Interfacial nanoarchitectonics for molecular manipulation and molecular machine operation

The nanoarchitectonics concept enables us to produce functional systems and materials from nanoscale units through nanotechnological approaches together with the processes including chemical syntheses, atom/molecule manipulations, self-assemblies, self-organizations, field-induced material regulations, and bio-related processes. Especially, manipulations of molecules (molecular machines) and sophisticated organization would be attractive targets in interfacial nanoarchitectonics. In this short review, we introduce several typical examples on manipulations of functional molecules and molecular machines at interfacial media. The examples are classified roughly according to driving forces of manipulations; (i) manipulations through chemical reactions and interactions; (ii) light-driven manipulations; (iii) electrically controlled manipulations; (iv) mechanical manipulations. Future possibilities of molecular manipulations at interfaces such as usages in biological systems are discussed in perspective section.     

Molecular Architectonics-guided Design of Biomaterials

The quest for mastering the controlled engineering of dynamic molecular assemblies is the basis of molecular architectonics. The rational use of noncovalent interactions to programme the molecular assemblies allow the construction of diverse molecular and material architectures with novel functional properties and applications. Understanding and controlling the assembly of molecular systems are daunting tasks owing to the complex factors that govern at the molecular level. Molecular architectures depend on the design of functional molecular modules through the judicious selection of functional core and auxiliary units to guide the precise molecular assembly and co-assembly patterns. Biomolecules with built-in information for molecular recognition are the ultimate examples of evolutionary guided molecular recognition systems that define the structure and functions of living organisms. Explicit use of biomolecules as auxiliary units to command the molecular assemblies of functional molecules is an intriguing exercise in the scheme of molecular architectonics. In this minireview, we discuss the implementation of the principles of molecular architectonics for the development of novel biomaterials with functional properties and applications ranging from sensing, drug delivery to neurogeneration and tissue engineering. We present the molecular designs pioneered by our group owing to the requirement and scope of the article while acknowledging the designs pursued by several research groups that befit the concept.     

几种自组装拉胀分子网络的分子模拟

报道了几种蜈蚣形、双足蜈蚣形聚合物 ,以及单箭头、双箭头形小分子通过氢键自组装形成拉胀分子网络的分子设计 .分子力学计算结果表明这些自组装分子网络靠氢键相互作用规则排列 ,具有类似倒插蜂窝网络结构 ,所设计的聚合物、小分子的合成较之以往报道的二维网络结构的合成简便易行 ,为真正分子水平意义上的拉胀结构的实现提供了新的思路和指导     

Experimental and theoretical electronic charge densities in molecular crystals

Electronic charge density distribution in molecular systems has been described in terms of the topological properties. After briefly reviewing methods of obtaining charge densities from X-ray diffraction and theory, typical case studies are discussed. These studies include rings and cage systems, hydrogen bonded solids, polymorphic solids and molecular NLO materials. It is shown how combined experimental and theoretical investigations of charge densities in molecular crystals can provide useful insights into electronic structure and reactivity.     

Metal bis-1,2-dithiolene complexes in conducting or magnetic crystalline assemblies

Crystalline materials studied for their conducting or magnetic properties based on metal complexes of 1,2-dithiolene ligands are discussed emphasising the wide diversity of ligands now available and the variety of materials prepared from these. Complexes have been prepared using electronically delocalised dithiolene ligands where the core complex is extended with units such as thioethers, aromatics, tetrathiafulvalene (TTF) and other heterocycles to explore the influence of these variations on the solid-state structures and properties derived from them. Although superconductivity in dithiolene complexes has so far been limited to [M(dmit)₂]^X− salts, other ligand systems have given rise to numerous conducting and metallic salts and have proven informative in rationalising the criteria for design of the molecular units. Novel material properties have been observed in systems such as hybrid conducting ∣ magnetic materials and mixed dithiolene-metallocene salts. In particular, highly conducting and metallic single-component materials have recently been found uniquely within materials based on metal-bis-1,2-dithiolene complexes. Magnetic materials containing dithiolene-complex building blocks have yielded systems such as ferromagnets, ferrimagnets, metamagnets and spin ladders in addition to other model systems suitable for the study of magnetic ordering. These can involve systems where the dithiolene complex is the only paramagnetic component in addition to more complex systems involving other types of building block.     

