Temperature-driven surface morphology evolution of poly(3-hydroxybutyrate) single layer and poly(3-hydroxybutyrate)/poly(vinyl phenol) bilayer on Si wafers

 The specular and off-specular X-ray reflectivities were efficiently employed to study the evolution of surface morphology as a function of temperature in a single layer of poly(3-hydroxybutyrate) (PHB) and a bilayer of PHB/poly(vinyl phenol) (PVPh) on Si substrates. The results indicate that the changes of thickness and surface roughness caused by pre-melting of PHB crystals are not obvious for the single layer, whereas the surface roughness of the PHB layer and the intensity of the off-specular X-ray reflectivity for the bilayer exhibit a remarkable non-monotonic change in the temperature range of 100-150℃; the roughness parameter evaluated by the specular X-ray reflectivity reaches its maximum at 120℃. The interaction at the interface between PVPh and PHB certainly contributes to the non-monotonic changes. Such interaction also affects the crystallization and melting behavior of PHB thin film greatly. The crystallization of PHB thin film is inhibited even on the glassy surface of PVPh sublayer. In the melting process, the PHB crystals on PVPh sublayer feature a three-section melting curve separated by a plateau region of 120-140℃.     

The development of carbon capture by functionalized ionic liquids

The CO₂ capture by functionalized ionic liquids developed in recent years was critically reviewed, where the relationship between the capacity and the enthalpy as well as that between the structure and the viscosity were discussed. This work reviews with special emphasis on tuning the basicity and designing the structure for improving absorption properties, such as adjusting the capacity and energy consumption, and decreasing the viscosity of ionic liquid. Subsequently, some unconventional absorption phenomenon was also set out detailed. Finally, the recent efforts in understanding CO₂ absorption and the future research directions were outlined.     

Catalytic effects of hydrogen-bond acceptor solvent on nucleophilic aromatic substitution reactions in non-polar aprotic solvent: reactions of phenyl 2,4,6-trinitrophenyl ether with amines in benzene-acetonitrile mixtures

The effect of addition of small amounts of hydrogen-bond acceptor solvent, acetonitrile, to the benzene medium of the reactions of phenyl 2,4,6-trinitrophenyl ether with aniline and cyclohexylamine, respectively have been investigated. The addition produced similar effects in the two reactions—continuous rate increase with increasing amounts of acetonitrile. The results are interpreted in terms of the effect of amine-solvent interaction on the nucleophilicity of the amines and are in accord with our expectations based on the effects observed for hydrogen-bond donor solvent, methanol on the same reactions. It is also established from the results that the role of hydrogen-bond acceptor co-solvent could be played by an added more basic non-nucleophilic amine.     

Synthesis, characterization and mechanical properties of polyester-based aliphatic polyurethane elastomers containing hyperbranched polyester segments

Aliphatic polyester-based polyurethane (PU) elastomers with hyperbranched polyester segments were synthesized from polyester diol, hydroxyl-terminated hyperbranched polyester (HB-20), isophorone diisocyanate (PDI) and 1,4-butanediol. The crosslinking density of the PU elastomer was calculated by using Flory-Rehner equation. The degree of hydrogen bonding, the microstructure and the morphologies of these PU materials were characterized by means of FT-IR, WAXD and DSC, respectively. The experimental results showed that the PU elastomers containing small amount of HB-20 exhibited the enhanced hydrogen bonding and mechanical properties. As compared with the comparable PU specimen, the tensile strength of the polyester-based aliphatic PU containing 6 wt% HB-20 increased by 71.2 times, up to 36.1 MPa, and the elongation at break was still as high as 333.1%, resulting from the dual effects of the hydrogen bonding and the crosslinking density in the PU system.     

Calculation of hydrophobic parameters directly from three-dimensional structures using comparative molecular field analysis

Summary Capacity ratio (log k') values, which are a measure of hydrophobicity, were calculated directly from the three-dimensional structures of 17 furans and 54 triazines using the comparative molecular field analysis approach. The H₂O probe and the GRID force field, including hydrogen-bond potentials, yielded excellent correlations with the log k' values. Moreover, the predicted values of log k' from 14 additional triazine analogs showed excellent agreement with log k' values reported in the literature. Similar results were obtained for the octanol-water partition coefficients (log P) of 17 furans.     

