| Abstract | Metal-organic frameworks (MOFs) are dynamic three-dimensional networks that reveal unprecedented gas adsorption and storage capabilities, catalytic function, and other useful properties such as luminescence and magnetism. While we begin to see many possibilities for applications of these polymers, the goal of true rational design will only be achieved on the basis of intensive systematic investigations. The following five chapters will detail our efforts to advance the research goal of utilizing mild synthetic methods to investigate factors controlling the structure of crystalline, thermally stable coordination polymers utilizing N-functionalized phosphonic acids. Studies into preferred metal geometry and coordination modes, ligand flexibility, counterion, solvent, and pH will be addressed to discern useful patterns for future synthetic endeavors. Chapter 1 presents an introduction to the terminology, structural diversity, and chemical applications of this emerging field.^Chapter 2 describes the synthesis and crystallographic analysis of five polymers employing a bifunctional, zwitterionic 2-(pyridyl)phosphonic acid ligand, 2PyHPO3H, and salts of Zn(II), Cd(II), Hg(II), and Ag(I). Chapter 3 reports the influence that cation choice and ligand flexibility have on the dimensionality and structure of eight products containing Mn(II), Co(II), Fe(II), Fe(III), Ag(I), and Pb(II) cations and 2-(pyridylmethyl)phosphonic acid, 2PyCH2PO3H2. Chapter 4 explores the use of (aminomethyl)phosphonic acid (NH3CH2PO3H) as a bifunctional organic linker for the production of coordination polymers. The substitution of the amino group for the rigid heterocyclic ring of 2-(pyridylmethyl)phosphonic acid results in two-dimensional organophosphonate frameworks with Zn(II), Mn(II), Co(II), Cu(II), Gd(III), Sm(III), and Yb(III) cations.^Chapter 5 relates our efforts to evaluate the relationships between metal choice, counterion, and ligand geometric constraints on polymer architectures. Ca(II), Co(II) and Zn(II) salts produce both dimers and polymers with 2-(pyridylmethyl)phosphonic acid, and Ag(I) and Zn(II) salts form unique polymers with 3- and 4-(pyridylmethyl)phosphonic acid. Crystal structures of the compounds allow us to compare and contrast the final products of the self-assembly process. Other analytical techniques, such as IR, NMR, TGA, and mass spectroscopy, are used to support and interpret the crystallographic results. |
