Novel Luminescent Eu3+-Indandionate Complexes Containing Heterobiaryl Ligands

João B M Resende Filho,Hermi F Brito,Juliana A Vale,Wagner M Faustino,Ercules E S Teotonio,Maria C F C Felinto,Jannine C Silva,José G P Espínola

doi:10.5935/0103-5053.20140197

Abstract

Novel Ln3+-indandionate complexes of formulas [Ln(aind)3L(H2O)] and [Ln(bind)3L]∙H2O (L: 1,10-phenanthroline (phen) or 4,7-dimethyl-1,10-phenanthroline (dmphen), Ln3+: Eu3+ or Gd3+, aind: 2-acetyl-1,3-indandionate and bind: 2-benzoyl-1,3-indandionate) were synthesized and characterized by elemental analysis, infrared spectroscopy, and thermogravimetric analyses. The characterization data are consistent with the presence of a water lattice molecule in the [Ln(bind)3L]∙H2O compounds. However, the data also suggest that the water acts as a coordinated molecule in the [Ln(aind)3L(H2O)] ones. Theoretical geometries of the Eu3+-complexes have been optimized via the SPARKLE/AM1 Model for lanthanide complexes that are consistent with their luminescence experimental data. The photoluminescence properties of the Eu3+-compounds have been discussed in terms of experimental intensity parameters (Ω2 and Ω4), radiative (Arad), and non-radiative (Anrad) spontaneous emission coefficients. The higher values of emission quantum efficiency (η) of the [Eu(bind)3L]∙H2O compounds reflect the absence of luminescence-quenching water molecule in their first coordination spheres.

Highlights

2-acyl-1,3-indandiones compounds have been frequently used as precursor’s molecules for the synthesis of novel compounds exhibiting biological activities and spectroscopic properties.[1,2,3] They are well known for their
Based on the above considerations, in this work, we have reported the synthesis and spectroscopic studies of the novel [Ln(aind)3(L)(H2O)] and [Ln(bind)3(L)]∙H2O complexes, where aind = 2-acetyl-1,3-indandione, bind = 2-benzoyl-1,3-indandione, Ln = Eu3+ or Gd3+, and L = 1,10-phenanthroline or 4,7-dimethyl-1,10phenanthroline (Figure 1)
Hexahydrated lanthanide chlorides, LnCl3⋅6H2O, were prepared by reaction between Ln2O3 and hydrochloric acid purchased from Aldrich Co.18 2-acetyl-1,3-indandione, 2-benzoyl-1,3-indandione ligands, and [Ln(aind)3(H2O)2], [Ln(bind)3(H2O)2] precursor complexes were synthesized according to the procedures as reported in the literature.[4,11]

Summary

Introduction

2-acyl-1,3-indandiones (acind) compounds have been frequently used as precursor’s molecules for the synthesis of novel compounds exhibiting biological activities and spectroscopic properties.[1,2,3] They are well known for their. Lanthanide diketonate complexes containing heterobiaryl ligands have been the subject of extensive studies in the literature ranging from synthesis, characterization, and their photoluminescent properties to sensor applications.[14,15,16,17] the great coordinating ability of bidentate 1,10-phenanthroline and 4,7-dimethyl1,10-phenanthroline ligands through the two nitrogen atoms to the Ln3+ ions, up to now, to our knowledge, no work has been reported on luminescent properties of complexes containing indandionate and heterobiaryl as ancillary ligands. Optical properties have been investigated on the basis of experimental intensity parameters

Materials and methods

Conclusions