Chiral double helical silver complexes: subcomponent self-assembly and self-sorting

Four homochiral dinuclear complexes, namely, [Ag2(LC4)2](OTf)2 (1), [Ag2(LC4)2](ClO4)2 (2), [Ag2(LC5)2](OTf)2 (3), [Ag2(LC5)2](PF6)2 (4) have been successfully synthesized from subcomponent self-assembly of imidazole-2-carboxaldehyde derivatives, R-phenylethylamine and silver salt. LC4 and LC5 were flexible ligands, containing the same imidazole Schiff-bases coordination motif and varying in alkyl chain lengths with four and five carbon atom, respectively. Single crystal structures revealed that the silver(I) center in 1–4 coordinated with 4 N donor atoms from two symmetrical chiral ligands assuming Δ configuration with a tetrahedral coordination environment. [Ag2(LCn)2]2+ components all presented double helical structures exhibiting only P-handedness with Ag–Ag, π–π, and C–H⋯π intramolecular interactions. Highly selective narcissistic self-sorting behavior can be observed during the self-assembly of 1 and 3.

Graphical abstractFour novel homochiral dinuclear Ag(I) complexes have been successfully synthesized by subcomponent self-assembly. Highly selective narcissistic self-sorting behavior was observed in the self-assembly process of the Ag helicates from a mixture of similar components that only alkyl chain different. This was confirmed by overlaying the 1H NMR of the mixture with the individually synthesized chiral helicates.Figure optionsDownload full-size imageDownload as PowerPoint slide