Nanoscale molecular assemblies

Nanoscale molecules and molecular assemblies are being used more and more frequently as they reduce costs and use fewer resources. In order to be able to analyze and characterize these materials, new techniques have to be developed or refined. This two-volurne work brings together the knowledge from research and from industry of molecular nano dynamics. The topics are clearly divided into five parts over the 2 volumes, which focus on different topics. 

Mechanically interlocked molecular compounds, including catenanes, rotax-anes, and carceplex, are constituted of molecules composed of two or more components that cannot be separated from each other [95-98]. The development of strategy for achieving controlled self-assembling systems by non-covalent interaction enables one to prepare such attractive compounds for applications in nanoscale molecular devices. The dithiafulvene derivatives are effective electron donors, which are good candidates to form those supramolecular systems with appropriate acceptors by virtue of intermolec-ular CT interactions. In this chapter, dithiafulvene polymers forming rotax-ane structures are especially described. 

The generation of supramolecular structure of interest usually relies on molecular self-assembly and auto-organization processes. Much attention has been recently focused on the design of nanometer-scale (nanoscale) molecular devices. One approach to the molecular devices is the self - assembly of supramolecular structures such as the inclusion complexes [1,2,7,8],... 

In conclusion, this book is intended as an overview of the principles behind and state-of-the-art in interfacial supramolecular chemistry. The book is suitable for researchers and graduate students and focuses on assemblies that demonstrate at least the potential to produce useful devices such as solar cells, electrochromic devices, molecular wires, switches and sensors which are addressable by using electrochemical and optical stimuli. Molecular materials for nanoscale molecular devices remain an intriguing conceptual possibility. 

Dynamic covalent chemistry has been used in an atom-efficient self-assembly process to achieve a nearly quantitative one-pot synthesis of a nanoscale molecular container with an inner cavity of approximately 1.7 nm3. 

If the demands for tightness of the films are less stringent or irrelevant, other methods can be used for the formation of zeolite films. Spin-coating of zeolite suspensions (with nanoscale zeolite crystals) as well as molecular assembly of pre-synthesized zeolite crystals are viable methods for the deposition of rather smooth films. Furthermore, electrophoresis was successfully used to attach zeolite crystals to electrically conducting substrates. 

Interlocked molecular compounds consisting of a Ti-electron-rich component and a 71-electron-deficient unit can be assembled to form nanoscale molecular switches influenced by external electrochemical stimuli. Materials composed of CyDs include polyrotaxanes [34-36]. 

The third generation involved developing systems of nanosystems, for example chemo-mechanical processing of molecular assemblies, artificial organs built from the nanoscale, modified viruses and bacteria. 

Experimental results on the band dispersion in o-bond polymers are very limited due to difficulty in preparing thin films with oriented chains [20, 31, 32, 62]. Here, we introduce the band dispersion of quasi-one-dimensional polymer polyethylene. Early work on the band structure study was carried out on systems with alkyl chains and was aimed at understanding the electronic structure of polyethylene, in particular, the possible existence of one-dimensional band structure in thin films where molecular chains assemble via weak interchain interactions. There is renewed interest in the band dispersions as they determine carrier transport properties in nanoscale molecular electronics [63]. 

The self-assembly of supramolecular structures such as host-guest inclusion complexes has r ently bem the focus of a number of research efforts. This approach allows the d ign and building of nanoscale molecular device. It constitutes a conveni t route to realizing the polymerization of hydrophobic molecules (guests) such as thiophene derivatives in aqueous soluticm by using CDs (hosts) and to customizing the polymer ardiitectures 9-11). 

Molecular assemblers and nanorobots are two other potential tools. The assemblers would use specialized tips to form bonds with materials that would make specific types of materials easier to move. Nanorobots might someday move through a person s blood stream or through the atmosphere, equipped with nanoscale processors and other materials that enable them to perform specific functions. 

---