Au-induced polyvinylpyrrolidone aggregates with bound water for the highly shape-selective synthesis of silica nanostructures

Novel Au-induced polyvinylpyrrolidone (PVP) aggregates with bound water (PVP-water) were created for the highly shape-selective synthesis of distinctive silica nanostructures, such as core-shell spheres, rods, snakes, tubes, capsules, thornlike, and dendritic morphologies. A water/PVP/n-pentanol system was first designed to bind water to PVP, and then Au nanoparticles were used to induce the PVP-water species to aggregate into distinctive soft structures by exploiting the interplay between PVP and gold. This was confirmed by the IR absorption spectra. The bound water in the soft structures was consumed during the hydrolysis of tetraethylorthosilicate and the target silica nanostructures were obtained. The soft structures, and therefore, the silica morphologies, can be readily tuned by adjusting the experimental parameters. The tunable Au-induced PVP-water soft structures reported herein open up new dimensions for the synthesis of distinctive nanomaterials (other than silica) that have new physicochemical properties and applications. These soft structures were also successfully extended to synthesize ZnO and SnO(2) particles with remarkable shapes, such as spheres, leaves, T-shaped structures, and dendritic morphologies.     

Synthesis and Morphogenesis of Organic and Inorganic Polymers by Means of Biominerals and Biomimetic Materials

We have studied the simultaneous synthesis and morphogenesis of polymer materials with hierarchical structures from nanoscopic to macroscopic scales. The morphologies of the original materials can be replicated to the polymer materials. In general, it is not easy to achieve the simultaneous synthesis and morphogenesis of polymer material even using host materials. In the present work, four biominerals and three biomimetic mesocrystal structures are used as the host materials or templates and polypyrrole, poly(3‐hexylthiopehene), and silica were used as the precursors for the simultaneous syntheses and morphogenesis of polymer materials. The host materials with the hierarchical structure possess the nanospace for the incorporation of the monomers. After the incorporation of the monomers, the polymerization reaction proceeds in the nanospace with addition of the initiator agents. Then, the dissolution of the host materials leads to the formation and morphogenesis of the polymer materials. The scheme of the replication can be classified into the three types based on the structures of the host materials (types I–III). The type I template facilitates the hierarchical replication of the whole host material, type II mediates the hierarchical surface replication, and type III induces the formation of the two‐dimensional nanosheets. Based on these results, the approach for the coupled synthesis and morphogenesis can be applied to a variety of combinations of the templates and polymer materials.     

气-液界面有序介孔SiO2无机膜的仿生合成

早在几百万年以前,自然界就通过生物矿化过程形成了结构高度有序的有机/无机复合材料,如哺乳动物的牙床、骨骼以及贝壳珍珠层等[1]。随着对天然生物材料生物矿化过程研究的逐渐深入,材料研究者从中得到极为重要的启示:先形成有机物自组装体,无机先驱物在自组装聚集体与溶液相的界面处发生化学反应,在有机自组装体的模板作用下,形成有机/无机复合体,再将有机模板去除即可得到具有一定形状与组织结构的无机材料。这种模仿生物矿化中无机物在有机物调制下形成过程的材料合成,称为仿生合成(biomimetic synthesis)[2]。仿生合成过程中,通过选择有…     

无机材料的仿生合成

生物矿化重要的特征之一是细胞分泌的有机基质调制无机矿物的成核和生长, 形成具有特殊组装方式和多级结构特点的生物矿化材料(如骨、牙和贝壳)。仿生合成就是将生物矿化的机理引入无机材料合成, 以有机物的组装体为模板, 去控制无机物的形成,制备具有独特显微结构特点的无机材料, 使材料具有优异的物理和化学性能。仿生合成已成为无机材料化学的研究前沿。本文综述了无机材料仿生合成的发展现状。     

Biomimetic total synthesis of (+)-gelsemine

Challenging: (+)-gelsemine was synthesized from (R,R)-aziridine 1 in 25 steps with approximately 1 % overall yield. A multistep, one-pot enol-oxonium cyclization cascade was used to construct, simultaneously, the E ring, F ring, C3 stereocenter, and C7 quaternary stereocenter. This synthesis using the enol-oxonium cyclization reaction as a key step to make the cage structure has demonstrated the proposed biosynthetic pathway of the gelsemine family.     

