6 research outputs found
Thin Films for Immobilization of Complexes with Optical Properties
Thin film deposition techniques, such as dip coating, spin coating, and spray pyrolysis, are applied for the production of SiO2-, poly-(methylmethacrylate) (PMMA)-, and SiO2-/polyester-based âhybridâ matrices. The factors influencing the film properties are briefly discussed. The morphology of the films presented is studied by different microscopy techniques such as atomic force microscopy, electron (scanning and transmission) microscopy, and fluorescence microscopy. The composites based on SiO2-, PMMA-, and SiO2/polyster âhybridâ matrices possess the optical properties of the immobilized complexes of Ru(II) and Eu(III) with different organic ligands. The preparation of the PMMA matrix by the monomer methylmethacrylate polymerization (instead of using of PMMA solution) caused partial destruction of the less stable complexes and thereby a decrease in the fluorescence intensity
Molecular Design of Luminescent Complexes of Eu(III): What Can We Learn from the Ligands
The luminescent metal-organic complexes of rare earth metals are advanced materials
with wide application potential in chemistry, biology, and medicine. The luminescence of these
materials is due to a rare photophysical phenomenon called antenna effect, in which the excited
ligand transmits its energy to the emitting levels of the metal. However, despite the attractive
photophysical properties and the intriguing from a fundamental point of view antenna effect, the
theoretical molecular design of new luminescent metal-organic complexes of rare earth metals is
relatively limited. Our computational study aims to contribute in this direction, and we model
the excited state properties of four new phenanthroline-based complexes of Eu(III) using the TDDFT/TDA approach. The general formula of the complexes is EuL2A3
, where L is a phenanthroline
with â2âCH3OâC6H4
, â2âHOâC6H4
, âC6H5 or âOâC6H5 substituent at position 2 and A is Clâ or
NO3
â. The antenna effect in all newly proposed complexes is estimated as viable and is expected to
possess luminescent properties. The relationship between the electronic properties of the isolated
ligands and the luminescent properties of the complexes is explored in detail. Qualitative and
quantitative models are derived to interpret the ligand-to-complex relation, and the results are
benchmarked with respect to available experimental data. Based on the derived model and common
molecular design criteria for efficient antenna ligands, we choose phenanthroline with âOâC6H5
substituent to perform complexation with Eu(III) in the presence of NO3ÂŻ. Experimental results
for the newly synthesized Eu(III) complex are reported with a luminescent quantum yield of about
24% in acetonitrile. The study demonstrates the potential of low-cost computational models for
discovering metal-organic luminescent materials
Luminescent Complexes of Europium (III) with 2-(Phenylethynyl)-1,10-phenanthroline: The Role of the Counterions
New antenna ligand, 2-(phenylethynyl)-1,10-phenanthroline (PEP), and its luminescent Eu
(III) complexes, Eu(PEP)2Cl3 and Eu(PEP)2
(NO3
)3
, are synthesized and characterized. The synthetic
procedure applied is based on reacting of europium salts with ligand in hot acetonitrile solutions in
molar ratio 1 to 2. The structure of the complexes is refined by X-ray diffraction based on the single
crystals obtained. The compounds [Eu(PEP)2Cl3
]·2CH3CN and [Eu(PEP)2
(NO3
)3
]·2CH3CN crystal ize in monoclinic space group P21/n and P21/c, respectively, with two acetonitrile solvent molecules.
