Direct Synthesis of the 2D Copper(II) 5-Prop-2-ynoxyisophthalate MOF: Comment on "Surface Functionalization of Porous Coordination Nanocages Via Click Chemistry and Their Application in Drug Delivery".

Synthesis of metal-organic materials is often dependent on the reaction conditions of suitable solvent/solvent mixture and temperature. A new finding based on a previously described protocol is reported: instead of obtaining metal-organic polyhedra (MOP), a metal-organic framework (MOF) with a 2D layered structure is obtained, following the same reported protocol. The 2D Cu(II)-5-prop-2-ynoxyisophthlate MOF, crystallized in a kagomé-type structure, is synthesized using different solvent systems at room temperature, as well as under solvothermal (nonhydrothermal) conditions. Under harsh reaction conditions, alkyne functional groups maintain their integrity and the copper does not catalyze the oxidative coupling of the terminal alkyne groups. X-ray diffraction analyses confirm the structure and phase purity of the product. Based on the present results and the previous work reported by Zhao et al., it seems that two products, namely 0D MOP and 2D MOF, are equally possible when using the same reactants under same reaction conditions. However, the materials obtained in all the trials are MOF instead of MOP. From the structure point of view, there is a difference in connectivity of the initial building units that determines whether the product is MOP or MOF.