Phosphorus-containing Neutral Ligands Research Articles

Thermal and Luminescent Properties of Multi-Ligand Complexes of Europium(III) with Pyrazine-2-carboxylic Acid

Eu(III) compounds with pyrazine-2-carboxylic acid and nitrogen- and phosphorus-containing neutral ligands were synthesized. Using the methods of chemical elemental and thermal analysis and IR spectroscopy, the composition of the complexes and the method of coordination of carboxylate ions were established. The most thermally stable compounds have been identified. The luminescent characteristics of complex compounds have been studied. It was found that the maximum luminescence intensity is characteristic of europium(III) pyrazinate with triphenylphosphine oxide. The morphological structure and dispersion of the complexes were determined.

Spectral-Luminescent Properties of Mixed-Ligand Europium(III) Complexes with O-Methoxybenzoic Acid and Phosphorus-Containing Neutral Ligands

The spectral-luminescent properties of europium(III) complexes with o-methoxybenzoic acid and phosphorus-containing neutral ligands with an island structure and the compositions Eu(MOBA)3 · 3H2O and Eu(MOBA)3 · L, where MOBA is o-methoxybenzoic acid and L is hmpa (hexamethylphosphortriamide, tppo (triphenylphosphinoxide), and Et6pa (hexaethylphosphortriamide), are studied. It is found that the excitation energy transfer to the europium ion occurs from the levels of both o-methoxybenzoic acid and phosphorus-containing neutral ligands. The electronic absorption and luminescence excitation spectra, as well as the Stark structure of the 5D0−7Fj ( j = 0–2) electronic transitions in the luminescence spectra of mixed-ligand complexes of europium(III) o-methoxybenzoates, are analyzed. The highest luminescence intensity is demonstrated by europium(III) methoxybenzoate with triphenylphosphinoxide.

Mixed-Ligand Complex Compounds of Europium(III) with ortho-Methoxybenzoic Acid and Phosphorus-Containing Neutral Ligands

Luminescent coordination mixed-ligand compounds of europium(III) with ortho-methoxybenzoic acid and phosphorus-containing neutral ligands of the isle-like structure Eu(MOBA)3 · 3H2O and Eu(MOBA)3 · L have been synthesized. MOBA—ortho-methoxybenzoic acid, L—hmpa (hexamethylphosphotriamide), tppo (triphenylphosphinoxide), Et6pa (hexaethylphosphotriamide). Thermal properties of the complex mixed-ligand compounds of europium(III) have been investigated. It has been shown that thermolysis results in the splitting of a neutral ligand molecule proceeding within one stage along with an endothermic effect. The complex compound appeared to be stable up to 280°C. The composition and structure of the synthesized complexes have been established. Based on the IR spectroscopy data, it has been demonstrated that in ortho-methoxybenzoates of europium(III) ortho-methoxybenzoic acid is coordinated to a europium(III) ion bidentately.

Разнолигандные комплексные соединения европия (III) с o-метоксибензойной кислотой и фосфорсодержащими нейтральными лигандами

The luminescent coordination multi-ligand compounds of europium (III) with o-methoxybenzoic acid and island-containing phosphorus-containing neutral ligands of the composition Eu (MOBA) 3 • 3Н2О and Eu (MOBA) 3 • L, where MOBA is o-methoxybenzoic acid, D is hmpa (D hexamethylphosphoric triamide), tppo (triphenylphosphine oxide), Et6pa (hexaethylphosphotriamide). The composition, structure, and thermal properties of complex multi-ligand compounds of europium (III) were studied. It was shown that during thermolysis, detachment of a neutral ligand molecule occurs in one stage with an endothermic effect, complex compounds are stable up to 280 С.Based on the data of IR spectroscopy, it was found that in the europium (III) o-methoxybenzoates, the o-methoxybenzoic acid is coordinated to the europium (III) o-methoxybenzoic ion in a bidentate manner. The low luminescence intensity of multi-ligand europium (III) compounds is explained by the inefficient transfer of electronic excitation energy from o-methoxybenzoic acid and phosphorus-containing neutral ligands to the europium ion.

Спектрально-люминесцентные свойства разнолигандных комплексных соединений европия(III) c o-метоксибензойной кислотой и фосфорсодержащими нейтральными лигандами

The spectral and luminescent properties of complex compounds of europium (III) with o-methoxybenzoic acid and island-containing phosphorus-containing neutral ligands of the composition Eu (MOBA) 3 • 3Н2О and Eu (MOBA) 3 • L, where MOBA is o-methoxybenzoic acid, D is studied (hexamethylphosphoric triamide), tppo (triphenylphosphine oxide), Et6pa (hexaethylphosphotriamide). It was found that the excitation energy is transferred to the europium ion both from the levels of o-methoxybenzoic acid and from the levels of phosphorus-containing neutral ligands.The electronic absorption spectra, the luminescence excitation spectra, and the Stark structure of 5D0-7Fj (j = 0-2) electronic transitions in the luminescence spectra of mixed-ligand complex europium (III) complex o-methoxybenzoates are analyzed. Europium (III) methoxybenzoate with triphenylphosphine oxide has the highest luminescence intensity.

