The Syntheses, Crystal Structure and Luminescence Properties of Cone-Like Octadentate Europium (III) Complexes with Four Short Alkoxy Substituents

Tetsuji Moriguchi,Kenji Yoza,Akihiko Tsuge,Venkataprasad Jalli,Satoshi Hirosaki

doi:10.3390/cryst7030085

Abstract

Treatment of 1-(4′-methoxy or ethoxy phenyl)-4,4,4-trifluoro-1,3-butanedione with europium (III) chloride in the presence of piperidine resulted in the halide ligands exchange yielded new piperidinium tetrakis{1-(4′-methoxy or ethoxy phenyl)-4,4,4-trifluoro-1,3-butanedionato} europate (III) complexes 2a and 2b. Complexes 2a and 2b have been characterized by elemental analysis, 1H NMR spectroscopy, and FAB-MS, and their absolute structures were determined by single crystal X-ray diffraction analysis. The complexes 2a and 2b have the monoclinic space groups C2/c (No. 15, 4′-substituent = OCH3) and with P − 1 (No. 2, 4′-substituent = OC2H5), respectively. X-ray analysis results showed that eight coordinate structures of the complexes 2a and 2b have conelike structures, like calix[4]arenes, but their structures were slightly different due to the crystal packing and the existence of the solvent molecule. The complexes 2a and 2b exhibited identical, strong photoluminescence emissions in the solution phase.

Highlights

The luminescent properties of Lanthanide complexes with various organic ligands have been investigated for decades [1], and the search for novel Lanthanide complexes continues to attract many researchers due to their important applications as optical fiber lasers, electroluminescent displays, and organic light emitting diodes [2,3,4]
Europium (III) complexes with β-diketones possessing aromatics and fluorine substituents displayed very good to excellent photo luminescent properties
We report the synthesis, structural, and spectral properties of the octa-coordinate europium (III) complexes carrying four bidentate β-diketonato ligands having four alkoxy substituted aromatic moieties, fluorine substituents, and one piperidinium as a counter cation

Summary

Introduction

The luminescent properties of Lanthanide complexes with various organic ligands have been investigated for decades [1], and the search for novel Lanthanide complexes continues to attract many researchers due to their important applications as optical fiber lasers, electroluminescent displays, and organic light emitting diodes [2,3,4]. Europium (III) complexes with β-diketones possessing aromatics and fluorine substituents displayed very good to excellent photo luminescent properties. Various europium (III) complexes with β-diketones were synthesized and evaluated for their photo luminescent properties [4,5,6,7,8,9]. In this context, we report the synthesis, structural, and spectral properties of the octa-coordinate europium (III) complexes carrying four bidentate β-diketonato ligands having four alkoxy substituted aromatic moieties, fluorine substituents, and one piperidinium as a counter cation. This is due to the vibration relaxation of water molecule; that is to say, the excited energy on the f orbital (5 D levels) of the centered europium ion is effectively relaxed to 7 F levels

Methods

Discussion

Conclusion