Chiral recognition in cucurbituril cavities.
For the first time, achiral cucurbiturils (CBs) were endowed with significant enantiomeric and distereomeric discrimination by incorporating a strong chiral binder. Calorimetric, nuclear magnetic, light-scattering, and mass spectral studies revealed that (S)-2-methylbutylamine (as a strong binder) can be discriminated by two enantiomeric supramolecular hosts, composed of CB[6] and (R)- or (S)-2-methylpiperazine, with an unprecedented 95% enantioselectivity in aqueous NaCl solution. This is the highest enantioselectivity ever reported for a supramolecular system derived from an achiral host. Similarly, CB[7], with a larger cavity, exhibited diastereoselectivities up to 8 times higher for diastereomeric dipeptides, as demonstrated for L-Phe-L-Leu-NH3+ versus L-Phe-D-Leu-NH3+.
Rekharsky
Mikhail V
MV
Entropy Control Project, ICORP, JST, 4-6-3 Kamishinden, Toyonaka 560-0085, Japan.
Yamamura
Hatsuo
H
Inoue
Chika
C
Kawai
Masao
M
Osaka
Issey
I
Arakawa
Ryuichi
R
Shiba
Kouhei
K
Sato
Akihiro
A
Ko
Young Ho
YH
Selvapalam
Narayanan
N
Kim
Kimoon
K
Inoue
Yoshihisa
Y