CAREER: Development of metal-organic nanotubes with unique water transport and storage properties

University Of Iowa, Iowa City IA

Investigators

Abstract

TECHNICAL Nanotubular materials can have unique water transport and storage properties that have the potential to lead to technological advances in separations, catalysis, drug delivery, and environmental remediation. Development of novel hybrid materials, such as metal-organic nanotubes (MONs) are of particular interest as they are amenable to structural engineering strategies and may exhibit unique properties based upon the presence of inorganic components. The objective of this program is to determine the structural characteristics of the U(VI) MON that has recently been shown to promote the formation of structural water and promising exchange properties. The unique properties of the U(VI) MON are hypothesized to occur from a combination of: (1) the zwitterionic nature of the organic linker, (2) the overall diameter of the tube, and (3) the presence of uranyl (UO2) cation. The hypothesis will be tested by the synthesis of MONs with different structural features, characterization of water configuration, and examination the exchange properties of the resulting material by a combination of diffraction and spectroscopic techniques. Materials that contain organic linkers lacking amino groups will be initially targeted (Objective 1) to investigate the importance of the zwitterionic molecules for the attraction of H2O into the interior of the nanotube. Next, the importance of the internal diameter of the tube will be investigated by varying the chain length of the zwitterionic linker and the choice of organic chelator (Objective 2). Lastly, the importance of the uranyl ion will be examined by designing MONs containing other metals linked through zwitterionic molecules (Objective 3). The studies are significant because they will allow the determination of the structural component that exerts the greatest control over these enhanced exchange properties and develop novel nanomolecular materials for potential application in separations and storage technologies. NON TECHNICAL The planned studies are potentially transformative because fundamental information gained from the experimental results could lead to a greater understanding of nanoconfinement of water, which influences a wide variety of biological, geological, and physical systems. Experiments on the mobility of confined water within the MONs will support the NMR user facility that will enable the facility to update the current instruments that are widely available to all research groups. The work also has more general benefits to society through the development of novel materials for advanced applications in separations and storage media and the enhancement of undergraduate and graduate education in structural and nanomolecular chemistry. Educational contributions include mentoring of a graduate student on research related to the synthesis of MON materials and the development of initiatives aimed at promoting STEM education for undergraduate students. The initiatives include efforts to: (1) create an engaging curriculum on the structural nature of nanomaterials for undergraduate students in a 2nd-year inorganic chemistry course; (2) recruit underrepresented minority students into the research group to participate in the synthesis of nanotubular materials through the McNair Scholar program; and (3) integrate undergraduate students in informal science education efforts regarding the role of nanomaterials in water purification.