Design, Synthesis, Crystal Structure and Photoluminescence Properties of Four New Europium (III) Complexes with Fluorinated β-Diketone Ligand

Hiromasa Kawata,Venkataprasad Jalli,Tetsuji Moriguchi

doi:10.4236/csta.2021.101001

Abstract

The strong photoluminescence properties of europium complexes with organic ligands attracted the attention of many researchers and found a wide range of uses in medical, industrial and biological fields. In this article, four new Tetrakis europium complexes 3a, 3b, 3c and 3d have been prepared using 1-phenyl-4,4,4-trifluoro-1,3-butenedionato ligand and pyridinium, bipyridinium, piperazinium and piperidinium counter cations. These complexes have been characterized by negative FAB-mass. The crystal structures of 3a, 3b, 3c and 3d were determined by single crystal X-ray diffraction analysis. The complex 3a crystallized in monoclinic form, space group P21/n with four molecules in the unit cell. The complex 3b crystallized in monoclinic form, space group P2/n with two complex molecules in the unit cell. The complex 3c crystallized in monoclinic form, space group C2/c with sixteen molecules in the unit cell. The complex 3d crystallized in monoclinic form, space group P21/n with four complex molecules in the unit cell. The complex 3a has 1,2-alternative structure, 3b has 1,3-alternative structure, 3c has cone like structure and 3d has partial cone like structure. The photoluminescence properties of these complexes have been evaluated. Strong red emissions were observed in all four complexes due to 5D0 → 7F2 transition of Europium (III) ions under UV excitation. Four β-diketone ligands acted as strong antenna ligands and transferred the absorbed energy to europium (III) ion effectively; consequently strong red luminescence was observed.

Highlights

The photoluminescence properties of Lanthanide complexes with organic ligands have been greatly enhanced, and led to the development of strong luminescent Lanthanide complexes with important applications in medical, industrial and biological fields [1]-[7]
The strong photoluminescence properties of europium complexes with organic ligands attracted the attention of many researchers and found a wide range of uses in medical, industrial and biological fields
Europium (III) complex with organic ligands is an example of strong luminescent Lanthanide complex and Europium (III) complexes that have great importance in materials engineering chemistry due to significant improvement in photophysical parameters such as high luminescence emission efficiency, long fluorescence life time, large stokes shift, sharp emission bands [8] [9] [10] [11]

Summary

Introduction

The photoluminescence properties of Lanthanide complexes with organic ligands have been greatly enhanced, and led to the development of strong luminescent Lanthanide complexes with important applications in medical, industrial and biological fields [1]-[7]. In the past decade various high luminescent europium complexes have been engineered and evaluated for their photoelectronic properties such as OLEDs, electroluminescent displays, bioimaging, sensing and targeting specific DNA structures, melamine detection in milk protein. Albumin proteins in human serum have been detected by Europium complexes, which act as sensor materials [21]. The ligand that forms complexes with Europium (III) ion acts as antenna. This absorbs energy and transfers to Europium (III) ion through intersystem crossing to triplet excited states. In this context, europium complexes with substituted aromatic β-diketones as organic ligands were explored due to efficiency in generating triplet excited states in close contact with europium (III) ion. Various Europium (III) complexes with β-diketones were synthesized and evaluated for their photoluminescent properties [22] [23] [24] [25] [26]

Methods

Results

Conclusion