Spectral-Luminescent Properties of Mixed-Ligand Europium(III) Complexes with p-Methylbenzoic Acid

The spectral-luminescent properties of europium(III) complexes with p-methylbenzoic acid and nitrogen- and phosphorus-containing neutral ligands of compositions [Eu(p-MBA)3 · D]2 · xH2O and [Eu(p‑MBA)3 · 2H2O]n, where p-MBA is the anion of p-methylbenzoic acid and D is 1,10-phenanthroline (phen), 2,2' dipyridyl (dipy), triphenylphosphine oxide (tppo) (х = 0), hexamethylphosphortriamide (hmpa) (x = 1), or benzotriazole (bt) (x = 2) are studied. The electronic absorption spectra, the luminescence excitation spectra, and the Stark structure of 5D0−7Fj ( j = 0–2) electronic transitions in low-temperature luminescence spectra of complex europium(III) p-methylbenzoates are analyzed. It is found that the excitation energy transfer to europium ions occurs from the levels of both p-methylbenzoic acid and neutral ligands.

Luminescent Properties of Europium(III) Compounds with Quinolinic Acid and Phosphorus-Containing Neutral Ligands

Luminescent mixed-ligand europium(III) complexes with quinolinic acid and phosphorus-containing neutral ligands with a dimeric structure of the composition Eu2(QA)3 · 3Н2О, Eu2(QA)3 · D · 2Н2О, where QA is quinolinic acid and D is hmpa (hexamethylphosphortriamide), tppo (triphenylphosphinoxide), (hmpa), or Et6pa (hexaethylphosphortriamide), are synthesized. The thermal and spectral-luminescent properties of the synthesized complex mixed-ligand europium(III) compounds are studied. It is shown that the detachment of water and neutral ligand molecules during thermolysis occurs in two stages with endothermic effects and that the complex compounds are stable at temperatures up to 320°С. It is found by IR spectroscopy that quinolinic acid coordinates to the europium(III) ion by two carboxylate ions. The low luminescence intensity of mixed-ligand europium(III) quinolinates is explained by inefficient electronic excitation energy transfer from quinolinic acid and phosphorus-containing neutral ligands to europium ions.

Люминесцентные свойства соединений европия(III) с хинолиновой кислотой и фосфорсодержащими нейтральными лигандами

AbstractLuminescent mixed-ligand europium(III) complexes with quinolinic acid and phosphorus-containing neutral ligands with a dimeric structure of the composition Eu_2(QA)_3 · 3Н_2О, Eu_2(QA)_3 · D · 2Н_2О, where QA is quinolinic acid and D is hmpa (hexamethylphosphortriamide), tppo (triphenylphosphinoxide), (hmpa), or Et_6pa (hexaethylphosphortriamide), are synthesized. The thermal and spectral-luminescent properties of the synthesized complex mixed-ligand europium(III) compounds are studied. It is shown that the detachment of water and neutral ligand molecules during thermolysis occurs in two stages with endothermic effects and that the complex compounds are stable at temperatures up to 320°С. It is found by IR spectroscopy that quinolinic acid coordinates to the europium(III) ion by two carboxylate ions. The low luminescence intensity of mixed-ligand europium(III) quinolinates is explained by inefficient electronic excitation energy transfer from quinolinic acid and phosphorus-containing neutral ligands to europium ions.

Спектрально-люминесцентные свойства разнолигандных комплексных соединений европия(III) с n-метилбензойной кислотой

Abstract The spectral-luminescent properties of europium(III) complexes with p -methylbenzoic acid and nitrogen- and phosphorus-containing neutral ligands of compositions [Eu( p -MBA)_3 · D]_2 · x H_2O and [Eu( p ‑MBA)_3 · 2H_2O]_ n , where p -MBA is the anion of p -methylbenzoic acid and D is 1,10-phenanthroline (phen), 2,2' dipyridyl (dipy), triphenylphosphine oxide (tppo) ( х = 0), hexamethylphosphortriamide (hmpa) ( x = 1), or benzotriazole (bt) ( x = 2) are studied. The electronic absorption spectra, the luminescence excitation spectra, and the Stark structure of ^5 D _0−^7 F _ j ( j = 0–2) electronic transitions in low-temperature luminescence spectra of complex europium(III) p -methylbenzoates are analyzed. It is found that the excitation energy transfer to europium ions occurs from the levels of both p -methylbenzoic acid and neutral ligands.

The Fluorescent Properties and Electronic Structure of Nd(111) Complexes with Carboxylic Acids

Mixed-ligand neodymium(III) complexes with carboxylic acids and nitrogen- and phosphorus-containing neutral ligands, which luminesce in the near-IR region, are studied by luminescence and X-ray photoelectron spectroscopies. It is found that coordination of neutral ligands through the nitrogen donor atom leads to an increase in the electron density at the neodymium(III) ion.

