Mixed Metal Metal-Organic Frameworks

Metal-Organic Frameworks (MOFs) have emerged as a highly versatile class of materials, with applications spanning catalysis, gas separation, sensing, and energy storage. While conventional MOFs typically feature a single metal species in their secondary building units (SBUs), the incorporation of multiple metal elements within the same structure introduces additional complexity, enabling enhanced structural, electronic, and catalytic properties. This chapter provides a comprehensive exploration of mixed-metal MOFs, focusing on their classification, synthesis strategies, and characterization techniques. The discussion covers key metal distribution scenarios, including multivariate MOFs (MTV-MOFs), heterometallic SBUs, frameworks containing multiple distinct SBUs, and MOFs incorporating metal sites in both SBUs and organic linkers. Various synthetic approaches—such as direct synthesis and post-synthesis strategies—are examined, with selected case studies illustrating their implementation. Advanced characterization techniques, including diffraction, spectroscopy, and microscopy methods, are highlighted for their role in elucidating metal distribution and framework properties. Finally, the chapter explores emerging applications of mixed-metal MOFs, demonstrating their potential in fields such as optics or heterogeneous catalysis.