Orientational Tuning of Monolayers of Amphiphilic Ruthenium(II) Complexes for Optimizing Chirality Distinction Capability

The following six types of Ru(II) complexes were synthesized with an aim to develop a monolayer with chiral discrimination: 1 [Ru(bpy)2(4-C11bpy)](ClO4)2 (bpy = 2,2‘-bipyridine, 4-C11bpy= 4-methyl-4‘-undecyl-2,2‘-bipyridine); 2 [Ru(bpy)2(4,4‘-dC11bpy)](ClO4)2 (4,4‘-dC11bpy = 4,4‘-diundecyl-2,2‘ -bipyridine); 3 [Ru(bpy)2(5-C11bpy)](ClO4)2 (5-C11bpy= 5-methyl-5‘-undecyl-2,2‘-bipyridine); 4 [Ru(bpy)2(5,5‘-dC11bpy)](ClO4)2 (5,5‘-dC11bpy = 5,5‘-diundecyl-2,2‘-bipyridine); 5 [Ru(bpy)2(4-C18bpy)](ClO4)2 (4-C18bpy= 4-methyl-4‘-octadecyl-2,2‘-bipyridine); 6 [Ru(bpy)2(4,4‘-dC18bpy)](ClO4)2 (4,4‘-dC11bpy = 4,4‘-dioctadecyl-2,2‘-bipyridine). These complexes possess one or two alkyl chains at 4,4‘- or 5,5‘-positions of the 2,2‘-bipyridine ligand. A traditional amphiphile is a linear molecule with a polar head attached by one or two alkyl chains, whereas the present complexes cover both traditional (1, 2, 5, and 6) and nontraditional amphiphilic molecules (3 and 4). The monolayer behavior of these Ru(II) complexes on ...