Luminescent properties of europium carboxylates

Mixed-ligand europium carboxylates with nitrogen- and phosphorus-containing neutral ligands having polymer or island structure were studied by the luminescent and X-ray photoelectron spectroscopy methods. In similar groups of the compounds, the value of Stark splitting of the 7F1 – level decreased with decrease of the electron density transfer from europium ion to ligand (covalence of metal-ligand bond increases) and the relative intensity of electro-dipole 5D0 – 7F4 transition rised.

Luminescence of ytterbium(III) cinnamate compounds

The spectral luminescent characteristics of mixed-ligand compounds of ytterbium (III) with cinnamic acid, nitrogen- and phosphorus-containing neutral ligands were studied by the methods of fluorescent spectroscopy. The luminescence intensity of the obtained compounds was measured and it was found that the highest intensity of luminescence has the polymeric ytterbium(III) cinnamate.

Luminescence of neodymium(III) carboxylate complexes with different ligands

The spectral and luminescent characteristics of neodymium(III) carboxylate complexes with different nitrogen- and phosphorus-containing neutral ligands were studied and the relationship between the intensity of luminescence and the composition of the coordination sphere was established. The most intensive luminescence of neodymium(III) compounds in the IR region was observed from the complexes with toluic and cinnamic acids.

Neodimium(III) luminescence in the mixed ligand compounds with β-diketones

The luminescent spectral characteristics of neodymium(III) tris- and tetrakis-β-diketonates and β-diketonate acido complexes were investigated. The dependence between the intensity of the luminescence and the composition of the coordination sphere of the complexes was revealed. The most intense luminescence in the IR region possess the neodymium(III) compounds which are the mixed ligand complexes with β-diketones and phosphorus-containing neutral ligands.

Luminescence and magnetic properties of mixed-ligand europium trifluoroacetates

The luminescence and magnetic properties of mixed-ligand europium trifluoroacetates with nitrogen- and phosphorus-containing neutral ligands [Eu(TFA)3 · 3H2O]2 and Eu(TFA)3 · 2D · nH2O were studied (here TFA is the trifluoroacetic acid anion, and D is Phen (1,10-phenanthroline), n = 1; DMF (dimethylformamide), n = 1; or TPPO (triphenylphosphine oxide), n = 3). The molar magnetic susceptibility increased in the series of complex compounds Eu(TFA)3 · 2Phen · H2O < [Eu(TFA)3 · 3H2O]2 < Eu(TFA)3 · 2DMF · H2O < Eu(TFA)3 · 2TPPO · 3H2O. Correlations were found between the luminescent and magnetic characteristics of the complex compounds.

Luminescence of europium trifluoroacetates

The luminescence spectral characteristics of mixed-ligand europium trifluoroacetates with nitrogen- and phosphorus-containing neutral ligands were studied at different temperatures. For several trifluoroacetates, the intensity of luminescence increased with temperature. The diffuse reflectance data were analyzed, and a mechanism of thermal luminescence buildup was suggested.

The Fluorescent Properties of Heteroligand Europium Cinnamates

Heteroligand europium cinnamates with nitrogen- and phosphorus-containing neutral ligands were studied by luminescent and X-ray electron spectroscopy. A tendency toward an increase in the electron density on Eu3+ was observed when neutral ligands were coordinated by donor nitrogen atoms. The Δν0, ΔF1, and I(F0)/I(F2) values monotonically decreased as the donor properties of neutral ligands increased because of strengthening of the interaction of Eu3+ with the ligands.

Photochemical properties of mixed-ligand complexes europium carboxylates

The photochemical behavior of mixed-ligand complexes of europium carboxylates with nitrogen-and phosphorus-containing neutral ligands of island and dimer types, Eu(L)3 · xD · nH2O and [Eu(L)3 · xD]2 · nH2O (L is the trifluoroacetate, toluate, or cinnamate anion), was studied. During UV irradiation of the complexes of europium carboxylates with 1,10-phenanthroline and 2,2′-dipyridyl, a luminescence buildup was observed. EPR measurements demonstrated that the observed buildup of luminescence from europium occurs in parallel with the increase of the concentration of radical anions formed from neutral ligands.

Fluorescence properties of mixed-ligand europium carboxylates

Mixed-ligand binuclear and mononuclear europium carboxylate complexes with nitrogen-and phosphorus-containing neutral ligands have been studied by luminescence and X-ray photoelectron spectroscopy. The coordination of neutral ligands through the nitrogen donor atom leads to an increase in electron density at the Eu3+ atom. In groups of carboxylates of the same type, the coordination of neutral donor ligands leads to an increase in the relative intensity of the 5D0-7F4 electric dipole transition. Analysis of the luminescence excitation spectra points to the presence of two excitation energy transfer channels for mixed-ligand europium trifluoroacetate and toluate complexes and of one channel for europium cinnamate complexes with neutral ligands.