The effect of 4-halogenobenzoate ligands on luminescent and structural properties of lanthanide complexes: experimental and theoretical approaches

Author(s)

Monteiro, Jorge H. S. K. ^[1] ; de Bettencourt-Dias, Ana ^[2] ; Mazali, Italo O. ^[1] ; Sigoli, Fernando A. ^[1]

Affiliation

^[1] Univ Estadual Campinas, Dept Inorgan Chem, Inst Chem, Campinas, SP - Brazil

^[2] Univ Nevada, Dept Chem, Reno, NV 89557 - USA

• Document type: Journal article
• Source: NEW JOURNAL OF CHEMISTRY; v. 39, n. 3, p. 1883-1891, 2015.
• Web of Science Citations: 18

Abstract

The ligands 4-fluorobenzoate (4-fba), 4-chlorobenzoate (4-cba), 4-bromobenzoate (4-bba) and 4-iodobenzoate (4-iba) were chosen in order to synthesize europium(III), gadolinium(III) and terbium(III) complexes and compare the effect of halogens on their physical chemistry and luminescent properties. The homobimetallic complex {[}Eu(4-iba)(3)(H2O)(dmf)](2) crystallizes in the monoclinic P2(1)/c space group with unit cell parameters a = 8.3987(9) angstrom, b = 25.314(3) angstrom, c = 14.1255(17) angstrom, and beta = 105.347(2)degrees 1. FTIR spectroscopy indicates that the bidentate bridging mode of the carboxylato ligand was present in all complexes while bidentate chelate and a mixture of bidentate bridging and chelate modes were also found. According to emission spectra profiles and the Judd-Ofelt parameters the halogen of ligand molecules modifies the chemical environment symmetry around the europium(III) ion in their respective complexes. The complexes {[}Eu(4-fba)(3)(H2O)(2)] and {[}Eu(4-iba)(3)(H2O)(2)] have the highest symmetry around the europium(III) while the complexes {[}Eu(4-cba)(3)]center dot 2H(2)O, {[}Eu(4-bba)(3)]center dot 5/2H(2)O and {[}Eu(4-iba)(3)(H2O)(dmf)](2) have the lowest. The different halogens at the para position do not change the covalence degree of Eu-O bonds significantly, however they play a role in the ligand to metal charge transfer energies. The highest non-radiative energy transfer rates from ligand to europium(III) were found for the complexes {[}Eu(4-cba)(3)]center dot 2H(2)O and {[}Eu(4-bba)(3)]center dot 5/2H(2)O. (AU)

• FAPESP's process: 08/53868-0 - Synthesis and chacterization of novel materials strategically structured and organized to be applied in analytical and photonic devices
• Grantee: Lauro Tatsuo Kubota
• Support type: Research Projects - Thematic Grants
• FAPESP's process: 09/54066-7 - Multi-User Laboratory for Advanced Optical Spectroscopy
• Grantee: Yoshitaka Gushikem
• Support type: Multi-user Equipment Program