A promising Rhenium(I) complex with fluorine/oxadiazole-bifunctionalized diamine ligand: Synthesis, structure and photophysical property

In this paper, a diamine ligand of 2-(4-fluorophenyl)-5-(pyridin-2-yl)-1,3,4-oxadiazole (denoted as FPO) and its corresponding Re(I) complex of Re(CO)3(FPO)Br are synthesized. Full characterization on Re(CO)3(FPO)Br, including NMR, elemental analysis and single crystal analysis, confirms its molecular identity. Upon photon excitation, the emission of Re(CO)3(FPO)Br owns a long excited state lifetime of 8.95 μs in pure N2 atmosphere and shows a maximum intensity at 540 nm. Theoretical calculation on Re(CO)3(FPO)Br single crystal suggests that the excited state has a triplet metal-to-ligand-charge-transfer character. By embedding Re(CO)3(FPO)Br into a polymer supporting matrix of polystyrene, the emission signal is found to be sensitive towards varying oxygen concentrations, with a maximum sensitivity of 7.84. Due to the porous structure of nanofibrous polystyrene matrix, a short response time of 8 s towards molecular oxygen is also observed with stable quenching signal.

► We report a bifunctional diamine ligand and its Re(I) complex. ► Crystal structure, photophysical property and electronic nature are investigated. ► It owns long decay lifetime and large conjugation plane favoring oxygen sensing. ► It was doped into a polymer matrix to construct porous nanofibers. ► A maximum sensitivity of 7.84 with short response time of 8 s is realized.