Molecular electronics has become an important research field in the past decade, and molecular devices can be used as molecular wires, switches, rectifiers, and transistors etc. Construction of metal/molecule/metal (MMM) junctions is the most effective method for investigating the charge transport properties of molecular devices. However, the measurement of individual molecule junctions at the nanoscale is still very challenging because of many technical difficulties. This paper reviews the recent progress and the challenges in the measurement of single molecule conductance, and summarizes investigation of the charge transport mechanism.

We have developed a new empirical model, namely XLOGS, for computing aqueous solubility (logS) of organic compounds. This model is essentially an additive model, which employs a total of 83 atom/ group types and three correction factors as descriptors. Furthermore, it computes the logS value of a query compound by using the known logS value of an appropriate reference molecule as a starting point. XLOGS was calibrated on a training set of 4171 compounds with known logS values. The squared correlation coefficient (R²) and standard deviation (SD) in regression were 0.82 and 0.96 log units, respectively. The entire training set was further split into one subset containing liquid compounds only and another subset containing solid compounds only. Regression results of XLOGS were obviously better on the former subset (SD=0.65 vs 0.94 log units). The difference between log1/S and logP (partition coefficient, the ratio of concentrations of a compound in a mixture of water and n-octanol at equilibrium) was used as an indicator to investigate the performance of XLOGS on liquid compounds and solid compounds. Our results suggested that an additive model like XLOGS performed most satisfactorily when this difference was close to zero. Three other logS models, including Qikprop, MOE-logS, and ALOGPS, were also compared with XLOGS on an independent test set of 132 drug-like compounds. Put together, our study provides some general guidance for applying additive models to computation of aqueous solubility.

The ionic strength dependence of DNA mediated charge transport was studied on a DNA binding polyamide-modified electrode by the electrochemical method. The differential pulse voltammetry (DPV) peak potential of [Ru(NH₃)₆]³⁺ shifted negatively with the increase of support electrolyte concentration. Linear relationship between peak potential and ionic strength in the solution was found at the range of moderate salt concentration, which can be interpreted with Debye-Hückel theory using formal potential as a “bridge” linked experiments results and theoretical calculated values. Under high salt concentration this linear relationship deviated from Debye-Hückel theory prediction due to its range of validity is overstep. Without added salt in the solution, fully charged DNA duplex will strongly attract the probe molecule [Ru(NH₃)₆]³⁺ to the broadened p-stack of a DNA-polyamide complex, which facilitated DNA mediated charge transport.

We report the preparation, characterization and elelctrocatalytic properties of a novel nanocomposite cathode catalyst (TiOPc-Pt/NSWCNH) which is assembled using Pt nanoclusters, TiOPc nanocrystal, and nitrogen-doped single walled carbon nanohorns (NSWCNHs) as building blocks. TiOPc-Pt/NSWCNH is characterized by inserting most of the Pt nanoparticles in nano-networks formed by stacking of NSWCNHs, and contacting of a part of the Pt nanoparticles with TiOPc nanocrystals. TiOPc-Pt/NSWCNH exhibits high electrocatalytic activity, excellent selectivity and durability for oxygen reduction reaction (ORR) in the presence of methanol. In an O₂-saturated HClO₄ aqueous solution containing methanol (0.5 mol·L^-1), the onset potential over the TiOPc-Pt/NSWCNH catalyst shifted by more than 260 mV toward positive relative to that over a commercial Pt/C-JM catalyst. The mass activity and specific activity for ORR over TiOPc-Pt/NSWCNH at 0.85 V (versus a reversible hydrogen electrode (RHE)) was 83.5 A·g^-1 and 0.294 mA·cm^-2, respectively, which were much higher than those of Pt/C-JM. Cyclic voltammetry accelerated aging tests (0.6-1.0 V for 15000 cycles) in an O₂-saturated HClO₄ aqueous solution containing methanol revealed that TiOPc-Pt/NSWCNH possessed a higher durability compared to TiOPc-Pt/C. The high methanol tolerance of TiOPc-Pt/NCNH may be mainly derived from the electron transfer from TiOPc nanocrystals to Pt nanoparticles. The nano-network and the high graphitization degree of NSWCNHs are responsible for the excellent durability of TiOPc-Pt/NSWCNH.

Carbon microtubes (CMTs) were prepared by the carbonization of poplar catkins according to their natural microtubular structure. The CMTs were then used as the substrate for growing carbon nanotubes (CNTs) by chemical vapor deposition. The prepared three-dimensional CMT/CNT composites were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), and Raman spectroscopy. Two-electrode supercapacitor cells constructed with the CMT/CNT showed a specific capacitance of 77 F·g^-1 with 1 mol·L^-1Li₂SO₄ electrolyte, which is much higher than that for CMTs (23 F·g^-1).

TiO₂ nanocrystals were synthesized using a sol-gel method, and then the impregnation technique was used to modify the surface of the TiO₂ nanocrystals with FeO(OH). The optimal concentration of Fe³⁺ for the modification of the TiO₂ nanocrystals was determined by UV-Vis spectroscopy. A cobalt-phosphate (CoPi) water oxidation catalyst was electrochemically deposited onto the FeO(OH)- TiO₂ photoanodes. The resulting FeO(OH)-TiO₂/CoPi composite photoanodes were systematically characterized by transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM), X-ray diffraction (XRD), and scanning electron microscopy (SEM), and the photoelectrochemical water oxidation properties of the FeO(OH)-TiO₂/CoPi composite photoanodes were investigated in neutral conditions by electrochemical and photoelectrochemical methods. The results indicated that the TiO₂ particles were pure anatase nanocrystals, and the FeO(OH) phase on the TiO₂ surfaces was ethite. The optimal light absorption properties of the FeO(OH)-TiO₂ photoanodes were achieved when the photoanodes were prepared in the precursor solution with a Fe³⁺:TiO₂ mass ratio of 0.05%. The overpotential for oxygen evolution on the FeO(OH)-TiO₂/CoPi composite photoanodes under illumination decreased significantly compared with that obtained on the CoPi catalyst. The high oxygen evolution activity of the composite photoanodes can be attributed to modification of FeO(OH) on TiO₂ nanocrystal surfaces changing the light absorption band from the ultraviolet to the visible region and CoPi inhibited hole-electron recombination through facilitating the photon-induced hole transfer for water oxidation.

The present work investigates the use of synergistic interactions between zwitterionic and anionic surfactants to obtain ultra-low interfacial tension (IFT) in a high salinity reservoir. Zwitterionic surfactant N-hexadecyl-N,N-dimethyl-3-ammonio-1-propanesulfonate was found to be compatible with simulated high salinity water, reducing crude oil/water interfacial tension to a magnitude of 10^-2 mN·m^-1 in a surfactant concentration range of 0.07%-0.39% (mass fraction), whereas ultra-low IFT was obtained by adding anionic surfactant sodium dodecyl sulfate. Furthermore, the effects of total surfactant concentration, metal ion concentration, and molar ratio on the dynamic interfacial tension of zwitterionic/anionic surfactant mixtures were studied. Results showed that 10^-5 mN·m^-1 magnitude ultra-low IFT was obtained over a wide range of surfactant concentrations from as low as 0.04% and up to 0.37% in high salinity water. The synergistic mechanism of ultra-low IFT formed in zwitterionic/anionic surfactant systems was further analyzed.

Fluorescent microcapsules based on coordination supramolecular polymers of rare earth metal ions were prepared via a layer-by-layer technique that used electrostatic interaction. The holes in the capsule walls were very small, which reduced leakage of small molecular payloads. The capsules remained intact at salt concentrations as high as 500 mmol·L^-1, which shows they have potential in practical applications. Multicolored capsules were obtained simply using a mixture of terbium and europium ions.

Temperature-promoted hydrogel formation was investigated in a mixed solution of sodium cholate and metal ions. Transmission electron microscopy (TEM) was used to characterize the morphology of the microstructures of the hydrogels, and nanofibers were observed. The arrangement of the cholate and metal ions was proposed according to the X-ray diffraction (XRD) measurements. Rheological measurements revealed that the strength of the hydrogels increases with increasing temperature, while the fluorescence of the gels increased as well. Increasing the temperature also increased the gel formation rate. The critical micelle concentration of sodium cholate solution decreased slightly with increasing temperature. On the basis of the experimental results, we propose that the increased hydrophobicity of cholate ions with increasing temperature leads to stronger hydrogen bonding between cholate ions, which accounts for the unique heating-enhanced gelation behavior.

Conducting polymer hydrogels based on alkoxysulfonate-functionalized poly(3, 4-ethylenedioxythiophene) have been synthesized via oxidative coupling polymerization. Formation of hydrogels from zero dimensional (0D) monomer micelles to three dimensional (3D) hydrogels with two dimensional (2D) nanosheets as the building blocks and dimension change of the building blocks of the resulting hydrogels from 0D nanoparticles to 2D nanosheets induced by altering the reaction temperature or initial monomer concentration have been disclosed. A synthetic strategy for the synthesis of the conducting polymer hydrogels based on simultaneous use of one chemical as an oxidant and one multivalent metal ion as an ionic crosslinker has been developed, and metal ions used have significant effect on the morphology of the resulting hydrogels. In addition, the as-prepared conducting polymer hydrogels possess od electrochemical capacity, and exhibit selective adsorption and controllable release towards some dye molecules.

Methanol is an important platform molecule for the production of energy and chemicals. For its efficient utilization, it is of critical significance to clarify the relationship between the structures of the catalysts and their performance as well as the corresponding reaction mechanisms. In this review, we summarized some recent progress in the understanding of the active structures of several metal oxide-based catalysts and the reaction mechanism, and the consequent tuning of their redox and acid sites for the selective oxidation of methanol. The catalysts included supported molybdenum oxides, supported vanadium oxides, and heteropolyacids with Keggin structures as well as rhenium oxides and ruthenium oxides recently explored for the methanol oxidation. Such progress provides insights into the design of novel catalysts more efficient for the oxidative conversion of methanol towards the targeted products.

Many organic compounds will spontaneously disperse on the surface of a solid support to form monolayers, in a manner similar to that of inorganic salts and oxides, and numerous materials with useful properties can be designed and prepared based on this phenomenon. The dispersion behavior and orientation of organic compounds in monolayers depend not only on the molecular structure of organic compounds but also on the surface features and pore structure of the support. This short review summarizes the applications of monolayer-dispersed organic compounds in the preparation and texture control of related materials, including carbon/oxide composites, various other oxides, and mesoporous carbon with thin pore walls. Pyrolysis of organic monolayers can be used to prepare carbon/oxide composites with a uniformly thin carbon layer for use as photocatalysts, catalyst supports, and adsorbents for dyes. During the sol-gel preparation of porous oxides, organic monolayers can also prevent the aggregation of sol particles, thus producing oxides with high specific surface areas and adjustable pore volumes; γ-Al₂O₃ with a specific surface area as high as 506 m²·g^-1 can be prepared in this manner. During calcining under an inert atmosphere, the carbon layer in the aforementioned carbon/oxide composites can significantly inhibit the phase transformation of oxides. Calcining carbon/γ-Al₂O₃ in oxygen at high temperatures, however, results in a rapid γ to α phase transformation. The oxides in these composites can also act as templates for the preparation of carbon materials. Dissolving the support oxides is a convenient method for the preparation of mesoporous carbon materials with high specific surface areas, large pore volumes, high mesopore ratios, and thin pore walls. The morphology and size distribution of pores in these carbon materials can be controlled by choosing oxides with different textures.

g-C₃N₄photocatalysts were synthesized by copolymerization of diaminomaleonitrile (DMNA) with dicyanodiamide (DCDA) at high temperatures. The effect of copolymerization on the crystal structure, chemical structure, band structure, texture, optical property and photocatalytic performance of g-C₃N₄ was studied by such characterization techniques as X-ray diffraction patterns (XRD), Fourier transformed infrared (FT-IR), transmission electron microscopy (TEM), nitrogen-sorption (N₂-sorption),electron paramagnetic resonance (EPR), UV-Vis diffuse reflectance spectra (UV-Vis DSR) and photoluminescence (PL) analyses. Results demonstrated that the graphitic-like layer packing structure of g-C₃N₄ remained unchanged after the modification; however the copolymerization with DMNA can efficiently extend the delocalizationof π-electrons and induce the formation of surface junctions, greatly enhancing the light-harvesting abilityof g-C₃N₄ in visible light region and promoting the separation of photogenerated charge carriers, respectively. Photocatalytic performance showed that all DMNA-modified samples presented an enhanced H₂ evolution activity under visible light irradiation. The optimized weight-in amount of DMNA is found to be 0.01g, by which the modified sample shows the highest hydrogen evolution rate of 45.0 μmol·h^-1. This value is 4.5 times as high as that of the unmodified carbon nitride sample.

Dioxane lignin, a typical organosolv lignin, was degraded by supported noble metal catalysts and phosphoric acid by a two-step method at different temperatures. The results showed that under 4 MPa H2 at 270 ℃ using Rh/C and 1% (w) phosphoric acid as catalysts, the highest total yield of the monomers and dimer was 16.9% after the first step, based on gas chromatography (GC) and gas chromatographymass spectrometry (GC-MS) analyses. Moreover, the raw products from the first step were analyzed by Fourier transform infrared (FTIR) spectroscopy, X-ray photoelectron spectroscopy (XPS), element analysis (EA), and gel permeation chromatography (GPC) to improve the understanding of the chemical transformations involved. The results indicated that the C－O－C bond linkages in the dioxane lignin were cleaved to form lower molecular-weight products, resulting in the degradation of lignin, and the carbonyl and carboxyl groups were partly removed. Oxygen content was reduced dramatically with increasing reaction temperature, from 35% (w) to 21% (w) after reacting at 270 ℃ for 10 h. Based on the analysis results, a reaction pathway for the degradation of lignin was proposed. Finally, the products from the first step could be hydrodeoxygenated to alkanes with carbon numbers in the range of gasoline and diesel with high selectivity catalyzed by Pd/C and phosphoric acid at 250 ℃.

The conversion of xylose to furfural normally involves two steps: the isomerization of xylose to xylulose catalyzed by an enzyme, a base or a Lewis acid, followed by the acid-catalyzed dehydration of xylulose to furfural. To allow a more efficient single-step conversion, a new water-tolerant solid acid catalyst, mesoporous niobium phosphate was synthesized. This synthesis was performed using a soft template approach, with cetyltriethylammonium bromide (CTAB) as the template. The structure and properties of the catalyst thus synthesized were investigated by X-ray diffraction (XRD), N₂ sorption, transmission electron microscopy (TEM), temperature-programmed desorption of NH₃ (NH₃-TPD), and pyridine sorption FTIR (Py-FTIR). These studies determined that the niobium phosphate not only had a large surface area (>200 m²·g^-1) and narrow pore size distribution (3.5 nm), but also had relatively strong Lewis and Brønsted acidity. This catalyst was found to be capable of producing furfural via a simple one-pot process, including the isomerization of xylose to xylulose and subsequent dehydration. The influence of several variables including temperature, mass ratio of xylose/catalyst, and reaction time on the extent of xylose conversion and furfural yield were studied. Under optimal conditions, the yield of furfural in aqueous solution reached 49.8% with 96.5% xylose conversion. It was further determined that both the yield and the separation of furfural could be improved by employing a methyl isobutyl ketone (MIBK)/water (volume ratio 7:3) biphase containing NaCl in the aqueous phase, resulting in a 68.4% yield.

Using graphene-enhanced Raman scattering, the Raman signals of molecules attached to graphene can be obtained. For different molecules and vibrational modes, the enhancement factors are different. Here, we have investigated the variation in the adsorption behavior of lead phthalocyanine (PbPc) Langmuir-Blodgett (LB) films on graphene under annealing using Raman spectroscopy. With increasing annealing temperature, it was found that the Raman intensity of the PbPc molecules first increased and then decreased. At the sublimation temperature, the enhanced Raman signal was the strongest, indicating that the orientation of the PbPc molecules had changed from perpendicular to parallel to the graphene surface. As the annealing temperature was increased towards the sublimation temperature, some vibrational modes with low Raman scattering cross-section appeared, and they were enhanced at higher temperatures. This indicates that the PbPc molecules are deformed due to π-π interactions with graphene, and change their structure from nonplanar to planar. When the annealing temperature was increased even further, some new vibrational modes appeared, which can be attributed to the reduction of Pb(II) to Pb(0) in the PbPc molecules.

Protein-protein interactions are the essential events in life at the molecular level. The three-dimensional structures of protein-protein interactions provide clear pictures for the molecular details of various cellular processes. Understanding the basics of protein-protein interaction provides clues for revealing the secret of life, and useful information for designing proteins for various application purposes. The present review summarizes recent progresses of protein-protein interaction prediction, design, and modulation study, briefly introduces the progresses in the authors' group, and discusses future directions of the field. Protein-protein interaction network analysis, protein-protein interaction principles, and computational analysis of interfaces are briefly reviewed first. Methods and progress for predicting protein-protein interaction at sequence level, interaction-site level, and complex-structure level are given. Based on the knowledge about the nature of protein-protein interactions, protein-protein interaction design and modulation can be done on purpose. We give a summary of three kinds of protein-protein interaction design methods: redesign, grafting, and de novo, and three kinds of protein-protein interaction modulation methods using small molecules: direct competition, allosteric modulation, and stabilization. Protein design approaches for potential therapeutic applications targeting protein-protein interactions are also discussed.

Protein de novo design and protein folding are two different means to investigate“sequencestructure- function”relationship of proteins, which is one of the most important focuses in structural biology. The successful achievements in protein de novo design indicate the understanding accuracy of the knowledge in protein structure and interaction, while most of those designed proteins show different folding kinetic features from nature occurring proteins, which implies that there are still many challenges to the aim of getting them to play expected biological function. In this review, the status of research and development for protein de novo design, as well as the study progress of protein folding in experimental, theoretical and simulation aspects, have been introduced. Further, the investigations of folding mechanism of de novo designed proteins have been reviewed, and the new clue has been proposed that systematically investigation of the essence of different folding mechanism between the two types of protein would help to provide useful insight for more efficient protein rotational design.

RNA-protein interactions play key roles in many biological processes. The three dimensional (3D) structure of protein-RNA complexes can be determined experimentally by structural biologists. The recognition between protein and RNA can be understood from the 3D atomic structure. However, the structure determination of protein-RNA complexes by experimental methods is often difficult and costly, and limited to the binding strength. Thus, the prediction and design of protein-RNA complex structures is important in biological medical research. In this review, we will discuss the recent progress in protein-RNA interface prediction and design, which includes the following aspects: (1) protein-RNA docking and the conformational change on binding; (2) the recognition mechanism of protein-RNA binding; (3) the molecular design based on the protein-RNA interface. Improvement of the protein-RNA docking al rithm will help us annotate a large number of proteins and RNA with unknown function, and molecular design based on macromolecular interactions will be useful in drug design.

With the development of computer technology and software for molecular modeling, virtual screening plays an important role in drug discovery. In the flow of virtual screening, high quality compound libraries used are essential for success. In this paper, we analyzed two known drug libraries, a natural product library, compounds from plants used for traditional Chinese medicines (TCM), two frequently used commercial libraries, and a compound library in home. Features of these libraries were extracted and compared for molecular diversity, chemical space, and molecular scaffolds. We found similarities between drugs and the compounds used for TCM, which indicates TCM could be useful for virtual screening. These results aid understand of the chemical characteristics used in virtual screening libraries.

SARS coronavirus main protease (M^pro) is a key enzyme involved in the extensive proteolytic processing of the virus? polyproteins. The crystal structure of M^pro reveals that the enzyme exists in two different homo-dimeric forms: a three-dimensional (3D) domain-swapped form; and a non-3D domain-swapped form. The isolated C-terminal domain (M^pro-C) also forms a 3D domain-swapped structure similar to the full-length protein. Unlike conventional 3D domain-swapped structures, in which the swapped regions are located on the surface, M^pro-C swaps a helix at the core of a folded domain. In this work, we used molecular dynamics simulations and 3D domain-swapping predictions to investigate how a highly buried core helix in the helix bundle structure of M^pro-C can be swapped. We found that both structure- and sequence-based methods failed to predict the location of the hinge loop in M^pro-C and M^pro. Extensive molecular dynamics simulations were performed to investigate the structural properties of the unfolded monomer and the 3D domain-swapped dimer of M^pro-C. We found that, although the swapped region was buried in the native state, it was exposed in the unfolded monomer. Our results suggest that the opening of the swapped region in the fully or partially unfolded state may promote interactions between monomers and the formation of domain-swapped dimers.

The 1-(2-naphthlmethyl) isatin-5-formamide compounds can inhibit SARS-3CL proteinase by binding to its substrate pocket, while the N-terminal octapeptide of SARS-3CL proteinase was found to act as a dimerization inhibitor. In this work, the dual functional inhibitors which can occupy both substrate pocket of SARS-3CL proteinase and its dimer interface were designed. Six title compounds were tten by linking 1-(2-naphthlmethyl) isatin-5-formic acid and N-terminal octapeptides using a polyglycine linker through solid-phase peptide synthesis method. The in vitro inhibition activity against SARS-3CL proteinase was measured by continuous colorimetric assay using colorimetric substrate. Compound 3 showed the highest inhibition activity with an IC₅₀ (half maximal inhibitory concentration of a substance) of 3.8 μmol·L^-1. The change of inhibition activity with the linker length was studied. Inhibitors with the even spacers were showed better activity than the odd ones, which could be explained by the angle restriction of peptide bonds. The modulating of the aggregation state and enzyme activity towards SARS-3CL proteinase were studied using sedimentation velocity experiments. Compound 3 was found to not only inhibit the enzyme activity of SARS-3CL proteinase, but also shift the monomer-dimer equilibrium of the enzyme. The integrated control result is inhibiting SARS-3CL proteinase dimer formation. This work provides an example of using synthesized compounds to study enzyme activity regulation mechanism.

Three-dimensional (3D) topological insulators are a new state of quantum matter that are insulating in the bulk but have current-carrying massless Dirac surface states. Nanostructured topological insulators, such as quasi-two-dimensional (2D) nanoribbons, nanoplates, and ultrathin films with extremely large surface-to-volume ratios, distinct edge/surface effects, and unique physicochemical properties, can have a large impact on fundamental research as well as in applications such as electronics, spintronics, photonics, and the energy sciences. Few-layer topological insulator nanostructures have very large surface-to-volume ratios that can significantly enhance the contribution of exotic surface states, and their unique quasi-2D geometry also facilitates their integration into functional devices for manipulation and manufacturing. Here, we present our recent results on the controlled growth of quasi-2D nanostructures of topological insulators, as well as their novel functional devices. High quality quasi-2D nanostructures of Bi₂Se₃ and Bi₂Te₃ topological insulators have been synthesized by vapor-phase growth. Ultra-thin nanoplates of the topological insulators with uniform thickness down to a single layer have been grown on various substrates, including conductive graphene. A facile, high-yield method has been developed for growing single-crystal nanoplate arrays of Bi₂Se₃ and Bi₂Te₃ with well-aligned orientations, controlled thickness, and specific placement on mica substrates by van der Waals epitaxy. A systematic spectroscopic study, including angle-resolved photoemission spectroscopy (ARPES), micro-Raman spectroscopy, and micro-infrared spectroscopy, was carried out to investigate the quasi-2D nanostructures of topological insulators. Pronounced Aharonov-Bohm (AB) interference effects were observed in the topological insulator nanoribbons, providing direct transport evidence of the robust, conducting surface states. Transport measurements of a single nanoplate device, with a high-k dielectric top gate, showed a significant decrease in the carrier concentration and a large tuning of the chemical potential with electrical gating. We also present the first experimental demonstration of near-infrared transparent flexible electrodes based on few-layer topological insulator Bi₂Se₃ nanostructures that was epitaxially grown on a mica substrate by van der Waals epitaxy. Topological insulator nanostructures show promise as transparent flexible electrodes because of their od near-infrared transparency and excellent conductivity, which is robust against surface contamination and bending. Our studies suggest that quasi-2D nanostructures of topological insulators show promise for future electronic and optoelectronic applications.

There has been considerable focus on the synthesis of metal oxide nanostructures because of their extensive structures, unique properties, and wide applications. The morphological control of metal oxide nanostructures is of interest for tuning their performance and expanding their range of applications. Electrochemical methods have become a common way of controlling the morphologies of metal oxides, owing to their simple operation, ease of control, and flexible modes. This paper presents a brief overview of our research in the electrochemical synthesis and morphological control of metal oxide nanostructures. We will also discuss the crystal growth mechanism and the morphology control of different metal oxides during the electrochemical deposition process, which lays the foundation for orientation design and fabrication of functional materials.

Based on the solution post-synthesis method, we reviewed the process in the separation techniques of single-walled carbon nanotubes (SWCNTs) with single electrical type and chirality. We demonstrated the separation mechanism of SWCNTs by the different methods and comparatively pointed out their merits and disadvantages in purity, efficiency, cost, and scalability etc. Furthermore, some prospects for future study and application were proposed.

Recently, chemical vapor deposition (CVD) has been widely applied to the large-scale synthesis of graphene on various metal substrates. As a powerful and direct imaging method, scanning tunneling microscopy (STM) has been used to study the microscopic morphologies of graphene on metal substrates, for the purpose of further optimizing the growth parameters. This review presents the recent progress in the controlled growth of graphene on Cu foils, Pt foils, and Ni substrates, as well as the research of the microscopic morphologies, defect states, and stacking orders of graphene. Monolayer growth of graphene on Cu and Pt foils follows a surface catalyzed growth mechanism, while bilayer graphene growth follows an epitaxial growth mechanism. After the formation of a bilayer, the corrugated substrate breaks the planar conjugated π bonds of graphene, inducing a binding configuration change from sp² to sp³. Then, pristine wrinkles are introduced by the thermal expansion mismatch between graphene and the metal substrates. Finally, the roughness of graphene on the Pt foils is considerably less than that of graphene on Cu foils, and the multifaceted interweaving Pt substrate has almost no effect on the in-plane continuity of graphene.

The single atom thick sp² carbon structure of graphene gives rise to its unique properties and potential applications. However, one serious obstacle for its application is that graphene is prone to aggregate in suspension and gradually stack into graphite. Here, we report a novel approach to solve this problem. The basic idea is to introduce sp² carbon nano-islands on the graphene sheets that act as permanent ripples to prevent the stacking and graphitization of graphene and make it easy to re-suspend. Unlike most functionalization methods, this approach avoids the introduction of heteroatoms. Thus, it does not deteriorate the structure and change the properties of graphene. The carbon-rippled graphene has a remarkable electronic conductivity of ~65000 S·m^-1, and can be readily suspended in solvent.

We have designed and synthesized a new class of spiropyran derivatives (SP1-SP4) with functional chelating groups, such as pyridine or quinoline moieties and a methoxy group (―OMe), for use in metal ion sensing and information processing at the molecular level. It is notable that metal ions can favor coordination with chelating groups and facilitate the photoisomerization of spiropyran molecules from the closed form to the open merocyanine form without UV irradiation, thus leading to significant changes in their chemical and physical properties. UV-Vis absorption studies indicated that SP2 and SP4 exhibited metal ion-dependent reversible binding affinities that result in different hypsochromic shifts for the MC-Mⁿ⁺ complexes. These changes in color can be recognized by eye, thus offering an easy colorimetric method for metal ion detection. Further emission studies distinguished them as promising candidates for Zn2+ detection with od sensitivity and selectivity. Moreover, on the basis of their absorption and fluorescence spectra, several combinational logic gates were constructed for information processing at the molecular level. These results demonstrate that spiropyran derivatives with desired functionalities show great potential not only for chemical or environmental sensors, but also for future molecular computing.

Luminescent nanospheres (EuPHS, d_av=45 nm) containing 40% (w) of Eu(tta)₃dpbt (tta= thenoyltrifluoroacetonato;dpbt=2-(N,N-diethylanilin-4-yl)-4,6-bis(3,5-dimethylpyrazol-1-yl)-1,3,5-triazine) were prepared by encapsulating Eu(tta)₃dpbt in a hybrid matrix formed in situ from poly(styrene-co-methyl methacrylate), octyltrimethoxysilane, and poly(octylsiloxane). The EuPHS are promising luminescent markers for bioanalysis because of their od dispersibility in aqueous solutions, high photostability, low cytotoxicity, and bright Eu³⁺ luminescence under excitation at long wavelengths. EuPHS exhibited excellent visible light-sensitized and near-infrared two-photon-sensitized Eu³⁺ luminescence properties, with a visible-light excitation peak at 415 nm and an excitation window extending up to 475 nm. The quantum yield for Eu³⁺ luminescence was 0.31 (λ_ex=415 nm, T=23 ℃), and the two-photon excitation (TPE) action cross section was 5.0×10⁵ GM (1 GM=10^-50 cm⁴·s·photo^-1×particle^-1) at 830 nm. Bionanoprobes prepared by adsorbing transferrin on the surfaces of EuPHS were successfully applied in target-specific labeling and two-photon-excitation imaging of live HeLa cells.

