Allosteric and Chelate Cooperativity in Divalent Crown Ether/Ammonium Complexes with Strong Binding Enhancement.
A thorough thermodynamic analysis by isothermal titration calorimetry of allosteric and chelate cooperativity effects in divalent crown ether/ammonium complexes is combined with DFT calculations including implicit solvent on the one hand and large-scale molecular dynamics simulations with explicit solvent molecules on the other. The complexes studied exhibit binding constants up to 2×106m-1with large multivalent binding enhancements and thus strong chelate cooperativity effects. Slight structural changes in the spacers, that is, the exchange of two ether oxygen atoms by two isoelectronic methylene groups, cause significantly stronger binding and substantially increased chelate cooperativity. The analysis is complemented by the examination of solvent effects and allosteric cooperativity. Such a detailed understanding of the binding processes will help to efficiently design and construct larger supramolecular architectures with multiple multivalent building blocks.
Institut für Chemie und Biochemie, Organische Chemie, Freie Universität Berlin, Takustr. 3, 14195, Berlin, Germany.
Larissa K S
LK
von Krbek
Institut für Chemie und Biochemie, Organische Chemie, Freie Universität Berlin, Takustr. 3, 14195, Berlin, Germany.
Andreas J
AJ
Achazi
Zuse Institute Berlin (ZIB), Takustr. 7, 14195, Berlin, Germany.
Marthe
M
Solleder
Zuse Institute Berlin (ZIB), Takustr. 7, 14195, Berlin, Germany. weber@zib.de.
Marcus
M
Weber
Institut für Chemie und Biochemie, Organische Chemie, Freie Universität Berlin, Takustr. 3, 14195, Berlin, Germany. b.paulus@fu-berlin.de.
Beate
B
Paulus
Institut für Chemie und Biochemie, Organische Chemie, Freie Universität Berlin, Takustr. 3, 14195, Berlin, Germany. c.schalley@fu-berlin.de.
Christoph A
CA
Schalley
calorimetry; cooperative effects; density functional calculations; host-guest systems; molecular dynamics