Directed one-pot syntheses of enantiopure dinuclear silver(i) and copper(i) metallo-supramolecular double helicates

Enantiopure dinuclear silver(i) double helicates were prepared in simple one-pot reactions from commercially available starting materials and the pure complexes isolated as the hexafluorophosphate salts. The (R),(+) and (S),(−) enantiomers of 1,1'-binaphthalene-2,2'-diamine were used as spacer groups and reacted with pyridine-2-carbaldehyde to form chiral didentate imine ligands. These chiral ligands predetermine the chirality of the helicates: the R spacer gives a P helicate and the S spacer an M helicate. The dinuclear double helical structures are confirmed by single crystal X-ray analysis and their persistence in solution is supported by inter-strand NOE data. Enantiopure copper(i) dinuclear species were also prepared by similar one-pot procedures and analysed by ¹H NMR, mass spectrometry and circular dichroism.