The synthesis and luminescence of europium (III) complex based on deprotonated 1-(4-ethyl-4H-thieno[3,2-b]indol-6-yl)-4,4,4-trifluorobutane-1,3-dionate and 1,10-phenanthroline

Abstract

A new β-diketone ligand, 1-(4-ethyl-4H-thieno[3,2-b]indol-6-yl)-4,4,4-trifluoro-butane-1,3-dione(HL) was synthesized by four steps reaction (Suzuki–Miyaura cross-coupling, Cadogan cyclization, N-ethylation and Claisen condensation reaction) from 1-(4-bromo-3-nitrophenyl)ethanone and thiophen-2-ylboronic acid. Deprotonated ligand (L−1) and 1,10-phenanthroline (phen) coordinated to Eu3+ to obtain a new europium (III) complex, EuL3(phen). The complex was characterized by elementary analysis, IR, 1H NMR, UV–Visible absorption spectroscopy, thermogravimetric analysis (TGA) and photoluminescence (PL) measurements in detail. TGA shows that the decomposition temperature of the complex is up to 320°C. PL measurement results indicate that the Eu(III) complex exhibit intense red-emission with the characteristic of europium ion. Red LED device was successfully fabricated by employing the complex onto 380nm-emitting InGaN chip, which shows that the complex can act as red phosphor in combination with 380nm-emitting chips.