Molecular cocrystals of diphenyloxazole with tunable fluorescence, up-conversion emission and dielectric properties

The development of molecule-based solid-state materials with novel photofunctional and optoelectronic properties has received much attention recently. In this sense, the construction of two-component molecular systems (such as cocrystals) provides an effective way to adjust and optimize the molecular stacking, aggregation state and related performances. In this work, 2,5-diphenyloxazole (DPO) was chosen as a photoactive model system to study the structure-property relationship of its cocrystals. It was found that the as-prepared new cocrystals exhibited tunable fluorescence properties, up-conversion emission and thermal stability relative to the pure DPO solid. Moreover, the cocrystal based on DPO and hydroquinone has exhibited a pump-enhanced luminescence effect. The measurement of dielectric constants also suggests that the co-crystallization strategy can be applied in modulating the permittivity for the development of new materials in electro-optical applications. Therefore, this work provides a detailed picture on the relationship between the molecular stacking and optoelectronic properties of new DPO cocrystals and gives an alternative to achieve tunable fluorescence, up-conversion emission and dielectric properties.