Pluri-dimensional hydrogen-bonded networks of novel thiophene-introduced oligo(imidazole)s and physical properties of their charge-transfer complexes with TCNQ

Novel π-extended oligo(imidazole)s composed of imidazole and thiophene ring systems, bis(imidazolyl)thiophenes 1-4, were synthesized as new building blocks for electron-donor molecules having diverse hydrogen-bonding directionalities in order to explore hydrogen-bonded charge-transfer complexes and supramolecular assemblies. The cyclic voltammetry of these compounds showed increase of electron-donating ability compared with those of 2,2′- and 4,4′-biimidazoles. In the crystal structure, 1, 2 and 3 exhibited multi-dimensional hydrogen-bonded networks via solvent molecules including the π-π interaction. Charge-transfer complexes of 1, 2 and 4 with TCNQ were characterized as partial charge-transfer complexes with segregated stacks. The compressed pellets of the TCNQ complex of 2 showed a high electrical conductivity (σ_rt=5.2×10⁻² S cm⁻¹) at room temperature with semiconducting behavior (activation energy, E_a=71 meV).     

由氢键构筑的[Cu2(ETU)6]SO4三维超分子网络的合成与晶体结构

选用具有丰富配位模式(单齿、二齿或三齿)的亚乙基硫脲(ETU, 代森类杀菌剂的有毒降解物, 通过和金属离子配位有可能使其性状发生改变)作配体, 在溶剂热条件下合成出一种由氢键构筑的、新的三维超分子配位聚合物[Cu2(ETU)6]SO4(1), 并对其结构进行了详细表征.     

Solvent properties governing protein partitioning in polymer/polymer aqueous two-phase systems

Distribution coefficients of various proteins were measured in aqueous Dextran-Ficoll, Dextran-PES, and Ficoll-PES two-phase systems, containing 0.15M NaCl in 0.01 M phosphate buffer, pH 7.4. The acquired data were combined with data for the same proteins in different systems reported previously and known solvatochromic solvent properties of the systems to characterize the protein-solvent interactions. The relative susceptibilities of proteins to solvent dipolarity/polarizability, solvent hydrogen bond acidity, solvent hydrogen bond basicity, and solvent ability to participate in ion-ion and ion-dipole interactions were characterized. These parameters, which are representative of solute-solvent interactions, adequately described the partitioning of the proteins in each system. It was found that the relative susceptibilities of proteins to solvent dipolarity/polarizability are interrelated with their relative susceptibilities to solvent hydrogen bond acidity and solvent hydrogen bond basicity similarly to those established previously for small nonionic organic compounds.     

磺酰脒基桥连的锌卟啉-富勒烯化合物构型对光诱导电子转移机理的影响

通过"一锅法"多组分偶联反应合成了一种新型磺酰脒基桥连的卟啉-富勒烯化合物ZnP-H-C₆₀. 该化合物具有Z式和E式2种异构体, 其中Z式异构体中含有分子内氢键. 光物理研究结果表明, 2种异构体中的卟啉与富勒烯之间都可以发生光诱导电子转移, 但其相应的电子转移机理却完全不同. 在Z式异构体中, 卟啉或富勒烯被激发后直接发生电荷分离而形成电荷分离态, 其电荷分离机理是通过氢键进行电子传递; 在E式异构体中, 由于卟啉和富勒烯之间存在空间电子相互作用, 被激发后先形成卟啉-富勒烯激基复合物, 再进一步发生电荷分离形成电荷分离态, 电荷分离通过空间电子转移实现.     

槲皮素的共振光散射光谱研究

研究了槲皮素(Qu)的共振光散射光谱和吸收光谱,结果表明,pH在3.30～6.50范围内,Qu的共振光散射信号很强且稳定,当pH＞6.50时,共振光散射强度随pH的增大而迅速减小。在pH 4.00的B-R缓冲溶液中,在λ=497 nm处,共振光散射强度在一定浓度范围内与Qu的浓度成线性关系,线性范围为0.0～3.0×10-4 mol·L-1, 相关系数r＞0.999, 检测限为3.1×10-7 mol·L-1。同时运用量子化学计算方法对Qu分子内、分子间氢键进行了计算,理论计算表明: Qu共振光信号增强的原因是Qu分子通过4-4’分子间氢键聚合形成了超分子聚合体, 这一结论和实验得到的光谱数据完全吻合。