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Low-Temperature Solution-Phase Synthesis of Chalcogenide and Carbide Materials

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Low-Temperature Solution-Phase Synthesis of Chalcogenide and Carbide Materials Low-Temperature Solution-Phase Synthesis of Chalcogenide and Carbide Materials DISSERTATION Presented in Partial Fulfillment of the Requirements for the Degree Doctor of Philosophy in the Graduate School of The Ohio State University By Rick Albert Lionel Morasse Graduate Program in Chemistry The Ohio State University 2018 Dissertation Committee: Dr. Joshua E. Goldberger, Advisor Dr. L. Robert Baker Dr. James V. Coe Copyrighted by Rick Albert Lionel Morasse 2018 Abstract Despite the fact that new dimensionally reduced hybrid organic-inorganic compounds have attracted considerable interest due to their unique optical and electronic properties, the rational synthesis of these new materials remains elusive. Here we studied the influence of the major synthetic parameters including temperature, ligand structure, and ligand-to-metal stoichiometry on the preparation of dimensionally reduced TiS2. One-dimensional TiS2 phases tend to form at high ligand-to-metal ratios and relatively lower temperatures, while the parent two-dimensional lattices form at higher temperature. The organic ligand structure dictates the temperature window at which a dimensionally reduced phase can be accessed. Although a small change in ligand structure, such as from ethylenediamine, en, to propylenediamine, pn, will significantly influence the stability of these phases, it will only subtly change the electronic structure. By developing a systematic understanding of the effects of various factors during the synthesis, we provide a pathway to rationally create new dimensionally reduced materials. A second project in this dissertation focuses on the development of a solution-phase route towards germanium carbide materials. We hypothesized metal germanium carbide materials could be created via the transmetallation of precursors that ii contain four C-B(OR)2 bonds with germanium-halogen (Ge-X) bond-containing precursors to form networks containing Ge-C bonds. While this chemistry is an essential step in many well-known organic reaction pathways, it has not been explored for the synthesis of germanium carbide materials in part due to the lack of commercial availability and the complicated synthesis of the C[B(OR)2]4 precursors. To these ends, we established the synthesis of the tetrasubstituted cyclic boronic ester, tetrakis (1,3 propanediolatoboronate) methane, which we denote as C(Bpg)4. We have adapted and improved upon the previously reported route, which utilizes precursors that are not commercially available, and have been able to synthesize this material on the 20 g scale with an overall ~50% yield. Upon establishing the large scale synthesis of C(Bpg)4 precursors, we explored whether GeC can be created. GeC has attracted considerable theoretical interest, yet no such phase currently exists. In these experiments we describe the reactions between C(Bpg)4 with many different germanium precursors across multiple different solvent and temperature conditions. These reactions and subsequent characterizations reveal that an analogous precursor, HC(Bpg)3, generates an amorphous GeCH phase while the C(Bpg)4 precursor does not immediately react and rather forms an oxidized Ge phase. The X-ray diffraction (XRD) of these materials showed no long-range crystallinity, and synchrotron X-ray Pair-distribution function (PDF) identified the presence of Ge-C bonds at 1.86 Å in the amorphous GeCH phase in addition to Ge-O bonds at 1.74 Å in the GeO2 phase. The Raman analysis showed no crystalline modes in the GeCH phase until annealing above 500 oC, at which point graphite and crystalline germanium modes appear. The lack of iii direct reactivity between C(Bpg)4 with tetrasubstituted Ge precursors merits the future exploration of base-activation procedures. In summary, the low-temperature solution-phase syntheses of TiS2(en) and C(Bpg)4 and the progress towards carbides and small-molecule carbide analogues represent progress towards the wider use of solution-phase synthetic methods in order to generate advanced materials. iv This document is dedicated to my family. v Acknowledgments I would sincerely like to thank Dr. Joshua Goldberger for being my advisor during my graduate studies. I am thankful for the countless time he has invested into my professional career through exam, presentation, and dissertation preparation. I am grateful for this opportunity to perform exciting research, and am especially thankful for all the growth and learning that have come from addressing these challenging scientific endeavors. I would also like to thank all of my examination committee members over the years. I am thankful for your dedication to my professional career and for your warm collegiality within the department. Thank you to Dr. Coe and Dr. Wu for serving on my first year oral exam, to Dr. Badu-Tawiah, Dr. Baker, and Dr. Coe for serving on my candidacy committee, and Dr. Baker and Dr. Coe for serving on my PhD committee. Next, I would like to thank everyone in the OSU Department of Chemistry & Biochemistry involved with General Chemistry. During my time as a GTA, I have grown personally and professionally thanks to the guidance of the Lab Supervisors, Dr. Tatz, Dr. Zellmer, and Dr. Moga. Additionally, I am thankful for all of the support from Nate Williams and Tyler Weaver over the years of teaching. vi I am also grateful to the many people who have helped me with research, especially Dr. Ken Kuno, Dr. Jay Giblin, Dr. Ewan Hamilton, Dr. Judith Gallucci, Dr. Tanya Whitmer, Dr. Lisa Alexander, and Dr. Nicole Karn. I would also like to thank all the current and former members of the Goldberger Group for their years of advice, support, and many laughs. I am especially grateful to Dr. Tianyang Li and Zachary Baum for their many years of collaboration. They have helped me with countless experiments. Additionally, I would like to thank Dr. Maxx Arguilla and Nick Cultrara for timely help when running measurements. Most importantly, I would like to thank Maxx and Nick for the many culinary adventures. I could not have completed all of these years of study without the love, support, prayer, and encouragement of my friends and family. I am thankful for the friendships formed at the University of Notre Dame and the St. Thomas More Newman Center at OSU. Special thanks to Sean and Laura Puscas and Chris Schreyer. I would also like to thank my loving and patient girlfriend, Rachel, for all of her support during graduate school. Finally, thanks to my entire family, grandparents, parents, Pat and Paul, and brother, Mark. vii Vita June 2008 .......................................................Lakeshore Catholic High School May 2012 .......................................................B.S., Chemistry, University of Notre Dame 2012 to present ..............................................Graduate Teaching Associate, Department of Chemistry & Biochemistry, The Ohio State University Publications Morasse, R. A. L., Li, T., Baum, Z., Goldberger, J. E., “Rational Synthesis of Dimensionally Reduced TiS2 Phases” Chem. Mater., 2014, 26, 4776–4780. Fields of Study Major Field: Chemistry viii Table of Contents Abstract ............................................................................................................................... ii Acknowledgments.............................................................................................................. vi Vita ................................................................................................................................... viii Publications ...................................................................................................................... viii Fields of Study ................................................................................................................. viii Table of Contents ............................................................................................................... ix List of Tables .................................................................................................................... xii List of Reactions .............................................................................................................. xiii List of Figures .................................................................................................................. xiv Chapter 1 Introduction ................................................................................................... 1 1.1 Conventional Solid-State Synthesis Methods ........................................................... 2 1.2 Solution-Phase Synthesis Methods ........................................................................... 4 1.3 Overview of Dimensional Reduction ........................................................................ 9 1.4 TiS2 and Derivatives................................................................................................ 15 1.4.1 Structure and Applications of TiS2 ................................................................... 15 ix 1.4.2 Dimensional Reduction of TiS2 ........................................................................ 15 1.4.3 Solution-Phase Synthesis of TiS2 Derivatives .................................................. 18 1.5 Carbide Materials .................................................................................................... 19 1.5.1 Applications of Carbides .................................................................................. 19 1.5.2 Applications of Germanium Carbide ...............................................................
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