The Design Synthesis And Characterization Of Crystalline Molecular Machines With High Structural And Dynamic Complexities
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The Design, Synthesis, and Characterization of Crystalline Molecular Machines with High Structural and Dynamic Complexities
Molecular machines are molecular and supramolecular entities capable of producing quasi-mechanical movements. While many examples of functional artificial molecular machines have been studied in solution, crystalline aggregates of molecular machines have been explored infrequently because of the limited freedom of motion in closely packed solids. Although previous work on amphidynamic crystals has demonstrated that rotational dynamics in crystals could be achieved and engineered by proper structural design, the existing examples are limited to simple structures and small dynamic groups. As part of the efforts to prepare artificial molecular machines capable of performing useful work, the goals of my doctoral research were to design and synthesize crystalline molecular rotors with complex structures and explore their dynamics with solid-state NMR spectroscopy. I have prepared two shape-persistent dendritic molecular rotors with molecular weight over 2000 Da by different synthetic strategies. The molecular rotor prepared by a convergent synthesis provided crystals with a low packing density, which allowed megahertz rotation of all aromatic groups in the rotor. The softening of local environments with temperature, resulting from the dynamics of virtually all components in the crystal, led to a new concept of crystal fluidity. The divergent strategy used in the synthesis of the other macromolecular rotor made it possible to incorporate large rotator groups in the structure. When a bulky triptycene group was used, the shape-persistent rotor was able to support its kilohertz rotation in a semicrystalline sample. In order to realize faster triptycene rotations and to understand the structural elements required for effective solid-state gearing motions, I designed and prepared three pillared paddlewheel MOFs. I demonstrated that megahertz rotation of triptycene could be realized in a catenation-free framework, which offered a loose environment for the rotator. Since the rotator is in close contact only with the solvent molecules, its rotation is dictated solely by the hydrodynamic behavior of DMF and constitutes a diffusion-controlled process. As a result, the temperature dependence of observed rotation could shed light on the effective viscosity change of trapped solvents with temperature.
Crystal Engineering: A Textbook
Author: Gautam R Desiraju
language: en
Publisher: World Scientific Publishing Company
Release Date: 2011-06-20
This book is important because it is the first textbook in an area that has become very popular in recent times. There are around 250 research groups in crystal engineering worldwide today. The subject has been researched for around 40 years but there is still no textbook at the level of senior undergraduates and beginning PhD students. This book is expected to fill this gap.The writing style is simple, with an adequate number of exercises and problems, and the diagrams are easy to understand. This book consists major areas of the subject, including organic crystals and co-ordination polymers, and can easily form the basis of a 30 to 40 lecture course for senior undergraduates.
Handbook of Starch Science and Technology
Fifteen years have passed since the last major treatise on starch was published. Since then, knowledge of the molecular and macromolecular structures of starch; exploration of new sources of commercial starch; modification of the properties of starches via chemical, enzymic, genetic, and physical means; and investigations into potential uses of new products have proliferated. The Handbook of Starch Science and Technology explores new developments in starch science and technologies to achieve new paradigms in the development of natural glucose polymers. New developments of starches with enhanced nutritional and health benefits and specialized starch derivatives are discussed in terms of novel applications for the design of functional products and recent developments for structuring starch that have not been covered in the previous literature. Further, it discusses the uses of starch in the manufacture of starch inclusion complexes and nanoparticles and as a key component in carrier delivery applications. Features: Explores the genetics and physiology of starch biosynthesis Covers the source, isolation, structure, and properties of starches Identifies the structure and behavior of typical components in starch – amylose, amylopectin, and phytoglycogen Includes specific information on the modification and application of starch derivatives Presents current and emerging trends for starch science and technology This timely guide is for scientists and technologists working in the fields of agriculture, biotechnology, food, pharmaceuticals, chemical engineering, nutrition, and human health.