radiolytic product singlet state of hydrocarbons, the effect of water on the γ-radiolysis and pulse radiolysis of cyclohexane (C6H12)-tributylphosphate (TBP) solution was studied. In the γ-radiolysis of C6H12-TBP solutions, the addition of water can remarkably lower the yield of the acid product of TBP. The G value of the acid product dropped from 8.2 in the system containing no water to about 1.9 in the system saturated with water. This suggests that water inhibits not only the output of singlet TBP directly induced by the radiation energy absorbed by TBP itself, but also the energy transfer from the singlet C6H12 to TBP. In the pulse radiolysis of TBP-benzophenone (Bp) solution and C6H12-TBP-Bp solutions with Bp as a probe, the added water did not depress the yield of the radiolytic intermediate ketyl radicals. This phenomenon can be interpreted as that water reacted with the geminate ions [C6H12·+…e-] and [TBP·+…e-], giving ketyl radicals but depressing the formation of singlet C6H12 and singlet TBP. This might be direct evidence that most (G=1.3) of the singlet C6H12 and part (G=0.8) of the singlet TBP come from the recombination of geminate ions [C6H12·+…e-] and [TBP·+…e-], respectively. Due to its high polarity, water could be used as a specific scavenger of the geminate ions that can formexcited states via fast geminate recombination.

We measured the non-coincidence effect (NCE) in the Raman spectrum of poly(N-isopropylacrylamide) (PNIPAM) in aqueous methanol at -13 ℃ (below the lower critical solution temperature, LCST). This was done to investigate the solubility of PINPAM in aqueous methanol by considering molecular interactions. Changes of NCE when adding PNIPAM to an aqueous methanol solution show that at the molar fraction of methanol x=1.0-0.90, PNIPAMpreferentially adsorbs methanol and at x=0.80-0.50, PNIPAMpreferentially adsorbs water. At x=0.50-0.20, PNIPAM breaks down the ring structure composed of two methanol molecules and one water molecule. Further comparison between the changes of NCE when adding PNIPAM and its monomer NIPPA indicates that PNIPAM adsorbs methanol cooperatively through hydrophobic interactions. This cooperative interaction breaks down the methanol-water ring structure at low methanol concentrations. The cononsolvency phenomenon of PNIPAM in a methanol solution when heating above the LCST temperature is attributed to a reformation of the methanol-water ring structure.

The silylation of thin-film glass sheets with hexamethyl disilazane results in hydrophobic glass surfaces with water contact angles larger than 90°. The adsorption behavior of Rhodamine 6G (R6G) and methylene blue (MB) molecules on the hydrophobic glass from the individual aqueous solutions were investigated by time-resolved optical waveguide spectroscopy and the experimental data were compared with those obtained using hydrophilic glass. The adsorption and desorption rate constants as well as the adsorption free energy for R6G adsorption on the silylated glass were determined by fitting the experimental data with the Langmuir isotherm model. Glass silylation leads to an increased adsorption rate constant, a decreased desorption rate constant, and an enhanced adsorption free energy as compared to those obtained for R6G adsorption on hydrophilic glass. The comparisons indicate that R6G and MB molecules prefer to adsorb onto hydrophobic glass over hydrophilic glass from aqueous solution. Moreover, it was observed that glass silylation can effectively prevent the aggregation of dye molecules at the water/glass interface.

Aggregation induced fluorescence blue-shift of the newly synthesized zinc bis (8-hydroxyquinoline) modified with cholesteryl (Zn(ChQ)2) is studied by static and picosecond transient emission spectroscopy. Fast solvent-induced charge transfer is found when Zn(ChQ)2 is dissolved in polar solvents. The twisted intramolecular charge transfer (TICT) state is formed as new emission state. Its emission spectra of Zn(ChQ)2 in aggregation form (film state) are blue-shifted compared to those in polar solvents. Steric hindrance induced weakened intermolecular interaction in aggregations lead to blue-shifted emission and enhanced quantum efficiency. Intermolecular energy transfer is found in solid filmand independent on emission wavelength.

