Aryl and Super Aryl-Extended Calix[4]pyrroles: Synthesis and Applications

Identificador:  TDX:3209

Handle: https://hdl.handle.net/20.500.11797/TDX3209

Autores:  Sun, Qingqing

Resumen:
This PhD Thesis describes the design and synthesis of a series of supramolecular receptors featuring polar aromatic clefts and cavities. The prepared receptors include organometallic receptors, water-soluble containers, metallocages and metallocavitands. We selected aryl and super aryl-extended calix[4]pyrrole scaffolds (AE-C[4]P and SAE-C[4]P) as their main building blocks. We studied the molecular recognition properties of the synthetic receptors with tetraalkylammonium chloride salts, as well as neutral polar guests, in organic solvents and in water. Specifically, we prepared a mono-gold(I) phosphine substituted AE-C[4]P and studied its binding properties towards tetraalkylammonium chloride salts in dichloromethane and acetone solutions. The inclusion organometallic complexes featured a reduced thermodynamic stability with respect to its parent symmetrical “two-wall” counterpart. These results were explained considering the stronger repulsive anion-π interactions present in the chloride complex of the organometallic receptor. Next, we explored the application of a water-soluble SAE-C[4]P in the acid-catalyzed hydrolysis of aliphatic bis-isonitriles. The SAE-C[4]P receptor formed thermodynamically stable 1:1 complexes with the bis-isonitriles, mono-isonitrile-mono-formamides and bis-formamides. The bound mono-reacted compounds featured the formamide group in exclusive cis-conformation. This arrangement protected the unreacted isonitrile group from water solvation and induced yield enhancements for the mono-reacted compounds. We also reported the self-assembly of water-soluble metallocage featuring two endohedral polar binding sites. We showed that the efficient assembly of the metallcage requires the encapsulation of neutral mono-and ditopic polar guests. The assembled metallocage displayed conformational selectivity in the binding of aliphatic bis-formamides having different methylene spacers. Finally, we described the synthesis of an unprecedented tetra-oxazolo[4,5-b]pyrazinyl SAE-C[4]P ligand. We reported the self-assembly of a bis-metallocavitand based on the SAE-C[4]P ligand and Pt(II) precursors. Similarly, we showed that the inclusion of suitable polar guest was mandatory for the metallocavitand formation. The SAE-C[4]P ligand chelated only two Pt(II) metals between its adjacent substituents affordin