A luminescent tris(2-thenoyltrifluoroacetonato)europium(iii) complex covalently linked to a 1,10-phenanthroline-functionalised sol?gel glass (original) (raw)
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Journal of Luminescence, 2005
The solubility and uniform distribution of lanthanide complexes in sol–gel glasses can be improved by covalently linking the complexes to the sol–gel matrix. In this study, several lanthanide β-diketonate complexes (Ln=Nd, Sm, Eu, Tb, Er, Yb) were immobilized on a 1,10-phenanthroline functionalized sol–gel glass. For the europium(III) complex, a sol–gel material of diethoxydimethylsilane (DEDMS) with polymer-like properties was derived. For
Inorganic Chemistry, 2005
The synthesis of a new ligand (1) containing a single phenanthroline (phen) chromophore and a flexibly connected diethylenetriamine tetracarboxylic acid unit (DTTA) as a lanthanide (Ln) coordination site is reported [1 is 4-[(9methyl-1,10-phenantrol-2-yl)methyl]-1,4,7-triazaheptane-1,1,7,7-tetraacetic acid]. From 1, an extended series of watersoluble Ln‚1 complexes was obtained, where Ln is Eu(III), Tb(III), Gd(III), Sm(III), Dy(III), Pr(III), Ho(III), Yb(III), Nd(III), and Er(III). The stoichiometry for the association was found 1:1, with an association constant K A g 10 7 s -1 as determined by employing luminescence spectroscopy. The luminescence and photophysical properties of the series of lanthanide complexes were investigated in both H 2 O and D 2 O solutions. High efficiencies for the sensitized emission, φ se , in air-equilibrated water were observed for the Ln‚1 complexes of Eu(III) and Tb(III) in the visible region (φ se ) 0.24 and 0.15, respectively) and of Sm(III), Dy(III), Pr(III), Ho(III), Yb(III), Nd(III), and Er(III) in the vis and/or near-infrared region [φ se ) 2.5 × 10 -3 , 5 × 10 -4 , 3 × 10 -5 , 2 × 10 -5 , 2 × 10 -4 , 4 × 10 -5 , and (in D 2 O) 4 × 10 -5 , respectively]. For Eu‚1 and Tb‚1, luminescence data for water and deuterated water allowed us to estimate that no solvent molecules (q) are bound to the ion centers (q ) 0). Luminescence quenching by oxygen was investigated in selected cases.
New Journal of Chemistry, 2004
Lanthanide-doped sol-gel-derived materials are an attractive type of luminescent materials that can be processed at ambient temperatures. However, the solubility of the lanthanide complexes in the matrix is a problem and it is difficult to obtain a uniform distribution of the complexes. Fortunately, these problems can be solved by covalently linking the lanthanide complex to the sol-gel-derived matrix. In this study, luminescent Eu 31 and Tb 31 bipyridine complexes were immobilized on sol-gel-derived silica. FT-IR, DTA-TG and luminescence spectra, as well as luminescence decay analysis, were used to characterize the obtained hybrid materials. The organic groups from the bipyridine-Si moiety were mostly destroyed between 220 and 600 1C. The luminescence properties of lanthanide bipyridine complexes anchored to the backbone of the silica network and the corresponding pure complexes were comparatively investigated, which indicates that the lanthanide bipyridine complex was formed during the hydrolysis and co-condensation of TEOS and modified bipyridine. Excitation at the ligand absorption wavelength (336 nm for the hybrid materials and 350 nm for the pure complexes) resulted in strong emission of the lanthanide ions:
Luminescence spectroscopy of lanthanide(III) ions in solution
Journal of Alloys and Compounds, 2002
Luminescence spectroscopy of Ln(III) ions, characterised by very narrow emission bands and a long decay time, is an important technique for the study of coordination, analytical and photophysical aspects of lanthanide chemistry. Factors affecting the Ln(III) luminescence in solution that can both quench or increase the intensity and lifetime of luminescence, are described. The quenching processes of the Ln(III) excited states, strongly dependent on energy of vibrators resulting from ligands (and / or solvents) and energy gaps, DE, between the emissive state and the highest sublevel of the ground state of Ln(III), are presented. Effectiveness of quenching of 2 the luminescent excited state of the Ln(III) ions by O-H, N-H and a strong deactivating power of the azide ion, N , are described. The 3 factors which markedly increase luminescence, efficiently reducing nonradiative energy degradation of Ln(III) ions are presented. Highly luminescent Ln(III) systems based on complex and ternary complex formation with several groups of ligands (e.g. crytptands, b-diketones, macrocyclic ligands, heterobiaryl ligands, etc.) as well as energy transfer processes are discussed. The use of europium 7 5 luminescence excitation spectroscopy of the F → D transition as a unique and sensitive way to characterize the number of Eu(III) 0 0 species present in solution, binding sites of various ligands and complex stoichiometries, is briefly reviewed. Recent developments in the use of the excitation spectroscopy of Eu(III) and a wealth of information which can be obtained from this method are presented.