A monomer of diarylfluorene containing triphenylamine and dialkylfluorene groups at the 9-position and its copolymers, TPAFF-co-F and TPAFF-co-P, were successfully synthesized by a Suzuki cross-coupling polycondensation to obtain stable and highly efficient blue light-emitting polymers. The dialkylfluorenes on the polyfluorene chain served as an antioxidant function as well as a shielding effect. Triphenylamine groups are favorable for hole-injection at the ITO/emitting-layer interface. The combination impart od thermal, morphological and spectral stabilities. Annealing experiments for 24 h in air at 200 ℃show that the sequence of green indexes (Igreen/Iblue) decreases as follows: poly(9,9-dioctylfluorene) (1.07)>TPAFF-co-F(0.65) >TPAFF-co-P (0.47). These results indicate that dialkylfluorene plays a role in the antioxidant function. Devices were fabricated with the following configuration: ITO/PEDOT:PSS(40 nm)/TPAFF-co-F or TPAFF-co-P(80 nm)/Ba(4 nm)/Al (120 nm). Preliminary results confirmed that they have stable electroluminescent spectra with Commission Internationale d'Eclairage (CIE) coordinates of (0.22, 0.24) at a current density of 547 mA·cm-2 for TPAFF-co-F and a CIE of (0.24, 0.26) for TPAFF-co-P with a maximumcurrent efficiency of 0.712 cd·A-1.

Problems associated with intrinsically destructive sensing mechanisms of organic field-effect transistors constitute one of the main obstacles to using them for the practical applications in sensing and switching. Here we report a smart system, in which a photochromic spiropyran (SP) combined with polymethyl methacrylate (PMMA) is used as a gate dielectric, to develop functional molecular devices capable of photoswitching their electrical conductivity in a noninvasive manner. Significant and reversible capacitance and current transitions in devices are generally demonstrated experimentally when the SP molecules under their documented reversible photoisomerization. This concept of conformation-induced capacitive coupling offers attractive new prospects for the development of functional devices by utilizing other stimuli-responsive molecular materials.

We have previously studied molecular fuzzy symmetry and mainly focused on the fuzzy point group symmetry and less on the fuzzy space group symmetry. As a kind of one-dimensional linear fuzzy periodic molecule, polyynes have been studied by us. Although the fuzzy symmetry of their molecular skeletons has been comprehensively investigated, the study of their molecular orbital (MO) has been limited to a fewtypical molecules because of the tedious calculations involved. In this work, we characterized the MO fuzzy symmetry of different kinds of polyyne molecules systematically and we found correlations between the fuzzy symmetry parameter of the MOs of the polyyne molecules and the number of carbon atoms. In addition, we also analyzed the MOs of related systems such as the cumulative polyene. Although their molecular structures are non-linear, the carbon atoms within the π-MO are linearly positioned and could still be analyzed using the fuzzy group G11. Finally, on the basis of the Born-Karman approximation (one-dimensional periodic symmetry group containing n units is isomorphic with the Cn point group), the symmetry and the fuzzy symmetry of the MOs of the full carbon ring molecules were investigated. We, therefore, endeavored to characterize the one-dimensional periodic fuzzy symmetry for these molecules.

The ion-pairs of the anionic surfactants (dodecyl sulfonate, dodecyl carboxylate) and the cations (Na+, Ca2+, Mg2+) were optimized using density functional theory (DFT) at the B3LY/6-31G level and the interaction between the surfactants and ions were studied at the molecular level. The results showed that: i) a 2:1 type of ion-pair was formed in which two oxygen atoms from the polar group in the surfactant bound with one ion; ii) the α-methylene nearest the headgroup should be classified as the part of the polar head because of its negative charge before ion bonding; iii) the charge of the α-methylene group can be converted from a weak negative into a weak positive charge by the cations, which decreased the effect of the polar headgroup. This calculation also showed that the tail chain had a weak positive charge in the micelle resulting in the core of the micelle having polarity. This core polarity of the micelle is somewhere between the oil phase polarity and the water phase polarity, which favors surfactant aggregation in solution.

