Guest encapsulation and self-assembly of molecular capsules in polar solvents via multiple ionic interactions.
Herein we report the formation and characterization of a novel type of capsules resulting from the self-association between oppositely charged complementary building blocks in MeOH/H2O. The assembly is based on the interaction between tetraamidinium calix[4]arenes 1a-d and tetrasulfonato calix[4]arene 2. Evidence for the formation of the expected 1:1 assemblies is provided by proton NMR, ESI-MS, and ITC. The association process is fast on the NMR time scale and strongly entropy driven, with association constants in the range of 10(6) M-1. The system 1a.2 shows binding affinity toward acetylcholine, tetramethylammonium, and N-methylquinuclidinium cations.
Corbellini
Francesca
F
Laboratory of Supramolecular Chemistry and Technology, MESA+ Research Institute, University of Twente P.O. Box 217, 7500 AE Enschede, The Netherlands.
Fiammengo
Roberto
R
Timmerman
Peter
P
Crego-Calama
Mercedes
M
Versluis
Kees
K
Heck
Albert J R
AJ
Luyten
Ingrid
I
Reinhoudt
David N
DN