Novel Ligands Incorporating Phosphinoxide Groups as Particularly Efficient Sensitizers for Lanthanide Emission

Helical molecular assemblies of bile acids and their derivatives were systematically investigated. These molecules have a common asymmetric structure with three different directions, and form characteristic inclusion crystals with the following hierarchical structure. First, such molecules arrange along their helical axes to yield the helical tapes with a definite direction. Second, the helical tapes are combined in a parallel fashion by using their side-chains through hydrogen bonds to produce chiral sheets. Third, the sheets stack together through van der Waals forces in a parallel or antiparallel fashion. Fourth, there exist chiral spaces for including guests among their sheets. Such hierarchical structure enables us to explain a role of the side-chains with different hydrogen bonding groups and length.