Two cationic metal-organic frameworks based on cadmium and α,ω-alkanedisulfonate anions and their photoluminescent properties

We have successfully synthesized three cadmium-based metal-organic frameworks by utilizing two separate organic linkers to direct the structure. The first material is a three-dimensional neutral framework based on 2D cadmium ethanedisulfonate layers pillared by a 4,4'-bipyridine linker. The other two materials are 3D cationic frameworks and are the first with propanedisulfonate and butanedisulfonate as extraframework charge balancing anions. Both structures occupy a high symmetry hexagonal crystal system where Cd-bipy chains are arranged into three crystallographically distinct layers that stack spirally along [001]. The framework is stabilized by alkanesulfonate anions that are electrostatically and hydrogen bonded to the framework. Each material was characterized by single-crystal and powder X-ray diffraction. The thermal and luminescent properties were also investigated by thermogravimetric analysis and photoluminescence spectroscopy, respectively. All three materials exhibit high thermal stability to above 300. degrees C and efficient blue emissive photoluminescence centered at 425 nm to 450 nm upon 350 nm excitation.