Anthracene derivatives bearing thiourea and glucopyranosyl groups for the highly selective chiral recognition of amino acids: Opposite chiral selectivities from similar binding units

Abstract

[GRAPHICS] Two new anthracene thiourea derivatives, 1 and 2, were investigated as fluorescent chemosensors for the chiral recognition of the two enantiomers of (alpha-amino carboxylates. Especially, host 2 displayed K-L/K-D values as high as 10.4 with t-Boc alanine. Furthermore, the D/L selectivity of hosts 1 and 2 is opposite, even though both hosts bear the same glucopyranosyl units. These intriguing opposite D/L binding affinities by 1 and 2 were obtained without/with H-pi interaction between anthrancene moiety and the methyl groups, which were explained by extensive high-level theoretical investigations taking into account the dispersion energy as well as the 2D-NMR chemical shifts.