Controlling the supramolecular assembly of redox-active dendrimers at molecular printboards by scanning electrochemical microscopy.
Redox-active ferrocenyl (Fc)-functionalized poly(propylenimine) (PPI) dendrimers solubilized in aqueous media by complexation of the Fc end groups with beta-cyclodextrin (betaCD) were immobilized at monolayers of betaCD on glass ("molecular printboards") via multiple host-guest interactions. The directed immobilization of the third-generation dendrimer-betaCD assembly G3-PPI-(Fc)16-(betaCD)16 at the printboard was achieved by supramolecular microcontact printing. The redox activity of the patterned dendrimers was mapped by scanning electrochemical microscopy (SECM) in the positive feedback mode using [IrCl(6)](3-) as a mediator. Local oxidation of the Fc-dendrimers by the microelectrode-generated [IrCl(6)](2-) resulted in an effective removal of the Fc-dendrimers from the host surface since the oxidation of Fc to the oxidized form (Fc+) leads to a concomitant loss of affinity for betaCD. Thus, SECM provided a way not only to image the surface, but also to control the binding of the Fc-terminated dendrimers at the molecular printboard. Additionally, the electrochemical desorption process could be monitored in time as the dendrimer patterns were gradually erased upon multiple scans.
Nijhuis
Christian A
CA
Laboratories of Supramolecular Chemistry and Technology and Molecular Nanofabrication, MESA Institute for Nanotechnology, University of Twente, P.O. Box 217, 7500 AE Enschede, The Netherlands.
Sinha
Jatin K
JK
Wittstock
Gunther
G
Huskens
Jurriaan
J
Ravoo
Bart Jan
BJ
Reinhoudt
David N
DN
D050091:Dendrimers / Q000737:chemistry*; D005296:Ferrous Compounds / Q000737:chemistry; D018625:Microscopy, Atomic Force; D008855:Microscopy, Electron, Scanning; D015394:Molecular Structure; D010084:Oxidation-Reduction; D011126:Polypropylenes / Q000737:chemistry; D047392:beta-Cyclodextrins / Q000737:chemistry
D050091:Dendrimers; D005296:Ferrous Compounds; D011126:Polypropylenes; D047392:beta-Cyclodextrins; C443641:poly(propyleneimine); C031215:betadex