Ning Ren

Lanthanide complexes with 3,4,5-triethoxybenzoic acid and 1,10-phenanthroline: synthesis, crystal structures, thermal decomposition mechanism and phase transformation kinetics

Three novel lanthanide complexes [Ln(3,4,5-TEOBA)3phen]2 (Ln = La(1), Pr(2), Eu(3); 3,4,5-TEOBA = 3,4,5-triethoxybenzoate; phen = 1,10-phenanthroline) were synthesized and characterized. Single crystal X-ray diffraction showed that the complexes are isostructural. Each complex has two center metals and each center is coordinated with seven oxygen atoms and two nitrogen atoms to form a distorted monocapped square antiprism geometry. A carboxylic group adopts three modes coordinated with center metal: bidentate chelate, bridging bidentate and bridging tridentate. The luminescence of complex 3 showed the characteristic emission of Eu3+ (5D0 → 7F0–3). The thermal decomposition mechanism of title complexes was studied by TG/DSC-FTIR technology. The heat capacities of complexes 1–3 were measured by DSC over the temperature range from 263.15 to 463.15 K. In the temperature range from 280 to 350 K, there was a solid-to-solid phase transition for each complex, which was further evidenced by four thermal circulating processes with the scanning rate of 10 K min−1. A study of the phase transition of four thermal circulating processes under different heating rates revealed a fine linear relationship between the activation energy (E) and the percent conversion (α). In the heating and cooling runs, supercooling was observed and the endothermic and exothermic enthalpies behaved differently.

A series of lanthanide complexes with different N-donor ligands: synthesis, structures, thermal properties and luminescence behaviors

Four novel lanthanide complexes, [Ln(2,4-DClBA)3(terpy)(H2O)]·H2O (Ln = Eu(1), Tb(2)); [Ln(2,4-DClBA)3(5,5′-DM-2,2′-bipy)(C2H5OH)]2 (Ln = Eu(3), Tb(4); 2,4-DClBA: 2,4-dichlorobenzoate; terpy: 2,2′:6′,2′′-terpyridine; 5,5′-DM-2,2′-bipy: 5,5′-dimethyl-2,2′-bipyridine) have been synthesized via a conventional solution method at room temperature and structurally characterized by single crystal and powder X-ray diffraction. Complexes 1–2 exhibit mononuclear lanthanide architectures and each Ln3+ ion is nine-coordinated adopting a distorted monocapped square antiprismatic molecular geometry, while complexes 3–4 exhibit binuclear lanthanide architectures in which each Ln3+ ion is eight-coordinated adopting a distorted square antiprismatic molecular geometry. Mononuclear complexes 1–2 are stitched together via Cl–π and hydrogen bonding interactions to form the 1D, 2D, 3D supramolecular structures. While complexes 3–4 are packed together through Cl–Cl, π–π, and hydrogen bonding interactions to form 1D, 2D supramolecular structures. Luminescence investigation reveals that complexes 1, 3 and 2, 4 display strong red and green emission respectively, showing that terpy and 5,5′-DM-2,2′-bipy can act as sensitizing chromophores, but the former is more effective. The IR, TG-DTG, and the heat capacities of complexes 1–4 were also measured.

Lanthanide complexes with 3-bromine-4-methyl benzoic acid and 1,10-phenanthroline

The crystal structures of complexes [Tb(3-Br-4-MBA)3phen]2(1), [Ho(3-Br-4-MBA)3(phen)H2O]2(2) and [Er(3-Br-4-MBA)3(phen)H2O]2(3) (3-Br-4-MBA=3-bromine-4-methylbenzoate, phen=1,10-phenanthroline) have been solved by single-crystal X-ray diffraction methods. All obtained products were examined and characterized by elemental analysis, molar conductivity, IR, UV and XRD techniques. The thermogravimetric analysis of 1 to 3 was studied, indicating that the decomposition processes of 2 and 3 are different from 1. The mass loss of the first step for 2 and 3 is attributed to the H2O molecules. The three-dimensional IR accumulation spectra of gaseous of 1 to 3 were also recorded. Complex 1 emits strong and bright green fluorescence under UV light at the room temperature. The bacteriostatic activities of the three complexes against bacteria, such as Escherichia coli and Staphylococcus aureus, and fungus (Candida albicans) were tested.

