Deciphering Three Beneficial Effects of 2,2 '-Bipyridine-N,N '-Dioxide on the Luminescence Sensitization of Lanthanide(III) Hexafluoroacetylacetonate Ternary Complexes

Lanthanide hexafluoroacetylacetonate ternary complexes with 2,2'-bipyridine-N,N'-dioxide, [Ln(hfa)3(bpyO2)], were synthesized for Ln = Eu, Gd, Tb, and Lu and fully characterized by elemental, thermal, and mass-spectrometric analyses. The X-ray crystal structure of [Eu(hfa) 3(bpyO2)].0.5C6H6 reveals an octa-coordinate metal ion lying in a severely distorted trigonal dodecahedron geometry; the Eu-O distances lie in the range 2.36-2.44 Å with no significant difference between hfa- and bpyO2. A detailed comparative photophysical investigation has been carried out to determine the exact influence of the introduction of bpyO2 in the inner coordination sphere of the metal ion in replacement of the two water molecules in [Ln(hfa)3(H2O)2]. While this replacement is detrimental for Tb, it leads to a 15-fold increase in the overall quantum yield for Eu. This large improvement originates from (i) a better sensitization efficiency, the ancillary ligand being responsible for 3/4 of the energy transfer, (ii) elimination of nonradiative deactivation pathways through harmonics of O-H vibrations, and (iii) reduction in the radiative lifetime. The latter influence is rarely documented, but it accounts here for ã25% increase in the intrinsic quantum yield, so that more attention should be given to this parameter when designing highly luminescent lanthanide complexes. © 2011 American Chemical Society

A cultura escolar em conflito: ensino técnico e matemática moderna em Portugal

Disponível em: http://www2.pucpr.br/reol/pb/index.php/dialogo?dd1=16276&dd99=view&dd98=pbO artigo estuda as transformações exigidas às escolas do ensino profissional português durante a reforma da matemática moderna que ocorrem a partir de finais dos anos 1960. Em primeiro lugar, traça um quadro das normas associadas às escolas técnicas portuguesas antes da reforma, recorrendo à legislação fundadora, aos manuais e a artigos de opinião de professores. Em segundo, detalha o debate que antecipou a introdução da reforma recorrendo a artigos e aopiniões expressas durante os cursos preparatórios, onde são notórias as pressões para mudanças na cultura escolar, especialmente nas suas representações, suscitadas pela nova matemática. Finalmente, observar-se como se materializou a reforma nos livros de texto da experiência

On Strategic Orientation of Student Educational Activity

The article deals with the research in the field of the strategic orientation of educational activities in higher education. The necessity of applying a student-centered approach in such studies is revealed. It is noted that the factors influencing the strategic orientation of the student educational activity relate either to the space of ‘due’ or to the space of ‘being’. The invariant core of the graduate competence model belongs to the target-oriented space of the ‘due’. It includes 12 clusters of competencies and describes the normative context of the strategic orientation of the student educational activity. The personal context of this orientation is formed on the basis of a va riety of students’ goals in the space of ‘being’. It is characterized by student’s ideas about the relative importance of the qualities that one will need in future after graduation. The technique of establishing a hierarchy of combined graduate qualities is described. This hierarchy is determined by the student’s goals, which can be reflected through the subjective significance of the considered qualities for one. The analysis of results showed that the gender of the student and the character of his future labour activity significantly influence one’s strategic orientation

Reactive Chemical Vapor Deposition Method as New Approach for Obtaining Electroluminescent Thin Film Materials

The new reactive chemical vapor deposition (RCVD) method has been proposed for thin film deposition of luminescent nonvolatile lanthanide aromatic carboxylates. This method is based on metathesis reaction between the vapors of volatile lanthanide dipivaloylmethanate (Ln(dpm)3) and carboxylic acid (HCarb orH2Carb′) and was successfully used in case of HCarb. Advantages of the method were demonstrated on example of terbium benzoate (Tb(bz)3) and o-phenoxybenzoate thin films, and Tb(bz)3 thin films were successfully examined in the OLED with the following structure glass/ITO/PEDOT:PSS/TPD/Tb(bz)3/Ca/Al. Electroluminescence spectra of Tb(bz)3 showed only typical luminescent bands, originated from transitions of the terbium ion. Method peculiarities for deposition of compounds of dibasic acids H2Carb′ are established on example of terbium and europium terephtalates and europium 2,6-naphtalenedicarboxylate

Dimeric lanthanide hexafluoroacetylacetonate adducts with 4-cyanopyridine-N-oxide

A series of new dimeric complexes with composition [Ln2(hfa)6(4-cpyNO)3] (2:3 adduct, Ln = SmIII–DyIII, TmIII) were synthesized and fully characterized. X-ray diffraction data of [Tb2(hfa)6(4-cpyNO)3]·CHCl3 confirmed the dimeric structure; Tb ions are nine-coordinated by six O atoms from three hfa− ligands and three O atoms from three bridging 4-cpyNO molecules. The photophysical properties (absolute quantum yields and luminescence lifetimes) of the EuIII and TbIII 2:3 adducts are presented and compared with those of the 2:2 adducts

