还原席夫碱型三角架式金属配合物的合成和性质研究

由2，2，′，2＂-三氨基三乙胺(tren)与N-氧化吡啶醛经席夫碱型缩合，然后还原C=N双键形成的产物为配体(L¹)，合成了一系列新三角架式过渡金属配合物：［ML¹］²⁺［M=Mn(Ⅱ)、Ni(Ⅱ)和Zn(Ⅱ)］。利用元素分析、红外光谱、电子光谱和室温磁化率对配合物的结构和性质进行了研究。     

Effects of pressure pulsation on oxygen transfer rate measured by sulfite method

Pressure pulsation (PP) was investigated for its effects on oxygen transfer rate (OTR) measured by sulfite oxidation. By manipulating airflow rate, 0.41–1.2 vvm, and a control valve in a 4-L bioreactor, the frequency of PP was varied at different gas pressures3–15 psig. A mathematical model of OTR was built and compared to experimental data. OTR was also examined at constant gas pressure, 4.5–15.0 psig. The results indicate a good agreement between measurement and model prediction. OTR above 9 psig during PP showed significant enhancement at 25°C. This proves that PP not only affects the elevation of DO level, but also increases the interfacial area and mass transfer coefficient.     

Ethanol fermentation in a tower fermenter using self-aggregatingSaccharomyces uvarum

A self-aggregating strain ofSaccharomyces uvarum (U4) was used as a biocatalyst to carry out continuous ethanol fermentation in a tower fermentor equipped with a cell separator. Cell aggregates (2–3 mm) formed a stable packed bed in the fermentor, and the cell separator retained yeast cells effectively. Corn steep liquor was used as a nitrogen source for the fermentation of corn syrup and black strap molasses. An ethanol productivity of 54 g/L/h was reached using corn syrup at a dilution rate of 0.7/h, and sugar concentration in the feed was 15% (w/v). For molasses fermentation, an ethanol productivity of 22 g/L/h was obtained at a dilution rate of 0.7/h, and sugar concentration in the feed was 12.5% (w/v). Ethanol yields obtained from tower fermentation are higher than those obtained from flask fermentation (96% for corn syrup fermentation and 92% for molasses fermentation). No significant loss in fermentation activity was observed after 3 mo of operation.     

Hypervalency avoided: simple substituted BrF3 and BrF5 molecules. Structures, thermochemistry, and electron affinities of the bromine hydrogen fluorides HBrF2 and HBrF4

Five different pure density functional theory (DFT) and hybrid Hartree-Fock/DFT methods have been used to search for the molecular structures, thermochemistry, and electron affinities of the bromine hydrogen fluorides HBrF(n)/HBrF(n)(-) (n = 2, 4). The basis sets used in this work are of double-zeta plus polarization quality in conjunction with s- and p-type diffuse functions, labeled as DZP++. Structures with Br-F and Br-H normal bonds, that is, HBrF(2)/HBrF(2)(-) with C(2v) or C(s) symmetry and HBrF(4)/HBrF(4)(-) with C(4v) or C(s) symmetry, are genuine minima. However, unlike the original BrF(3) and BrF(5) molecules, the global minima for HBrF(n)/HBrF(n)(-) (n = 2, 4) species are predicted to be complexes, some of which contain hydrogen bonds. The demise of the hypervalent structures is due to the availability of favorable dissociation products involving HF, which has a much larger dissociation energy than F(2). Similar reasoning suggests that PF(4)H, SF(3)H, SF(5)H, ClF(2)H, ClF(4)H, AsF(4)H, SeF(3)H, and SeF(5)H will all be hydrogen bond structures incorporating diatomic HF. The most reasonable theoretical values of the adiabatic electron affinities (EA(ad)) are 3.69 (HBrF(2)) and 4.38 eV (HBrF(4)) with the BHLYP method. These electron affinities are comparable to those of the analogous molecules: Br(2)F(n), ClBrF(n), and BrF(n)(+1) systems. The first F-atom dissociation energies for the neutral global minima are 60 (HBrF(2)) and 49 kcal/mol (HBrF(4)) with the B3LYP method. The first H-atom dissociation energies for the same systems are 109 (HBrF(2)) and 116 kcal/mol (HBrF(4)). The large Br-H bond energies are not sufficient to render the hypervalent structures energetically tenable. The dissociation energies for the complexes to their fragments are relatively small.     