Methyl arachidonyl fluorophosphonate (MAFP) is an inhibitor of the fatty acid amide hydrolase (FAAH). We studied the phosphonylation reaction of the serine241 (Ser241)-serine217 (Ser217)-lysine142 (Lys142) catalytic triad of FAAH by MAFP, which leads to the loss of FAAH enzyme activity. This theoretical study was carried out by employing the B3LYP/6-311G(d,p) and MP2/6-311G(d,p) methods through a simplified model. Two reaction pathways were considered. Path A is a two-step addition-elimination process of the FAAH catalytic triad and the first step (addition process) is the rate-determining step and involves a zwitterionic tri nal bipyramidal intermediate. In this reaction pathway, both Ser217 and Lys142 in FAAH contribute to the base-catalyzed activation of the nucleophile Ser241 while Ser217 serves as a bridge between Lys142 and Ser241. In addition, one of the solvent water molecules performs a key role to act as a“hydrogen bridge”connecting the Lys142 residue and MAFP by donating and accepting protons to promote long-range proton transfer. Path B (after mutation of the Lys142 residue to alanine) is also a stepwise process. The bulk effect of water as a solvent was considered via the polarizable continuummodel (PCM). The obtained results show that for this phosphonylation reaction, Path A is the most favorable mechanism with an activation free energy barrier of 64.9 kJ·mol-1 in aqueous solution. We also conclude that the mutation of the FAAH catalytic triad at the Lys142 residue decreases the rate of phosphonylation. This is in od agreement with the experimental observations.

Over the last half century, the overwhelming advances in biological sciences have been greatly aided by the physical and technological innovations, such as X-ray diffraction methods, nuclear magnetic resonance (NMR) and mass spectroscopy, etc. In recent years, single-molecule experiments have changed the way many biological problems are addressed. Knowledge fromthese experiments continues to emerge.We are nowable to followbiochemical reactions of a single enzyme molecule in real time, and monitor gene expression in a living cell on a single molecule basis. These new methodologies will likely revolutionize our understanding of biological systems for many years to come. In this review, we highlight the achievements in the past decade in the fields of single molecule enzymology, live cell studies of gene expression and DNA protein interactions, emphasizing on the work of Sunney Xie's laboratory.

Protein-protein interactions (PPI) play essential roles in biological processes. Understanding PPI from a structural, thermodynamic, and kinetic point of view gives us a better understanding about these building blocks of living systems. This review summarizes the recent progresses in PPI research, including the basic properties of the interfaces, different methods for the calculation of binding free energies, key determinants in the kinetic process of PPI, and successful examples of PPI design. Interfaces of specific biological protein complexes are distinct from non-specific crystal packing interfaces in many aspects, such as the interfacial size, the conservation of amino acid residues, and structural dynamic properties. Hotspots, hot regions, and modular structures can be found at the biological PPI interface. The binding free energy of PPI can be calculated using different approaches, such as MM-PBSA, potential of mean force, and various free energy models, based on structures of protein complexes. Various approaches and successes have been reported for new PPI design based on current knowledge, however, much needs to be done to further improve the manipulation of diverse PPI. We propose that the protein association/dissociation kinetic process should be considered in future PPI design studies, which may provide more options for the manipulation and engineering of PPI.

The slow dynamics of hydration water has long been recognized as a major determinant of protein stability, function, and folding. However, an atomic level mechanism is still lacking on the origin of the slow dynamics of hydration water and how it is involved in protein folding. Using forty 100-ns all-atom molecular dynamics simulations of the Trp-cage mini-protein as a case study, we analyzed the dynamics of hydration water in the protein folding process to explore the origin of the slow dynamics of hydration water in detail. During the folding process, even if the topological structure of the protein changed greatly, there were certain intermediate protein structures where the hydration water showed slow dynamics. By providing rich hydrogen bond connections and the advantage of a convex topology these structures enslave water molecules for very long time and we refer to these as“residence centers”. Residence centers are the possible origin of the slow dynamics of hydration water. Additionally, the distribution of residence centers is closely related to the folding process. In folded trajectories, the residues around the hydrophobic core form a main residence center. These results are helpful in explaining the origin of the slow water dynamics on protein surfaces and may provide some insight into further experimental study to probe important intermediate structures during the process of protein folding by capturing slowhydration water dynamics.

Many in vitro techniques have been employed to elucidate the interaction between DNA and protein. However, one of the most significant differences between in vitro and in vivo studies is that DNA fragments used for in vitro experiments are usually much shorter than genomic DNA. Therefore, several investigators have sought to examine the effects of linear DNA ends on DNA-protein interactions in different systems. Surprisingly, the various efforts have led to contradictory results. Here, we revisit this issue using the DNA-Mnt repressor interaction system. Using surface plasmon resonance (SPR), we monitor both the association and dissociation of the Mnt repressor with a series of DNA fragments. We conclude that Mnt repressor dissociation from DNA near the ends occurs faster than that frominternal positions. In addition, we find that proximity to the end can directly influence protein-specific binding for binding sites near the end.

