title: Assembly of a supramolecular capsule on a molecular printboard.
abstract: A molecular capsule based on ionic interactions between two oppositely charged calix[4]arenes, 1 and 2, was assembled both in solution and on a surface. In solution, the formation of the equimolar assembly 1.2 was studied by (1)H NMR, ESI-MS, and isothermal titration calorimetry, giving an association constant (K(a)) of 7.5 x 10(5) M(-1). A beta-cyclodextrin self-assembled monolayer (beta-CD SAM) on gold was used as a molecular printboard to anchor the tetraguanidinium calix[4]arene (2). The binding of tetrasulfonate calix[4]arene 1 was monitored by surface plasmon resonance spectroscopy. Rinsing of the surface with a high ionic strength aqueous solution allows the removal of the tetrasulfonate calix[4]arene (1), while by rinsing with 2-propanol it is possible to achieve the complete desorption of the tetraguanidinium calix[4]arene (2) from the beta-CD SAM. The K(a) for the capsule formation on a surface is 3.5 x 10(6) M(-1), thus comparing well with the K(a) determined in solution.
authors.affiliation: Laboratory of Supramolecular Chemistry and Technology, MESA Institute for Nanotechnology, University of Twente, P.O. Box 217, 7500 AE Enschede, The Netherlands.
authors.forename: Francesca
authors.initials: F
authors.lastname: Corbellini
authors.forename: Alart
authors.initials: A
authors.lastname: Mulder
authors.forename: Andrea
authors.initials: A
authors.lastname: Sartori
authors.forename: Manon J W
authors.initials: MJ
authors.lastname: Ludden
authors.forename: Alessandro
authors.initials: A
authors.lastname: Casnati
authors.forename: Rocco
authors.initials: R
authors.lastname: Ungaro
authors.forename: Jurriaan
authors.initials: J
authors.lastname: Huskens
authors.forename: Mercedes
authors.initials: M
authors.lastname: Crego-Calama
authors.forename: David N
authors.initials: DN
authors.lastname: Reinhoudt