Structural optimization of Cu-Ag-Au trimetallic clusters by adaptive immune optimization algorithm.

The putative global minimum structures of Cu-Ag-Au trimetallic clusters with 19 and 55 atoms are obtained by adaptive immune optimization algorithm (AIOA) with the Gupta potential. For the 19-atom trimetallic clusters, the results indicate that all of them have double-icosahedral motifs. For the optimized structures of Cu(13)Ag(n)Au(42-n) (n = 1-41), the clusters can be categorized into 19 Mackay icosahedral structures, 1 6-fold pancake structure, and 21 ring-like structures linked by three face-sharing double-icosahedra. Furthermore, the segregation phenomena of the Cu, Ag, and Au atoms in the Cu-Ag-Au trimetallic clusters are studied to provide useful information for geometric character. Results show that Cu and Ag atoms prefer to locate in the inner-shell and on the surface, respectively, whereas Au atoms mainly locate in the middle-shell and tend to solve into Cu and Ag atoms.

Facile synthesis of water-soluble and size-homogeneous cadmium selenide nanoparticles and their application as a long-wavelength fluorescent probe for detection of Hg(II) in aqueous solution.

Highly luminescent uncoated water-soluble and mono-disperse CdSe nanoparticles (NPs) have been prepared facilely. Uncoated CdSe core NPs possessing a good size distribution was accompanied with long wavelength of fluorescence emission. It is interesting to note that these functionalized NPs are soluble in water medium stably for more than 1 month, and no significant changes were found in the optical characteristics in comparison with fresh CdSe NPs prepared. The functionalized CdSe NPs exhibited strong specific affinity for mercury(II) through their surface functional groups. Based on the significant quenching of fluorescence emission of functionalized CdSe NPs with a long-wavelength 630nm, a simple, rapid and specific detection for Hg(II) was proposed. Under optimum conditions, the response of linearly proportional to the concentration of Hg(II) is between 0mol/L and 1.25x10(-6)mol/L, and the limit of detection is 4.50x10(-9)mol/L. The relative standard deviation (R.S.D.) of six replicate measurements is 2.0% for 2.0x10(-7)mol/L of Hg(II). In terms of fluorescence quenching at 630nm of CdSe NPs, no obvious wavelength shift or no new emission band in presence of Hg(II) at pH 7.50 of phosphate buffer solution were found; furthermore, a significant reduction in absorbance at 230nm of CdSe NPs was first observed in our work. We could speculate that Hg(II) as an effective quencher (even at low concentration) for functionalized CdSe NPs emission suggests that it is capable of directly intercepting one of the charge carriers, thus disrupting the recombination process.

Functionalized CdS quantum dots-based luminescence probe for detection of heavy and transition metal ions in aqueous solution.

Strong luminescence CdS quantum dots (QDs) have been prepared and modified with l-cysteine by a facile seeds-assistant technique in water. They are water-soluble and highly stable in aqueous solution. CdS QDs evaluated as a luminescence probe for heavy and transition metal (HTM) ions in aqueous solution was systematically studied. Five HTM ions such as silver(I) ion, copper(II) ion, mercury(II) ion, cobalt(II) ion, and nickel(II) ion significantly influence the photophysics of the emission from the functionalized CdS QDs. Experiment results showed that the fluorescence emission from CdS QDs was enhanced significantly by silver ion without any spectral shift, while several other bivalent HTM ions, such as Hg(2+), Cu(2+), Co(2+), and Ni(2+), exhibited effective optical quenching effect on QDs. Moreover, an obvious red-shift of emission band was observed in the quenching of CdS QDs for Hg(2+) and Cu(2+) ions. Under the optimal conditions, the response was linearly proportional to the concentration of Ag(+) ion ranging from 1.25 x 10(-7) to 5.0 x 10(-6)molL(-1) with a detection limit of 2.0 x 10(-8)molL(-1). The concentration dependence of the quenching effect on functionalized QDs for the other four HTM ions could be well described by typical Stern-Volmer equation, with the linear response of CdS QDs emission proportional to the concentration ranging from 1.50 x 10(-8) to 7.50 x 10(-7)molL(-1) for Hg(2+) ion, 3.0 x 10(-7) to 1.0 x 10(-5)molL(-1) for Ni(2+) ion, 4.59 x 10(-8) to 2.295 x 10(-6)molL(-1) for Cu(2+) ion, and 1.20 x 10(-7) to 6.0 x 10(-6)molL(-1) Co(2+) ion, respectively. Based on the distinct optical properties of CdS QDs system with the five HTM ions, and the relatively wide linear range and rapid response to HTM ions, CdS QDs can be developed as a potential identified luminescence probe for familiar HTM ions detection in aqueous solution.

