Design and Synthesis of Novel Bio-MOF UTSA-16 (Zn) Catalyst for One-Pot Synthesis of 3,3-Di(indolyl)indolin-2-ones: Their Molecular Docking, Anti-Microbial, and Anti-Oxidant Evaluation

This study explored the catalytic potential of the bio-MOF UTSA-16 (Zn) for the synthesis of novel 3,3-di (indolyl)indolin-2-ones through one-pot reactions between isatins and indoles. The present approach involved water as an eco-friendly solvent, and the hydrothermally synthesized bio-MOF UTSA-16 (Zn) catalyst has been comprehensively characterized by using XRD, SEM, EDX, TG-DTA, FT-IR, and BET analytical techniques. The UTSA-16 (Zn) MOF exhibited catalytic efficiency toward the candidates for 3,3-di (indolyl)indolin-2-one, which were fully characterized using ¹H and ¹³C NMR spectrometry. Furthermore, the catalyst demonstrated excellent reusability and stability, maintaining its catalytic performance across five successive cycles without significant loss of reactivity. Additionally, the in vitro antimicrobial activity of the synthesized 3,3-di (indolyl)indolin-2-one derivatives and reference drugs was evaluated against gram-negative and gram-positive bacteria, specifically Escherichia coli and Staphylococcus aureus. Compounds 3b and 3e consistently demonstrated the most potent antimicrobial activity against E. coli and S. aureus, showing zones of inhibition of 6–7 mm and 15 mm at a concentration of 100 μg/mL. The DPPH assay indicated that Compound 3e exhibited the most significant antioxidant activity, with an IC₅₀ value of 52.34 ± 0.20 μg/mL, reflecting its high efficacy in scavenging DPPH radicals. Moreover, molecular docking studies were conducted on the synthesized compounds, aligning with the in vitro results and supported by a structural activity relationship study. This protocol highlights several key advantages, including green solvent, operational simplicity, short reaction times, reusability, high product yields, and availability of high surface area of the UTSA-16 (Zn) catalyst.