Crystal structures, thermal behavior and biological activities of lanthanide compounds with 2,4-dichlorobenzoic acid and 1,10-phenanthroline

Five new binuclear lanthanide compounds [Ln(2,4-DClBA)3phen]2 (Ln = Pr(1), Eu(2), Tb(3), Ho(4) and Er(5); 2,4-DClBA = 2,4-dichlorobenzoate; phen = 1,10-phenanthroline) have been synthesized and structurally characterized by X-ray crystallography. And all of them were carefully investigated by elemental analysis, molar conductance, IR, UV and TG/DSC-FTIR technology. Single-crystal X-ray diffraction studies revealed that compounds 1–5 were binuclear molecules with an inversion center and the Ln3+ ions contained two kinds of coordination environment that was a distorted monocapped square-antiprism in the compounds 1–2, and a distorted square-antiprism geometry in the compounds 3–5. The 3D surface graphs for the FTIR spectra of gaseous products for the compounds 1–5 were recorded using simultaneous TG/DSC-FTIR technique which is intended to further analysis of the thermal decomposition processes. Hence the gaseous products were identified by the solved single IR spectra obtained at different temperatures from the 3D surface graphs. Furthermore, the Eu(III) and Tb(III) ternary compounds exhibited intense luminescence under the radiation of UV light. And the results for antimicrobial test show that these compounds exhibit good bacteriostatic activity against Staphylococcus aureus, and better antimicrobial activity against Escherichia coli and Candida albicans.

Synthesis, Spectroscopic, Thermochemical Properties of Lanthanide Complexes with 3,4-Diethoxybenzoic Acid and 1,10-Phenanthroline

Three novel lanthanide complexes [Ln(3,4-DEOBA)3phen]2[Ln=Eu(1), Tb(2), Dy(3); 3,4-DEOBA=3,4- diethoxybenzoate; phen=1,10-phenanthroline] were synthesized and characterized by elemental analysis, molar conductance, X-ray diffraction and infrared spectrometry. The luminescence spectra of complexes 1 and 2 show the characteristic emission of Eu3+ ion(5D0→7F0—3) and Tb3+ ion(5D4→7F6—3). The thermal decomposition mechanism of the title complexes and the analysis of the evolved gases were investigated by thermogravimetry/differential scanning calorimetry-Fourier transform infrared(TG/DSC-FTIR) technology. The results indicate the complexes are thermally stable. In the thermal decomposition of the complexes, phen molecules lost firstly, and then 3,4-DEOBA ligand decomposed into H2O, CO2 and other gaseous molecules. Besides, several gaseous organic fragments were also detected. The heat capacities of complexes 1―3 were measured by DSC in a temperature range of 263.15―340.15 K. Based on the fitted polynomial and thermodynamic equations, the smoothed heat capacities and thermodynamic functions of the three complexes were calculated. The study on biological activity showed that the complexes exhibited good antibacterial activity against Candida albicans, Staphylococcus aureus and Escherichia coli.

Crystal structures and thermal decomposition kinetics of lanthanide complexes with 3,4,5-trimethoxybenzoic acid and 1,10-phenanthroline

A series of lanthanide complexes with the 3,4,5-trimethoxybenzoic acid (3,4,5-tmoba) and 1,10-phenanthroline(phen), [Ln(3,4,5-tmoba)3phen]2(Ln = Pr(1), Nd (2) and Ho(3)), have been synthesized and characterized by a series of techniques including elemental analysis, IR spectra, X-ray crystallography and TG/DSC-FTIR technology. The three complexes have two kinds of coordination modes, in which the Pr3+ and Nd3+ cations are nine-coordinated and the Ho3+ cation is eight-coordinated. The three-dimensional IR accumulation spectra of gaseous products for complexes 1–3 were analyzed and the gaseous products were identified by the typical IR spectra obtained from the 3D surface graphs. Meanwhile, we obtained the activation energy E of the first steps of complexes 1–3 by the integral isoconversional non-linear (NL-INT) method and discussed the non-isothermal kinetics of complexes 1–3 using the Malek method. Finally, SB(m, n) was defined as the kinetic method of the first-step thermal decomposition. The thermodynamic parameters ΔG≠, ΔH≠ and ΔS≠ of activation at the peak temperature were also calculated.

Synthesis and crystal structure of the complex [Sm(p-MOBA)3bipy]2 · 2C2H5OH

AbstractA new binuclear complex [Sm(p-MOBA)3bipy]2 · 2C2H5OH (p-MOBA = p-methoxybenzoate, bipy = 2,2′-bipyridine) has been prepared via dissolution reaction in an ethanol/water mixed solution and characterized by elemental analysis, IR, UV, XRD and molar conductance, respectively. Its single crystal was characterized by X-ray single crystal diffraction. The crystal belongs to triclinic system, space group P

Rare earth compounds with 3-methoxybenzoic acid and terpyridine ligands: Structures, thermal and spectroscopic properties

\bar 1