1,721,127 research outputs found
Synthesis of 8-hydroxyquinoline functionalised DO3A ligand and Eu(III) and Er(III) complexes: Luminescence properties
No full textThe synthesis of a new DO3A-based macrocyclic ligand bearing a 8-hydroxyquinoline residue together with the preparation of its Eu(3+) and Er(3+) neutral complexes are described. In a previous report IF. Rizzo, A. Papagni, F. Meinardi, R. Tubino, M. Ottonelli, G.F Musso, G. Dellepiane. Synth. Met. 147 (2004) 1431, we have shown that lanthanide complexes display very high stability combined with a good luminescence in aqueous solution under UV radiation, which indicate an energy transfer process from the excited 8-hydroxyquinoline moiety to the metal. In this work, we correlate the ability to transfer the energy from the sensitizer to lanthanide ion with pH behaviour of the antenna. Furthermore, the variation of pH in Eu(3+) complex supports the hypothesis of presence of charge-transfer transitions. The good Solubility and sensitized emission in different solvents (organic and water) are very important aspects for their technologic applications as luminescent probes or NIR-emitting devices. (C) 2009 Elsevier B.V. All rights reserved
Environment effects on the CO vibrational shifts in the lanthanide complex: a quantum chemical study
No full textSemiempirical calculations of the collective optical excitations in substituted oligodiacetylenes
No full textEffects Evolution of the bipolaronic structure from one- to two-dimensional π-system models
No full textLong neutral and doubly charged oligodiacetylenes (with a maximum of 30 repeat units) as well as some of their aggregates have been studied in a semiempirical framework. By analyzing the plots of the one-electron ground-state density matrices, we have shown that the 12-units long oligomer is the borderline between two different behaviors of the electronic structure of the isolated charged systems. For oligomers shorter than this limit the bipolaronic structure is the dominant one, while for larger oligomers the polaron-pair structure is preferred. The major conclusion of this work concerns the effects of the interchain interactions in bipolaron systems, which are usually neglected in theoretical works. It is predicted that as a consequence of the latter in the bulk system a bipolaron generated on a single polymer chain will soon split into two polarons on adjacent chains. © 2008 American Chemical Society
Semiempirical calculations of the collective optical excitations in substituted oligodiacetylenes
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