Effect of 4f-shell excitation of Eu(fod)3 on its complex formation with alicyclic ketones

The complex formation of alicyclic ketones, viz., camphor, cyclohexanone, menthone, and cytisine, with the Eu(fod)₃ chelate (fod is 7,7-dimethyl-1,1,1,2,2,3,3-heptafluorooctane-4,5-dione) in the ground and excited states was studied by chemiluminescence and kinetic luminescence spectroscopy, respectively. The stability constants and thermodynamic parameters of complex formation were determined. An increase in the stability of the electron-excited complexes [Eu(fod)₃*·Ketone] is explained by the enhancement of the acceptor ability of the Eu³⁺ chelate due to an increase in the fraction of the covalent component caused by the involvement of 4f-orbitals. The results obtained give direct evidence for the effect of the 4f-shell excitation of Eu(fod)₃ on complex formation due to the involvement of f-electrons in the chemical bonds.     

NMR位移试剂Eu(fod)~4^-对锍盐^1H和^1^3C NMR的影响

合成了八种新的四氟硼酸二甲基苯基锍，用元素分析和核磁共振对其结构进行了表征。研究了以CDCl~3为溶剂，NMR位移试剂Eu(fod)~4^-对所合成锍盐的^1H和^1^3C NMR的影响。结果表明，Eu(fod)~4^-是一个对锍盐非常有效的位移试剂，且Eu(fod)~4^-对二甲基苯基锍盐之甲基的^1H和^1^3C NMR的位移呈线性关系。     

Mechanically induced chemiluminescence in the dispiro(adamantane-1,2-dioxetane)—Eu(fod)3 system

Luminescence accompanying an impact mechanical treatment of solid particles of the complex of Eu(fod)₃ (fod is 1,1,1,2,2,3,3-heptafluoro-7,7-dimethyloctane-4,6-dione) with dispiro(adamantane-1,2-dioxetane) (1) was discovered and studied. The luminescence has a complex structure, and its spectrum belongs to the excited Eu^III ions. The emission of light is observed only in a mechanical mixture of the Eu(fod)₃ with dioxetane1 and in their cocrystallized form, but not in the case of the components taken separately. The mechanism by which the impacts cause the luminescence is considered. It was shown that the luminescence is not triboluminescence, but is chemiluminescence induced by the decomposition of compound1.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 5, pp. 1159–1162, May, 1996.     

Thermal quenching of photoluminescence of Eu3+ ions in an Eu(fod)3 complex

We have studied the photoluminescence (PL) spectra of Eu³⁺ ions in the complex Eu(fod)₃ (fod = 6,6,7,7,8,8,8-heptafluoro-2,2-dimethyl-3,5-octadione) and also in polymers doped with Eu(fod)₃ with the help of supercritical carbon dioxide. We have established that in the temperature range 20°C–100°C, we observe thermal quenching of the photoluminescence of Eu³⁺ ions, and this quenching is most efficient in polycrystalline Eu(fod)₃ powder and Eu(fod)₃-doped polypropylene. __________ Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 73, No. 3, pp. 315–319, May–June, 2006.     

Effect of the external medium on the spectral characteristics of polypropylene films doped with Eu(fod)<Subscript>3</Subscript> molecules

We have studied the effect of external factors (humidity, pressure, temperature) on the stability of the organometallic compound Eu(fod)3 (fod = 6,6,7,7,8,8,8-heptafluoro-2,2-dimethyl-3,5-octadione) impregnated into polypropylene (PP) using supercritical CO₂. We have established that under the influence of external conditions, there is a decrease in the integrated intensity of the absorption band for the Eu(fod)₃ molecule and the photoluminescence (PL) of Eu³⁺ ions as a function of the properties of the medium, and in the presence of water molecules the shape of the bands for these spectra changes. We propose a physical model explaining the behavior of the absorption and photoluminescence spectra when the polypropylene films are stored under different conditions. __________ Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 74, No. 1, pp. 42–47, January–February, 2007.     

Photosensitivity and thermosensitivity of polymers doped with Eu(fod)<Subscript>3</Subscript> molecules

We have studied the photoluminescence (PL) spectra of Eu³⁺ ions and the decay kinetics for the photoluminescence intensity on exposure to temperature and UV radiation in polypropylene and oligo(urethane methacrylate) (OUM) doped with Eu(fod)₃ molecules (fod = 6,6,7,7,8,8,8-heptafluoro-2,2-dimethyl-3,5-octadione) by soaking in a supercritical CO₂ solution. We have established that the decay kinetics for the photoluminescence intensity on exposure to UV radiation depends on the temperature of the sample and the concentration of the dopant in it. Based on studies of the spectral characteristics of doped OUM samples, we suggest that this material can be used as a two-color luminescent temperature sensor. Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 76, No. 1, pp. 104-111, January-February, 2009.