Synthesis, self-assembly and disassembly of mono-dispersed Mo-based inorganic-organic hybrid nanocrystals

Mono-dispersed Mo-based inorganic-organic hybrid nanocrystals (HNCs) in water phase with a uniform size of ca. 3 nm have been successfully synthesized via a simple and facile method at room temperature. With the help of comprehensive characterizations, the chemical composition and structure of this hybrid material was determined: Mo8O264- as the inorganic core and long-chain quaternary ammonium cations as the organic shell. Interestingly, the resultant nanocrystals can spontaneously self-assemble into lamellar mesoscale nanocomposites with an alternative arrangement of inorganic and organic layers when simply removing water or adding ethanol into the solution. The distance between two layers depends on the length of the quaternary ammonium cations used, indicating that the cationic surfactant functions as a structure-directing agent and induces the formation of an ordered lamellar mesostructure. Moreover, we found that the lamellar mesoscale structure can be disassembled into well-dispersed HNCs when being re-dispersed into a large amount of water. The unique self-assembly and disassembly behavior of the mono-dispersed HNCs may have great potential for fabricating Mo-based functional materials.