Controlling dynamic stereoisomerism in transition-metal folded baskets

Abstract

We synthesized chiral molecular baskets (R3/S3)-1, containing three pyridine rings at the rim of a bowl-shaped platform. Each pyridine was tethered to the platform via a CH(CH)3 stereogenic center. In line with prior studies, we found that chiral basket (R3)-1 would coordinate to Ag(I) cation forming a Ag(I)–(R3)-1 complex (ΔG° = −5.9 kcal mol−1 at 298.0 K). Furthermore, we used spectroscopic methods (1H NMR, UV-Vis and CD) to establish that the CH(CH)3 stereogenic center with R configuration in Ag(I)–(R3)-1 would direct the twisting of the pyridine rings at the rim in a clockwise orientation (P configuration). UV-Vis and CD spectra of Ag(I)–(R3)-1(P) were also computed (TD-DFT; BHLYP/SV(P),TZVP), showing good agreement with the experimental data. Controlling dynamic stereoisomerism in basket-like systems is important and the results of this study will be useful for examining the relationship between chiral recognition and reactivity in gated and confined environments.