Issue 18, 2017

Effects of electron-withdrawing groups in imidazole-phenanthroline ligands and their influence on the photophysical properties of EuIII complexes for white light-emitting diodes

Abstract

Herein, three europium complexes (Eu(TTA)3Phen-Ph-Ph, Eu(TTA)3Phen-mCF3-Ph, and Eu(TTA)3Phen-pCF3-Ph) were designed and synthesized. The N1-functionalization of the phenanthro-imidazole ring by phenyl and substituted phenyl moieties (CF3, an electron-withdrawing group) and their influences on the photophysical and electrochemical properties of EuIII complexes were determined through experimental and theoretical analyses. All the complexes in the solid state and in solution showed the distinctive emission of EuIII ion at 612 nm due to the electric dipole transition (5D07F2). Absence of ligand emission (400–600 nm; solution, thin film, and solid states) in the PL emission spectra of EuIII complexes clearly indicates efficient energy transfer from the ligand to the central metal ion (antenna effect). This was confirmed by the values of the singlet and triplet energy levels of the ligands calculated via density functional theory and time-dependent density functional theory (DFT, TD-DFT) analyses. The HOMO–LUMO levels of the complexes were determined through cyclic voltammetric studies. In addition, the Eu-complex was doped in poly(methyl methacrylate) (PMMA) to fabricate composite film devices; Eu(TTA)3Phen-pCF3-Ph complex showed highest quantum yield (78.7%). Red emission from the fabricated LEDs (EuIII complexes coated on InGaN-based LED (395 nm)) was obtained with the CIE values of x = 0.65, y = 0.34.

Graphical abstract: Effects of electron-withdrawing groups in imidazole-phenanthroline ligands and their influence on the photophysical properties of EuIII complexes for white light-emitting diodes

Supplementary files

Article information

Article type
Paper
Submitted
27 Jun 2017
Accepted
28 Jul 2017
First published
28 Jul 2017

New J. Chem., 2017,41, 9826-9839

Effects of electron-withdrawing groups in imidazole-phenanthroline ligands and their influence on the photophysical properties of EuIII complexes for white light-emitting diodes

B. Rajamouli, R. Devi, A. Mohanty, V. Krishnan and S. Vaidyanathan, New J. Chem., 2017, 41, 9826 DOI: 10.1039/C7NJ02291C

To request permission to reproduce material from this article, please go to the Copyright Clearance Center request page.

If you are an author contributing to an RSC publication, you do not need to request permission provided correct acknowledgement is given.

If you are the author of this article, you do not need to request permission to reproduce figures and diagrams provided correct acknowledgement is given. If you want to reproduce the whole article in a third-party publication (excluding your thesis/dissertation for which permission is not required) please go to the Copyright Clearance Center request page.

Read more about how to correctly acknowledge RSC content.

Social activity

Spotlight

Advertisements