Dimeric Complexes of Lanthanide(III) Hexafluoroacetylacetonates with 4-Cyanopyridine N-Oxide: Syn thesis, Crystal Structure, Magnetic and Photoluminescent Properties

A series of new mixed-ligand lanthanide complexes [Ln(hfa)3(4-cpyNO)]2 (Ln = SmIII-HoIII and TmIII; hfa- = hexafluoroacetylacetonate; 4-cpyNO = 4-cyanopyridine N-oxide) have been synthesised by treating the corresponding lanthanide hexafluoroacetylacetonates with 4-cpyNO (molar ratio 1:1) in chloroform. Single-crystal X-ray analysis revealed that [Tb(hfa)3(4-cpyNO)]2 and [Ho(hfa)3(4-cpyNO)]2 are isostructural and are comprised of two types of symmetrically independent dimetallic molecules. Within a dimer, the eightfold-coordinated metal atoms are bridged by two 4-cpyNO ligands through the oxygen atoms of the N-oxide groups. The magnetic susceptibility data for the GdIII and TbIII complexes indicate the presence of weak antiferromagnetic interactions within the dimetallic Ln2O2 units. The thermal stability of the [Ln(hfa)3(4-cpyNO)]2 adducts was studied by thermogravimetric analysis and their volatility estimated from sublimation experiments under reduced pressure. The photoluminescent properties were measured for solid samples upon excitation at 330-360 nm. The mixed-ligand complexes of SmIII, EuIII, TbIII, DyIII and TmIII exhibit metal-centred luminescence in the entire visible spectral range with characteristic pink, red, green, yellow and blue emission, respectively. The introduction of ancillary 4-cpyNO molecules into the coordination sphere of the lanthanide(III) ions was found to significantly affect their luminescence quantum yields. [Eu(hfa)3(4-cpyNO)]2 thin films on quartz substrates were obtained by the vacuum evaporation technique and their photoluminescent properties were found to be enhanced when compared with those of the bulk samples. This suggests that these dimers could be good candidates for the fabrication of emitting layers for light-emitting diodes. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006

Role of the Ancillary Ligand N,N-Dimethylaminoethanol in the Sensitization of EuIII and TbIII Luminescence in Dimeric β-Diketonates

Two types of dimeric complexes [Ln2(hfa)6(í2-O(CH2)2NHMe2)2] and [Ln(thd)2(í2,è2-O(CH2)2NMe2)]2 (Ln ) YIII, EuIII, GdIII, TbIII, TmIII, LuIII; hfa- ) hexafluoroacetylacetonato, thd- ) dipivaloylmethanato) are obtained by reacting [Ln(hfa)3(H2O)2] and [Ln(thd)3], respectively, with N,N-dimethylaminoethanol in toluene and are fully characterized. X-ray single crystal analysis performed for the TbIII compounds confirms their dimeric structure. The coordination mode of N,N-dimethylaminoethanol depends on the nature of the â-diketonate. In [Tb2(hfa)6(í2-O(CH2)2NHMe2)2], eight-coordinate TbIII ions adopt distorted square antiprismatic coordination environments and are O-bridged by two zwitterionic N,N-dimethylaminoethanol ligands with a Tb1âââTb2 separation of 3.684(1) Å. In [Tb(thd)2(í2,è2-O(CH2)2NMe2)]2, the N,N-dimethylaminoethanol acts as chelating-bridging O,N-donor anion and the TbIII ions are seven-coordinate; the Tb1âââTb1A separation amounts to 3.735(2) Å within centrosymmetric dimers. The dimeric complexes are thermally stable up to 180 °C, as shown by thermogravimetric analysis, and their volatility is sufficient for quantitative sublimation under reduced pressure. The EuIII and TbIII dimers display metal-centered luminescence, particularly [Eu2(hfa)6(O(CH2)2NHMe2)2] (quantum yield QLn L ) 58%) and [Tb(thd)2(O(CH2)2NMe2)]2 (32%). Consideration of energy migration paths within the dimers, based on the study of both pure and EuIII- or TbIII-doped (0.01-0.1 mol %) LuIII analogues, leads to the conclusion that both the â-diketone and N,N-dimethylaminoethanol ligands contribute significantly to the sensitization process of the EuIII luminescence. The ancillary ligand increases considerably the luminescence of [Eu2(hfa)6(O(CH2)2NHMe2)2], compared to [Ln(hfa)3(H2O)2], through the formation of intra-ligand states while it is detrimental to TbIII luminescence in both â-diketonates. Thin films of the most luminescent compound [Eu2(hfa)6(O(CH2)2NHMe2)2] obtained by vacuum sublimation display photophysical properties analogous to those of the solid-state sample, thus opening perspectives for applications in electroluminescent devices

Lanthanide 9-anthracenate: solution processable emitters for efficient purely NIR emitting host-free OLEDs