Intra- and inter-ligand Ï-Ï stacking interactions are present in solid stat and are realized between
the phenanthroline moieties, as well as between the substituents and the phenanthroline units. The
optical properties of the complexes are investigated in solid state, acetonitrile and dichloromethane
solution. Both compounds exhibit bright red luminescence caused by the organic ligand acting as
antenna for sensitization of Eu (III) emission. The newly designed complexes differ in counter ions
in the inner coordination sphere, which allows exploring their influence on the stability, molecular
and supramolecular structure, fluorescent properties and symmetry of the Eu (III) ion. In addition,
molecular simulations are performed in order to explain the observed experimental behavior of the
complexes. The discovered structure-properties relationships give insight on the role of the counter
ions in the molecular design of new Eu (III) based luminescent materials
Luminescent Complexes of Europium (III) with 2-(Phenylethynyl)-1,10-phenanthroline: The Role of the Counterions
New antenna ligand, 2-(phenylethynyl)-1,10-phenanthroline (PEP), and its luminescent Eu (III) complexes, Eu(PEP)2Cl3 and Eu(PEP)2(NO3)3, are synthesized and characterized. The synthetic procedure applied is based on reacting of europium salts with ligand in hot acetonitrile solutions in molar ratio 1 to 2. The structure of the complexes is refined by X-ray diffraction based on the single crystals obtained. The compounds [Eu(PEP)2Cl3]·2CH3CN and [Eu(PEP)2(NO3)3]∙2CH3CN crystalize in monoclinic space group P21/n and P21/c, respectively, with two acetonitrile solvent molecules. Intra- and inter-ligand π-π stacking interactions are present in solid stat and are realized between the phenanthroline moieties, as well as between the substituents and the phenanthroline units. The optical properties of the complexes are investigated in solid state, acetonitrile and dichloromethane solution. Both compounds exhibit bright red luminescence caused by the organic ligand acting as antenna for sensitization of Eu (III) emission. The newly designed complexes differ in counter ions in the inner coordination sphere, which allows exploring their influence on the stability, molecular and supramolecular structure, fluorescent properties and symmetry of the Eu (III) ion. In addition, molecular simulations are performed in order to explain the observed experimental behavior of the complexes. The discovered structure-properties relationships give insight on the role of the counter ions in the molecular design of new Eu (III) based luminescent materials
Surface Roughness Characterization of Poly(methylmethacrylate) Films with Immobilized Eu(III) ÎČ-Diketonates by Fractal Analysis
Effects of once-weekly exenatide on cardiovascular outcomes in type 2 diabetes
BACKGROUND: The cardiovascular effects of adding once-weekly treatment with exenatide to usual care in patients with type 2 diabetes are unknown. METHODS: We randomly assigned patients with type 2 diabetes, with or without previous cardiovascular disease, to receive subcutaneous injections of extended-release exenatide at a dose of 2 mg or matching placebo once weekly. The primary composite outcome was the first occurrence of death from cardiovascular causes, nonfatal myocardial infarction, or nonfatal stroke. The coprimary hypotheses were that exenatide, administered once weekly, would be noninferior to placebo with respect to safety and superior to placebo with respect to efficacy. RESULTS: In all, 14,752 patients (of whom 10,782 [73.1%] had previous cardiovascular disease) were followed for a median of 3.2 years (interquartile range, 2.2 to 4.4). A primary composite outcome event occurred in 839 of 7356 patients (11.4%; 3.7 events per 100 person-years) in the exenatide group and in 905 of 7396 patients (12.2%; 4.0 events per 100 person-years) in the placebo group (hazard ratio, 0.91; 95% confidence interval [CI], 0.83 to 1.00), with the intention-to-treat analysis indicating that exenatide, administered once weekly, was noninferior to placebo with respect to safety (P<0.001 for noninferiority) but was not superior to placebo with respect to efficacy (P=0.06 for superiority). The rates of death from cardiovascular causes, fatal or nonfatal myocardial infarction, fatal or nonfatal stroke, hospitalization for heart failure, and hospitalization for acute coronary syndrome, and the incidence of acute pancreatitis, pancreatic cancer, medullary thyroid carcinoma, and serious adverse events did not differ significantly between the two groups. CONCLUSIONS: Among patients with type 2 diabetes with or without previous cardiovascular disease, the incidence of major adverse cardiovascular events did not differ significantly between patients who received exenatide and those who received placebo