Chiral metallocycles: Rational design and applications in enantioselective processes

Supramolecular chemistry has undergone explosive growth over the past two decades and has become a mature field. In particular, metal-directed self-assembly has been widely used to construct supramolecular systems such as molecular squares and other polygonal structures. Examples of chiral macrocyclic structures based on metal-ligand coordination are however very uncommon, and explorations of their applications are even rarer. We have become interested in the rational design and synthesis of chiral macrocyclic systems based on metal-ligand coordination for potential applications in enantioselective events such as sensing, separations, and catalysis. We describe in this thesis rational design of chiral metallocycles using chiral atropisomeric bridging ligands based on the 1,1′ -binaphthalene framework, and their applications in chiral sensing and asymmetric catalysis.; Chapter 1 describes fundamental concepts, design strategies, and a brief history of chiral macrocycles. Earlier work involved design and preparation of chiral macrocycles. More recent efforts have been focused on their applications in enantioselective processes.; Chapter 2 investigates the synthesis and characterization of a family of chiral molecular squares based on fac-Re(CO) ₃Cl metallocorners and enantiopure atropisomeric bipyridine bridging ligands. This molecular square exhibits interesting enantioselective luminescence quenching by 2-amino-1-propanol.; Chapter 3 explores the synthesis of organometallic chiral macrocycles for asymmetric catalysis. Molecular triangles chiral hidydroxy groups in combination with Ti(iOPr)₄ have been shown to be excellent catalyst for highly enantioselective additions of diethylzinc to aromatic aldehydes to afford chiral secondary alcohols.; Chapter 4 describes stepwise directed assembly of chiral tetrameric macrocycles. The self-assembly of metallocycles can be controlled by temperature, solvents and concentration of subunits.; Chapter 5 is concerned with self-assembly of chiral molecular squares based on angular bipyridine ligands. The reaction of Pd(II) or Pt(II) triflates with properly designed flexible atropisomeric angular bridging ligands results in the formation of highly symmetric chiral tetrameric cyclic complexes.