Searching for new NIR emitting materials, lanthanide 9-anthracenates Ln(ant)3 were synthesized and thoroughly characterized. Ytterbium 9-anthracenate Yb(ant)3, that demonstrated the highest NIR luminescence efficiency, was successfully used as an emission layer of a host-free OLED and its electroluminescence quantum efficiency, corresponding to the sole band at 1000 nm, reached 0.21%. This performance could be achieved due to the high quantum yield of Yb(ant)3, which reached 1.5% and was increased up to 2.5% by partial Yb3+ substitution with Lu3+, as well as its high electron mobility due to the extended stacking in its crystal structure. The first gadolinium-based PHOLED was prepared based on Gd(ant)3

Профессиональные факторы и роль индивидуальной восприимчивости к развитию и течению бронхолегочных заболеваний

Over the past decades, the world has seen an increase in occupational lung diseases, the leaders being asthma and chronic obstructive pulmonary disease (COPD). The article presents the results of 5-year observation of food industry workers. Clinical functional and molecular genetic studies have been carried out to identify the frequency and severity of asthma and COPD along with the individual predisposition to pulmonary conditions.Methods. 76 people of both sexes with the average age of 43.5 ± 3.6 years were examined on an outpatient basis. All subjects had daily contact with toxic and allergenic aerosols and organo-mineral dust. The respiratory function and the presence of bronchial hyperresponsiveness to occupational factors was assessed by spirography and peak flowmetry in response to exposure and elimination of industrial aerosols. Immunological and molecular genetic tests were performed: identification of hyposecretory alleles of the α1 -АТ gene, determination of polymorphisms of the GSTM1 and GSTT1 genes, immunoglobulin levels (IgE, IgM, IgG) and cytokine status (IL-4, -6, -8; TNF-α).Results. During the 5-year follow-up period, there was a significant increase in the number of employees with severe respiratory symptoms – 36.8% (95% CI – 21.2–36.8; p < 0.05) and a statistically significant decrease in the respiratory function (p < 0.001). Progressive decrease in the respiratory function in healthy individuals and the appearance of new and more severe cases of asthma and COPD were registered primarily among workers with hyposecretory alleles of the α1 -АТ gene and/or zero alleles of the glutathioneS-transferase genes (GSTM1 and GSTT1) in combination with abnormal cytokine status.Conclusion. Individual risk factors for the development of asthma and COPD in individuals working in contact with toxic and allergenic aerosols and organo-mineral dust are hyposecretory PiMZ variant of the α1 -АТ gene and deletions in the glutathione-S-transferase genes (GSTM1 0/0 and GSTT1 0/0) in combination with abnormal cytokine status. Long-term research results suggest the prognostic value of assessing individual sensitivity to industrial aerosols and the development of bronchopulmonary pathology.За последние десятилетия в мире отмечен рост профессиональных легочных заболеваний, среди которых ведущее место занимают бронхиальная астма (БА) и хроническая обструктивная болезнь легких (ХОБЛ). В статье представлены результаты 5-летнего наблюдения работников пищевой промышленности. Проведены клинико-функциональные и молекулярно-генетические исследования, при помощи которых выявлены частота и степень выраженности БА и ХОБЛ с определением индивидуальной предрасположенности к развитию легочной патологии.Материалы и методы. В амбулаторных условиях обследованы мужчины и женщины (n = 76; средний возраст – 43,5 ± 3,6 года), осуществлявшие повседневный контакт с токсикоаллергенными аэрозолями и пылью органоминерального состава. Проводилась оценка состояния функции внешнего дыхания (ФВД) и наличия гиперреактивности бронхов к профессиональным факторам методом спирографии и пикфлоуметрии в динамике экспозиции и элиминации производственных аэрозолей. Проведены иммунологические и молекулярно-генетические исследования – выявление гипосекреторных аллелей гена α1 -АТ, определение полиморфизмов генов GSTМ1 и GSTТ1, определение иммуноглобулинов (Ig)-E, -M, -G и цитокинового статуса (уровень интерлейкинов (IL)-4, -6, -8; фактора некроза опухоли-α).Результаты. За период 5-летнего наблюдения отмечен значимый рост (36,8 %) числа лиц с выраженными респираторными симптомами (95%-ный доверительный интервал – 21,2–36,8) и статистически достоверным снижением показателей вентиляционной функции легких (p < 0,05; р < 0,001). Прогрессирующее снижение показателей ФВД у практически здоровых лиц и появление новых случаев БА и ХОБЛ с ухудшением течения регистрировались в первую очередь среди лиц с гипосекреторными аллелями гена α1 -АТ и / или нулевыми аллелями генов глутатион-S-трансферазы (GSTM1 и GSTT1) в сочетании с нарушениями цитокинового статуса.Заключение. Индивидуальными факторами риска развития БА и ХОБЛ у лиц, работающих в контакте с токсикоаллергенными аэрозолями и органоминеральной пылью, являются наличие гипосекреторного PiMZ варианта гена α1 -АТ и делеция генов глутатион-S-трансферазы (GSTМ1 0/0 и GSTТ1 0/0) с нарушениями цитокинового статуса. По данным отдаленных результатов исследований указывается на прогностическое значение оценки индивидуальной чувствительности к производственным аэрозолям и развитию бронхолегочной патологии