Development of novel porous coordination polymers with interest in catalysis, structure directing agents, and magnetism
Porous coordination polymers (PCPs) have emerged as a novel and versatile class of crystalline materials since the late 1990’s due to their high porosity and tunable reactivity. Applications for these materials have spread to areas including gas storage and separations, sensing, magnetism, and more recently, catalysis. However, designing a PCP-based material for a specific application remains a struggle within this field due to their unpredictable self-assembly. In order to overcome this hurdle, linker design has become paramount to the process. The Humphrey Group has developed a new class of PCPs called Phosphine Coordination Materials (PCMs). These materials incorporate one or more phosphorous sites within the linker to act as a point of functionalization. The lone pair of each P(III) site can act as a tunable handle, which allows for access to increased chemical versatility. With this larger goal in mind, the research discussed herein has been focused on the development of novel materials on three fronts: catalytically active linkers, employment of structure directing agents, and examination of PCMs in magnetism. Several catalytically active organic linkers were developed for the purpose of taking known homogenous reactivity and applying that knowledge to a heterogeneous framework. The linker systems described herein include trans-RuCl2(1,2-C6H4-((P-C6H4-p-CO2H)2)2, the ferrocene backbone system Fe(C5H4)2-(P-(C6H4-p-CO2H)2)2, and the extended building block 1,2-C6H4-(P-(¬p-C6H4-p-C6H4-CO2H)2)2. The second study examined a [Me-P-(C6H4-p-CO2H)3]+ Cl- linker to create a series of frameworks through variation of only the alkali hydroxide added during synthesis. This resulted in five frameworks, four of which were non-isostructural. Designated PCMs 6-9, the frameworks demonstrated unusual pore topology as well as the highest cryogenic oxygen uptake to date for a saturated metal site material. Next, two isostructural materials termed Ln-PCM-21 were synthesized and their experimental bulk magnetic properties were studied. Afterwards, three theoretical models were considered in relation to this experimental data and their relatability was reported. The final study explored the magnetic behavior of a set of 1-dimensional coordination polymers that conversely employed thiolate groups; referred to as Thiolate Coordination Materials (TCMs). One material, Fe-TCM-1, was extensively studied and two isostructural materials were attempted (CoII, MnII), with interest in single-chain magnetic behavior.