Doctoral Dissertations
Date of Award
8-2025
Degree Type
Dissertation
Degree Name
Doctor of Philosophy
Major
Chemistry
Major Professor
David M. Jenkins
Committee Members
Viktor N. Nemykin, Mark D. Dadmun, Mahshid Ahmadi
Abstract
Ligand multivariance, or the incorporation of different ligands within one homogeneous material, has long been studied in metal-organic frameworks (MOFs). Metal-organic nanotubes (MONTs), a subclass of MOFs, share many properties and applications with MOFs. MONTs, however, possess only one dimension of growth, as opposed to the isotropic growth of most MOFs, and aggregate via weak interactions between individual tubes rather than covalent bonds as in MOFs. The role of these weak interactions was illuminated in this work through the growth of ligand multivariate MONTs, enabling MONT growth to be understood as a class of anisotropic materials.
Despite the similarities between MOFs and MONTs, ligand multivariance has not been studied in MONTs. Utilizing a semi-rigid di-1,2,4 triazole and its partially fluorinated analog as linking ligands, multivariate MONTs were synthesized in varying ratios. The resulting materials were shown to possess a statistically random mixture of the two ligands through a suite of nondestructive techniques.
The influence of neighboring ligands was further investigated through three binary combinations of ligands. Each formed a pure MONT possessing a differing amount of intertube interactions in the backbone. As MONT aggregation relies upon relatively weak intertube interactions, as opposed to the covalent bonds between ligands and the secondary building units (SBU)s of MOFs, understanding these interactions is a key differentiating factor between MONTs and MOFs.
To exploit MONTs as materials, their morphology and aggregation must be understood. To this end, MONTs were grown in solutions of varying polarity and protic or aprotic nature to tune their size and aspect ratio. In a second study, a ligand, its partially deuterated analog, and a MOF-forming di-triazole ligand were copolymerized and the growth mechanism was established via small angle neutron scattering.
These results lay the groundwork to exploit the sensitivity of MONT ligands to their surrounding tubes. With the mechanism of growth of multivariate MONTs, as well as the morphological tunability of pure MONTs established, future work aimed at exploiting the unique anisotropic properties of MONTs can be performed.
Recommended Citation
Barrett, Jacob A., "Growth and Characterization of Ligand Multivariate Metal–Organic Nanotubes. " PhD diss., University of Tennessee, 2025.
https://trace.tennessee.edu/utk_graddiss/12683