Anthracene Derivatives Bearing Thiourea and Glucopyranosyl Groups for the Highly Selective Chiral Recognition of Amino Acids:  Opposite Chiral Selectivities from Similar Binding Units

Two new anthracene thiourea derivatives, <b>1</b> and <b>2</b>, were investigated as fluorescent chemosensors for the chiral recognition of the two enantiomers of α-amino carboxylates. Especially, host <b>2</b> displayed <i>K</i><sub>l</sub>/<i>K</i><sub>d</sub> values as high as 10.4 with <i>t</i>-Boc alanine. Furthermore, the d/l selectivity of hosts <b>1</b> and <b>2</b> is opposite, even though both hosts bear the same glucopyranosyl units. These intriguing opposite d/l binding affinities by <b>1</b> and <b>2</b> were obtained without/with H-π 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.