ABSTRACT SYNTHESIS AND PROPERTIES OF LANTHANIDE METAL-ORGANIC FRAMEWORKS AND LANTHANIDE-METALLOID COMPLEXES: STRUCTURAL DETERMINATION, PHOTOLUMINESCENCE, AND APPLICATIONS Timothy Perkins, Ph.D. Department of Chemistry and Biochemistry Northern Illinois University, 2018 Chong Zheng, Director Materials synthesis is a field at the intersections of chemistry and physics with wide- ranging applications. There is a rich diversity of techniques to develop novel materials, but very little fundamental understanding of the mechanisms that drive the formation of solids, leading to an inability to predict a synthesis for a material with targeted properties. Solvothermal synthesis has garnered much attention in the field due to its relative predictability by combining solution- phase dynamics with reactive inorganic precursors. By incorporating composition-guided organic chemistry, which often benefits from predictable properties, metal-organic frameworks (MOFs) synthesized solvothermally have emerged among the most rationally designed solids in modern science. MOFs are a class of crystalline materials composed of metal-centers linked by organic ligands, forming large, porous networks. Structures, thus some properties, can be predicted given motifs for previously determined metal-center geometries and ligand-bonding environs. Further, targeted properties can be chemically tuned via optimization of the ligand and/or metal. Early efforts in the field resulted in the intriguing materials that failed to be commercially viable due to stability issue. Metal-organic frameworks using lanthanide metal-centers (Ln-MOFs) are thought to increase thermodynamic stability of the material and present unique electronic properties such as photoluminescence. The projects presented herein focus on investigating the properties and stability of lanthanide metal-organic frameworks with a naphthalene-based ligand. To be a commercially viable material, among other things a MOF must be stable in addition to having practical properties. The increased complexity in both the accessible geometries and electronic properties of lanthanides relative to light transition metals makes this work largely exploratory. Novel, isostructural cerium, neodymium, and europium Ln-MOFs comprised of two-dimensional sheets of metal-carboxylate centers bridged by naphthalene were synthesized and photoluminescence properties analyzed. The series of Ln-MOFs studied show they have robust photoactivity that may be exploited in small molecule or ion sensing. Compound [Ce(NO3)(NDC)]n was found to be stable under basic and acidic aqueous conditions, but not thermally stable to 400°C. Small aromatic molecules were screened against [Nd(NO3)(NDC)]n and fluorescence quenching shown to be correlated to spectral overlap, with significant signal quenching of benzene, but no observed selective change in excitation or emission wavelengths. Further, the compound was found to be stable to 300°C in open air. In particular, compound [Eu(NO3)(NDC)]n was shown to be highly fluorescent in water and is readily quenched by trace concentrations of hazardous industrial by-product chromic acid. These investigations represent a broad effort to characterize Ln-MOFs in hopes of guiding the development of similar materials that exhibit robust chemical and thermal stability and relevant properties. Isoreticular synthesis is generally, but not exactly, an appropriate tool for replicating the synthesis with naphthalene-based ligands but different lanthanide metals. Procedurally altering the reported successful synthetic conditions with lanthanide metals is highly likely to produce isostructural and comparably stable compounds that exhibit unique electronic properties. Solvothermal synthesis using thiourea as a reactive solvent was also shown to produce unique lanthanide-metalloid complex germanium (II) sulfide doped lanthanum (III) hydroxide. The complex was found to photocatalytically degrade dye methylene blue in water under UV irradiation. While, not as efficient as known photocatalyst anatase titania, it represents a new class of lanthanum oxides doped with small band gap semiconductors that may be more easily optimized for photocatalytic processes than investigations on titanium dioxide have proven to be. Such intercalated lanthanum oxides may even have other relevant photo-driven applications, such as light harvesting or water-splitting. NORTHERN ILLINOIS UNIVERSITY DE KALB, ILLINOIS AUGUST 2018 SYNTHESIS AND PROPERTIES OF LANTHANIDE METAL-ORGANIC FRAMEWORKS AND LANTHANIDE-METALLOID COMPLEXES: STRUCTURAL DETERMINATION, PHOTOLUMINESCENCE, AND APPLICATIONS BY TIMOTHY PERKINS © 2018 Timothy Perkins A DISSERTATION SUBMITTED TO THE GRADUATE SCHOOL IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE DOCTOR