仿生无机纳米材料改造生物体的研究进展

在进化的过程中,生物体学会了利用材料来改造自身以适应环境的变化。自然界中的一些生物体可以通过生物矿化合成无机纳米材料为自己提供保护或其他特殊功能。但是自然界中还有部分生物体不具备生物矿化功能,受到自然界生物体利用纳米材料的启发,科学家们开始尝试通过人工赋予生物体纳米材料来对其进行改造。本文就基于生物-材料界面复合技术的纳米材料对生物体的改造,依次从调控机制、改造方法、功能应用等方面做了系统的阐述,重点介绍了通过仿生矿化对生物体进行纳米改造的研究进展,对仿生无机纳米材料改造生物体的领域现状做了分析和总结,并且对该领域的发展前景进行了展望。     

Biomimetic Synthesis of Shaped and Chiral Silica Entities Templated by Organic Objective Materials

Organic molecules with accompanying self‐organization have been a great subject in chemistry, material science and nanotechnology in the past two decades. One of the most important roles of organized organic molecules is the capability of templating complexly structured inorganic materials. The focus of this Minireview is on nanostructured silica with divergent morphologies and/or integrated chirality directed by organic templates of self‐assembled polyamine/polypeptides/block copolymers, chiral organogels, self‐organized chiral amphiphiles and chiral crystalline complexes, etc., by biomimetic silicification and conventional sol–gel reaction. Among them, biosilica (diatoms and sponges)‐inspired biomimetic silicifications are particularly highlighted.     

生物矿化、仿生合成与形貌调控

介绍了生物矿化材料的种类、结构、特点、形貌调控原则以及基于微生物、蛋白质、多肽、氨基酸和核酸等晶体调节剂的生物矿化材料的合成,总结了近年来生物矿化和彷生合成领域的研究进展.     

Biomimetic silica formation: analysis of the phosphate-induced self-assembly of polyamines

The highly siliceous cell walls of diatoms are probably the most outstanding examples of nanostructured materials in nature. Previous in vitro experiments have shown that the biomolecules found in the cell walls of diatoms, namely polyamines and silaffins, are capable of catalysing the formation of silica nanospheres from silicic/oligosilicic acid solutions. In a previous publication, silica precipitation was found to be strictly correlated with a phosphate-induced microscopic phase separation of the polyamines. The present contribution further characterises the phase separation behaviour of polyamines in aqueous solutions. In particular, a pronounced pH-dependence of the average particle diameter is found. It is, furthermore, shown that the ability of phosphate ions to form polyamine aggregates in aqueous solutions cannot be a purely electrostatic effect. Instead, a defined hydrogen-bonded network stabilised by properly balanced electrostatic interactions should be considered. Finally, solid-state 31P NMR studies on phase-separated polyamines, synthetic silica precipitates, and diatom cell walls from the species Coscinodicus granii support the assumption of a phosphate-induced phase separation process taking place during cell wall formation.     

二苯乙烯类低聚物的仿生合成

天然二苯乙烯低聚物是一类自然界分布广泛的多酚化合物,因其结构复杂且生物活性多样而受到密切关注,但此类化合物天然资源的稀少极大限制了其构效关系的调查及活性药物的筛选。近年来许多化学家对此类低聚物的仿生合成方法做了广泛而深入的研究,已形成一个新的研究热点。本文详尽综述了迄今三十多年来二苯乙烯类低聚物的仿生合成研究进展,包括在不同介质中的酶催化或金属氧化剂催化的氧化偶联方法、光催化的异构化及强酸催化下的环合反应,由不同的二苯乙烯前体通过仿生合成途径,构建出结构多样的二苯乙烯低聚物。此外,本文对该类低聚物的仿生合成研究前景做了展望。