Controlling the Supramolecular Assembly of Redox-Active Dendrimers at Molecular Printboards by Scanning Electrochemical Microscopy

Abstract

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.

Electrochemical study of β-Cyclodextrin binding with ferrocene tethered onto a gold surface via PAMAM dendrimers

“…24,16 The resulting electrode surfaces were washed by dipping them in gently stirred clean buffer solutions.…”

Synthesis of Metal Complex Modified Phospholipids by Phospholipase D-Catalyzed Transphosphatidylation

“…A cyclic voltammogram (Figure 3) recorded at a 25 µm diameter Pt microelectrode presents the classical sigmoidal shape characteristic of microelectrodes where the steady state current, i ss , is directly related to the bulk concentration of FcMeOH in solution. Finally, the use of FcMeOH in the fabrication of ferrocenyl-functionalized poly(propylenimine) (PPI) dendrimers (16) was also an encouraging parallel study that suggested that FcMeOH might be amenable to surface functionalization of liposomes. In enzymatic-assisted synthesis, it is important to control the parameters related to the enzyme activity, such as the enzyme strain, environment and reaction temperature.…”

Porous Carbons – Hyperbranched Polymers – Polymer Solvation

“…The study of Nunez et al [250] on the rheological behavior of hb polyesters and their blends with linear polymers observed a drastic decrease in viscosity depending on the hb polymer concentration in the blends. More recently, Li et al [251] employed hb poly(ether ether ketone) (hb-PEEK) at 1-5 wt% as a rheology modifier towards linear poly(ether ether ketone) (LPEEK) for improving the melt processability.…”