Inclusion complexation of a deep cavitand with imidazoquinoxaline flaps forming stable vase-like conformation

摘要

The stability of the vase-like conformation of a deep cavitand 1 with four imidazoquinoxaline flaps was studied in CDCl3/CD3OD by H-1 NMR method. The annular tautomerism of cavitand 1.4MeOD in CDCl3/CD3OD (1:9 v/v) was investigated by H-1 NMR and the free energy of activation (Delta G(268)(double dagger)) of this process was measured as 12.9 kcal/mol at a coalescence temperature of 263 K. The inclusion complexation of 1 with various rod-like fatty amides and fatty esters resulted the formation of host-guest complexes in 1:1 stoichiometry where the alkyl chain of guests are coiled within the cavity and stabilized by CH/pi interactions with the enlarged aromatic pi surfaces of imidazoquinoxaline flaps. (C) 2018 Elsevier Ltd. All rights reserved.