Design synthesis and host guest properties of neutral pd ii coordination cages supported by imido p v anions

Abstract

Self-assembly encompasses the ability of a system to spontaneously organize itself into an ordered aggregate by a rational combination of complimentary components. Metal-organic cages (MOCs) are one such important class of compounds constructed from metal ions and organic ligands by a coordination-driven self-assembly process. These assemblies possess the advantages of exhibiting distinct portals and well-defined permanent intrinsic cavities, which makes them excellent candidates for exploring host-guest chemistry with high affinity and selectivity for the recognition of guest molecules. This thesis begins with a general introduction to metallo-supramolecular cage chemistry. Further, the various bonding techniques employed to synthesize these cages have been discussed, followed by a general concept of host-guest chemistry as a pronounced application of these supramolecular cages, especially neutral cage systems. In this regard, neutral polyhedral cages supported by Pd(II) ions, imido ligands, and carboxylate linkers are one of the emerging classes of supramolecular cages owing to their charge neutrality and excellent host-guest properties. Over the years our group has focused on the main group-based imido-P(V) anions as suitable co-ligands for the construction of polyhedral cages for Pd(II) ions in the presence of suitable organic linkers. Thereafter the following chapter reports a study of the mechanistic pathways and the intermediates behind the self-assembly of these cage assemblies, together with their structural and reactivity details. The guest encapsulation capabilities of these cages in solution and in the solid state, probed with a range of analytical techniques has been discussed in detail. The further chapter elaborates on the synthesis of cages with larger cavities and a preferential encapsulation of larger, regio-isomeric guest molecules where instead of traditional guest encapsulation, we employed an in-situ strategy to synthesize the cages in presence of the guest molecules.