Effect of the aromatic substituent on the para-position of pyridine-bis(oxazoline) sensitizers on the emission efficiency of their EuIII and TbIII complexes

2020 ◽  
Vol 49 (48) ◽  
pp. 17699-17708
Author(s):  
Ana de Bettencourt-Dias ◽  
Jeffrey S. K. Rossini ◽  
Josiane A. Sobrinho
Keyword(s):  
Green Emission ◽  
Lanthanide Ions ◽  
Para Position ◽  
Aromatic Substituent ◽  
Emission Efficiency

PyboxPh and Pybox2Th bind to Eu and Tb and sensitize the red and green emission of these two lanthanide ions with good efficiencies.

Synthesis, RNA binding and nuclease activity of porphyrin-hydroxamic acid derivatives

2012 ◽  
Vol 16 (09) ◽  
pp. 997-1005 ◽  
Author(s):  
Maria Marketaki ◽  
Eleftherios Touloupakis ◽  
Georgios Charalambidis ◽  
Marie-Cécile Chalbot ◽  
Demetrios F. Ghanotakis ◽  
...  
Keyword(s):  
Hydroxamic Acid ◽  
Rna Binding ◽  
Phenyl Group ◽  
Nuclease Activity ◽  
Lanthanide Ions ◽  
Para Position ◽  
Aliphatic Chain ◽  
Interaction Mode ◽  
Acid Function ◽  
Hydroxamic Acid Derivatives

The interaction modes and nuclease activity against RNA of methylpyridiniumyl/phenyl-hydroxamic acid porphyrin adducts have been investigated. These compounds are derived from the tetracationic meso-tetrakis(N-methyl-4-pyridiniumyl)porphyrin (H2TMPyP-4) by replacing one or two pyridinium rings with a phenyl group. This group is bearing an aliphatic chain of three carbon atoms in the para position to a hydroxamic acid. A different interaction mode is observed depending on the number of charges and hydroxamic acid function. The nuclease activity of the porphyrin adducts against RNA has been demonstrated. Also the effect of the presence of various lanthanide ions on the porphyrin nuclease activity has been tested.

scholarly journals Luminescent Properties of Lanthanoid-Poly(Sodium Acrylate) Composites: Insights on the Interaction Mechanism

Polymers ◽  
2020 ◽  
Vol 12 (6) ◽  
pp. 1314
Author(s):  
Alan F. Y. Matsushita ◽  
María José Tapia ◽  
Alberto A. C. C. Pais ◽  
Artur J. M. Valente
Keyword(s):  
Metal Ions ◽  
Polymer Composites ◽  
Metal Ion ◽  
Interaction Mechanism ◽  
Green Emission ◽  
Luminescent Properties ◽  
Lanthanide Ions ◽  
Molar Ratio ◽  
Sodium Acrylate ◽  
Wide Range

The interaction between polyelectrolytes and metal ions is governed by different types of interactions, leading to the formation of different phases, from liquid state to weak gels, through an appropriate choice of metal ion/polyelectrolyte molar ratio. We have found that lanthanide ions, europium(III) and terbium(III), are able to form polymer composites with poly(sodium acrylate). That interaction enhances the luminescent properties of europium(III) and terbium(III), showing that Eu3+/poly(sodium acrylate) (PSA) and Tb3+/PSA composites have a highly intense red and green emission, respectively. The effect of cations with different valences on the luminescent properties of the polymer composites is analyzed. The presence of metal ions tends to quench the composite emission intensity and the quenching process depends on the cation, with copper(II) being by far the most efficient quencher. The interaction mechanism between lanthanoid ions and PSA is also discussed. The composites and their interactions with a wide range of cations and anions are fully characterized through stationary and non-stationary fluorescence, high resolution scanning electronic microscopy and X-ray diffraction.

scholarly journals Mononuclear Copper(I) 3-(2-pyridyl)pyrazole Complexes: The Crucial Role of Phosphine on Photoluminescence

Molecules ◽  
2021 ◽  
Vol 26 (22) ◽  
pp. 6869
Author(s):  
Kristina F. Baranova ◽  
Aleksei A. Titov ◽  
Alexander F. Smol’yakov ◽  
Andrey Yu. Chernyadyev ◽  
Oleg A. Filippov ◽  
...  
Keyword(s):  
Excited States ◽  
Theoretical Calculations ◽  
Green Emission ◽  
Emission Efficiency ◽  
Bright Yellow ◽  
Ligand Type ◽  
Wide Range ◽  
Emission Behavior ◽  
Triplet Excited States

A series of emissive Cu(I) cationic complexes with 3-(2-pyridyl)-5-phenyl-pyrazole and various phosphines: dppbz (1), Xantphos (2), DPEPhos (3), PPh3 (4), and BINAP (5) were designed and characterized. Complexes obtained exhibit bright yellow-green emission (ca. 520–650 nm) in the solid state with a wide range of QYs (1–78%) and lifetimes (19–119 µs) at 298 K. The photoluminescence efficiency dramatically depends on the phosphine ligand type. The theoretical calculations of buried volumes and excited states explained the emission behavior for 1–5 as well as their lifetimes. The bulky and rigid phosphines promote emission efficiency through the stabilization of singlet and triplet excited states.

scholarly journals Enhanced luminescence of rare-earth Tb (III) obtained by mixing of Gd (III) in a fumarate complex and intra-molecular energy transfer

2015 ◽  
Vol 33 (4) ◽  
pp. 685-691 ◽  
Author(s):  
M.D. Shah ◽  
B. Want
Keyword(s):  
Optical Properties ◽  
Energy Transfer ◽  
Rare Earth ◽  
Green Emission ◽  
Lanthanide Ions ◽  
Luminescence Spectra ◽  
Mixed Complex ◽  
Energy Transfer Mechanism ◽  
Terbium Complex ◽  
Diffusion Technique

AbstractTrivalent lanthanide ions display fascinating optical properties. Therefore, the rare-earth complexes of terbium fumarate heptahydrate and GdTb fumarate heptahydrate were grown by using a single gel diffusion technique. The crystals were characterized by different physicochemical techniques of characterization. UV-Vis and photoluminescence spectrophotometric experiments were carried out to study the optical properties of the grown crystals. Under various excitations (339 nm, 350 nm or 368 nm) the terbium fumarate complex emitted characteristic (4f-4f) green emission of Tb3+ (5D4-7FJ, J = 6, 5, 4 and 3, respectively). Luminescence spectra showed that Gd3+ ions in the mixed complex have not affected the luminescence emission peak positions, but remarkably increased the luminescent intensities of the terbium complex. The energy-transfer mechanism between the ligand and the central Tb3+ ions and from the Gd3+ to the Tb3+ was discussed.

scholarly journals Exploring the Slow Magnetic Relaxation of a Family of Photoluminescent 3D Lanthanide–Organic Frameworks Based on Dicarboxylate Ligands

2021 ◽  
Vol 7 (3) ◽  
pp. 41
Author(s):  
Itziar Oyarzabal ◽  
Sara Rojas ◽  
Ana D. Parejo ◽  
Alfonso Salinas-Castillo ◽  
José Ángel García ◽  
...  
Keyword(s):  
Near Infrared ◽  
Three Dimensional ