Green synthesis of metal–organic frameworks: A state-of-the-art review of potential environmental and medical applications

Sustainable methods of synthesizing metal–organic frameworks (MOFs) are of paramount importance to energy conservation efforts and environmental remediation. It can be a significant tool in the global campaign to avoid use of hazardous substances, such as metal ions, organic solvents, and complexes in metal–organic chemistry. MOFs with porosity and crystalline nature offer structural tunability via variation in metal node and organic linker that promote their wide applicability at both scientific and industrial level. Besides fascinating properties of MOFs, their real field applications are still limited due to adverse environmental impact of the conventional synthesis approaches. Considerable research efforts have been devoted to devising clean and sustainable synthesis routes for MOFs to reduce the environmental impact of their preparation. This review covers the design strategies for greener, more energy-efficient, and less-toxic MOF synthesis through application of 12 green chemistry principles. Attention is given to development of green and industrially acceptable MOF chemistry based on (i) safer solvent/or reaction media, (ii) sustainable metal ions, and (iii) biocompatible (i.e., biomolecule/biomass-derived) organic linkers. The versatile functionality, biodegradability, biocompatible nature, and high drug loading capacity of green MOFs are highly promising for environmental and medical applications. In this review, the recent update on applicability of green MOFs in catalysis, adsorption/separation processes, and therapeutics is highlighted. In the last section, outlook and future challenges are illustrated, keeping in view their disposal and health related concerns.