A charge-transfer salt, 3,5-dimethyl-1-(4-nitro-benz-yl)pyridinium 7,7,8,8-tetra-cyano-quinodimethane.

In the title salt, C(14)H(15)N(2)O(2) (+)·C(12)H(4)N(4) (-), the asymmetric unit contains one cation and one anion. C-H⋯N and C-H⋯N and C-H⋯O hydrogen bonds and π-π stacking inter-actions (inter-planar distance 3.845 Å) are found in the crystal structure.

[Charge-transfer compounds based on TCNQ: synthesis and spectroscopic properties].

Charge-transfer materials based on organic donors and acceptors have been under investigation, beginning with the first reports of conducting salts of organocyanide acceptors such as TCNQ. Charge-transfer compounds of the pi-electron acceptor 7,7,8,8,-tetracyanoquinodimethane (TCNQ) show unusual electrical and magnetic properties. The form of TCNQ has a dramatic effect on the properties of the kinds of charge-transfer compounds. In order to further study the vibrational spectroscopy of the organic semiconductor, two kinds of (1:1) charge transfer compounds of TCNQ and [RBz(4-CH3)Py][TCNQ](R==Br(1), I (2)) were synthesized and characterized by elemental analysis, infrared spectrum and Raman spectrum. The tested results of elementary analysis of the charge transfer compounds (1) and (2) were consistent with theoretical values. The IR and Raman spectra of (1) and (2) which indicate the presence of a type of TCNQ species, general speaking, the C[triple bond]N stretching frequencies around 2200 cm(-1), were used to determine the average charge on the TCNQ units, v(CN)for the neutral TCNQ molecule is higher than 2200 cm(-1)), however, v(CN) for the compounds is from 2185 to 2156 cm(-1), both shift to lower frequencies, which were consistent with the frequencies of the TCNQ radical anion In conclusion, the results of IR and Raman spectrum were consistent with the TCNQ radical anion in the compounds, namely TCNQ-.

[Synthesis and infrared spectroscopic study of 1-D magnetic chain compound based on [BrBzPy [Ni (dmit) 2]].

The synthesis and functional study of one-dimensional free radical-metal chain compound has been a hotspot task in molecule material, especially in composing high Tc molecule ferromagnet. A new compound [BrBzPy] [Ni(dmit)2] has been prepared and characterized. The crystal structure at room temperature was determined. The crystal is triclinic with space group P21/c, a = 0.627 5(1) nm, b = 1.743 8(3) nm, c = 2.283 9(3) nm, alpha = 90 degrees, beta = 91.87(1) degrees, gamma = 90 degrees, V = 2.497(7) nm3, Z = 4, Mr = 700. 57, and Dc = 1.863 g x cm(-3). The planar [Ni(dmit)2]- is nearly perfect, which shows that it has good conjugate characteristic and is a 1-D magnetic chain compound.

[Hydrothermal synthesis of Co9S8 nanocrystalline aggregations and spectral study].

Co9S8 nanocrystalline aggregations were synthesized in hydrazine hydrate (N2H4 x H2O) solvent at 180 degrees C for 12 h through a hydrothermal method using cobalt sulfate hydrate (CoSO4 x 7H2O) and sodium sulfate (Na2SO3) as the starting materials. The prepared samples were characterized using X-ray diffraction (XRD), field-emission scanning electron microscope (FE-SEM), and transmission electron microscope (TEM). FTIR spectrum was measured using Fourier-transform infrared spectrometer. The results showed that the products were mainly composed of Co9S8 hexagonal flakes, which were about 2.1 microm in diameter and 200 nm in thickness. The flakes consisted of Co9S8 nanocrystallites with an average size of 2.5 nm.

[Preparation and spectroscopic study of two new charge transfer salts].

TCNQ (TCNQ= tetracyanoquinodimethane) salts have good conductivity. The magnetic properties of substituted benzylpridiniums, such as ferromagnetism, antiferromagnetism and spin Peierls transition, have widely been investigated. In order to obtain some new materials with both conductivity and magnetism, two new organic salts, [NO2BzPy]Cl (1) and [NO2 BzPyNH2]Cl (2), were synthesized and characterized. Further more, two new charge transfer salts, [NO2BzPy] [TCNQ]2 (3) and [NO2BzPyNH2] [TCNQ]2 (4) were synthesized and characterized. The tested results of elementary anAlysis of charge transfer salts (3) and (4) were consistent with theoretical values, and the results of IR indicated that there exist TCNQ and TCNQ anions. One-dimensional molecular column of TCNQ has been formed. Partial charge transfer takes place from [TCNQ]2- to cation.

[Spectral research on the effect various metal ions on the of photocatalytic degradation properties of TiO2 nanocrystal].

