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From Amino Acid Amphiphiles to Azobenzene Phosphoramidites

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From Amino Acid Amphiphiles to Azobenzene Phosphoramidites SELF-ASSEMBLY AND FOLDING: FROM AMINO ACID AMPHIPHILES TO AZOBENZENE PHOSPHORAMIDITES. THESIS Presented in Partial Fulfillment of the Requirements for the Degree Master of Science in the Graduate School of The Ohio State University By Jacob Paul Dumbleton Graduate Program in Chemistry The Ohio State University 2012 Master’s Examination Committee Professor Jonathan R. Parquette, Advisor Professor Jovica Badjic Copyright by Jacob Paul Dumbleton 2012 Abstract Reported are the studies of the self-assembly and polymerization of nanotubes derived from L-lysine based amphiphiles and the synthesis of an azobenzene phosphoramidite catalyst. One dimensional (1D) assembled nanoscale molecules are of particular interest due to the development of optoelectronic nanodevices. While there are many examples of molecular self-assembly of defined nanostructures, there are few that exploit the functionalization with polymeric motifs. Polymerization of defined nanostructures has been shown to improve structural elements as well as allow for the versatility of polymer chemistry to design hybrid materials. Our design focuses on a series of naphthalene diimide (NDI) substituted L-lysine derivatives functionalized at the terminus with strained groups capable of undergoing polymerization. Self-assembly of these systems are induced from the amphiphilicity derived from the hydrophobic and hydrophilic interactions of the molecule, as well as stabilization of the NDI core through long range π-π interactions. Aqueous ring opening metathesis polymerization (ROMP) was performed on these self assembled systems using Grubb’s 1st and 2nd generation catalysts. The studies reveal that a stable polymer nanotube is achieved after aqueous polymerization. This polymer becomes disturbed upon the addition of an organic solvent and is no longer capable of adopting a helical structure when re introduced into water. ii Co-self-assembly studies were performed with a bolaamphiphile known to assemble into discrete tubular structures and an achiral C3 symmetric discotic observed to assemble in aqueous media. Samples were mixed at various concentrations in attempts to elucidate successful chirality transfer from the nanotube to the discotic. UV and CD spectroscopy were used to investigate if self-assembly had occurred. Lastly, a phosphoramidite catalyst was proposed exploiting the folding nature of an azobenzene oligomer. Since it is known that axial chirality in phosphoramidites can be derived from diols such as BINOL and TADDOL, an achiral azobenzene oligomer was designed to investigate if the dynamic chirality of the oligomer can control asymmetric catalysis. The oligomer design is derived from the meta- connectivity of the aromatic groups that forces the molecule to adopt a folded state stabilized through hydrogen bonding and π-π stacking. Incorporation of the azobenzene moieties allows for the potential to control catalysis photochemically. iii For my parents and Bob. iv Acknowledgments I would like to thank my advisor Dr. Jon Parquette who encouraged and challenged me throughout my academic endeavors. I would especially like to thank him for his patience, guidance and good humor over the past few years. I couldn’t imagine working for anyone else. I would also like to thank the Parquette group members for all the help and inspiration while in lab, especially Dr. Eric King for the privilege to have worked next to him for the majority of my graduate school career. His continual advice and support is greatly appreciated. Lastly, I would like to thank my family, Mom, Dad and Jenna for always being there no matter what. Words cannot express the appreciation I have for the love and support my parents have shown, and the sacrifices they have made to help me succeed. I love you. v Vita April 18, 1986 ............................................... Born Grosse Pointe, Michigan 2004 ............................................................... B.A. Chemistry, Albion College 2008 to present ............................................. Graduate Teaching and Research Assistant, Department of Chemistry, The Ohio State University Fields of Study Major Field: Chemistry vi Table of Contents Abstract ............................................................................................................................... ii Dedication .......................................................................................................................... iv Acknowledgments ............................................................................................................... v Vita ..................................................................................................................................... vi List of Figures ..................................................................................................................... x List of Schemes ................................................................................................................ xiv List of Abbreviations ......................................................................................................... xv Chapter 1: Structure and Self-assembly of Amphiphilic Molecules in Water ................... 1 1.1 Introduction. ............................................................................................................ 1 1.2 Secondary Interactions. ........................................................................................... 2 1.3 Amphiphilic Self-Assembly. ................................................................................. 10 1.4 Self-Assembly of L-Lysine NDI Derived Structures. ........................................... 13 1.5 Polymerization and Post Functionalization. .......................................................... 15 1.6 References. ............................................................................................................. 19 Chapter 2: Aqueous Self-Assembly and Polymerization of L-Lysine Amphiphiles ....... 22 2.1 Introduction. .......................................................................................................... 22 2.2 Research Design. ................................................................................................... 24 vii 2.3 Results and Discussion. ......................................................................................... 26 2.4 Conclusions. .......................................................................................................... 37 2.5 Experimental Section ............................................................................................ 28 2.6 References. ............................................................................................................. 48 Chapter 3: Investiagion into Chrality Transfer to a Co-Assembled Structure ................. 49 3.1 Introduction. .......................................................................................................... 49 3.2 Chirality Transfer to a Hierarchical Structure. ...................................................... 57 3.3 Research Design. ................................................................................................... 61 3.4 Results and Discussion. ........................................................................................ 63 3.5 Conclusions. .......................................................................................................... 67 3.6 Experimental Section ............................................................................................ 68 3.7 References. ............................................................................................................ 76 Chapter 4: Investigation into the Synthesis of Azobenzene Phosphoramidite Catalysts . 78 4.1 Introduction. .......................................................................................................... 78 4.2 Synthesis and Structure of Phosphoramidites. ...................................................... 79 4.3 Phosphoramidites and Catalysis. ........................................................................... 81 4.4 Phototuning of Azobenzene. ................................................................................. 87 4.5 Azobenzene as a Method of Chiral Induction ....................................................... 89 4.6 Research Design. .................................................................................................... 97 4.7 Synthesis, Results and Discussion ........................................................................ 98 4.8 Conclusions. ........................................................................................................ 102 4.9 Experimental Section .......................................................................................... 103 4.10 References. ......................................................................................................... 110 viii Bibliography .................................................................................................................... 114 Apendix A. 1H- and 13C- NMR Spectra…. ..................................................................... 124 ix List of Figures Figure 1.1 Schematic of amphiphilic self-assembly .......................................................... 1 Figure 1.2 Schematic of micelle assembly of PPQ-PS rod-coil copolymer. ...................... 2 Figure 1.3 Morphologies of Jenekhe's poly (phenylquinoline) block structure ................. 3
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