Collaborative Research: Metal-Organic Nanotubes as Tunable Porous Fibers

University Of Tennessee Knoxville, Knoxville TN

Investigators

Abstract

Non-technical Abstract With the support of the Solid State and Materials Chemistry program in the Division of Materials Research, professors David Jenkins (U. Tennessee) and Nathan Gianneschi (Northwestern U.) are studying metal organic nanotubes (MONTs), the 1D analogues of metal organic frameworks (MOFs). Metal organic nanotubes are straws on the nanometer scale that are built from chemical bonds between metals and organic components (ligands). Changing the design of the ligands changes the size of pores within the structures, which is achieved with synthetic organic chemistry from the Jenkins group. Changing and tuning the pore size is important for applications such as gas separations. For MONTs to achieve their goal as new nanomaterials capable of drawing up fluids and gases and transporting them, it is critical to control their structure and understand them at the nanometer length scale. Therefore, the Gianneschi group studies their formation processes with electron microscopy. Finally, mixing ligands together allows for copolymerized MONTs in a manner structurally reminiscent of copolymerization in plastics. Blending these ligands together offers opportunities to tune the surfaces of these materials. The project also encompasses research opportunities for students. Moreover, the professors make their research accessible to the general public by showcasing research on MONTs through digital methods such as YouTube and Wikipedia. Technical Abstract With the support of the Solid State and Materials Chemistry program in the Division of Materials Research, professors David Jenkins (U. Tennessee) and Nathan Gianneschi (Northwestern U.) are studying metal organic nanotubes (MONTs), the 1D analogues of metal organic frameworks (MOFs). Because the dimensionality of any material dictates its properties, functionality and application scope, MONTs are a critical new tunable porous material that are complementary to MOFs. The fundamental aspiration of this project is to develop a method to control the pore size, tube packing, particle size, and composition of MONTs systematically. The pore size is controlled through isoreticular synthesis of organic ligands that form 2-pillared MONTs. Ligand design is also employed to tune the non-covalent interactions, which leads to tube packing, between the MONT tubes. The particle size is controlled through biphasic reaction mixtures such as emulsions. Finally, the composition is controlled through blending ligand pairs yielding copolymerization of these materials. Macroscopic MONTs are studied using measurements such as single-crystal X-ray diffraction, powder X-ray diffraction, and solid-state NMR. Nano bundles of MONTs and dynamic processes during synthesis are investigated with electron microscopy techniques including liquid phase TEM. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.