Lanthanide inorganic-organic hybrid materials based on calix[4]arene-carboxylate: Synthesis, characterization and solid-state luminescent properties

Full text: Calixarenes, macrocyclic compounds possessing unique cavity-like structure, have received much attention due to their interesting and versatile complexing properties. Depending on their functionalization, they may act as hosts for cations, anions or even neutral molecules. More recently, modified calixarenes have been described as promising candidates for construction of extended structures, nanostructured coordination polymers. The formation of coordination polymers based on calixarenes is of particular interest since such materials may combine properties of both, the ligand and the structural framework, showing two levels of porosity. In this work, carboxylate derivative of calix[4]arene was used as a building block for preparation of lanthanide (Eu3+, Tb3+, Gd3+) coordination polymers and their solid-state luminescent properties were investigated. Moreover, the results were compared to those obtained for a simple calix-carboxylate-Tb3+ complex which X-ray crystal structure is also shown here for the first time. The organic-inorganic hybrid materials were obtained by solvothermal syntheses in DMF/ACN (dimethylformamide/acetonitrile) solvent mixture at 90°C for 1 to 3 days. We found that the crucial parameter of a synthesis leading to different self-assembled structures was the ligand/metal molar ratio. The materials obtained were characterized by XRD, IR, SEM and PL spectroscopy. (author)