Low-Symmetric Water-Soluble Molecular Hosts for Molecular Separation and Optical Modulation

Abstract

Nature employs the strategy of self-assembly in a remarkable way at every scale to construct numerous functional architectures. Various noncovalent interactions, such as hydrogen bonding, 𝜋-𝜋 stacking, and electrostatic interactions, are very crucial in the formation of self-assembled architectures. Cavities of natural hosts like enzymes are of low symmetry and contain a mix of different functionalities such as recognition sites, catalytic groups, and conformational switches.1 Over the past few decades, scientist capitalized the principle of self-assembly to synthesize various aesthetic 2D and 3D architectures for a variety of applications.2 In literature, symmetrical ligands have been extensively utilized to construct the hosts of numerous shapes and sizes. However low symmetrical ligands are largely ignored due to their synthetic difficulties as well as their tendency to form a mixture of statistical isomers upon self-assembly. Recently, due to their ability to form architectures of low symmetry with enhanced functional property, scientist have shifted their endeavour toward the synthesis of low symmetrical molecular architectures.3 In my thesis presentation, I will first introduce the design and synthesis of an unsymmetrical tetraimidazole ligand and its utilization for the synthesis of water-soluble tweezer shaped molecular architecture via metal-ligand coordination-driven self-assembly for the application in encapsulation and separation of isomeric quinones in water.4 Next, I will present the design of an analogous tetrapyridyl ligand for the synthesis of molecular bowl and its application for encapsulation and separation of isomeric polycyclic aromatic hydrocarbons (PAHs) in aqueous meadium.5 Lastly, I will discuss the synthesis of ligands with mixed denticity (having different sets of donor groups) for the construction of water-soluble molecular barrels of low symmetry and their applications in encapsulation and separation of fullerenes6 and optical modulation.