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41.
The octahedral Au6 core is explored for the formation of novel SP3‐hybrid superatomic molecules by considering and Au6 clusters (X= F, Cl, Br, I). The bonding between the four capping atoms and the Au6 core requires a combination of 1S and 1P shells of the core leading to a set of four equivalent hybrid orbitals. Thus, combining the superatom concept with both the Lewis structure model and VSEPR theory contributes to the rationalization of structure and bonding in metal clusters. For example, our results consider the Au6 clusters as analogues of the simplest perhalogenated hydrocarbon, CX4. 相似文献
42.
Fluorescent molecularly imprinted polymer-coated CdSe/ZnS quantum dots were prepared in an efficient one-step synthesis. Their application as fluorescent nanoparticles for the direct quantification of cholesterol in milk was characterized. The quantum dots were used as cores to produce fluorescence. The molecularly imprinted polymer shells provided specific binding sites for cholesterol. The system exhibited good linearity for cholesterol from 0.5 to 150?µg?mL?1, a low detection limit of 0.15?µg?mL?1, and acceptable reproducibility with a relative standard deviation of 4.2% for six replicates. The molecularly imprinted polymer-coated quantum dots were used to determine cholesterol in fortified milk. Recoveries were from 87.0 to 105.2% and a possible mechanism is proposed. The fluorescent molecularly imprinted polymer-coated quantum dots exhibited excellent selectivity and provide a simple, rapid, selective, and effective analytical approach. 相似文献
43.
Bijun Liu Yin Tian Qianhong Yu Qiang Li Wanjun Mu Zhaoyi Tan Fengchang Wu Dongqi Wang Xingliang Li 《Journal of solution chemistry》2017,46(12):2281-2292
O-Phospho-l-serine is one of the naturally occurring phosphorylated amino acids, having important pharmacological activity and bioactivity. The protonation constants of O-phospho-l-serine were determined by means of potentiometric titrations at 25 °C and ionic strength of 0.5 mol·L?1 (NaCl). The heat effects of the protonation reaction of the O-phospho-l-serine were measured by direct calorimetry. NMR spectroscopy has demonstrated that the first protonation site occurs at the nitrogen atom in the amino group, followed by one of the oxygen atoms in the phosphono group, and finally the carboxyl oxygen atom. This trend is in good agreement with the enthalpy of protonation and quantum chemical calculations. These data will help to predict the speciation of O-phospho-l-serine in physiological systems. 相似文献
44.
Syntheses,Structures, Electrochemistry,and Electrocatalysis of Three Copper(II) Coordination Polymers constructed from 5‐[4‐(1H‐Imidazol‐1‐yl)phenyl]‐1H‐tetrazole 下载免费PDF全文
Three coordination polymers (CPs) based on the 5‐[4‐(1H‐imidazol‐1‐yl)phenyl]‐1H‐tetrazole ( HL ) ligand, namely, [Cu(μ2‐ L )(μ4‐pbda)(H2O)] ( 1 ), [Cu2(μ‐Hbtc)(H2btc)(μ3‐OH)(μ4‐ HL )] ( 2 ) and [Cu5(μ3‐ L )(μ4‐ L )(μ3‐ip)(μ3‐OH)(H2O)2] · 2H2O ( 3 ) (H2pbda = 1,4‐benzenedicarboxylic acid, H3btc = 1,3,5‐benzenetricarboxylic acid, H2ip = isophthalic acid) were hydrothermally synthesized and structurally characterized. Complex 1 represents “weave”‐type 2D layers consisting of wave‐like 1D chains and 1D straight chains, which are further connected by hydrogen bonds to form a 3D supramolecular structure. Complex 2 exhibits a uninodal (4)‐connected 2D layer with a point symbol of {44 · 62}, in which the L ligand can be described as μ5‐bridging and the H2btc– ions display multiple kinds of coordination modes to connect CuII ions into 1D “H”‐type Cu‐H2btc chains. In complex 3 , 2D Cu‐ L layers with two kinds of grids and 1D “stair”‐type Cu‐ip chains link each other to construct a 3D {412 · 63} framework, which contains the pentanuclear subunits. Deprotonated degree and coordination modes of carboxylate ligands may consequentially influence the coordination patterns of main ligands and the final structures of complexes 1 – 3 . Furthermore, electrochemical behaviors and electrocatalytic activities of the title complexes were analyzed at room temperature, suggesting practical applications in areas of electrocatalytic reduction toward nitrite and hydrogen dioxide in aqueous solutions, respectively. 相似文献
45.
Quanwu Mu 《Frontiers of Mathematics in China》2017,12(6):1457-1468
Let d ? 3 be an integer, and set r = 2d?1 + 1 for 3 ? d ? 4, \(\tfrac{{17}}{{32}} \cdot 2^d + 1\) for 5 ? d ? 6, r = d2+d+1 for 7 ? d ? 8, and r = d2+d+2 for d ? 9, respectively. Suppose that Φ i (x, y) ∈ ?[x, y] (1 ? i ? r) are homogeneous and nondegenerate binary forms of degree d. Suppose further that λ1, λ2,..., λ r are nonzero real numbers with λ1/λ2 irrational, and λ1Φ1(x1, y1) + λ2Φ2(x2, y2) + · · · + λ r Φ r (x r , y r ) is indefinite. Then for any given real η and σ with 0 < σ < 22?d, it is proved that the inequality has infinitely many solutions in integers x1, x2,..., x r , y1, y2,..., y r . This result constitutes an improvement upon that of B. Q. Xue.
