Grafting of the gold surface by heterocyclic moieties derived through electrochemical oxidation of amino triazole - an experimental and "ab initio" study.

Surface modification of gold is accomplished by using the aminyl radicals formed through the electrochemical oxidation of the amino-triazole molecule dissolved in organic media (acetonitrile). The electrochemistry of the grafting process and the redox behavior of the grafted heterocyclic layer are similar to those of aliphatic amines. The presence of AT groups on the electrode surface was studied by cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) before and after the functionalization process to confirm and prove the formation of a layer on the surface. The capability of the modified surfaces for blocking redox reaction was assessed using a ferrocyanide-ferricyanide redox couple and displayed important differences. The redox probes display a decrease in electron transfer rate. The increase of the charge transfer resistance of the grafted layer is suggestive of a compact layer formation. Furthermore, the Au13 cluster was used to compute BDEs (bond dissociation energies) and a number of other important parameters such as bond strength and length of the interface, etc. These parameters were computed using ONTEP software (Order-N Total Energy Package), intended specifically for calculations on large systems, and it employs density functional theory (DFT) in the density matrix formulation.

Experimental and Theoretical Study of the Covalent Grafting of Triazole Layer onto the Gold Surface.

Finding novel strategies for surface modification is of great interest in electrochemistry and material sciences. In this study, we present a strategy for modification of a gold electrode through covalent attachment of triazole (TA) groups. Triazole groups were electrochemically grafted at the surface of the electrode by a reduction of in situ generated triazolediazonium cations. The resulting grafted surface was characterized before and after the functionalization process by different electrochemical methods (cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS)) confirming the presence of the grafted layer. The grafting of TA on the electrode surface was confirmed using analysis of surface morphology (by atomic force microscopy), the thickness of the grafted layer (by ellipsometry) and its composition (by X-ray photoelectron spectroscopy). Density functional theory (DFT) calculations imply that the grafted triazole offers a stronger platform than the grafted aryl layers.