2-(2-Hydroxyphenyl) substituted benzimidazole derivatives: Suitable sensitizers for Tb³⁺ characteristic luminescence

Abstract

Two series of 2-(2-hydroxyphenyl) substituted benzimidazole derivatives, (1-phenyl-2-(2-hydroxy-3-methoxyphenyl)benzimidazole, HL¹; 1-methyl-2-(2-hydroxy-3-methoxyphenyl)benzimidazole, HL²) and their bimetallic complexes Zn–Ln(III)–L (Ln = Tb, Nd, Eu and Y) were prepared. The structures of ligands and complexes were characterized by ¹H-NMR, FT-IR and single crystal X-ray diffraction. The UV–Visible absorption spectra, emission spectra and luminescent lifetime were measured. These results suggested that the ligands could efficiently sensitize the characteristic luminescence of Tb(III) and the photoluminescence quantum yield(PLQY) for Tb(III) complexes 3 and 7 were 74.8% and 55.3% respectively. While Nd(III) complexes 1 and 5 shown weak emission, and the Eu(III) complexes could not give the typical emission of lanthanide ions maybe due to the photo-induced electron transfer. In addition, the internal quantum yields of Nd(III) complexes were calculated utilizing luminescent lifetime.

Keywords:

• Benzimidazole
• lanthanide
• luminescence

Disclosure statement

No potential conflict of interest was reported by the author(s)

Additional information

Funding

This research was supported by the National Natural Science Foundation of China (Nos. 21103135, U1903133, 21301139 and 21373158), Shaanxi innovative Talent Promotion Project (No. 2017KJXX55), Natural Science Basic Research Plan in Shaanxi Province of China (Nos. 2016JM2011 and 2018JQ2061) and the Analytical instrumentation center of XUST.