The most efficient method for the synthesis of metal-organic frameworks MOFs using renewable and sustainable precursors as starting materials is the solvothermal synthesis method combined with the use of bio-based ligands and metal sources.1. Solvothermal synthesis: This method involves the reaction of metal ions and organic ligands in a solvent at elevated temperatures and pressures. Solvothermal synthesis allows for the formation of MOFs with high crystallinity, porosity, and stability. It also enables the use of a wide range of solvents, including water and other environmentally friendly solvents, which can be easily recycled and reused.2. Bio-based ligands: To make the synthesis of MOFs more sustainable, it is essential to use renewable and sustainable organic ligands. Bio-based ligands can be derived from biomass, such as lignin, cellulose, and chitin. These ligands can be functionalized to form carboxylate, imidazolate, or other coordinating groups that can bind to metal ions and form MOFs.3. Sustainable metal sources: The choice of metal ions is also crucial for the sustainability of MOF synthesis. Transition metals, such as iron, copper, and zinc, are abundant and have low environmental impacts compared to rare earth metals. Additionally, metal sources can be derived from waste materials, such as electronic waste or industrial byproducts, further reducing the environmental impact of MOF synthesis.In summary, the most efficient method for the synthesis of MOFs using renewable and sustainable precursors as starting materials is the solvothermal synthesis method combined with the use of bio-based ligands and sustainable metal sources. This approach not only ensures the formation of high-quality MOFs but also minimizes the environmental impact of their synthesis.