Bis(2,2′-bipyridine-κ2 N,N′)tris­(nitrato-κ2 O,O′)erbium(III)

The asymmetric unit of the title compound, [Er(NO3)3(C10H8N2)2], contains one-half mol­ecule situated on a twofold rotation axis. The ErIII ion is in a tenfold coordination by six O atoms from three NO3 − anions and four N atoms from two 2,2′-bipyridine ligands in a distorted bicapped dodeca­hedral geometry. In the crystal, weak C—H⋯O hydrogen bonds hold the mol­ecules together

Speciation, Luminescence, and Alkaline Fluorescence Quenching of 4-(2-methylbutyl)aminodipicolinic acid (H2MEBADPA)

4-(2-Methylbutyl)aminodipicolinic acid (H2MEBADPA) has been synthesized and fully characterized in terms of aqueous phase protonation constants (pKa\u27s) and photophysical measurements. The pKa\u27s were determined by spectrophotometric titrations, utilizing a fully sealed titration system. Photophysical measurements consisted of room temperature fluorescence and frozen solution phosphorescence as well as quantum yield determinations at various pH, which showed that only fully deprotonated MEBADPA2– is appreciably emissive. The fluorescence of MEBADPA2– has been determined to be quenched by hydroxide and methoxide anions, most likely through base-catalyzed excited-state tautomerism or proton transfer. This quenching phenomenon has been quantitatively explored through steady-state and time-resolved fluorescence measurements. Utilizing the determined pKas and quenching constants, the fluorescent intensity of MEBADPA2– has been successfully modeled as a function of pH

Solution and solid state spectroscopy of tetrakis complexes of 2,2′-bipyridine-1,1′-dioxide with europium(III)

Previous studies on the crystal structure of a complex formed with 2,2′-bipyridine-1,1′-dioxide (bpyO2) and La(III) ions have shown the existence of an tetrakis eight coordinate complex in which the metal ion sits in a site of approximate D4 symmetry. In this paper we describe high-resolution luminescence and circularly polarized luminescence results on Eu(bpyO2)43+. The appearance of several crystal-field transitions in the emission for the Eu(III) complex are interpreted in terms of distortions from the D4 symmetry seen for the La(III) analog. Extraordinarily large absorption and emission intensities for the hypersensitive transitions of Nd(bpyO2)43+ and Eu(bpyO2)43+ are observed and discussed. Large circularly polarized luminescence is observed from Eu(bpyO2)43+ dissolved in acetonitrile following circularly polarized laser excitation. This result suggests that the complex occurs in solution as a racemic complex that does not racemize on the emission time scale

The view of the technical and computer science specialization in the survey of their students

The article presents the results of the chosen research of Institute of Technology Students of Technical and Computer Science Specialization with use of questionnaire. For the research were chosen students from the last and the first year of study so that we can define the attitude to specialization and university of students who are finishing the study but also we can define expectations of people who had just begin their studies. Collected data were analyzed with the use of SPSS programme. Keywords: motives of study, sources of information about studies, compliance with the faculty student’s interests

Perturbation of the Racemic Equilibrium between D \u3c inf\u3e 3 Lanthanide Complexes through the Addition of Sugars

The perturbation of the racemic equilibrium of the D3 complexes of lanthanide (III) ions with 2, 6-pyridinedicarboxylate by a number of sugars is studied by circularly polarized luminescence spectroscopy. Various spectroscopic probes show that the addition of the chiral sugar has no observable effect on the structure of the lanthanide complex. The dependence of the enantiomeric excess on the concentration of added sugar is shown to be linear for all of the sugars studied. This dependence is in agreement with an equilibrium model in which the optically-active lanthanide complex forms weakly bound diastereomeric outer-sphere associated species with the various sugars. No structural correlation is found between the configuration and conformation of the sugars studied and the sign of the enantiomeric excess. © 1995, American Chemical Society. All rights reserved