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Abstract

Bimetallic metal–organic frameworks (MOFs) have gained significant attention for their enhanced physicochemical and biomedical properties compared to their monometallic counterparts. In this study, monometallic zeolitic imidazolate frameworks (ZIFs), ZIF-8 (Zn-based) and ZIF-67 (Co-based), were synthesized alongside two core–shell bimetallic structures, ZIF-8@ZIF-67 (Zn-core, Co-shell) and ZIF-67@ZIF-8 (Co-core, Zn-shell), via a one-pot approach to evaluate their structural, thermal, and functional performance. Structural characterization confirmed that ZIF-8@ZIF-67 maintained a well-defined rhombic dodecahedral morphology, while ZIF-67@ZIF-8 exhibited a slightly rougher surface. FTIR spectroscopy and XRD validated successful coordination via Zn/Co–N bonds (422 cm⁻ 1 ) and retained crystallinity in all samples. Thermal analysis revealed that while ZIF-8 showed the highest degradation temperature (585 °C), the bimetallic composites ZIF-8@ZIF-67 (536 °C) and ZIF-67@ZIF-8 (498 °C) exhibited greater thermal stability than ZIF-67 (475 °C), confirming the stabilizing effect of metal integration. BET analysis showed higher surface areas for ZIF-8@ZIF-67 (1819.88 m 2 /g) and ZIF-67@ZIF-8 (1711.67 m 2 /g) compared to ZIF-8 (1621.33 m 2 /g) and ZIF-67 (1677.08 m 2 /g), confirming that bimetallic ZIFs possess superior porosity. Antimicrobial evaluation against E. coli and S. aureus demonstrated 99% bacterial inhibition efficiency and MIC 50 µg/mL through colony counting assays, highlighting the synergistic effect of Zn/Co integration. Biocompatibility studies using human dermal fibroblasts (HDFs) revealed that all MOFs maintained over 80% cell viability across 1 and 3 days, confirming their cytocompatibility. These findings highlight the potential of bimetallic ZIFs for applications in drug delivery, antibacterial coatings, catalysis, and environmental remediation, offering