Guest-specific diffusion anisotropy in nanoporous materials: Molecular dynamics and dynamic Monte Carlo simulations

For anisotropic nanoporous materials, guest diffusion is often reflected by a diffusion tensor rather than a scalar diffusion coefficient. Moreover, the resulting diffusion anisotropy may notably differ for different guest molecules. As a particular class of such systems, we consider an array of two types of channels, mutually intersecting each other, where the rates of diffusion in the different directions depend on the nature of the guest molecules. The simultaneous adsorption of two types of guest molecules is considered, as in technical applications of porous materials such as catalysis. A case study is presented in which atomistic molecular dynamics (MD) and coarse-grained dynamic Monte Carlo (DMC) simulations are compared and shown to yield qualitatively similar results for non-steady-state diffusion. The two techniques are complementary. MD simulations are able to predict the details of molecular propagation over distances of a few unit cells, whereas the evolution of sorption profiles over distances comparable with entire crystallites can be studied with DMC simulations. Consideration of these longer length and time scales is necessary for applications of such systems in chemical separations and heterogeneous catalysis.     

Molecular and nanoscale materials and devices in electronics

Over the past several years, there have been many significant advances toward the realization of electronic computers integrated on the molecular scale and a much greater understanding of the types of materials that will be useful in molecular devices and their properties. It was demonstrated that individual molecules could serve as incomprehensibly tiny switch and wire one million times smaller than those on conventional silicon microchip. This has resulted very recently in the assembly and demonstration of tiny computer logic circuits built from such molecular scale devices. The purpose of this review is to provide a general introduction to molecular and nanoscale materials and devices in electronics.     

复杂条件下高分子材料老化规律、寿命预测与防治研究新进展

复杂条件下有机高分子材料的老化、寿命预测和防治研究对满足相关行业发展的迫切需求,实现节能减排、环境保护及可持续发展等战略目标具有重大意义。本文重点综述了近年来针对聚烯烃、工程塑料、橡胶、涂料等大宗高分子材料在我国复杂大气环境中的自然老化及人工模拟加速老化研究的新进展,对材料老化失效基本规律和分子机理、老化数据库的建立及老化分级图谱的绘制进行了介绍,探讨了户外自然环境和人工模拟环境下材料老化失效规律的对应关系、服役寿命理论的预测模型及失效防治延寿新方法,并对其中存在的问题及下一步发展方向进行了展望。     

The impact of molecular emission in compositional depth profiling using Glow Discharge-Optical Emission Spectroscopy

The scope of this paper is to investigate and discuss how molecular emission can affect elemental analysis in glow discharge optical emission (GD-OES), particularly in compositional depth profiling (CDP) applications. Older work on molecular emission in glow discharges is briefly reviewed, and the nature of molecular emission spectra described. Work on the influence of hydrogen in the plasma, in particular elevated background due to a continuum spectrum, is discussed. More recent work from sputtering of polymers and other materials with a large content of light elements in a Grimm type source is reviewed, where substantial emission has been observed from several light diatomic molecules (CO, CH, OH, NH, C₂). It is discussed how the elevated backgrounds from such molecular emission can lead to significant analytical errors in the form of “false” depth profile signals of several atomic analytical lines. Results from a recent investigation of molecular emission spectra from mixed gases in a Grimm type glow discharge are presented. An important observation is that dissociation and subsequent recombination processes occur, leading to formation of molecular species not present in the original plasma gas. Experimental work on depth profiling of a polymer coating and a thin silicate film, using a spectrometer equipped with channels for molecular emission lines, is presented. The results confirm that molecular emission gives rise to apparent depth profiles of elements not present in the sample. The possibilities to make adequate corrections for such molecular emission in CDP of organic coatings and very thin films are discussed.     

