Homochiral and Heterochiral Coordination Polymers and Networks of Silver(I)

The self-assembly of racemic and enantiopure binaphthylbis(amidopyridyl) ligands 1,1‘-C20H12{NHC(O)-4-C5H4N}2,
1, and 1,1‘-C20H12{NHC(O)-3-C5H4N}2, 2, with silver(I) salts (AgX; X = CF3CO2, CF3SO3, NO3) to form extended
metal-containing arrays is described. It is shown that the self-assembly with racemic ligands can lead to homochiral
or heterochiral polymers, through self-recognition or self-discrimination of the ligand units. The primary polymeric
materials adopt helical conformations (secondary structure), and they undergo further self-assembly to form sheets
or networks (tertiary structure). These secondary and tertiary structures are controlled through secondary bonding
interactions between pairs of silver(I) centers, between silver cations and counteranions, or through hydrogen
bonding involving amide NH groups. The self-assembly of the enantiopure ligand R-1 with silver trifluoroacetate
gave a remarkable three-dimensional chiral, knitted network composed of polymer chains in four different
supramolecular isomeric forms.