The amyloid fibrillization of proteins and peptides is related to many human diseases including Alzheimer's disease. Currently there is no effective therapy for these diseases, because the mechanism of the amyloid fibrillization is still not clear. Understanding how to effectively inhibit amyloid formation will shed light on the prevention and treatment of these diseases. Transtheritin (TTR) and itsmutants easily formamyloid fibrils and are related tomany diseases.MjHSP16.5, a small heat shock protein (SHSP) from Methanococcus jannaschii shows high chaperone-like activity under acidic conditions, and these conditions promote the fibrillization of many peptides. We studied the influence of Mj HSP16.5 on the fibrillization of the peptide WTTR (sequence: WYTIAALLSPYS, i.e., the 105-115 fragment of TTR with a tryptophan added to its N-terminal). Mj HSP16.5 was found to significantly inhibit the growth and maturation of the WTTR fibrils resulting in much thinner fibrils compared to those under normal conditions. More interestingly, Mj SHSP16.5 can dissociate the matured WTTR fibrils. Based on our experimental results, a possible inhibition mechanismwas proposed in which Mj SHP16.5 interacted with WTTR fibrils and/or seeds.

Purple photosynthetic bacterium Thermochromatium (Tch.) tepidum is a moderate thermophile growing in an optimal temperature range of 48-50℃. Its light-harvesting complex 2 (LH2) possesses heterogeneous compositions of apoprotein and carotenoid (Car), but the high-resolution crystallographic structure remains unknown. We have attempted an ultrafast time-resolved spectroscopic study of the isolated LH2 complex from Tch. tepidum. The spectral dynamics and population kinetics of n-dodecyl-β-D-moltoside (DDM) and lauryldimethylamine oxide (LDAO) preparations of LH2 reveal efficient S2-state mediated Car-to-Car and Car-to-bacteriochlorophyll (BChl) singlet excitation energy transfer (EET) occurring in a time scale of ~100 fs, as well as the Qy-state mediated B800-to-B850 singlet EET for the DDM preparation proceeding with a time constant of ~1.2 ps. These ultrafast EET processes suggest that the Cars with 11 and 12 conjugated C=C double bonds (NC=C) coexist in the LH2 complex, and that the B800-B850 mutual orientation in LH2 differs considerably from those in the LH2s from some of the previously investigated bacterial species. In addition, anhydrorhodovibrin (NC=C=12) as a minor Car composition is found to act as an efficient trap of excitation energy, which is considered to be an important photoprotection mechanism. Furthermore, based on the results of ultrafast Car band shift in response to BChl excitation, we propose that, compared to other Car compositions, (OH-)spirilloxanthin (NC=C=13) locates in closer proximity to BChl. Our results may facilitate to understand the light-harvesting and the photoprotection mechanisms of Tch. tepidum living under harsh natural conditions.

Luminescent nanoparticles (dav=35 nm) of Eu(tta)3dpbt (dpbt= 2-(N,N-diethylanilin-4-yl)-4,6-bis (3,5-dimethylpyrazol-1-yl)-1,3,5-triazine, tta=thenoyltrifluoroacetonato) protected by bovine serum albumin (BSA) were prepared by a precipitation method. These particles disperse well in aqueous solutions to form stable and transparent colloidal solutions. The BSA-protected Eu(tta)3dpbt nanoparticles exhibit high photostability and excellent long-wavelength sensitized EuIII luminescence properties. The quantum yield of EuIII luminescence is 0.20 (λex=415 nm, 25 ℃), and the excitation band for the EuIII luminescence centers at 415 nm and extends to 470 nm. Upon two-photon excitation, the prepared nanoparticles emit pure-red light with a two-photon excitation action cross section of 2.4×10⁵ GM (λex=830 nm, 1 GM=10^-50 cm4·s·photo^-1·particle^-1). The prepared nanoparticles and the reported preparation method are promising for the development of luminescent bionanoprobes with excellent biocompatibility and luminescent properties.

