Development of GO-NU1000 MOF Electrode and Sustainable HNFM@ZnCl3 DES Electrolyte, Solvent and Catalyst: A Rapid Electro-Organic C-H Amination Approach for Synthesizing Indoles and Evaluation of Their Anti-Cancer Activity

Abstract

To perform chemical reactions, whether through traditional methods or electrochemical processes, the inclusion of a solvent, catalyst, and electrolyte is crucial for achieving optimal results. However, relying on a variety of materials and reagents can result in environmental pollution, higher production costs, and complications in wastewater treatment. This study introduces a novel electrode made from graphene oxide (GO) modified with the NU1000 metal–organic framework (MOF) and utilizes HNFM@ZnCl₃ deep eutectic solvent (DES) as a multifunctional electrolyte, solvent, and catalyst. The GO-NU1000 MOF electrode aims to improve electrical conductivity and surface area for efficient electro-synthesis. The HNFM@ZnCl₃ DES showcases versatility by functioning as an electrolyte, solvent, and catalyst, which helps reduce production costs and environmental impact. The innovative system was applied in a rapid electro-organic C-H amination method to synthesize indole derivatives 3(a-m) from 2-phenylacetaldehyde 1(a-m) and NH₃ 2(a) gas, achieving yields of 90 to 97% at a current of 5 mA within 1 h at room temperature. Characterization of the electrode was performed using various techniques including SEM, FT-IR, EDS, TGA, XPS, BET, CV, and XRD. The synthesized indole derivatives were further characterized through melting point analysis, CHN, and 1HNMR testing. The study emphasizes the integration of advanced materials and sustainable electrolytes in electrochemical processes, promoting more efficient and environmentally friendly synthetic methods in organic chemistry. The synthesized indole derivatives 3(a-m) were evaluated for their cytotoxic effects on HT-29 colon cancer, MDA-MB-231 breast cancer, and HEK-293 normal cell lines. Notably, some compounds exhibited IC50 values below 10 μM against MDA-MB-231 and HT-29 cell lines, indicating strong anticancer potential. In contrast, all indole derivatives showed weak cytotoxicity on HEK-293 normal cells with IC50 values ranging from 56 to 138 μM.