Recent breakthroughs in the solvothermal assisted synthesis of luminescent metal-organic frameworks

Photoluminescent metal-organic frameworks (MOFs) are excellent probe materials for diverse analytical purposes. The photoluminescent attributes of MOFs are contingent to various experimental parameters (e.g., linkers with π-electron cloud, linker induced sensitization of metal ions, and charge transfer mechanisms between the linker molecules). Such luminescent metal-organic frameworks (LMOFs) are generally synthesized by solvothermal approach, which comprises combination of a multidentate organic bridging linker with a metal node at elevated temperatures. To begin with, a brief comparison of LMOFs with other luminescent materials (quantum dots, organic dyes, and upconversion nanomaterials) is presented in terms of their luminescent attributes, mechanism of luminescence generation, and photostability. Next onwards, the review describes salient features of LMOFs, which contribute to their sensing applications. The review is further extended to include various mechanisms which contribute towards origin of luminescence in LMOFs. An illustration on the recent progress made in the solvothermal approaches used for fabrication of LMOFs is presented. Subsequently, the discussion extends to provide a comparison between the solvothermal approach with other synthetic routes utilized for the assembly of LMOFs. This comparison facilitates the selection of the best possible route for LMOFs synthesis in terms of scalability and performance. Finally, a brief comment on the applications and challenges of LMOFs for their commercial applications is provided. As such, the manuscript presents a roadmap for the future innovations in the solvothermal assisted synthesis of LMOFs.