Luminescent lanthanide mixed N-phthaloylglycinate and terephthalate coordination polymers: Structural and optical properties.

A new class of lanthanide mixed-carboxylate ligands compounds with formula {[Ln (phthgly) (bdc)(H O) ]·(H O) } , labelled as Ln : Eu (1) and Gd (2) coordination polymers (CP) were synthesized under mild reaction conditions between lanthanide nitrate salts and a solution of N-phthaloylglycine (phthgly) and terephthalic (bdc) ligands. The (1) and (2) coordination polymers were formed by symmetric binuclear units, in which phthgly and bdc carboxylate ligands are coordinated to the lanthanide ions by different coordination modes. Surprisingly, all organic ligands participate in hydrogen bonding interactions, forming an extremally rigid crystalline structure.

Enhancing the Luminescence of Eu(III) Complexes with the Ruthenocene Organometallic Unit as Ancillary Ligand.

Five novel Eu(III)-β-diketonate complexes containing ruthenocene ancillary ligands (1,1'-bis(diphenylphosphoryl)ruthenocene─RcBPO) were synthesized and characterized. The coordination compounds presented the general formula [Eu(β-dik)(RcBPO)], where β-dik stands for 2-thenoyltrifluoroacetonate (tta), 3-benzoyl-1,1,1-trifluoroacetone (btf), 2-dibenzoylmethanate (dbm), 2-acetyl-1,3-indandionate (aind), and 2-benzoyl-1,3-indandionate (bind), and RcBPO stands for 1,1'-bis(diphenylphosphoryl)ruthenocene. The [Eu(aind)(RcBPO)] complex crystallizes in a monoclinic Cc non-centrosymmetric space group with the europium site environment, assuming a bicapped trigonal prism coordination polyhedron with the symmetry point group close to .

Random Lasing at Localization Transition in a Colloidal Suspension (TiO@Silica).

Anderson localization of light and random lasing in this critical regime is an open research frontier, which besides being a basic research topic could also lead to important applications. This article investigates the random laser action at the localization transition in a strongly disordered scattering medium composed of a colloidal suspension of core-shell nanoparticles (TiO@Silica) in ethanol solution of Rhodamine 6G. The classical superfluorescence band of the random laser was measured separately by collecting the emission at the back of the samples, showing a linear dependence with pumping fluence without gain depletion.

Luminescent and magnetic materials with a high content of Eu(3+)-EDTA complexes.

Bifunctional optical magnetic materials with a high europium content have been prepared. Chelating groups were introduced on the Fe3O4 surface with organosilanes containing ethylenediaminetetraacetic acid (EDTA) derivatives, which were previously prepared via a reaction between EDTA-dianhydride and aminoalkoxysilane agents: 3-(trimethoxysilyl)propylamine (1N), N-[3(trimethoxysilyl)propyl]ethylenediamine (2N) and N(1)-(3-trimethoxysilylpropyl)diethylenetriamine) (3N). The first coordination sphere of Ln-EDTA complexes present on the modified surfaces of Fe3O4 particles was completed by addition of β-diketonate ligands (tta: thenoyltrifluoroacetone, dbm: dibenzoylmethane, bzac: benzoylacetone and acac: acetylacetone) in order to improve their luminescence properties.

Anderson localization of light in a colloidal suspension (TiO2@silica).

In recent years, there has been dramatic progress in the photonics field in disordered media, ranging from applications in solar collectors, photocatalyzers, random lasing, and other novel photonic functions, to investigations into fundamental topics, such as light confinement and other phenomena involving photon interactions. This paper reports several pieces of experimental evidence of localization transition in a strongly disordered scattering medium composed of a colloidal suspension of core-shell nanoparticles (TiO2@silica) in ethanol solution. We demonstrate the crossover from a diffusive transport to a localization transition regime as the nanoparticle concentration is increased, and that an enhanced absorption effect arises at localization transition.

In vitro and in vivo documentation of quantum dots labeled Trypanosoma cruzi--Rhodnius prolixus interaction using confocal microscopy.

Semiconductor quantum dots (QDs) are highly fluorescent nanocrystals markers that allow long photobleaching and do not destroy the parasites. In this paper, we used fluorescent core shell quantum dots to perform studies of live parasite-vector interaction processes without any observable effect on the vitality of parasites. These nanocrystals were synthesized in aqueous medium and physiological pH, which is very important for monitoring live cells activities, and conjugated with molecules such as lectins to label specific carbohydrates involved on the parasite-vector interaction.

Eu(III) dithiocarbamate complex and N-p-tolylsulfonylphenylalanine as a novel chiral catalyst for the asymmetric synthesis of cyanohydrins.

The use of a new chiral lanthanide complex derived from a europium dithiocarbamate complex and a N-tosylated amino acid for the asymmetric synthesis of cyanohydrins is described. In some cases, high enantioselectivities were observed.

Photoluminescence of europium(III) dithiocarbamate complexes: electronic structure, charge transfer and energy transfer.

For the first time, we observed photoluminescence in Eu(III) dithiocarbamate complexes at room temperature -- more specifically in [Eu(Et(2)NCS(2))(3)phen], [Eu(Et(2)NCS(2))(3)bpy] and the novel [Eu(Ph(2)NCS(2))(3)phen], where phen stands for 1,10-phenanthroline and bpy for 2,2'-bipyridine. Correlations between the electronic structure of the dithiocarbamate ligands on one hand, and covalency, intensity, and ligand field spectroscopic parameters on the other, could be established. Moreover, the relative values of the emission quantum efficiencies obtained for these complexes, as well as their dependence with temperature, could be satisfactorily described by a theoretical methodology recently developed.

Intramolecular energy transfer through charge transfer state in lanthanide compounds: a theoretical approach.

A theoretical approach for the intramolecular energy transfer process involving the ligand-to-metal charge transfer (LMCT) state in lanthanide compounds is developed. Considering a two-electron interaction, both the direct Coulomb and exchange interactions are taken into account, leading to expressions from which selection rules may be derived and transfer rates may be calculated. These selection rules show that the direct Coulomb and exchange mechanisms are complementary, in the same way as obtained in previous works for the case of ligand-lanthanide ion energy transfer processes.