Silver sulfide hollow sphere-silver nanoparticle heterostructures were prepared by the simultaneous cation exchange and oxidation-reduction reactions of Cu₂S hollow spheres with Ag⁺ ions in aqueous solution. The obtained Ag₂S-Ag hybrid hollow spheres consisted of Ag₂S hollow spheres about 600 nm in diameter and 20-30 nm in thickness with a single Ag nanoparticle attached to the outer surface of each Ag₂S hollow sphere. The products were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), and energy dispersive X-ray spectroscopy (EDS). When CuS hollow spheres were used as the reactive template instead of Cu₂S hollow spheres, Ag₂S hollow spheres were the predominant product under similar reaction conditions, indicating that the Cu(I) in the Cu₂S hollow spheres served as a reductant for reducing Ag⁺ ions to metallic Ag, and hence played a key role in the formation of the Ag₂S-Ag hybrid hollow spheres. Furthermore, secondary deposition of Ag on the Ag₂S-Ag hybrid hollow spheres resulted in the formation of larger Ag₂S-Ag hybrid hollow spheres consisting of Ag₂S hollow spheres with around a half of the surface coated by a Ag film.

Uniform sphere-like Co-doped iron oxide nanoparticles were synthesized by the thermolysis of iron oleate and cobalt oleate precursors in octadecene in the presence of oleic acid. The Co/Fe mole ratios in the final Co-doped iron oxide can be controlled by changing their ratios in the reaction precursors. With the increase of Co/Fe mole ratios from 0.024 to 0.156 in the final iron oxide nanoparticles, the magnetic saturation values of the nanoparticles slightly decreased from 39 to 30 emu·g^-1, while their coercivity values increased from 0 to 190 Oe. The sizes of the Co-doped iron oxide nanoparticles increased from 7 to 14 nm when the thermolysis time was increased from 0.5 to 3 h with a thermolysis temperature 305℃. Generally, with increasing thermolysis time the metal elements in the final nanoparticles were partially reduced. The domain polymorph of the final nanoparticles was magnetite with a very small amount of ferrous oxide for thermolysis time less than 1 h, while the phases were a mixture of magnetite and wüstite ferrous oxide for thermolysis time longer than 2 h. Further increasing thermolysis time to 3 h, except Fe₃O₄ and FeO, CoFe alloys appear too. It indicates that the iron (cobalt) elements were reduced from trivalence to bivalence, and finally to zero valence. The sizes of the iron oxide nanoparticles increased and more ferrous oxide appeared in the final products with increasing the thermolysis temperature.

This paper reports the preparation in large quantity of bifilar helix-like nanobelts of single crystalline Zn₂SnO₄, a face-centered cubic spinel and transparent semiconductor that possesses wide applications in photovoltaic devices and sensors for humidity and combustible gases, by using a unique approach that combines chemical vapor deposition, aluminothermal reaction, vapor-liquid-solid growth, mergence of polar planes, and kinetic control by steady-state turbulent flow. The bifilar helix-like nanobelt was formed by the twisting and merging of two independent Zn₂SnO₄ nanobelts, as analyzed by scanning electron microscopy, transmission electron microscopy, electron diffraction, X-ray diffraction, Raman spectroscopy, and photoluminescence. It had a periodicity along the axial direction and hence, is actually a super-lattice material. The photoluminescence measurements showed a strong light emission at 326.1 nm from the as-prepared sample with a line width of about 1.5 nm. The combined approach used in this study, in particular its aluminothermal reaction and steady-state turbulent gas flow perturbation steps, may be helpful in preparing other similar materials.