Russian Nesting Doll Complexes of Molecular Baskets and Zinc Containing TPA Ligands

In this study, we examined the structural and electronic complementarities of convex 1–Zn(II), comprising functionalized tris(2-pyridylmethyl)amine (TPA) ligand, and concave baskets 2 and 3, having glycine and (S)-alanine amino acids at the rim. With the assistance of 1H NMR spectroscopy and mass spectrometry, we found that basket 2 would entrap 1–Zn(II) in water to give equimolar 1–Zn⊂2in complex (K = (2.0 ± 0.2) × 103 M–1) resembling Russian nesting dolls. Moreover, C3 symmetric and enantiopure basket 3, containing (S)-alanine groups at the rim, was found to transfer its static chirality to entrapped 1–Zn(II) and, via intermolecular ionic contacts, twist the ligand's pyridine rings into a left-handed (M) propeller (circular dichroism spectroscopy). With molecular baskets embodying the second coordination sphere about metal-containing TPAs, the here described findings should be useful for extending the catalytic function and chiral discrimination capability of TPAs.