Divalent binding of a bis(adamantyl)-functionalized calix[4]arene to beta-cyclodextrin-based hosts: an experimental and theoretical study on multivalent binding in solution and at self-assembled monolayers.
The divalent binding of a bis(adamantyl)-functionalized calix[4]arene (1) to an EDTA-tethered beta-cyclodextrin (CD) dimer (2) in solution (1.2 x 10(7) M(-)(1)) was 3 orders of magnitude weaker than the binding constant ( approximately 10(10) M(-)(1)) for the interaction of 1 at CD self-assembled monolayers (SAMs) on gold. This difference in binding is rationalized using a theoretical model, which interprets the divalent binding as two consecutive monovalent binding events, i.e., an intermolecular interaction followed by an intramolecular binding event, the latter of which is associated with an effective concentration term accounting for the close proximity of the two interacting species. The methodology presented in the model is applicable to divalent binding both in solution and at SAMs and indicates that the difference in observed binding constants mainly stems from a difference in effective concentration.
Mulder
Alart
A
Laboratory of Supramolecular Chemistry & Technology, MESA Institute for Nanotechnology, University of Twente, PO Box 217, 7500 AE Enschede, The Netherlands.
Auletta
Tommaso
T
Sartori
Andrea
A
Del Ciotto
Susanna
S
Casnati
Alessandro
A
Ungaro
Rocco
R
Huskens
Jurriaan
J
Reinhoudt
David N
DN