TiO2 nanocrystalline was prepared by a emulsion method in the mixed solvent of cyclohexane and acetic anhydride using, titanyl organic compound as the precursor. The prepared product was characterized by means of X-ray diffraction (XRD) and Fourier transform infrared spectrum (FTIR). The photocatalytic oxidation of methyl orange with TiO2 loaded with various metal ions was discussed. The spectral research results showed that the photocatalytic reaction of methyl orange with TiO2 loaded with Bi3+ was promoted, some metal ions caused almost no promotion of TiO2 oxidation of methyl orange, and Ni2+ and Fe3+ ions caused a little promotion. The best mass proportion of Bi3+ and TiO2 was defined as 1:8, which has a good photocatalytic activity. The photocatalytic degradation reaction of methyl orange was affected by the concentration of TiO2 nanocrystal, and when the mass proportion of Bi3+ and TiO2 is 1:8, the best photocatalytic activity concentration of TiO2 is about 1.6 g x L(-1).

[Synthesis of nanocrystalline ZnO and its luminescence spectrum].

ZnO nanocrystal was prepared with Zn(CH3COO)2.2H2O and CO(NH2)2 as precursor by a solvothermal process. The products were characterized by X-ray diffraction (XRD), transmission electron microscope (TEM), and photoluminescence spectrum (PL). The results show that the ZnO nanocrystal has good characteristics, and the average particle size of the ZnO nanocrystal is about 17.2 nm. There is a broad PL peak for ZnO nanocrystal between 500-700 nm.

[Research on the synthesis and spectroscopy of the copolymer of polyvinyl alcohol and amino acid].

In this paper, a series of new polymers with grafted amino acids were synthesized. The purpose of the research is to develop a kind of polymer drugs with grafted amino acids for the treatment of some patients. The preparations of polyvinyl alcohol and amino acid were described by using inorganic acid as catalyst. The reaction methods were investigated in order to find the optimal conditions for the highest yield and purity. The copolymers were analysed and characterized by IR and 1HNMR. The result indicated that the reaction products were what we needed and the yield of the polymer of polyvinyl alcohol and glycine was higher than that of polyvinyl alcohol and alanine.

[Bimetallic coordination polymers [[ML][FeIIFeIII(ox)3].1.5H2O] infinity with layer structure syntheses, spectra characterization].

Two new schiff base complexes, NiL(ClO4).3H2O (1) and CuL(ClO4).4H2O (2) [L was condensed from equation molar salicylaldehyde and diethylenetriamine] have been synthesized and characterized. Further, two new bimetallic coordination polymers, [[ML][FeIIFeIII(ox)3].1.5H2O] infinity were synthesized and characterized, where ox2- = oxalate, M = Ni2+ (3) or Cu2+ (4). The tested results of elementary analysis of coordination polymers (3) and (4) were according with the theoretical value, and the results of the IR indicated that the coordination of oxalate were bridgetype in compound (3) and (4). 2-D layer coordination polymers were synthesized by oxalate and Fe3+, Fe2+. The result of Mössbauer spectra of (3) and (4) in room temperature revealed that two different postural ferric ions were found in coordination polymer (3) and (4), and anions layer was formed by [FeIIFeIII(ox)3]- unit. The compounds of (3) and (4) were bimetallic coordination polymers.

[Simultaneous determination of copper and iron by catalytic kinetic spectrophotometry].

A simultaneous catalytic effect copper (II) and iron (III) on the oxidation of acid chrome blue K by potassium bromate in dilute sulfuric acid medium was observed. But there was an obvious difference in their reaction rates, and the ratio of the reaction constant changed with time. And their spectral addiitive properties were not satisfactory. The simultaneous determination of copper and iron by catalytic kinetic spectrophotometric method was realized by using a three-layer Levenberg-Marquardt BP neural network to cope with the experimental data. The optimum conditions of reaction and determination were studied. The calculation results of the determination in synthetic samples and human hair were satisfactory.

UV light assisted synthesis of ternary reduced graphene oxide hybrid materials and their photocatalytic performance.

Freely-assembled ternary hybrids consisting of Pt, reduced graphene oxide (RGO) and P25 were synthesized by a direct solution process with the assistance of UV light. The Pt-RGO/P25 hybrids were characterized by Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), field emission scanning electron microscopy (SEM), transmission electron microscopy (TEM), ultraviolet visible (UV-vis) diffuse reflectance spectroscopy (DRS) and photoluminescence spectra (PL). Importantly, when Pt-RGO/P25 hybrids were used as photocatalysts, they could show a superior photocatalytic performance when compared to commercial P25 and RGO/P25 hybrids under UV, solar light and λ > 600 nm visible light irradiation, which could be explained on the basis of the plasmonic response and the formation of Pt Schottky barrier at the interface between TiO2 and graphene. This work could provide new insight for enhancing graphene/TiO2 photocatalytic performance and facilitate their application in environmental protection.

