Science in China Series B: Chemistry

Using n-propylamine as a template, deioned water and secondary-butanol (butan-2-ol) as solvents, a three-dimensional (3D) open-framework aluminophosphate [C3NH10]·[HAl3P3O13] (1) and a two-dimensional layered aluminophosphate [C3NH10]3·[Al3P4O16] (2) were crystallized from the initial mixtures with compositions of Al2O3: 2.4 P2O5: 5.0 n-propylamine: 100 H2O/butan-2-ol, respectively. They are characterized by X-ray powder diffraction (XRD), thermogravimetric (TG), and elemental (CHN) analyses and structurally determined by single-crystal X-ray diffraction analysis. Compound 1 crystallizes in the monoclinic space group P21/c with a = 0.85831(13) nm, b = 1.7677(3) nm, c = 1.04353(12) nm, β = 123.887(9)°, and V = 1.3143(3) nm3. Compound 2 crystallizes in the monoclinic space group P21/c with a = 1.1313(2) nm, b = 1.4874(3) nm, c = 1.8020(6) nm, β = 125.07(2)°, and V = 2.4817(11) nm3. The results show that the properties of solvent have a significant influence on the structure-directing effect of n-propylamine in the crystallization of the open-framework aluminophosphates.

The electron-acoustic phonon scattering for charge transport in organic semiconductors has been studied by first-principles density functional theory and the Boltzmann transport equation with relaxation time approximation. Within the framework of deformation-potential theory, the electron-longitudinal acoustic phonon scattering probability and the corresponding relaxation time have been obtained for oligoacene single crystals (naphthalene, anthracene, tetracene and pentacene). Previously, the electron-optic phonon scattering mechanism has been investigated through Holstein-Peierls model coupled with DFT calculations for naphthalene. Numerical results indicate that the acoustic phonon scattering intensity is about 3 times as large as that for the optic phonon and the obtained mobility is in much better agreement with the result of the experiment done for ultrapure single crystals. It is thus concluded that for closely packed molecular crystal where the electron is partly delocalized, acoustic phonon scattering mechanism prevails in the charge transport. Moreover, it is found that the intrinsic electron mobility is even larger than hole mobility. A frontier orbital overlap analysis can well rationalize such behavior.

Reactive extraction is an emerging technology for large-scale continuous resolution of drug enantiomers. The enantioselective extraction of R,S-naproxen by hydrophilic HP-β-CD in 1,2-dichloroethane was studied at 5 °C. The experimental data were described by a reactive extraction model with a homogeneous aqueous phase reaction of R,S-naproxen with HP-β-CD which couples a complete description of chemical equilibria in aqueous phase with the overall phase equilibria of the system. Important parameters of this model were determined experimentally. The physical distribution coefficients for molecular and ionic NAP were 0.041 and 1.730, respectively. Here we show that the efficiency of extraction depends strongly on two process variables including pH and HP-β-CD concentration. The model predictions are compared graphically with the results of previous experiments and there is a good agreement between each other. By the use of modeling and experiment, an optimized extraction condition with pH of 2.5 and HP-β-CD concentration of 0.1 mol/L was obtained with high enantioselectivity (α?) of 1.59 and performance factor (pf) of 0.049. The model gives a good means of predicting enantiomers partitioning over a range of experimental conditions.

We report the first Rh2(II)-catalyzed asymmetric cycloisomerization of activated enynes to provide cyclopropane-fused tetra-hydropyridines in good yields and excellent enantioselectivities under mild conditions. The activated group, CHZ (Z is electron-withdrawing group (EWG)), in the enyne substrates exerts two synergetic roles, one is to activate alkyne for the cyclopropanation reaction; the other is to introduce the C-H···O interaction between substrate and catalyst (reducing the energy barrier of the reaction). This double-mode activation was supported by both density functional theory (DFT) calculations and experimental tests. This strategy was also extended to other CH2Z (Z can be OH, OMe, F) as activating groups that made the CH2 more acidic so that the substrates could also form increased C-H···O interaction with the catalyst.

DNA modified nanoparticles (AuNPs) are an established and widely used type of nucleotide sensor. We sought to improve the design by applying short rigid DNA duplexes near the surface of the AuNPs forming a so called double-anchored AuNP sensor, and compared it with other conventional DNA modified AuNPs. The improved design exhibited higher assembly efficiency, and consequently increased its sensitivity to target DNA.

Molecular modeling of acrylates (acrylamides) with Dl protein ofPisum sativum is presented. Studies show that the binding force mainly includes H-bond interaction, Van der Waals and π-ring stacking interaction. It was found that SER 268 in Dl protein might be an important binding site. It is important for high inhibitory activity of compounds whether an electronegative atom in alkyl of ester linkage could make H-bond interaction with SER 268 in Dl protein. Thus some new acrylates (acrylamides) were designed and synthesized. Bioassay indicated that these new compounds showed expected Hill reaction inhibitory activity.

The conversion of fuel-N to NO x is the main contribution of NO x from coal-fired industrial boilers and is the least-studied modelling problem arising from coal combustion. This paper summarises the current understanding of the mechanisms that account for the formation of NO x from fuel-N during coal combustion. Further experimentation on NO x emissions during bituminous coal combustion was simulated with attention focused on the contribution of char-N and volatile-N to fuel-NO x through the Coal/Char combustion method. The critical analysis of this issue allowed for the identification of uncertainties and produced well-founded conclusions. The results indicated that fuel-NO x formation was a very complex physical-chemical process involving many competing mechanisms. These mechanisms included chemical reactions, convective mass transfer, heat transfer, adsorption and desorption. The contribution of char-N in this experiment varied between 30% and 70%. There may be a slight question as to the exact identity of the main contributor to fuel-NO x , and no definitive conclusion can be made as of yet. This uncertainty is because the contribution of char-N to fuel-NO x was heavily affected by the combustion conditions and the contribution of char-N increased monotonically as temperature increased. There was a critical point in the relationship between particle size, air flow, O2 concentration and the contribution of char-N. The contribution of char-N increased with the increase of particle size and air flow initially when less than the critical value, and decreased when more than thecritical value. The contribution of char-N initially decreased when the O2 concentration was increased from 10% to 15% and increased more with the further increase in O2 concentration.