基于电致酸/碱理论的手性光学切换体系

手性分子光学开关在光学储存、 光学通信以及三维立体显示等领域有着重要的应用价值. 但是目前的手性分子光学开关存在材料种类少、 光学可调性差、 稳定性差等缺点, 如何构筑出具有高光学可调性以及稳定性的手性光学切换体系依旧是一项严峻的挑战. 本工作基于电致酸/碱理论, 通过将手性联萘官能团引入到酸响应的罗丹明主体结构中, 设计并合成了一种新型的酸响应手性光学开关分子, 并将其与电致酸材料相结合, 成功实现了电场驱动的手性光学开关过程, 开发了一种新型的手性光学切换体系. 发现在合适的电场控制下, 其颜色、 荧光以及圆二色谱信号均能发生可逆的变化. 这种方法为构筑新型手性光学开关体系提供了一种新思路, 对手性光学开关材料的应用拓展具有重要的参考价值.     

中孔分子筛MCM-41形成机理的考察

MCM－41分子筛是九十年代初期美国Mobil公司开发的一种新型中孔（mesoporous）材料[1]．它以C8－C16季俊碱表面活性剂作为模板剂水热法合成，具有2－10nm的孔径，孔道六方有序排列，高比表面和高吸附容量，中等酸性和稳定性，是一种有潜在应用前景的吸附和催化材料．目前，关于     

Dynamic Covalent Self-sorting in Molecular and Polymeric Architectures Enabled by Spiroborate Bond Exchange

Self-sorting is commonly observed in complex reaction systems, which has been utilized to guide the formation of single major by-design molecules. However, most studies have been focused on non-covalent systems, and using self-sorting to achieve covalently bonded architectures is still relatively less explored. Herein, we first demonstrated the dynamic nature of spiroborate linkage and systematically studied the self-sorting behavior observed in the transformation between spiroborate-linked well-defined polymeric and molecular architectures, which is enabled by spiroborate bond exchange. The scrambling between a macrocycle and a 1D helical covalent polymer led to the formation of a molecular cage, whose structures are all unambiguously elucidated by single-crystal X-ray diffraction. The results indicate that the molecular cage is the thermodynamically favored product in this multi-component reaction system. This work represents the first example of a 1D polymeric architecture transforming into a shape-persistent molecular cage, driven by dynamic covalent self-sorting. This study will further guide the design of spiroborate-based materials and open the possibilities for the development of novel complex yet responsive dynamic covalent molecular or polymeric systems.     

Azulene-based organic functional molecules for optoelectronics

Design and synthesis of new organic functional materials with improved performance or novel properties are of great importance in the field of optoelectronics. Azulene, as a non-alternant aromatic hydrocarbon, has attracted rising attention in the last few years. Different from most common aromatic hydrocarbons, azulene has unique characteristics, including large dipole moment, small gap between the highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO). However, the design and synthesis of azulene-based functional materials are still facing several challenges. This review focuses on the recent development of organic functional materials employing azulene unit. The synthesis of various functionalized azulene derivatives is summarized and their applications in optoelectronics are discussed, with particular attention to the fields including nonlinear optics (NLO), organic field-effect transistors (OFETs), solar cells, and molecular devices.     

