TY - JOUR A1 - Chatziefthimiou, Spyros D. A1 - Inclán, Mario A1 - Giastas, Petros A1 - Papakyriakou, Athanasios A1 - Yannakopoulou, Konstantina A1 - Mavridis, Irene M. T1 - Molecular recognition of N-acetyltryptophan enantiomers by β-cyclodextrin JF - Beilstein Journal of Organic Chemistry PY - 2017/// VL - 13 SP - 1572 EP - 1582 SN - 1860-5397 DO - 10.3762/bjoc.13.157 PB - Beilstein-Institut JA - Beilstein J. Org. Chem. UR - https://doi.org/10.3762/bjoc.13.157 KW - β-cyclodextrin KW - enantiomeric discrimination KW - N-acetyltryptophan KW - NMR KW - X-ray structure N2 - The enantioselectivity of β-cyclodextrin (β-CD) towards L- and D-N-acetyltryptophan (NAcTrp) has been studied in aqueous solution and the crystalline state. NMR studies in solution show that β-CD forms complexes of very similar but not identical geometry with both L- and D-NAcTrp and exhibits stronger binding with L-NAcTrp. In the crystalline state, only β-CD–L-NAcTrp crystallizes readily from aqueous solutions as a dimeric complex (two hosts enclosing two guest molecules). In contrast, crystals of the complex β-CD–D-NAcTrp were never obtained, although numerous conditions were tried. In aqueous solution, the orientation of the guest in both complexes is different than in the β-CD–L-NAcTrp complex in the crystal. Overall, the study shows that subtle differences observed between the β-CD–L,D-NAcTrp complexes in aqueous solution are magnified at the onset of crystallization, as a consequence of accumulation of many soft host–guest interactions and of the imposed crystallographic order, thus resulting in very dissimilar propensity of each enantiomer to produce crystals with β-CD. ER -