Synthesis, characterization and oxygen-sensing performance of a rhenium complex having an enlarged sensing area

In this paper, we reported a Re(I) complex Re(CO)3(IPD-Et)Br having an enlarged conjugation chain for oxygen sensing purpose, where IPD-Et=4-(1-ethyl-1 H-imidazo [4,5-f][1,10] phenanthrolin-2-yl)-N,N-diphenylaniline. Its conjugation chain was composed of triphenylamine group and imidazole group. In addition, an alkyl chain was connected with this N-N ligand to breach π-π attraction between ligand planes. It was assumed that above two factors could improve oxygen sensing sensitivity. Theoretical calculation and analysis firstly confirmed this hypothesis. Then photophysical measurement on Re(CO)3(IPD-Et)Br suggested that its emission was a lon-lived one peaking at 545 nm and thus vulnerable to molecular O2. Composite systems were constructed for oxygen sensing, using Re(CO)3(IPD-Et)Br as probe and mesoporous silicate MCM-41 as supporting matrix, respectively. Linear Stern-Volmer curves, short response time of ~13 s and high sensitivity of 3.99 were finally obtained.