Toward rational and modular molecular design in soft matter engineering

This essay discusses some preliminary thoughts on the development of a rational and modular approach for molecular design in soft matter engineering and proposes ideas of structural and functional synthons for advanced functional materials. It echoes the Materials Genome Initiative by practicing a tentative retro-functional analysis(RFA) scheme. The importance of hierarchical structures in transferring and amplifying molecular functions into macroscopic properties is recognized and emphasized. According to the role of molecular segments in final materials, there are two types of building blocks: structural synthon and functional synthon. Guided by a specific structure for a desired function, these synthons can be modularly combined in various ways to construct molecular scaffolds. Detailed molecular structures are then deduced, designed and synthesized precisely and modularly. While the assembled structure and property may deviate from the original design, the study may allow further refinement of the molecular design toward the target function. The strategy has been used in the development of soft fullerene materials and other giant molecules. There are a few aspects that are not yet well addressed:(1) function and structure are not fully decoupled and(2) the assembled hierarchical structures are sensitive to secondary interactions and molecular geometries across different length scales. Nevertheless, the RFA approach provides a starting point and an alternative thinking pathway by provoking creativity with considerations from both chemistry and physics. This is particularly useful for engineering soft matters with supramolecular lattice formation, as in giant molecules, where the synthons are relatively independent of each other.     

原位聚合法分子复合材料的研究进展

论述了原位复合材料的发展及最新研究动态，重点介绍了近十几年来国内外在原位聚合分子复合材料的制备、结构与性能、增强机理等方面的研究状况、预示了原位分子复合材料的开发前景。     

Optical manipulation in conjunction with photochemical/photothermal responses of materials

This article reviews optical manipulation coupled with photochemical/photothermal responses of nanometer sized materials including molecular systems, polymers, and inorganic nanoparticles. After the introduction, section 2 overviews the optical trapping of nanometer sized molecular systems including early-stage studies, such as trapping of polymer chains, micelles, and molecular aggregates in solution at room temperatures. Then, the conformation control of macromolecule assemblies and gels by optical force are introduced, followed by micro-fabrications achieved by combining optical trapping and photochemical reactions. Section 3 summarizes studies on the evaluation of optical force acting on nanometric molecular systems using fluorescence correlation techniques. Approaches to control optical force by using photochemical reactions are show in section 4, where the absorption band of target materials are modified through photochromic reactions, leading to micromechanical motion of small particles synchronizing with the photochemical reactions. Section 5 overviews photothermal effect in optical manipulation such as natural convection, Marangoni convection and thermophoresis, and applications of the thermal effects to develop new methods of micromanipulation achieved by combining optical force and photothermal responses.     

多孔晶体材料的分子工程学研究

功能无机晶体材料的定向设计与合成是化学及材料科学领域中一项重要的前沿课题。本文介绍了近十几年来我们在多孔晶体材料,主要包括分子筛和金属有机骨架晶体材料的分子工程学研究方面所取得的一些进展。其中包括提出了定向设计具有特殊孔道结构和特殊计量比分子筛多孔骨架结构的计算机方法;在国际上率先建立了分子筛多孔晶体材料合成与结构数据...     

Conformational Study of Glycal-Type Neuraminidase Inhibitors

The conformational flexibility of two glycal-type neuraminidase inhibitors has been studied, using several molecular modeling techniques. In agreement with the experimental data available, an intramolecular hydrogen bond, representing a key structural feature that controls the conformer distribution in solution, has been identified. The contribution of each substituent to the overall equilibrium was evaluated using simplified derivatives. Additionally, four methods for estimating NMR coupling constants from dihedral angles were evaluated and the Haasnoot method was found to be appropriate for this class of sugars. These results should allow a better understanding of the structural parameters governing physico-chemical properties of glycal-like compounds. Supplemental materials are available for this article. Go to the publisher's online edition of Journal of Carbohydrate Chemistry to view the free supplemental file.     

The atom assignment problem in automated de novo drug design. 1. Transferability of molecular fragment properties

Summary This paper is the first of a series which examines the problems of atom assignment in automated de novo drug design. In subsequent papers, a combinatoric optimization method for fragment placement onto 3D molecular graphs is provided. Molecules are built from molecular graphs by placing fragments onto the graph. Here we examine the transferability of atomic residual charge, by fragment placement, with respect to the electrostatic potential. This transferability has been tested on 478 molecular structures extracted from the Cambridge Structural Database. The correlation found between the electrostatic potential computed from composite fragments and that computed for the whole molecule was encouraging, except for extended conjugated systems.