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Abstract:
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Nanoscale science and technology represents a tremendous opportunity to gain unprecedented insight into the unique phenomena that exists at the nanometer scale , and to use that knowledge to develop materials and devices with novel characteristics . This dissertation explores the unique properties of calix[4]arene -based synthetic nanotubes , the process of filling and characteristics of materials confined in one dimension .
Chapter 1 provides an overview of recently developed nanoscale materials , particularly single -walled carbon nanotubes and their ability to encapsulate materials in a one -dimensional configuration . Molecules inside carbon nanotubes are reported to exhibit structural and dynamic properties that are not observed in the bulk . Approaches are also discussed towards synthetic nanotubes as a supplement to carbon nanotubes .
Chapter 2 deals with calix[4]arenes as building blocks for constructing nanotubes . Multiple calix[4]arenes in the 1 ,3 -alternate conformation are covalently connected to build robust synthetic nanotubes using conventional organic chemistry protocols . The dimensions of the nanotubes are controlled precisely and easily . They effectively pack into infinite tubular bundles in the solid state .
In Chapter 3 , the calix[4]arene -based nanotubes are filled with multiple NO+ guests . They exhibit typical properties of calix[4]arene -NO+ complexes as evidenced by UV -vis , 1H NMR and FTIR spectroscopy . The stoichiometry of the complexes reveals the encapsulation of one NO+ guest per calixarene cavity . NO+ guests are entrapped deep inside the nanotube tunnel and experience strong electron donor -acceptor interactions .
In Chapter 4 , the dynamics of the filling material inside calix[4]arene nanotubes are discussed . The tunnel of the nanotube allows the NO+ guests to freely rotate along the N -O axis and also tumble within the cavity at room temperature . Though the filled nanotube is stable , it allows the release and re -entry of guests within its hollow structure . NO+ can be transferred to and from another host such as 18 -crown -6 . The guest exchange and dynamics are monitored by conventional spectroscopic techniques . |