A cobalt-based metal‒organic framework (Co-MOF) derived from 2-nitroterephthalic acid and succinic acid ligands was synthesized via solvothermal method. The synthesized MOF was characterized via different techniques including FTIR, XRD, FESEM, EDX/elemental mapping, HR-TEM, TGA, BET, elemental analysis, XPS, DLS and zeta potential. FT-IR spectrum of Co-MOF displayed a shift in the carbonyl group stretching peak at 1702 cm−1 to a lower wavenumber (1630 cm−1), confirming the coordination of carboxylate with the metal. The XRD analysis confirmed the crystalline nature of the material and the FE-SEM images revealed a distinctive hexagonal shape. The presence of cobalt in + 2 oxidation state in the synthesized metal‒organic framework was confirmed by XPS analysis. The BET analysis indicated surface area of 28 m2/g and thermogravimetric analysis confirmed the thermal stability up to 250 °C. The synthesized Co-MOF displayed significant activity in adsorption of methylene blue dye, with an optimal MOF dosage of 30 mg, 45 °C temperature, 40 min contact time and neutral pH. The reusability of the cobalt-based MOF was evaluated over five consecutive cycles of dye adsorption with 74% efficiency in the first cycle and 43% after fifth cycle, which demonstrated excellent stability with a decrease in performance with each cycle. Further, kinetic studies of dye adsorption demonstrated that the intraparticle diffusion model was most suitable. Ciprofloxacin (antibacterial) and fluconazole (antifungal) drugs were used as positive controls for antimicrobial studies. Co-MOF exhibited dose-dependent antibacterial activity (P. aeruginosa, E. coli, S. aureus, K. pneumoniae, and B. subtilis) with inhibition zones of 36.2 mm against S. aureus, 27.9 mm against E. coli, 25.70 mm against P. aeruginosa, 23.52 mm against K. pneumoniae, 28.51 mm against B. subtilis. The antifungal (S. cerevisiae, A. niger and C. albicans) activity at concentrations of 50–200 mg/mL with inhibition zones of 23.32 mm (S. cerevisiae), 18.71 mm (A. niger) and 21.29 mm (C. albicans). The cytotoxicity studies of Co-MOF were also done on A375 (liver cancer cell lines) and the results of the study showed that Co-MOF had low cytotoxicity and viable cells remained at 93.80%, 90.79% and 88.20% over 24, 48 and 72 h respectively. This study also emphasizes the potential of the synthesized Co-MOF as an efficient antimicrobial agent and as an effective solution for methylene blue dye removal. Graphical Abstract

Investigating the Functionality of a Cobalt Metal‒Organic Framework for Dye Adsorption, Antimicrobial and Cytotoxicity Activity

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发表日期：

2025年5月3日

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Chandandeep Kaur Behl,
Archana Thakur

摘要

A cobalt-based metal‒organic framework (Co-MOF) derived from 2-nitroterephthalic acid and succinic acid ligands was synthesized via solvothermal method. The synthesized MOF was characterized via different techniques including FTIR, XRD, FESEM, EDX/elemental mapping, HR-TEM, TGA, BET, elemental analysis, XPS, DLS and zeta potential. FT-IR spectrum of Co-MOF displayed a shift in the carbonyl group stretching peak at 1702 cm⁻¹ to a lower wavenumber (1630 cm⁻¹), confirming the coordination of carboxylate with the metal. The XRD analysis confirmed the crystalline nature of the material and the FE-SEM images revealed a distinctive hexagonal shape. The presence of cobalt in + 2 oxidation state in the synthesized metal‒organic framework was confirmed by XPS analysis. The BET analysis indicated surface area of 28 m²/g and thermogravimetric analysis confirmed the thermal stability up to 250 °C. The synthesized Co-MOF displayed significant activity in adsorption of methylene blue dye, with an optimal MOF dosage of 30 mg, 45 °C temperature, 40 min contact time and neutral pH. The reusability of the cobalt-based MOF was evaluated over five consecutive cycles of dye adsorption with 74% efficiency in the first cycle and 43% after fifth cycle, which demonstrated excellent stability with a decrease in performance with each cycle. Further, kinetic studies of dye adsorption demonstrated that the intraparticle diffusion model was most suitable. Ciprofloxacin (antibacterial) and fluconazole (antifungal) drugs were used as positive controls for antimicrobial studies. Co-MOF exhibited dose-dependent antibacterial activity (P. aeruginosa, E. coli, S. aureus, K. pneumoniae, and B. subtilis) with inhibition zones of 36.2 mm against S. aureus, 27.9 mm against E. coli, 25.70 mm against P. aeruginosa, 23.52 mm against K. pneumoniae, 28.51 mm against B. subtilis. The antifungal (S. cerevisiae, A. niger and C. albicans) activity at concentrations of 50–200 mg/mL with inhibition zones of 23.32 mm (S. cerevisiae), 18.71 mm (A. niger) and 21.29 mm (C. albicans). The cytotoxicity studies of Co-MOF were also done on A375 (liver cancer cell lines) and the results of the study showed that Co-MOF had low cytotoxicity and viable cells remained at 93.80%, 90.79% and 88.20% over 24, 48 and 72 h respectively. This study also emphasizes the potential of the synthesized Co-MOF as an efficient antimicrobial agent and as an effective solution for methylene blue dye removal.

Graphical Abstract