Internal motions of a high molecular weight (Afw = 8.12 X 106) polystyrene with a narrow distribution of Mz/Mw < 1.04 in benzene has been studied by dynamic light scattering. By means of a prism-cell light-scattering spectrometer, the translational diffusion of the center of mass of the polymer coil has been precisely determined at KRS « 1 corresponding to using the self-beating technique at a scattering angle < 3°. With the experimentally measured translational diffusion coefficient, a solid base for internal motion studies could be formulated. The first cumulant obtained from the cumulante analysis of the measured intensity time correlation function approached K3 dependence at KRg > 1, indicating that the polymer chain dynamics could be described in terms of the non-free-draining model. Extraction of information on the internal motions was made by comparing the contin output line-width distributions from the experimental data with those from the simulated data based on a theoretical model for polymer coils in the non-freedraining limit. By selecting appropriate KRe ranges, the first two internal relaxation times could be obtained. At regimes of 1 < x < 3 and 3 < x < 6, where x = (KRt)2, the first internal relaxation time n (the longest one) and the second internal relaxation time r2 were determined, respectively. To our knowledge, for a flexible polymer coil in solution, t2 was determined experimentally for the first time. The experimental observations agreed very well with the theoretical predictions based on polymer chain dynamics with hydrodynamic interactions.
An undulated two-dimensional CTC-based covalent organic framework, CTC-COF, was synthesized through solvothermal reaction for the first time. This mesoporous material stacks in an eclipsed mode in the microcrystalline state. CTC-COF has a surface area of 1710 m 2 g À1 , with a pore width of 2.26 nm calculated by the NL-DFT modelling. The bowl-shaped core unit led to a larger surface area than its analogue, COF-5 constructed by planar subunits. This material has higher low pressure hydrogen uptake than other 2D COFs with similar structures, and even close to the 3D COF materials.
A novel nanotubular metal-organic frameworkwas prepared by assembly of the rigid, trigonal pyramidal ligand tri-(4-carboxy-phenyl)trimethoxycyclobenzylene (H 3 L) and Cu(NO 3 ) 2 $3H 2 O via solvothermal reaction. The Cu(II) ions in the crystal serve as square and linear molecular building blocks, thus forming a framework with ternary topology. One single open-ended nanotube contains two identical orthogonally interpenetrated twonodal nets. This framework exhibits permanent microporosity and relatively high surface area.
Dephosphorization process of high phosphorus oolitic iron ore by acid leaching and leaching kinetics were investigated in the paper. The high phosphorus ore samples (51%T.Fe, 0.52%P) used in this work were analysed by SEM-EDS and XRD, which showed their oolitic structure and mineral phases. Among the three kinds of acids (H2SO4, HCl and HNO3), sulfuric acid was the most appropriate one for dephosphorization, and structure changes after leaching were also investigated through the SEM and EDS analysis. The effects of acidity, particle size, stirring speed and temperature were researched in detail. Through acid leaching, phosphorus could be removed effectively, and iron loss was negligible, which was also studied by thermodynamic calculation. The experimental data could be well described by the unreacted shrinking core model and rate controlling step was found to be chemical reaction between apatite and acid. The apparent activation energy was calculated as 45.02 kJ/mol.
An efficient palladium-catalyzed Suzuki-Miyaura coupling method involving the reaction between CTV-Br(3) and a variety of aryl and heteroaryl boronic acids in the presence of indolyl phosphane ligands has been developed. This reaction procedure provided a series of C(3)-symmetric aryl-extended rigid cavitands for the first time. X-ray crystal structure analysis revealed that the phenyl substituted cavitand 5a has much larger rim edges and cavity height. This macrocyclic host adopts a linear head-to-tail "hand-shake" self-inclusion arrangement in the crystalline state. The fluorescence of 5a was considerably quenched upon the addition of C(60), with a binding constant of 78,700 ± 2300 dm(3) mol(-1) and a 1:1 stoichiometry according to the Job's plot. The interaction of C(60) with 5a in the excited state is stronger than that with CTV, which could be attributed to more binding sites in the extended arms of 5a. Moreover, optically active C(3)-symmetric cavitands (+)- and (-)-6 were easily obtained with high efficiency through chemical resolution.
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