We report the controlled fabrication of Ni nanotube and nanowire arrays by electrodeposition using anodic aluminum oxide (AAO) as a template. Ni nanotube arrays or nanowire arrays were obtained by changing the concentration of the electrolyte and the overpotential of the electrodeposition. The introduction of chelating species is crucial for nanotube formation because they can regulate the effective concentration of the electrolyte. A possible mechanism for the formation of the nanotubes/nanowires is proposed by considering the different contributing factors for the growth rate of the wall (Vw) and that of the bottom (Vb). Ni nanotube arrays can be obtained when Vw>Vb either at a high electrolyte concentrations (CNi2+) and at a more negative electrodeposition potential (Ued) or at a lower CNi2+ with a less negative Ued. Ni nanowire arrays can also be obtained when Vw≈Vb either at a high CNi2+ with a less negative Ued or at a lower CNi2+ with a more negative Ued. This mechanism may be used as a general strategy for the controlled synthesis of nanotube or nanowire arrays containing many kinds of metals such as Cu, Co, and Au etc.

Using tetraethylorthosilicate (TEOS) as a silicon source and tetrapropylammonium hydroxide (TPAOH) as a structure-directing agent, we prepared highly b-oriented silicalite-1 thin films with smooth surfaces and excellent continuity by optimizing the preparation parameters such as the gel composition and reaction time. The influence of gel composition and substrate surface roughness on the orientation, size, and distribution of the microcrystals in the silicalite-1 thin films were investigated. We achieved highly orientated silicalite-1 crystal growth on the substrates as well as excellent control of crystal size and filmmicrostructure. The preparation procedure reported here is feasible and has excellent reproducibility. In addition, the thin films were further characterized by scanning electron microscopy (SEM) and X-ray diffraction (XRD).

We successfully prepared ZnO thin films through spin-coating a mixture of zinc acetate dihydrate, poly(ethylene oxide) (PEO) and deionized H2O. Smooth and pure ZnOthin films were obtained by using PEO, because of its low thermal decomposition temperature. The morphology, crystallinity, band gap energy (Eg), and conductivity of the ZnO thin films annealed at different temperatures were determined. Atomic force microscopy (AFM) showed that the rootmean square (rms) surface roughness of films annealed at 400, 450, and 500 ℃ was 3.3, 2.7, and 3.6 nm, respectively. TEMimages showed that the ZnOfilms were composed of ZnOnanocrystals. The band gap energy (Eg) for the films was calculated as 3.3 eV from the absorption edge at 373 nm. From their current-voltage (I-V) curves the resistivities of ZnO thin films annealed at 400, 450, and 500 ℃ were calculated as 3.3×109, 2.7×109, and 6.6×109 Ω·cm, respectively. High annealing temperature is useful in improving purity and density of the film and increasing adsorbed oxygen on the film. The film with high purity and density will exhibit low resistivity. The film with more adsorbed oxygen will exhibit high resistivity, due to higher grain boundary barrier. Consequently, the ZnO thin film annealed at 450 ℃ exhibited the lowest resistivity, while the ZnO thin filmannealed at 500 ℃ had the highest resistivity.

N-carboxyl propionyl chitosan sodium (CPCS) was used to reinforce chitosan (CS) rods by an in-situ precipitation method. Fourier transforminfrared (FTIR) spectroscopy, X-ray diffraction (XRD), thermogravimetric (TG) analysis, scanning electron microscopy (SEM), and mechanical test were used to study the properties of the composite rods. The FTIR spectra confirmed that the amino and acetamido groups on CS had a strong electrostatic attraction to the carboxylate groups on CPCS. The XRD patterns showed that the crystals in CS were destroyed because of the addition of CPCS. The thermal stability of the CPCS/CS composite rods was better than those of pure CS rods and pure CPCS as a strong interaction exists between CS and CPCS molecules. The layer-by-layer structure of the CPCS/CS composite rods became tighter compared with that of pure CS rods, which resulted in improved mechanical properties for the composite rods. As 15% (w) CPCS in the composite rods, the bending strength and the bending modulus were 156.0 MPa and 5.3 GPa, which increased by 68.8% and 29.3% compared with that of pure CS rods, respectively. Therefore, CPCS reinforces CS rods effectively and these composite rods with excellent mechanical properties can be used in novel biomedical devices to fix the bone fracture.