OF PHILOSOPHY DEPARTMENT OF CHEMISTRY AND BIOCHEMISTRY Doctoral Director: Chong Zheng ACKNOWLEDGEMENTS I am eternally grateful to my advisor, Dr. Chong Zheng. Under his tutelage, he gave me freedom to make mistakes, to learn, and ultimately to earn my successes. His willingness to put so much trust in me and give me latitude over the lab has provided me a solid foundation in successfully designing and executing relevant research. His support is evidenced in the (several) organizational overhauls of the laboratory he has stoically endured, and the collaborative trips to both Beijing and Shanghai we took. I would like to thank Dr. Fuqiang Huang of Peking University and the Shanghai Institute of Ceramics for extending the invitation to use their excellent facilities, and especially his students Jianqiao He and Xian Zhang who taught me so much and were the senior colleagues I did not have at Northern Illinois University. I would also like to extend my gratitude to the members of my committee: Dr. Victor Ryzhov, Dr. Lee Sunderlin, and Dr. Zhili Xiao. Their support and input have been critical not only in helping me shape my work into a completed dissertation, but for years prior. Dr. Ryzhov often acted as a second advisor and has provided me with guidance without which I could not have succeeded. I would very much like to thank Dr. Sunderlin for letting me stop by his office unannounced for many stimulating conversations, as well as lending me tools from his lab more times than he knows. I would be remiss if I did not acknowledge the faith in me Dr. Zhili Xiao placed by recommending me to a colleague at Argonne National Laboratory, which gave me access to some of the best facilities available and exposed me to a professional safety culture I have strived to implement at NIU. iii My group members James O’Sullivan, Sura Ginting, and Crystal Ferels have always been available to lend a hand and bounce around ideas. My undergrad Noel Amaro was a delight to work with and often enabled me to be in two places at once. Aaron Sturtz, the laboratory mechanic, has helped me repair and modify so much equipment he has surely saved the university more than his salary, and saved me countless hours. The electrical expertise of Mike Figora probably saved me from getting shocked a few times, and I couldn’t have upgraded our ovens and furnaces without him. I am also sincerely grateful for all the support Dr. Taesam Kim, instrumental specialist, has provided our research lab over the years. He is not only the first line of defense when troubleshooting but an excellent teacher. I need to give a special thank you to my parents, Dennis and Cindy Perkins, who have unconditionally supported me at every step. Finally, I thank Katherine Didier, who has been my best friend and companion, and has always been a source of encouragement and love. Our responsibility is to do what we can, learn what we can, improve the solutions, and pass them on. Richard Feynman vi TABLE OF CONTENTS Page LIST OF FIGURES…………………………………………………………………………...…vii LIST OF TABLES………………………………………………………………...……………...xi LIST OF APPENDICES…….……………………………………………………..…………....xii LIST OF ABBREVIATIONS …………….……………………………………………………xiii CHAPTER ONE: PERSPECTIVES OF SOLID-STATE PHYSICS, INORGANIC CHEMISTRY, AND THE MATERIALS SCIENCES ................................... 1 1.1. Epistemological Framework ..................................................................................... 1 1.2. Modern Frameworks for Materials Synthesis ........................................................... 6 1.3. Metal-Organic Frameworks .................................................................................... 18 1.4. Lanthanide-Metal-Organic Frameworks ................................................................. 40 CHAPTER TWO: THE SYNTHESIS AND PHOTOLUMINESCENCE PROPERTIES OF [CE(NO3)(NDC)•2DMA]n............................................................................. 45 2.1. Synthesis of [Ce(NO3)(NDC)•2DMA]n ................................................................. 45 2.2. Structural Characterization of [Ce(NO3)(NDC)•2DMA]n ...................................... 46 2.3. Stability of [Ce(NO3)(NDC)•2DMA]n .................................................................... 53 2.4. Photoluminescence Properties of [Ce(NO3)(NDC)]n.............................................. 55 CHAPTER THREE: THE SYNTHESIS AND PHOTOLUMINESCENCE PROPERTIES OF [ND(NO3)(NDC)•2DMA]n ............................................................................ 61 3.1. Structural Characterization of [Nd(NO3)(NDC)•2DMA]n ..................................... 61 3.2. Stability of [Nd(NO3)(NDC)•2DMA]n ................................................................... 66 3.3. Photoluminescence Properties