Investigation of electrochemical behaviour of some indole derived schiff bases, binding properties to carbon surface and analytical applications

In this study, firstly, electrochemical behaviour, the transferred electron numbers, diffusion coefficients and reaction mechanisms on the electrode surface of N-(1H-indole-3yl) methylene thiazole-2-amine (IMT2A) Schiff base and N,N'-bis (indole-3-carboxaldimine)-1,2 diaminocyclohexane (Indol-dach) Schiff base were investigated by using cyclic voltammetry (CV), chronoamperometry (CA) and rotating disc electrode (RDE) in acetonitrile medium containing 0.1 M tetrabutylammonium tetrafluoroborate (TBATFB) as supporting electrolyte. Diffusion coefficients for IMT2A and Indol-dach were determined as (3.87±0.40)x10-6 cm2/s and (4.88±0.65)x10-7 cm2/s, respectively. It was proposed that Schiff bases have irreversible oxidation peak on the glassy carbon electrode (GCE) surface in this medium, they attached to the surface by EC mechanism with 2 and 4 electrons, respectively. At following step of this study, the IMT2A-GCE and Indol-dach-GCE modified electrodes were prepared by attaching IMT2A and Indol-dach Schiff bases to the GCE surface by electrochemical oxidation. Prepared surfaces were characterized by cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), atomic force microscopy (AFM), profilometry and contact angle measurements (CAM) as electrochemical, spectroscopic and microscopic. Furthermore, the two modified surfaces were performed for the determination of dopamine (DA) by differential pulse voltammetry (DPV) in the presence of uric acid (UA) and ascorbic acid (AA). And then, UA determination was performed in the presence of DA and AA. At IMT2A-GCE, the limit of detection (LOD) and limit of quantification (LOQ) were determined for DA as 0.086 µM and 0.29 µM, for UA as 7.51 µM and 25 µM, respectively. At Indol-dach-GCE, LOD and LOQ were determined for DA as 0.18 µM and 0.60 µM, for UA as 9.73 µM and 32.4 µM respectively. Prepared electrodes were shown to use the determination of DA in commercial injections serum and UA in human urine samples.