Europium complexes with large conjugation plane in diamine ligands: Synthesis, characterization, photophysical features and oxygen sensing performance

Abstract In this paper, two europium complexes with large conjugation planes and proper triplet levels in their diamine ligands, Eu(DBM) 3 IPD and Eu 3 (DBM) 9 TBB, were synthesized and explored for oxygen sensing purpose, where DBM = 1,3-diphenyl-propane-1,3-dione, IPD = 4-(1H-imidazo[4,5-f][1,10]phenanthrolin-2-yl)-N,N-diphenylaniline, TBB = 1,3,5-tris((2-(pyridin-2-yl)-1H-benzo[d]imidazol-1-yl)methyl)benzene. It was anticipated that large conjugation planes and proper triplet levels could improve oxygen sensing performance by increasing collision probability with O 2 molecules. The two europium complexes were firstly characterized through single crystal analysis, UV–Vis absorption spectra, emission spectra and excited state lifetimes. Then, by doping them into a polymer matrix of poly(vinylpyrrolidone) with electrospinning technique, oxygen sensing parameters of the resulting composite fibers were studied and compared. Maximum sensitivity of 3.38 and short response time of 12 s were obtained. Linear Stern–Volmer plots were observed.