Mixed component metal-organic frameworks: Heterogeneity and complexity at the service of application performances

[Display omitted] •Mixed-component MOFs are organised and described here in four main categories.•Mixed-component MOFs can improve MOFs' performance in a wide range of applications.•The main applications of Mixed-component MOFs are discussed in this work.•Mixed-component MOFs offer unique perspectives in enzymatic and metal cluster catalysis. The synthesis of mixed-component metal-organic frameworks (MOFs) –including multivariate MOFs (MTV-MOFs), multicomponent MOFs, mixed-metals MOFs and mixed-ligands and metals MOFs– is becoming a very active research field. This is mainly based on the unique possibilities these materials offer to incorporate multiple functionalities and in how this heterogenity and complexity is translated in unexpected properties, which are not just the sum of each component. This review critically encompasses the progress made in this field, covering the synthetic approaches, and specially focusing on the current reported applications –such as gas storage and separation, catalysis, luminescence, conductivity, biological ones and water remediation. It also raises, as a perspective, some of the challenges the field has to overcome to reach their full-potential, and through two applications –(bio)enzymatic catalysis and synthesis of heterometallic subnanometric clusters and nanoparticles–, as exemplary cases, present some promising ways to take advantage of the intrinsic properties of mixed-components MOFs to make a breakthrough on the respective fields of application.