Systematic mechanochemical preparation of a series of coordination pillared layer frameworks.

A detailed investigation into the mechanochemical synthesis of coordination pillared-layer frameworks (CPLs), particularly CPL-1, was carried out. In the case of CPL-1, a two-step reaction was observed (from the starting reactants to the final product). In the conventional solution process, no intermediate state was detected. We found that moisture is essential in both the reaction steps. After the final product was washed, it showed the same sorption ability as the product prepared from a solution process. We further demonstrated the systematic preparation of other CPLs (CPL-2, 3, 4, 5, and 15) by the mechanochemical method under humid conditions, even though some of the ligands are almost insoluble in water. Our findings indicate that mechanochemical synthesis is a promising alternative method for the systematic and large-scale production of PCPs. Its advantages include the following: reduced pollution, low cost, simplicity of the process, ease of handling, efficient reaction rate, selectivity, and the issue of low solubility of reactants is overcome.