Dynamic “Molecular Portraits” of Biomembranes Drawn by Their Lateral Nanoscale Inhomogeneities

To date, it has been reliably shown that the lipid bilayer/water interface can be thoroughly characterized by a sophisticated so-called “dynamic molecular portrait”. The latter reflects a combination of time-dependent surface distributions of various physicochemical properties, inherent in both model lipid bilayers and natural multi-component cell membranes. One of the most important features of biomembranes is their mosaicity, which is expressed in the constant presence of lateral inhomogeneities, the sizes and lifetimes of which vary in a wide range—from 1 to 10³ nm and from 0.1 ns to milliseconds. In addition to the relatively well-studied macroscopic domains (so-called “rafts”), the analysis of micro- and nanoclusters (or domains) that form an instantaneous picture of the distribution of structural, dynamic, hydrophobic, electrical, etc., properties at the membrane-water interface is attracting increasing interest. This is because such nanodomains (NDs) have been proven to be crucial for the proper membrane functioning in cells. Therefore, an understanding with atomistic details the phenomena associated with NDs is required. The present mini-review describes the recent results of experimental and in silico studies of spontaneously formed NDs in lipid membranes. The main attention is paid to the methods of ND detection, characterization of their spatiotemporal parameters, the elucidation of the molecular mechanisms of their formation. Biological role of NDs in cell membranes is briefly discussed. Understanding such effects creates the basis for rational design of new prospective drugs, therapeutic approaches, and artificial membrane materials with specified properties.     

一维链状钴配合物的合成、结构及热稳定性

在水热法条件下,以N,N-二甲基甲酰胺（DMF）和水（VDMF∶VH2O=2∶1）为溶剂,基于1,2,4,5-苯四甲酸（H4BTA）、咪唑（Im）和氯化钴（CoCl2.6H2O）合成了一维链状配合物[Co（Im）2（H4BTA）0.5]n（1）。晶体结构分析表明：该配合物属于三斜晶系,P1空间群,在不对称结构单元中一个钴原子与两个咪唑中的两个氮原子、H4BTA中的一个氧原子配位。同时,配合物（1）通过分子间和一维链间氢键作用形成三维超分子。     

Investigation of the degree of homogeneity and hydrogen bonding in PEG/PVP blends prepared in supercritical CO2: Comparison with ethanol-cast blends and physical mixtures

The degree of homogeneity and H-bond interaction in blends of low-molecular-mass poly(ethylene glycols) (PEG, M_w = 400, 600, 1000) and poly(vinylpyrrolidone) (PVP, M_w = 9 × 10³) prepared in supercritical CO₂, ethanol and as physical mixtures were studied by differential scanning calorimetry (DSC), Fourier-transform infrared (FTIR) spectroscopy and dynamic mechanical analysis (DMA) techniques. Homogeneity of samples prepared in supercritical CO₂ were greater than physically mixed samples, but slightly less than ethanol-cast samples. PEG-PVP H-bond interaction was higher for ethanol-cast blends when compared to blends prepared in supercritical CO₂. This reduced interaction was attributed to a combination of: (1) shielding of PEG-PVP H-bond interactions when CO₂ is dissolved in the blend; (2) rapidly reduced PEG and PVP chain mobility upon CO₂ venting, delaying rearrangement for optimum PEG-PVP H-bond interaction.     

Supramolecular Capsules Derived from Resorcin[4]arenes by H-Bonding and Metal Coordination: Synthesis,Characterization, and Single-Molecule Force Spectroscopy

Self-assembly by H-bonding and by metal-coordination of functionalized calix[4]arenes and cavitands to large supramolecular capsules is described. In addition, a new method of analyzing supramolecular recognition processes at the single molecule level is discussed. By measuring interaction forces in a hydrogen-bonded assembly using single-molecule force spectroscopy (SMFS), the dynamics of the self-assembly process can be evaluated. In the future, consequent application of this new technique will influence supramolecular design principles and the use of non-covalent interactions as construction elements in the field of nanotechnology.     

基于π-π/H-键协同作用制备含芘小分子增强高韧性石墨烯纸

轻质高强且具备高韧性的石墨烯组装材料在抗冲击防护领域有着潜在的应用价值.在这项工作中,我们通过在还原氧化石墨烯层间界面交联1-氨基芘AP和1-芘丁酸PB共轭小分子,可以获得具有高导电、高韧性的超强复合石墨烯纸(AP/PB-GPs).结果表明,超过10μm厚度的复合石墨烯纸具有超高的平均韧性(~69.67±15.3 MJ m^-3),同时抗拉伸强度接近1 GPa;尤其在抗冲击性能方面,在高速弹道冲击速度下,仍然可以获得优异的比穿透能量吸收值(~0.17 MJ kg^-1).详细的界面和结构分析表明,界面增强是由相邻石墨烯层间与共轭分子之间的π-π相互作用和氢键连接共同决定的.尤其是石墨烯纳米片内的孔洞及边缘缺陷更有利于共轭小分子充分的吸附,这必然会使界面结合最大化,在连续高的加载应力下能够有效促进裂纹的偏转和塑性变形.密度泛函理论(DFT)模拟表明,石墨烯纳米片边缘的–COOH极性官能团与AP/PB分子表面的–NH₂、–COOH之间的耦合对氢键网络的形成起着关键作用.     

