On an oxadiazole-pyridine derived diimine ligand and its Re complex: Synthesis, characterization and photophysical features

Recent development of optoelectronic functional films, photovoltaic devices, photocatalysts and display devices has attracted widespread attention on the design and synthesis of emitters and dyes with optoelectronic functions. Among these proposed emitters and dyes, polypyridine Re(I) carbonyl complexes are unique ones due to their simple molecular structure, which makes their chemical modification easy to perform. These Re(I) complexes could be explored as singlet oxygen (O-1(2)) photosensitizer, which broadens their application. In this work, an electron-accepting diimine ligand with -CF3 group was incorporated into a Re(I) complex (denoted as ReLCF3). This Re(I) complex was characterized by single crystal analysis, electronic structure analysis, photophysical property analysis, so that its phosphorescent nature was confirmed. Then Re-LCF3 was dispersed into nanofibers of polyvinylpyrrolidone by means of electro-spinning method, hoping to improve O-1(2)-producing performance of the resulting composite nanofibers (denoted as Re-LCF3@PVP). A full comparison between ReLCF3 in solid state, in solution, in polymer fibers was performed, including their absorption, emission, quantum yield, lifetime and O-1(2)-producing performance. It was found that the photophysical performance of ReLCF3@PVP was better than that of pure Re-LCF3 in solid state, showing emission blue shift, improved photostability, longer lifetime and better emission quantum yield. The O-1(2)-producing performance of Re-LCF3@PVP was better than that of pure Re-LCF3 in solid state.