Sonodegradation and photodegradation of methyl orange by InVO4/TiO2 nanojunction composites under ultrasonic and visible light irradiation.

The InVO(4)/TiO(2) nanojunction composites with different weight ratio of 1:10, 1:25, 1:50 and 1:100 were successfully constructed using an ion impregnate method, followed by calcining temperature 400°C for 2h in Ar. The sono- and photo-catalytic activities of the InVO(4)/TiO(2) nanojunction composites were evaluated through the degradation of methyl orange (MO) in aqueous solution under ultrasonic and visible light irradiation, respectively. The experimental results determined that the (1:50) InVO(4)/TiO(2) nanojunction composite has exhibited the highest sonocatalytic activity. It can be ascribed to vectorial charge transfer at the co-excited InVO(4)/TiO(2) interface under ultrasonic irradiation, results in the complete separation of electrons and holes. Interestingly, the (1:25) InVO(4)/TiO(2) nanojunction composite displayed superior photocatalytic activity for MO degradation under visible light, indicating that InVO(4) as a narrow band gap sensitizer can expand photocatalytic activity of TiO(2) to visible region, and the charge transfer can be formed from high energy level of InVO(4) conduction band to the low energy level of TiO(2) conduction band in a present of excited InVO(4) alone under visible light irradiation. The sono- and photo-catalytic activities of the InVO(4)/TiO(2) nanojunction composites were found to be dependent significantly on different InVO(4) contents, which can be explained by the influence of charge transfer on the basis of the work functions of different catalysis mechanism.

A functionalized gold nanoparticles and Rhodamine 6G based fluorescent sensor for high sensitive and selective detection of mercury(II) in environmental water samples.

A gold-nanoparticles (Au NPs)-Rhodamine 6G (Rh6G) based fluorescent sensor for detecting Hg(II) in aqueous solution has been developed. Water-soluble and monodisperse gold nanoparticles (Au NPs) has been prepared facilely and further modified with thioglycolic acid (TGA). Free Rh6G dye was strongly fluorescent in bulk solution. The sensor system composing of Rh6G and Au NPs fluoresce weakly as result of fluorescence resonance energy transfer (FRET) and collision. The fluorescence of Rh6G and Au NPs based sensor was gradually recovered due to Rh6G units departed from the surface of functionalized Au NPs in the presence of Hg(II). Based on the modulation of fluorescence quenching efficiency of Rh6G-Au NPs by Hg(II) at pH 9.0 of teraborate buffer solution, a simple, rapid, reliable and specific turn-on fluorescent assay for Hg(II) was proposed. Under the optimum conditions, the fluorescence intensity of sensor is proportional to the concentration of Hg(II). The calibration graphs are linear over the range of 5.0x10(-10) to 3.55x10(-8) mol L(-1), and the corresponding limit of detection (LOD) is low as 6.0x10(-11) mol L(-1). The relative standard deviation of 10 replicate measurements is 1.5% for 2.0x10(-9) mol L(-1) Hg(II). In comparison with conventional fluorimetric methods for detection of mercury ion, the present nanosensor endowed with higher sensitivity and selectivity for Hg(II) in aqueous solution. Mercury(II) of real environmental water samples was determined by our proposed method with satisfactory results that were obtained by atomic absorption spectroscopy (AAS).

A novel fluorescent array for mercury (II) ion in aqueous solution with functionalized cadmium selenide nanoclusters.

Mono-disperse CdSe nanoclusters have been prepared facilely and functionalized with l-cysteine through two steps by using safe and low cost substances. They are water-soluble and biocompatible. Especially these functionalized quantum dots can be stably soluble in water more than for 30 days, and the intensity of fluorescence and absorbance was decreased less than 15% of fresh prepared CdSe colloids. These functionalized CdSe QDs exhibited strong specific affinity for mercury (II) through QDs interface functional groups. Based on the quenching of fluorescence signals of functionalized CdSe QDs at 530 nm and no obvious wavelength shift or no new emission band in present of Hg (II) at pH 7.75 of phosphate buffer solution, a simple, rapid and specific array for Hg (II) was proposed. In comparison with conventional organic fluorophores, these nanoparticles are brighter, more stable against photobleaching, and do not suffer from blinking. Under optimum conditions, the response of linearly proportional to the concentration of Hg (II) between 0 and 2.0 x10(-6) mol L(-1), and the limit of detection is 6.0 x 10(-9) mol L(-1). The relative standard deviation of six replicate measurements is 1.8% for 1.0 x 10(-7) mol L(-1) Hg (II). The mechanism of reaction is also discussed. The proposed method was successfully applied for Hg (II) detection in four real samples with a satisfactory result that was obtained by cold vapor atomic fluorescence spectrometry (CV-AFS).