The synthesis and photoluminescent properties of Ln(III)-TTA complexes (Ln¼ Eu(III) and Sm(III) ions; TTA ¼ 3-thenoyltrifluoroacetonate) with N-methyl-ε-caprolactam (NMC) are reported. The Ln complexes were characterized by elemental analysis, complexometric titration with EDTA and infrared spectroscopy. The molecular structures of the [Eu(TTA) 3 (NMC)(H 2 O)] and [Sm(TTA) 3 (NMC)(H 2 O)] Á H 2 O compounds were determined by single crystal X-ray crystallography. In these structures, the three TTA molecules are coordinated to the metal in anionic form as bidentate ligands, while the H 2 O and NMC molecules are coordinated to the metal in neutral form as monodentated ligands. The coordination polyhedron around the Ln(III) atom can be described as square antiprismatic molecular geometry. The geometry of the [Eu(TTA) 3 (NMC)(H 2 O)] complex was optimized with the Sparkle/RM1 model for Ln(III) complexes, allowing analysis of intramolecular energy transfer processes of the Eu(III) compound. The spectroscopic properties of the 4f 6 intraconfigurational transitions of the Eu(III) complex were then studied experimentally and theoretically. The low value of emission quantum efficiency of 5 D 0 emitting level (η) of Eu (III) ion (ca. 36%) is due to the vibrational modes of the water molecule that act as luminescence quenching. In addition, the luminescence decay curves, the experimental intensity parameters (Ω λ), lifetimes (τ), radiative (A rad) and non-radiative (A nrad) decay rates, theoretical quantum yield (q cal) were also determined and discussed.
Chemistry of Materials, 2004
The near-infrared luminescence of lanthanide complexes of 4′, 5′-bis[N,N-bis(carboxymethyl)aminomethyl]fluorescein (calcein) and pyridine-2,6-dicarboxylic acid (dipicolinic acid, dpa) doped in a hybrid sol-gel material was investigated. The silica-poly(ethylene glycol) (silica-PEG) inorganic-organic materials were prepared at a neutral pH. The lanthanide ions are well shielded from the environment by the calcein and dpa ligands, and the complexes are stable in the sol-gel matrix after preparation. The dysprosium and neodymium dipicolinate complexes showed near-infrared luminescence (NIR-luminescence) by direct excitation to the 4f-levels. The ytterbium dipicolinate complex doped in the sol-gel showed NIR-luminescence by excitation of the ligand in the UV region. All other tested lanthanide ions (Ln ) Pr, Sm, Er, Ho) did not show luminescence. Neodymium and ytterbium complexes with calcein show intense NIR-luminescence when the ligand is excited by visible light. The corresponding erbium complex doped in the silica-PEG matrix also showed NIR-luminescence at 1525 nm. No NIR-luminescence could be detected for the other lanthanide complexes doped in the matrix (Ln ) Pr, Sm, Dy, Ho).
Journal of materials science, 2000
Microporous silica gel has been prepared by the sol-gel method utilizing the hydrolysis and polycondensation of tetraethylorthosilicate (TEOS). The gel has been doped with the luminescent ternary europium complex Eu(TTA) 3 ·phen: where HTTA = 1-(2-thenoyl)-3,3,3-trifluoracetone and phen = 1,10-phenanthroline. By contrast to the weak f-f electron absorption bands of Eu 3+ , the complex organic ligand exhibits intense near ultraviolet absorption. Energy transfer from the ligand to Eu 3+ enables the production of efficient, sharp visible luminescence from this material. Utilizing the polymerization of methyl methacrylate or ethyl methacrylate, the inorganic/polymer hybrid materials containing Eu(TTA) 3 ·phen have also been obtained. SEM micrographs show uniformly dispersed particles in the nanometre range. The characteristic luminescence spectral features of europium ions are present in the emission spectra of the hybrid material doped with Eu(TTA) 3 ·phen. C 2000 Kluwer Academic Publishers
Luminescent lanthanide complexes with liquid crystalline properties
Liquid Crystals, 2002
Lewis-base adducts of tris(b-diketonato)lanthanide(III) complexes were prepared, where the b-diketone is para-alkoxy-substituted 1,3-diphenyl-1,3-propanedione. These compounds are the rst examples of liquid crystalline lanthanide complexes in which the mesomorphism is introduced via a b-diketonate ligand. Depending on the type of the Lewis base, the metallomesogens exhibit a monotropic smectic A or a monotropic highly ordered smectic phase. Intense photoluminescence was observed for the europium(III) complexes at room temperature.
Improving Visible Light Sensitization of Luminescent Europium Complexes
Journal of Fluorescence, 2008
The synthesis and characterization of the new ligands L 1 , L 2 and L 4 are described with the series of four europium complexes of formula [EuL n (TTA) 3 ] in which TTA refers to 2-thenoyltrifluoroacetonate and L n to tridentate ligands with nitrogen containing heterocyclic structure, such as a 2,6-bis(3-methyl-pyrazolyl)-4-(p-toluyl-ethynyl)triazine for L 1 , or terpyridines functionalized at the 4′ position by a phenyl-vinylene for L 2 , a p-dimethylaminophenylene for L 3 , or a p-aminophenyl-ethynylene for L 4 . The spectroscopic properties of the ligands and of the complexes are studied by means of UV-Vis absorption spectroscopy, as well as steady-state and time-resolved luminescence spectroscopy. All complexes display europium centred luminescence upon ligand excitation. Careful examination of the excitation spectra revealed differences in the ligand based sensitization efficiencies. For complexes of L 1 and L 2 , excitation of europium is mainly achieved through the TTA moieties and the photo-physical studies on [EuL 1 (TTA) 3 ] evidenced a weaker coordination of the bispyrazolyltriazine tridentate ligand, resulting from a partial decomplexation upon dilution. Complexes of L 3 and L 4 display intense excitation through the tridentate units, which extend down to 460 nm in the visible region. In the case of L 3 , selective excitation reveals the presence of a ligandcentred emission band at 520 nm which is likely ascribed to a L 3 centred charge transfer state. Fig. 4 Luminescence spectra of [EuL 3 (TTA) 3 ] in CH 2 Cl 2 (l exc = 350 nm, slits=0.5 nm, delay time 30 μs)