Large third-order nonlinear optical properties of C70 fullerene in the infrared regime

The nonlinear third-order optical susceptibility of C₇₀ in a toluene solution is measured for the first time by the method of degenerate four-wave mixing using 10 ns laser pulses at 1.06 m. The third-order susceptibility X _in ⁽³⁾ is 5.6×10^–12 esu for a C₇₀ toluene solution at a concentration of 0.476 g/l. The correspondent magnitude of the hyperpolarizability ₁₁₁₁ of the C₇₀ molecule is 1.2×10^–30 esu which is in a good agreement with the prediction given by the model of a free electron in a spherical box.     

Synthesis of conducting polyaniline using novel anionic Gemini surfactant as micellar stabilizer

The Gemini surfactant 9B-4-9B containing sodium sulfonate as hydrophilic head group was synthesized based on nonylphenol and characterized by FTIR, ¹H NMR spectroscopy and the surface tension measurement. The CMC and C₂₀ of the 9B-4-9B were smaller than that of sodium dodecylbenzene sulfonate and sodium dodecylsulfate, respectively, indicating excellent efficiency of micelle formation and reduced surface tension. Conducting polyaniline salts were synthesized by chemical oxidative micellar polymerization of aniline in water firstly using Gemini surfactant 9B-4-9B as the micelle stabilizer and ammonium peroxydisulfate as the oxidant at 0 °C. The stable polyaniline dispersions have been obtained when the molar ratio of the 9B-4-9B to aniline was equal to or above 0.5 used in the polymerization system. The obtained granular polyaniline particles with the size of 1-2 μm were characterized by FTIR, UV-Vis, SEM, WAXD and conductivity measurement.     

Synthesis and Properties of Polyetherketones Containing Sulfide and Phthalazinone

High molecular weight copoly(ether ketone)s (PEK) based on 4-(4-hydroxyphenyl)-1-phthalazinone (DHPZ)/4,4′-thiobisphenol (TBP)/4,4′-diflourodiphenylketone (DFK) were prepared by nucleophilic substitution polycondensation. The copolymers were characterized by FT- and ^1H-NMR. Thermal properties and solubility of copolymers were studied.     

Method and algorithm of obtaining the molecular intrinsic characteristic contours (MICCs) of organic molecules

The molecular intrinsic characteristic contour (MICC) is defined as the set of all the classical turning points of electron movement in a molecule. Studies on the MICCs of some medium organic molecules, such as dimethylether, acetone, and some homologues of alkanes, alkenes, and alkynes, as well as the electron density distributions on the MICCs, are shown for the first time. Results show that the MICC is an intrinsic approach to shape and size of a molecule. Unlike the van der Waals hard-sphere model, the MICC is a smooth contour, and it has a clear physical meaning. Detailed investigations on the cross-sections of MICCs have provided a kind of important information about atomic size changing in the process of forming molecules. Studies on electron density distribution on the MICC not only provide a new insight into molecular shape, but also show that the electron density distribution on the boundary surface relates closely with molecular properties and reactivities. For the homologues of alkanes, Rout(H), Dmin, and Dmax (the minimum and maximum of electron density on the MICC), all have very good linear relationships with minus of the molecular ionization potential. This work may serve as a basis for exploring a new reactivity indicator of chemical reactions and for studying molecular shape properties of large organic and biological molecules.     

Differentiation of Resina Draconis from Sanguis Draconis by CE

A simple, accurate method based on capillary electrophoresis with electrochemical detection (CE–ED) has been developed to determine loureirin A, loureirin B and dracorhodin for differentiation of Resina Draconis from Sanguis Draconis. The effects of some important factors such as acidity and concentration of running buffer, separation voltage, injection time, and applied potential on the CE–ED working electrode were investigated. Under the optimum conditions, the three analytes could be well separated within 30 min in a 75 cm capillary at a separation voltage of 14 kV in a 80 mmol L^?1 borate buffer (pH 9.24). The working electrode was a 300-μm-diameter carbon disc electrode positioned opposite the outlet of the capillary in a wall-jet configuration and was set at a potential of 0.90 V (vs. SCE). Excellent linearity was established over two orders of magnitude with detection limits (S/N = 3) ranging from 3 × 10^?7 g mL^?1 to 1 × 10^?6 g mL^?1 for all three analytes. The relative standard deviations of peak current and migration times of loureirin A, loureirin B and dracorhodin were 2.1, 1.7, 4.4 and 2.9, 2.8, 3.3% (n = 5), respectively. The recoveries of three constituents ranged from 98.8 to 101.8%. The methodology has been successfully applied to analyze and differentiate the actual samples with satisfactory assay results.