New Cu(II) Metal-Organic Cages (MOCs) assembled starting from an asymmetric β-diketone/carboxylic ligand: synthesis, characterization and host-guest study

Metal-Organic Cages (MOCs) [1] based on carboxylic functionalities are of particular interest thanks to their possible applications in gas storage, drug-delivery and as nanoreactors in catalysis. In the search for new carboxylic-based MOCs we reacted the asymmetric β-diketone/carboxylic ligand 1- (4'-carboxyacetophenyl), 3-phenyl-1,3-propandione (H2L) [2] with copper acetate. From the reaction were isolated three new isostructural Cu(II)/carboxylate MOCs of cubic-like shape and formula [Cu16(L)16(A)n(B)8](S)x [A= THF (tetrahydrofurane), n=8, B=H2O (1); A=diox (dioxane), n=4, B=H2O (2); A = B = dme (dimethoxyethane), n=8 (3)]. The different number and coordination of the solvent molecules on the cages of 1, 2 and 3 affect their packing. Interestingly, the cages resulted to be very stable in water showing a great affinity for O-donor molecules and their potential in host-guest chemistry in aqueous solutions