Reactivity mapping with electrochemical gradients for monitoring reactivity at surfaces in space and time

Abstract

Studying and controlling reactions at surfaces is of great fundamental and applied interest in, among others, biology, electronics and catalysis. Because reaction kinetics is different at surfaces compared with solution, frequently, solution-characterization techniques cannot be used. Here we report solution gradients, prepared by electrochemical means, for controlling and monitoring reactivity at surfaces in space and time. As a proof of principle, electrochemically derived gradients of a reaction parameter (pH) and of a catalyst (Cu(I)) have been employed to make surface gradients on the micron scale and to study the kinetics of the (surface-confined) imine hydrolysis and the copper(I)-catalysed azide-alkyne 1,3-dipolar cycloaddition, respectively. For both systems, the kinetic data were spatially visualized in a two-dimensional reactivity map. In the case of the copper(I)-catalysed azide-alkyne 1,3-dipolar cycloaddition, the reaction order (2) was deduced from it.

Electrochemical nanoarchitectonics and layer-by-layer assembly: From basics to future

“…By using interdigitated microelectrode networks, Krabbenborg et al could locally probe by fluorescence microscopy the electroclick formation of mono and bifunctional gradients on azide-terminated silane monolayers (Fig. 17c) [384]. By increasing the electroclick time, both the coverage density and the length of the one-dimensional gradient could be tuned.…”

“…The stabilization of Cu(I) with tris[(1-benzyl-1H-1,2,3-triazol-4-yl)methyl]amine (TBTA) allowed for better control of the ionic gradient [389]. As a result, 50 m long gradients could be formed by electroclicking an alkyne-modified biotin on an azido-silanized substrate [384]. These works gave promising insight toward the design of biomedical devices for investigation of physiological processes like polarization and cellular migration.…”

“…Local generation and propagation of Cu(I) catalytic ions can be triggered by (a) microelectrodes [330], (b) local probes [380,381], (c) electrogenerated gradients [383,384], and (d) bipolar electrochemistry [382]. [381,387,388] Azido-silane monolayer Electro-generated gradients 50 Biomaterials, cellular migration control [383,384,389] PEDOT-N 3 Bipolar electro-chemistry Unknown Energetic devices, Biomaterials [382] resolution. For instance, by using 25 and 12.5 m diameter UMEs at a distance of 10 m from the surface, Quinton et al could improve the resolution to 75 m [387].…”

“…Cu(I) ions are indeed unstable in the presence of dissolved oxygen, which restricts their diffusion and permits the coupling reactions to occur only close to the electrode. Consequently, micro-electrodes [330], local probe microscopies [380,381], bipolar electrodes [382] and gradient devices [383,384] have been used to locally induce electroclick as described in Fig. 17.…”

Reactive self-assembled monolayers: from surface functionalization to gradient formation

“…116 Electrochemically derived solution gradients of a reaction parameter (pH) and of a catalyst (Cu(I)) were employed to fabricate micron-scale surface chemical gradients and to study the kinetics of the surface-conned imine hydrolysis and the CuAAC (Fig. 116 Electrochemically derived solution gradients of a reaction parameter (pH) and of a catalyst (Cu(I)) were employed to fabricate micron-scale surface chemical gradients and to study the kinetics of the surface-conned imine hydrolysis and the CuAAC (Fig.…”