一维NiⅡ配合物的合成、结构及热稳定性

在甲醇-水溶剂中,用四溴代对苯二甲酸(H2TBTA)、1,3-二(4-吡啶基)丙烷(BPP)、硝酸镍为原料合成了一维链状配合物[Ni(BPP)2(TBTA)(H2O)2]n。该配合物晶体中NiII金属离子与两个BPP的两个N原子、两个H2TBTA中的两个羧基O原子及两个水分子中的O原子配位,形成六配位的变形八面体结构。晶胞参数:三斜晶系,P-1空间群,a=9.444(5),b=9.602(5),c=11.356(6),V=882.2(8)3,Z=1,Dcalc=1.828 mg/mm3,R1[I>2σ(I)]=0.0329,wR2(all data)=0.1058。对晶体进行热稳定性分析表明:配合物在122℃以下稳定性良好。     

Hydrophilic membranes for pervaporation: An analytical review

An analytical review has been attempted on the issues encountered in selecting polymers for hydrophilic pervaporation (PV) membranes. It is well known that permselectivity is determined by selective sorption and by selective diffusion. Selective sorption is governed by the presence of the active centers in the polymer which are capable of specific interactions with water. The analysis of the influences of the type of interactions of water-active centers of the polymer on the membrane performances are presented. Selective diffusion is governed by the rigidity and the regularity of the polymer structure and also by the constructure of the polymer's interspace. There is a net of bonds and crosslinks in the polymer due to existence of inter- and intramolecular interactions in it. This net is responsible for the stability of the mass transfer properties of the polymer to the feed water. The influences of the degree of swelling and frequencies of the crosslinks in the polymer are analysed. The main role of the selective diffusion in the selective permeation is demonstrated. The possibility of the existence of two different channels (hydrophilic and hydrophobic) for the permeation of water and organics is discussed, and it has been concluded that there are two different channels for friable polymers which have fragments with not so strong inter- and intra-molecular interactions. But in the polymers with strong inter- and intra-molecular interactions and a narrow net of these bonds (e.g., polyelectrolyte complexes), the hydrophobic channels are strongly collapsed. They can be opened only by water at its high feed concentrations. It was concluded that one of the most prospective ways to create highly permeative and highly selective materials for dehydration of organics by PV is using polyelectrolyte complexes (especially for the separation of water with organic molecules, which have more than three carbon atoms in total).     

无机阴离子对丙酮酸络合萃取的影响

采用三元模拟体系 ,以三辛胺为萃取剂 ,在不同离子类型及离子强度下对丙酮酸的络合萃取过程进行了研究 ,证实无机阴离子的存在对萃取效果产生极大的消极影响 ;通过理论分析及实验验证 ,对于无机阴离子的作用机理进行了讨论 ,初步推测无机阴离子可能是通过同离子竞争 ,削弱丙酮酸根离子与络合剂的离子对缔合作用 ,从而使萃取过程只能以氢键缔合方式进行     

配合物[Cd（ttcH2）2（3-bpt）2]·2H2O的合成、结构及性质研究

采用常温搅拌法合成了2,3,6-三巯基均三嗪(ttcH3)和4-氨基-3,5-二(3-吡啶基)-1,2,4-三唑(3-bpt)与过渡金属镉的配合物[Cd(ttcH2)2(3-bpt)2]·2H2O,对其结构进行了X-射线单晶衍射、红外光谱、元素分析以及热重分析等表征。X-射线单晶衍射分析显示该配合物为单核,属于三斜晶系,空间群P-1。配合物在氢键作用下拓展为3D超分子网络结构。热重分析显示该配合物的骨架稳定性较好。     

Remotion of the antibiotic tetracycline by titania and titania-silica composed materials

Removal of the antibiotic tetracycline (TC) by TiO₂ and the mesoporous binary system TiO₂-SiO₂ have been studied in batch experiments by performing adsorption isotherms/kinetics and photodegradation kinetics under different conditions of pH, supporting electrolyte concentration, temperature, adsorbent amount, and TiO₂-loading. On the one hand, the adsorption of TC on the studied materials is strongly dependent on pH, increasing as pH decreases. The adsorption mechanism, controlled by diffusion processes, is strongly related to electrostatic attractions and H-bond formations mainly between amide, carbonylic and phenolic groups of the antibiotic and the functional groups of TiO₂. The adsorption capacity at constant pH increases in the order TiO₂ < TiO₂-SiO₂ mainly due to the highly surface area that the silica offers and to the homogenously dispersion of the TiO₂ nanocrystallites. On the other hand, the photodegradation rate is affected by the presence of the studied materials at several pH, although its photocatalytic activities are more important at pH 7 or lower. The photodegradation mechanisms seem to be related to the formation of OH radicals which are responsible for the decomposition of TC. The composed titania-silica materials might act not only as an excellent adsorbent but also act as an alternative photocatalyst for pollution control.