反相液相色谱中lgI对极性小分子溶质色谱行为的表征

以极性溶质正链醇同系物及芳香醇同系物的实验数据对反相液相色谱中计量置换表征参数lgI进行了多方面验证 ,并将lgI值与溶质的其他物理化学参数做了比较 ,证明了lgI在限定条件下分别可作为溶质的种类和大小、流动相中置换剂、所选用固定相特性及有关溶质分离选择性大小的表征参数 ,也证明了极性溶质体系的lgI亦具有热力学平衡常数的性质。

有关相似相溶规律的讨论

根据一些配位化学实验结果对相似相溶规律进行了初步讨论。认为在某些具体情况下应用相似相溶规律时应当注意相溶时和溶剂分子相似的不一定是溶质分子整体 。

Density Functional Study on Structures and Relative Stability of Gd（H2O）n^3＋ （n=8,9）

Density functional theory calculations were performed to study the structures and relative stability of the gadolinium complexes, Gd（H2O）n^3＋ （n=8,9）, in vacuo and in aqueous solution. The polarizable continuum model with various radii for the solute cavity was used to study the relative stability in aqueous solution. The calculated molecular geometries for n=8 and 9 obtained in vacuo are consistent with those observed in experiments. It was found that while the nona-aqua complex is favored in the gas phase, in aqueous solution the octa-aqua conformation is preferred. This result, independent of the types of cavities employed, is in agreement with the experimental observation. The reliability of the present calculation was also addressed by comparing the calculated and experimental free energy of hydration, which revealed that the UA0, UAHF, and UAKS cavities are most appropriate when only the first solvation shell is treated explicitly.

Effect of Environment on Photo-detachment Dynamics of Halide Ions： A Model Approach

A two dimensional model approach for the photodetachment dynamics of closed shell an-ionic systems in presence of external light field have been proposed in the context of polar environmental media. The effects of strong coupling between the solvent polarization and the extra charge in the system were studied by a simple model. The electronic states of con-cerned halide ions are represented by a two dimensional model Hamiltonian with a potential V（x,y）=-V0e^-σ（x^2＋y^2）. The time dependent Fourier grid Hamiltonian method have been used to follow the detachment process with fairly high intensities of light. The environmental effects on the dynamics are sought to be modeled by two different ways. The first one was the presence of polar solvents which perturb the energy levels of anionic systems by changing the effective potential surface and the second one was allowing the fluctuation of the well depth randomly to mimic the system in a more realistic view point. The average detachment rate constant is calculated as a function of important parameters of the used light field to explain the effects of solvent field on the dynamical behavior of dipole bound anionic system at least in a qualitative way.

Influence of Solvent Polarity and Conditions on Extraction of Antioxidant, Flavonoids and Phenolic Content from A verrhoa bilimbi

This paper presents the influence of solvent polarity and extraction conditions on the extraction of total flavonoid, total phenolic and antioxidants from Averrhoa bilimbi. The experiment was performed using a different solvent at different extraction conditions, including extraction time （15-240 min）, temperature （30-70 ℃） and agitation speed （50-300 rpm）. Results showed that yields of extraction varies with solvent polarity. Extraction using 50% aqueous methanol gives the highest antioxidant activity and flavonoid content. The highest total flavonoid content （193.3 μg quercetin equivalent/g dry weight）, total phenolic content （717.8 μg gallic acid equivalent/g dry weight） and antioxidant activity （77%） was achieved using 50% methanol, at 70 ℃ and agitation speed of 300 rpm. This work may be useful for obtaining higher bioactive compounds during the extraction process of A. bilimbi.

Effect of Solvent Polarity on Excited-State Double Proton Transfer Process of 1,5-Dihydroxyanthraquinone

The excited-state double proton transfer(ESDPT)properties of 1,5-dihydroxyanthraquinone(1,5-DHAQ)in various solvents were investigated using femtosecond transient absorption spectroscopy and the DFT/TDDFT method.The steady-state fluorescence spectra in toluene,tetrahydrofuran(THF)and acetonitrile(ACN)solvents presented that the solvent polarity has an effect on the position of the ESDPT fluorescence emission peak for the 1,5-DHAQ system.Transient absorption spectra show that the increasing polarity of the solvent accelerates the rate of excited state dynamics.Calculated potential energy curves analysis further verified the experimental results.The ESDPT barrier decreases gradually with the increase of solvent polarity from toluene,THF to ACN solvent.It is convinced that the increase of solvent polarity can promote the occurrence of the ESDPT dynamic processes for the 1,5-DHAQ system.This work clarifies the mechanism of the influence of solvent polarity on the ESDPT process of 1,5-DHAQ,which provides novel ideas for design and synthesis of new hydroxyanthraquinone derivatives.

Solvent-molecule interaction induced gating of charge transport through single-molecule junctions

To explore solvent gating of single-molecule electrical conductance due to solvent-molecule interactions, charge transport through single-molecule junctions with different anchoring groups in various solvent environments was measured by using the mechanically controllable break junction technique. We found that the conductance of single-molecule junctions can be tuned by nearly an order of magnitude by varying the polarity of solvent. Furthermore, gating efficiency due to solvent–molecule interactions was found to be dependent on the choice of the anchor group. Theoretical calculations revealed that the polar solvent shifted the molecular-orbital energies, based on the coupling strength of the anchor groups. For weakly coupled molecular junctions, the polar solvent–molecule interaction was observed to reduce the energy gap between the molecular orbital and the Fermi level of the electrode and shifted the molecular orbitals. This resulted in a more significant gating effect than that of the strongly coupled molecules. This study suggested that solvent–molecule interaction can significantly affect the charge transport through single-molecule junctions.

Converting biomass into efficient oxygen reduction reaction catalysts for proton exchange membrane fuel cells

It is urgent to develop low-cost but efficient oxygen reduction reaction(ORR)catalysts for the emerging clean energy devices of fuel cells based on proton exchange membrane.Herein,we report a facile method to covert the biomass of black fungus into an efficient ORR catalyst.The black fungus undergoes hydrothermal and pyrolysis processes to transform into carbon-based materials.The as-obtained BF-N-950 catalyst shows prominent ORR catalytic activities in both acidic and alkaline electrolytes with a half-wave potential reaching 0.77 and 0.91 V,respectively.A membrane electrolyte assembly was fabricated with the as-obtained BF-N-950 as the cathode catalyst which shows a high peak power density of255 mW cm^-2.The study shows the potential of converting conventional biomass into low-cost ORR catalyst,which is promising for the fuel cell technology.