Fine-Tuned Graphene Oxide Nanocomposite: Harnessing Copper(II)–Imidazole Complex for Enhanced Biological Responses and Balanced Photocatalytic Functionality

In this study, the synthesis of biologically active copper(II) complex Cu(im)2Cl2 was achieved using a reported method. Subsequently, this copper(II) complex was strategically grafted onto graphene oxide, resulting in the formation of a nanocomposite denoted as copper(II)-complex-grafted graphene oxide (Cu-GO). The comprehensive characterization of Cu-GO was conducted through various techniques, including X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FT-IR), UV-visible spectroscopy, emission spectra analysis, X-ray photoelectron spectroscopy (XPS), and Copper K-edge X-ray Absorption Near Edge Structure (XANES) spectroscopy. The antibacterial efficacy of Cu-GO compounds was assessed using disk diffusion and microbroth dilution methods. Notably, the copper complex exhibited the highest effectiveness, showcasing a Minimal Inhibitory Concentration (MIC) value of 500 µL against Klebsiella bacteria. The antibacterial activities of all compounds were systematically screened, revealing the superior performance of the copper complex compared to standalone copper compounds. Expanding the scope of the investigation, we explored the antioxidant and anti-obesity activities of the copper complexes against Klebsiella organisms. The results underscore promising directions for the further exploration of the diverse health-related applications of these compounds. Moreover, the photocatalytic performance of the Cu-GO nanocomposite was evaluated under sunlight irradiation. Notably, the antioxidant and anti-obesity activities of Cu-GO, assessed in terms of percentage inhibition at a concentration of 200 mg/mL, exhibited values of 41% and 45%, respectively. Additionally, the Cu-GO composite exhibited exceptional efficacy, achieving a degradation efficiency of 74% for RhB under sunlight irradiation, surpassing both graphite and GO. These findings not only demonstrate enhanced biological activity, but also highlight a notable level of moderate photocatalytic performance. Such dual functionality underscores the potential versatility of Cu-GO nanocomposites across various applications, blending heightened biological efficacy with controlled photocatalysis. Our study offers valuable insights into the multifunctional attributes of copper(II)-complex-grafted graphene oxide nanocomposites, thereby paving the way for their broader utilization in diverse fields.