Photoluminescent Layered Crystal Consisting of Anderson-Type Polyoxometalate and Surfactant toward a Potential Inorganic-Organic Hybrid Laser.

The hybridization of inorganic and organic components is a promising strategy to build functional materials. Among several functions, luminescence is an important function which should be considered for practical usage. Inorganic-organic hybrid luminescent materials have been investigated as phosphors, sensors, and lasers. Organic luminescent centers such as dye molecules have often been hybridized with inorganic matrices. Polyoxometalate anions (POMs) are effective inorganic luminescent centers due to their luminescent properties and structural designability. However, most luminescent POM components are limited to lanthanide-based POMs. In this report, a photoluminescent inorganic-organic hybrid crystal based on a non-lanthanide POM was successfully synthesized as a single crystal. Anderson-type hexamolybdochromate ([CrMo 6 O 18 (OH) 6 ] 3- , CrMo 6 ) anion exhibiting emission derived from Cr 3+ was utilized with n -dodecylammonium ([C 12 H 25 NH 3 ] + , C 12 NH 3 ) surfactant cation to obtain a photoluminescent hybrid crystal. The grown single crystal of C 12 NH 3 -CrMo 6 comprised a distinct layered structure consisting of inorganic CrMo 6 layers and interdigitated C 12 NH 3 layers. In the CrMo 6 layers, the CrMo 6 anions were associated with water molecules by hydrogen bonding to form a densely packed two-dimensional network. Steady-state and time-resolved photoluminescence spectroscopy revealed that the C 12 NH 3 -CrMo 6 hybrid crystal exhibited characteristic emission from the CrMo 6 anion. Preliminary lasing properties were also observed for C 12 NH 3 -CrMo 6 , which shows the possibility of using the C 12 NH 3 -CrMo 6 hybrid crystal as an inorganic-organic hybrid laser.