Materials Surgery – Reactivity Differences of Organic Groups in Hybrids

Synergistic properties in hybrid materials can emerge if the inorganic matrix has an electronic influence on the organic constituents and vice versa. This paper describes the drastic effect of SiO₂ in periodically ordered mesoporous organosilica materials (PMOs) on ethylene groups. A sophisticated, in situ solid‐state NMR spectroscopy study showed that the ozonolysis of ethylene groups follows an entirely different mechanism than is normal for organic, molecular groups. Ultimately, this leads to the topotactic transformation of the PMO material. Only if silicon is not in the alpha position to the double bond does it became possible to establish a new method to functionalize PMOs materials: the targeted scission of the ethylene group and the creation of functionalized pockets inside the pore walls of the mesoporous solid.     

Steric and electronic selectivity in the synthesis of Fe- 1,2,4,5-tetracyanobenzene （TCNB） complexes on Au（111）： From topological confinement to bond formation

A study of the surface assisted self-assembly of 1,2,4,5-tetracyanobenzene （TCNB） acceptor molecules and Fe atoms on an Au（111） surface is presented. While conditions to get the two-dimensional arrays of stable Fe（TCNB）4 complexes are clearly identified, ultrahigh vacuum scanning tunneling microscopy and spectroscopy （STM/STS） coupled with first-principles calculations reveals that situations may occur where Fe and TCNB survive on the surface （as Fe-4TCNB entities） at a higher density than the original molecular monolayer without forming coordination bonds with each other. It is found that the square planar coordination of the Fe（TCNB）4 monomer complexes cannot fully develop in the presence of lateral strain due to growth-induced confinement. A phenomenon similar to steric hindrance involving a strongly modified chirality with a Fe-N-C bond angle of 120° compared to the 180° for the stable complex may then explain why the Fe atom keeps its metallic bond with the surface. The competition between steric and electronic effects, not reported before, may arise elsewhere in surface chemistry involved in the synthesis of new and potentially useful organic nanomaterials.     

PVP保护下纳米银颗粒的液相化学还原法制备及表征

以PVP为表面活性剂,甲酸铵为还原剂,采用液相还原法制备了纳米银颗粒。采用X射线衍射(XRD)、透射电子显微镜(TEM)和紫外-可见光吸收光谱(UV-Vis)对所制备样品进行表征。结果显示：当PVP与AgNO3的质量比为2.2：1,陈化时间24 h,得到立方块和六棱柱的银混合颗粒。     

Probing Bio–Nano Interactions between Blood Proteins and Monolayer‐Stabilized Graphene Sheets

Meeting proteins is regarded as the starting event for nanostructures to enter biological systems. Understanding their interactions is thus essential for a newly emerging field, nanomedicine. Chemically converted graphene (CCG) is a wonderful two‐dimesional (2D) material for nanomedecine, but its stability in biological environments is limited. Systematic probing on the binding of proteins to CCG is currently lacking. Herein, we report a comprehensive study on the interactions between blood proteins and stabilized CCG (sCCG). CCG nanosheets are functionalized by monolayers of perylene leading to significant improvement in their resistance to electrolyte salts and long‐term stability, but retain their core structural characteristics. Five types of model human blood proteins including human fibrinogen, γ‐globulin, bovine serum albumin (BSA), insulin, and histone are tested. The main drving forces for blood protein binding involve the π–π interacations between the π‐plane of sCCG and surface aromatic amonic acid (sAA) residues of proteins. Several key binding parameters including the binding amount, Hill coefficient, and binding constant are determined. Through a detailed analysis of key controlling factors, we conclude that the protein binding to sCCG is determined mainly by the protein size, the number, and the density of the sAA.     

纳米粒子及纳米化学研究进展

简要介绍了纳米粒子的概念、内涵、基本特性、液相化学合成方法、表征及纳米材料研究的现状和进展。     

Nanoparticles in Liquid Crystals: Synthesis,Self-Assembly,Defect Formation and Potential Applications

Revolutionary developments in the fabrication of nanosized particles have created enormous expectations in the last few years for the use of such materials in areas such as medical diagnostics and drug-delivery, and in high-tech devices. By its very nature, nanotechnology is of immense academic and industrial interest as it involves the creation and exploitation of materials with structural features in between those of atoms and bulk materials, with at least one dimension limited to between 1 and 100 nm. Most importantly, the properties of materials with nanometric dimensions are, in most instances, significantly different from those of atoms or bulk materials. Research efforts geared towards new synthetic procedures for shape and size-uniform nanoscale building blocks as well as efficient self-assembly protocols for manipulation of these building blocks into functional materials has created enormous excitement in the field of liquid crystal research. Liquid crystals (LCs) by their very nature are suitable candidates for matrix-guided synthesis and self-assembly of nanoscale materials, since the liquid crystalline state combines order and mobility at the molecular (nanoscale) level. Based on selected relevant examples, this review attempts to give a short overview of current research efforts in LC-nanoscience. The areas addressed in this review include the synthesis of nanomaterials using LCs as templates, the design of LC nanomaterials, self-assembly of nanomaterials using LC phases, defect formation in LC-nanoparticle suspensions, and potential applications. Despite the seeming diversity of these research topics, this review will make an effort to establish logical links between these different research areas.