Supramolecular catalysis, discrete aromatic stacks and sequential reactions in the organic solid state PDF
Preview Supramolecular catalysis, discrete aromatic stacks and sequential reactions in the organic solid state
University of Iowa Iowa Research Online Theses and Dissertations Spring 2014 Supramolecular catalysis, discrete aromatic stacks and sequential reactions in the organic solid state Jelena Stojakovic University of Iowa Copyright 2014 Jelena Stojakovic This dissertation is available at Iowa Research Online: http://ir.uiowa.edu/etd/4766 Recommended Citation Stojakovic, Jelena. "Supramolecular catalysis, discrete aromatic stacks and sequential reactions in the organic solid state." PhD (Doctor of Philosophy) thesis, University of Iowa, 2014. http://ir.uiowa.edu/etd/4766. Follow this and additional works at:http://ir.uiowa.edu/etd Part of theChemistry Commons SUPRAMOLECULAR CATALYSIS, DISCRETE AROMATIC STACKS AND SEQUENTIAL REACTIONS IN THE ORGANIC SOLID STATE by Jelena Stojakovic A thesis submitted in partial fulfillment of the requirements for the Doctor of Philosophy degree in Chemistry in the Graduate College of The University of Iowa 1 May 2014 Thesis Supervisor: Professor Leonard R. MacGillivray Copyright by JELENA STOJAKOVIC 2014 All Rights Reserved 2 Graduate College The University of Iowa Iowa City, Iowa CERTIFICATE OF APPROVAL _______________________ PH.D. THESIS _______________ This is to certify that the Ph.D. thesis of Jelena Stojakovic has been approved by the Examining Committee for the thesis requirement for the Doctor of Philosophy degree in Chemistry at the May 2014 graduation. Thesis Committee: _______________________________________ Leonard R. MacGillivray, Thesis Supervisor _______________________________________ Daniel M. Quinn _______________________________________ Geoff G. Z. Zhang _______________________________________ F. Christopher Pigge _______________________________________ Edward G. Gillan To my mentors, family, friends and princess 2 ii I do not think there is any thrill that can go through the human heart like that felt by the inventor as he sees some creation of the brain unfolding to success... such emotions make a man forget food, sleep, friends, love, everything. Nikola Tesla 3 iii ACKNOWLEDGMENTS I would like to express gratitude to my advisor Len MacGillivray whose care and patience guided me through my studies and life over last five years. I was also fortunate to share my years as a PhD student with wonderful MacGillivray group members Kristin, Rebecca, Katie, Jake, Michael, Beth, John, Poonam, Saikat, Joe, Manza and Nam. A lot of work in this thesis was done by my hardworking and talented undergrads Brian, Avery, Jacob and Taylor. Unfortunately, I just recently started working with Shawna and Roxy and I already wish I had more time to spend with them in the lab. The one, who helped me the most during my first months in Iowa, was undoubtedly Krešo. I would also like to thank our collaborators Jonas, Geoff and Rodger, and our crystallographer Dr. Dale Swenson. I would never find my way to Iowa, if it was not for prof. Judaš. I am grateful for my family that provided for me and gave me education. My friends gave me support and confidence when I needed it the most. 4 iv ABSTRACT The organic solid state is becoming more widely utilized to synthesize molecules that are inaccessible or difficult to realize from the liquid phase. A solid-state synthesis provides strict control of both geometry and stereochemistry. While essential for efficient and sustainable organic syntheses, catalysis in the organic solid state is expected to be difficult to achieve due to low diffusion rates of molecules in the crystals. However, recently a ditopic receptor was used as a small-molecule supramolecular catalyst to direct a topochemical [2+2] photodimerization of an olefin. To achieve catalytic turnover, mechanochemistry, in the form of a manual mortar-and-pestle dry grinding, had to be employed. A main obstacle in the manual grinding method is the fact that the mechanochemistry and photoreaction are conducted separately. Thus, an automated method that enables simultaneous grinding and irradiation would be preferred. However, such technology is not commercially available. We have developed a simple, readily accessible, and automated method to achieve the mechanochemical preparation of supramolecular materials. Importantly, method enables simultaneous grinding and irradiation. In effect, the vortex grinding serves as a ball mill that is UV irradiation transparent. The vortex method has been applied to the preparation of cocrystal and metal organic frameworks, as well as supramolecular catalysis. When conducted using vortex method, supramolecular catalysis proceeds four time faster than when conducted using 5 manual grinding. Accelerated rate of catalysis is attributed to combination of external stress exerted by grinding and internal stress arising from photoreaction. The scope of supramolecular catalysis is expanded to reaction of 2,2’-bpe, catalyzed by a similar ditopic receptor res. Importantly, in this system catalytic turnover proceeds spontaneously. The mechanism of catalysis was investigated using X-ray diffraction studies and gas-phase DFT calculations. The studies uncovered that 2,2’-bpe v and 2,2’-tpcb undergo rotational motion to release accumulated stress akin to action of a supramolecular torsional spring. We report an integration of aromatic stacks into discrete assemblies based on hydrogen bonds in the solid state. We used indolo[2,3-a]carbazole to organize aromatics into double, triple, and quadruple stacks within cocrystals. We also showed that aromatics within quadruple stack undergo topochemical [2+2] photodimerization to give a single photoproduct stereoselectively in up to maximal yield. We reveal the first example of a product of a templated solid-state that acts as a template in subsequent reaction. Both reactions proceed in 100% yield and stereoselectively. We also report the unique case of polymorphism where both polymorphs are photoreactive and within one polymorph photoreaction proceeds in SCSC manner. Due to effects of crystal packing, homology in solid state is difficult to achieve. We present the application of the template screening approach to solid-state photoreactivity among all olefins of a homologous series. To assess electronic effects of substituents on stability and hydrogen bonds of assemblies, we preformed gas-phase DFT calculations on a series of substituted assemblies. We found, that the strength of hydrogen-bonding varies and correlates with electronic nature of the substituents. Lastly, we incorporated principles of supramolecular chemistry, solid-state 6 reactivity, green chemistry and sustainability in undergraduate curriculum. In particular, students employ supramolecular chemistry to control photoreactivity in the organic solid state using the template approach. To form supramolecular assemblies, mechanochemistry, in form of mortar-and-pestle grinding, is used. To study reactivity in crystals, X-ray diffraction is used. Students are involved in all steps necessary to obtain crystal structure: growing suitable crystals, selection of the best crystals, data collection, solution, refinement and analysis of the crystal structures. Overall, students have hands- down experience in all aspects of crystallography. Although essential in chemical, vi biochemical, pharmaceutical and materials science, crystallography is rarely taught in undergraduates laboratories. 7 vii
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