An oxygen-sensing rhenium(I) complex with a carbazole “Shield” in its diamine ligand: Synthesis, characterization, photophysical property and sensing performance

In this paper, we synthesized a novel Re(I) complex of Re(CO)3Br(PBI-Cab) owing a diamine ligand of 9-(4-(2-(pyridin-2-yl)-1H-benzo[d]imidazol-1-yl)butyl)-9H-carbazole (PBI-Cab), where the carbazole moiety was connected by an alkyl chain, hoping to realize an optical sensor immune to surrounding interference. The geometric and electronic structures were revealed by single crystal and density functional theory calculation, which indicated that the carbazole moiety played as a shield for the emissive center. Re(CO)3Br(PBI-Cab) was proved to be a promising oxygen-sensing probe owing to the immunity of emission towards surrounding interference, proper emissive energy and long excited state lifetime. By doping Re(CO)3Br(PBI-Cab) into a polymer host of poly(vinylpyrrolidone), the oxygen sensing performance of the resulting composite material was obtained and discussed. Finally, a high sensitivity of 20.53 was achieved, with a short response/recovery time of 6 s/28 s.