Synthesis, crystal structure, luminescence and thermal decomposition kinetics of Eu(III) complex with 2,4-dichlorobenzoic acid and 2,2′-bipyridine

The complex of [Eu(2,4-DClBA)3(bipy)]2 (2,4-DClBA = 2,4-dichlorobenzoate; bipy = 2,2′-bipyridine) was obtained and characterized by elemental analysis, IR spectra, UV spectra, luminescence spectra, 1H NMR spectra, single crystal X-ray diffraction and TG–DTG techniques. Two Eu3+ ions are connected by four carboxylate groups through bridging bidentate and bidentate chelating-bridging mode. The coordination number of europium ion is nine. The thermal decomposition behavior of the title complex under a static air atmosphere can be discussed by TG–DTG, SEM and IR techniques. The non-isothermal kinetics was investigated by using double equal-double steps method and Starink method. The mechanism function of the first decomposition step was determined. Meanwhile, the thermodynamic parameters (ΔH≠, ΔG≠ and ΔS≠) and kinetic parameters (activation energy E and the pre-exponential factor A) were also calculated.

Graphical abstractThe complex of [Eu(2,4-DClBA)3(bipy)]2 (2,4-DClBA = 2,4-dichlorobenzoate; bipy = 2,2′-bipyridine) was obtained and characterized by elemental analysis, IR spectra, UV spectra, luminescence spectra, 1H NMR spectra, single crystal X-ray diffraction and TG–DTG techniques. The crystal is monoclinic with space group P2(1)/n. The unit cell parameters are: a = 11.9467(19) Å, b = 17.274(3) Å, c = 16.955(3) Å, α = 90°, β = 106.600(3)°, γ = 90°. Two Eu3+ ions are connected by four carboxylic groups through bridging bidentate and bidentate chelating-bridging mode. The coordination number of europium ion is nine. The thermal decomposition behavior of the title complex under a static air atmosphere can be discussed by TG–DTG, SEM and IR techniques. The non-isothermal kinetics was investigated by using double equal-double steps method and Starink method. The mechanism function of the first decomposition step was determined. Meanwhile, the thermodynamic parameters (ΔH≠, ΔG≠ and ΔS≠) and kinetic parameters (activation energy E and the pre-exponential factor A) were also calculated.Figure optionsDownload full-size imageDownload as PowerPoint slide