相似文献
$$\left| {\sum\limits_{i = 1}^r {{\lambda _i}\Phi {}_i\left( {{x_i},{y_i}} \right) + \eta } } \right| < {\left( {\mathop {\max \left\{ {\left| {{x_i}} \right|,\left| {{y_i}} \right|} \right\}}\limits_{1 \leqslant i \leqslant r} } \right)^{ - \sigma }}$$
46.
Ahmed AL-Osta Bushra Saleh Samer Vijaykumar V. Jadhav Umesh T. Nakate Rajaram S. Mane Mu. Naushad 《Journal of Solid State Electrochemistry》2017,21(9):2609-2614
Present work deals with a two-step synthesis and electrochemical properties of nickel oxide @copper oxide@copper (NiO@CuO@Cu) bilayered electrode. In the first step, anodization (40 V for 25 min) of Cu foil has been carried out for forming Cu-hydroxide@Cu which when annealed at 300 °C for 1 h produces CuO@Cu. In the second step, Ni-hydroxide is deposited onto CuO@Cu by applying current density of 0.03 A/cm2 for 3 min which when re-annealed at 300 °C for 1 h gives out NiO@CuO@Cu bilayered electrode. Obtained NiO@CuO@Cu bilayered electrode demonstrates separate CuO and NiO phases. The electrochemical properties have obtained using cyclic voltammetry, galvonostatic charge-discharge, and Nyquist plot measurements that reveal an importance of NiO@CuO@Cu as a potential electrode material in the electrochemical supercapacitor application with 58.14, 51.25, and 4.73 F g?1 values in 0.5 M, NaOH, KOH, and Na2SO4 electrolytes, respectively, measured at 2 mVs?1 scan rate. 相似文献
47.
M. A. Waghmare Mu. Naushad Z. A. Alothman A. U. Ubale H. M. Pathan 《Journal of Solid State Electrochemistry》2017,21(9):2531-2545
Zirconium oxide (ZrO2) is acquiring considerable attention of most of the research groups and leading to a large number of publications due to its unique properties, especially in the context of emerging trends in the third generation of solar cell research. ZrO2 films offer magnificent aspects related to physicochemical properties, and the properties are found to be dependent on synthesis methods. In the present review, various deposition techniques used to grow zirconium oxide thin films and their application to enhance the quantum efficiency of titanium oxide (TiO2) based dye-sensitized solar cells (DSSCs) are discussed. Also, the modulated performances of DSSCs fabricated by growing the conformal ZrO2 insulating films to retard interfacial recombination dynamics on preformed TiO2 films are discussed. 相似文献
48.
Yunfeng Xu Chong Zhang Pan Mu Na Mao Xue Wang Qian He Feng Wang Jia-Xing Jiang 《中国科学:化学(英文版)》2017,60(8):1075-1083
Two novel tetra-armed conjugated microporous polymers with different geometries have been designed and synthesized via Suzuki-Miyaura cross coupling polycondensation. Both polymers are stable in various organic solvents tested and are thermally stable. The pyrene-containing polymer of PrPy with the rigid pyrene unit shows a higher Brunauer-Emmet-Teller specific surface area of 1219 m2 g?1 than the tetraphenylethylene-containing polymer of PrTPE (770 m2 g?1), which leads to a high CO2 uptake ability of 3.89 mmol g?1 at 1.13 bar/273 K and a H2 uptake ability of 1.69 wt% at 1.13 bar/77 K. The photocatalytic hydrogen production experiments revealed that PrPy also shows a better photocatalytic performance than PrTPE due to the higher conjugation degree and planar structure, the broader UV-visible (UV-Vis) absorption, the lower photoluminescence lifetime, and the higher specific surface area. 相似文献
49.
Qing-yao Wang Jia-qi Fang Lu-lu Deng Xiao-jiang Hao Shu-zhen Mu 《Chemistry Central journal》2017,11(1):138
The regioselective demethoxylation and dehalogenation of dihalogenated dibenzocyclooctadiene lignans derivatives were realized in a one-step reaction with excellent yields in the sodium and t-butanol reaction system. 相似文献
50.
Dications of cycloparaphenyles ([n]CPPs) are known to exhibit in-plane global aromaticity, contained in a nanobelt structure. Recently synthesized ortho and meta isomers of [n]CPPs break the radial symmetry of π structure incorporating perpendicular oriented π orbitals. Herein we set to explore the aromaticity of neutral and dicationic ortho and meta isomers of [8]CPP by dissecting the induced magnetic field to contributions of the twofold radial/perpendicular π system using delocalized canonical molecular orbitals (CMO), and introducing the natural localized molecular orbitals (NLMO) analysis with DFT methods. The dications sustain a reduced global aromatic character of the radial π system under a perpendicular orientation of the external field which declines from ortho to meta isomer and reinforces local aromaticity of ortho ring while it destroys aromaticity of meta ring. Aromaticity variations are determined by symmetry governed rotational excitations of frontier π orbitals. The parallel orientation reveals a substantial reduction of local aromaticity verified with NICSπ analysis and electron delocalization indices. 相似文献