Light-Induced Organic Monolayer Modification of Iodinated Carbon Electrodes

Abstract

We report the modification of carbon electrodes formed from pyrolyzed photoresist films (PPF) via plasma iodination followed by the organic monolayer modification of these surfaces. The iodinated surfaces were characterized using cyclic voltammetry, atomic force microscopy, and X-ray photoelectron spectroscopy to enable the optimization of the iodination while preserving the stability and smoothness of the carbon surface. Subsequently, the C-I surface was further modified with molecules that possess an alkene or alkyne at one end through light activation with low energy (visible range λ 514 nm). The versatility of the modification reaction of the C-I surfaces is shown by reactions with undecylenic acid, 1,8-nonadiyne, and S-undec-10-enyl-2,2,2-trifluoroethanethioate (C11-S-TFA). Modification with 1,8-nonadiyne allows further modification via "click" chemistry with azido-terminated oligo(ethylene oxide) molecules demonstrated briefly to alter the hydrophilicity of the surface after attachment of ethylene oxide moieties. Furthermore, patterning of C11-S-TFA was demonstrated using a simple photolithography technique. Deprotection of the C11-S-TFA gave a free thiol allowed patterning of gold nanoparticles on the surface as verified using scanning electron microscopy (SEM). These results demonstrate that plasma iodination to form C-I is a versatile, simple, and modular approach to functionalize the carbon surface.

Fabrication of Biosensing Interface with Monolayers

“…In the case of surface modification for traditional carbon substrates, GC and HOPG, various methods have been reported, and diazonium, [31][32][33][34][35] amine, [36][37][38][39][40] azide, [41][42][43][44][45] and olefin [46][47][48][49] derivatives were examined to modify those surfaces. As a systematic study to evaluate the features of modified surfaces using those derivatives has not been reported, we were interested in the difference of those modified surfaces.…”

Modification of Carbon Electrode Surfaces

“…Iodine plasma can roughen the surface hence, using plasma of optimized power for an optimized time is crucial. The surface constructs explored to demonstrate the scope of this new carbon electrode modification strategy are shown in Scheme 6.7 [123]. As the strength of the carbon-iodine bond is less, modification of the iodinated PPF surface with both alkenes and alkynes was conducted with visible light ( = 514 nm).…”

Facile Electrochemical Hydrogenation and Chlorination of Glassy Carbon to Produce Highly Reactive and Uniform Surfaces for Stable Anchoring of Thiolated Molecules

“…Hydrogenation of GCE: H-termination of the GCEs was performed electrochemically as described previously for boron-doped diamond substrates [21] with some minor modifications. Briefly, the GCE was immersed in 2 m HCl and used as the cathode, and a platinum wire, immersed in 2 m H 2 SO 4 solution, was used as the anode.…”

“…[20] Recently, the feasibility of attaching iodine atoms to carbon films formed by photoresist pyrolysis with iodine plasma and the subsequent linking of both alkenes and alkynes to the iodinated surface has been demonstrated. [21] As another alternative, electrochemical methods for either the chlorination or hydrogenation of surfaces are attractive because of their simplicity, the ability to control the modification process, and reduced surface damage. Electrochemical hydrogenation of boron-doped diamond [22a] and germanium [22b] has been reported, and there have been several reports on the electrochemical conversion of CÀH to CÀX (X= F or Cl) for the functionalization of organic molecules.…”

“…An alternative approach exploits the photochemical grafting of organic alkenes to link functional organic molecules to carbon surfaces including diamond,1 amorphous carbon,15a glassy carbon (GC),19 highly ordered pyrolitic graphite (HOPG),13a, 14 and carbon nanofibers 20. Recently, the feasibility of attaching iodine atoms to carbon films formed by photoresist pyrolysis with iodine plasma and the subsequent linking of both alkenes and alkynes to the iodinated surface has been demonstrated 21…”