On-Demand Photochemical Modification of Glassy Carbon Surface

Chemical modification of carbonaceous materials is a convenient and reliable approach for the permanent fabrication of functional moieties. Among different linkers, diazirines offer a photogenerated reactive carbene that can insert into X–H (X; O, N) and add to π bonds to tether a variety of moieties on the surface of carbonaceous materials. Explicitly, 3-phenyl-3-(trifluoromethyl)-3H-diazirine is more thermally and chemically stable within the diazirine family. Here, we synthesized 3-(ferrocenylalkyloxy)-3-(trifluoromethyl)-diazirine derivatives and utilized them to covalently modify the surface of glassy carbon (GC). The photogenerated carbene enabled the tethering of the ferrocene (Fc) to the surface of a GC electrode (GCE). The modified surface properties were investigated using different electrochemical techniques, ellipsometry spectroscopy, and scanning electron microscopy. Electrochemical surface responses in KCl and Ru(NH₃)₆³⁺ solutions clearly exhibited ferrocene redox behavior and surface blocking during modification, respectively. Surface analysis results revealed a clear correlation between the thickness and capacitance current of the modified surface. More importantly, the obtained electrochemistry data show substantial chemical stability of the covalently tethered Fc on the GCE surface in both aqueous and nonaqueous media. The presented work offers an approach for the on-demand photochemical formation of carbene from diazirines to add functionality for applications of modified electrodes in electrocatalysis and sensing.