This dissertation focuses on the challenge of developing porous metal arylphosphonates with both high crystallinity and functional porosity by using different synthetic approaches. Metal phosphonates are an extensive class of materials based upon extended inorganic-organic architectures such as chains, layers and three-dimensional networks. Metal phosphonates generally favor extended inorganic architectures leading to pillared materials with no porosity. We found that the use of template molecules, type of ligand and choice of metal ions could be used to deviate from the pillared structure. Many of these structures had interesting properties that were explored. The results can be divided into three areas: We developed non-pillared monovalent metal phosphonates by investigating both the role of water and template molecules in the solvothermal synthesis. The role of water in solvothermal reactions was found to have a profound influence on the structure of monovalent metal phosphonates and the structures could be tailored from zero/one-dimensional to two-dimensional. Non-pillared structures could be synthesized by using template molecules. For a zinc phosphonate, we converted a layered structure into a three-dimensional framework by using small template molecules in the solvothermal reaction. The compound exhibited reversible dehydration behavior. The change in the framework structure and guest positions was monitored during this process. Two different ligands were used in the development of porous aluminum phosphonates. One series exhibited reversible dehydration behavior, which had a dramatic influence on permanent porosity of the material. The stability of the dehydrated phase is a result of the geometry of the aluminum atom, which in some cases has coordinatively unsaturated metal sites. The second series was developed with ion exchange applications in mind therefore the pore environment was tailored to favor ion exchange processes. The most important aspect is that these compounds exhibit high selectivity for Th^(4+) ions. In total 28 new compounds were prepared, and their utility and structures clarified.

The primary goal of the work described in this dissertation was the incorporation of functionality into metal phosphonates. This was done in one of several ways. The first involved using phosphonate ligands that had covalently attached organic functional groups. In some cases, these ligands undergo reactions during the solvothermal syntheses which can impart new chemical reactivity. Another method used to introduce functionality was to partially or completely substitute metal atoms within phosphonate clusters to create materials which may have interesting magnetic properties. By controlling the way these clusters pack in the solids, their magnetic properties may be able to be augmented. The final method used to impart functionality to metal phosphonates was the incorporation of N-donor and bulky aryl groups into the phosphonate ligands. These influences caused structural variations which exposed potentially active sites within the materials, including both Lewis acidic and basic sites, as well as Bronsted acid sites. The first strategy was employed in the design of tetravalent metal phosphonates which have covalently incorporated bipyridine moieties. The materials are porous so that the bipyridine sites can chelate Pd atoms from solution, which can then be reduced to stable nanoparticles trapped within the phosphonate matrix. This approach was also used in the synthesis of surface-functionalized divalent metal phosphonates which exhibit interesting amine uptake properties. Solvent and cation substitution effects were used to control the packing and connectivity of phosphonate-based clusters. The selective substitution of metal atoms within the clusters may lead to interesting magnetic materials. In other work, N-donor and bulky phosphonates were used to influence the structure of several SnII phosphonates, which resulted in the discovery of a new layered structure type. The effect of the Sn-N interaction on the structures is investigated, and found to have significant effects on the structural units formed and how they pack in the solid state. The work presented herein represents only a small fraction of the rich chemistry of metal phosphonates. Creative researchers will continue to push boundaries and find new and interesting applications for phosphonate-based materials.

Im Rahmen dieser Dissertation wurden (I) erstmalig Metallphosphonate mechanochemisch synthetisiert, (II) 21 neue Strukturen mit Hilfe der Röntgenpulverdiffraktometrie gelöst und (III) die Reaktionsverläufe mittels in situ Methoden untersucht. Die Mechanochemie erwies sich als sehr geeignete Methode, um Metallphosphonate mit verschiedenen Metallen, Liganden und Strukturen darzustellen. Durch Variation des Verhältnisses der Edukte können die Reaktionen gesteuert werden. Etliche neue Metallphosphonat-Strukturen konnten mit Hilfe der erhaltenen Röntgenpulverdiffraktometrie-Daten gelöst werden. Dabei war auch die Aufklärung seltener Strukturmotive möglich. Durch die Resultate existiert nun eine schnelle, einfache und umweltfreundliche Alternative für die Herstellung von Metallphosphonaten. Im Rahmen dieser Arbeit wurden drei experimentelle Aufbauten für die in situ Untersuchung von Reaktionen entwickelt: (i) für mechanochemische Reaktionen mittels Synchrotron-Röntgenpulverdiffraktometrie und Raman-Spektroskopie, (ii) für mechanochemische Reaktionen mittels Thermographie und Raman-Spektroskopie sowie (iii) für Fällungsreaktionen bei Raumtemperatur mittels Synchrotron-Röntgenpulverdiffraktometrie. Durch die erhaltenen Ergebnisse konnten tiefgreifende Einblicke in die Bildungsmechanismen von Metallphosphonaten gewonnen werden. Für die mechanochemische Darstellung von Metallphenylphosphonaten wurde ein mehrstufiger Diffusionsmechanismus gefunden. Anhand der thermographischen Messungen wird deutlich, dass die Reaktionstemperatur einen großen Einfluss auf die Gesamttemperatur des Systems hat. Klassische Erklärungsmodelle für mechanochemische Reaktionen können für die hier untersuchten Systeme ausgeschlossen werden. Die in dieser Arbeit gewonnen Erkenntnisse über die Bildungsmechanismen und Strukturen der di- und tetravalenten Metallphosphonate liefern einen wichtigen Beitrag auf dem Weg zur zielgerichteten Darstellung von Metallphosphonaten. / In this dissertation (I) metal phosphonates were mechanochemically synthesized for the first time, (II) 21 new structures were solved from powder X-ray diffraction data and (III) the reaction pathways were investigated with in situ methods. Mechanochemistry has shown to be very suitable for synthesizing metal phosphonates with different metals, ligands, and structures. By varying the ratio of the reactants, it is possible to control the reaction pathway. Several new metal phosphonate structures were solved from the powder X-ray diffraction data. It was also possible to elucidate rare structures. The results demonstrate a new fast, facile, and environmental friendly alternative for the preparation of metal phosphonates. During this dissertation three experimental setups for the in situ investigation of reactions were developed: (i) for mechanochemical reactions via synchrotron-powder X-ray diffraction and Raman spectroscopy, (ii) for mechanochemical reactions via thermography and Raman spectroscopy and (iii) for precipitation reactions via synchrotron-powder X-ray diffraction. The gained results provided an insight into the formation of metal phosphonates. For the mechanochemical synthesis of metal phenylphosphonates a multi-step diffusion mechanism was found. From the thermography studies, it is proven that the reaction temperature has a big impact on the temperature of the whole system. Classical theories for mechanochemical reactions can be ruled out for the investigated systems. The results gained in this thesis about the formation mechanisms and structures of di- and tetravalent metal phosphonates provide an important contribution for the targeted synthesis of metal phosphonates.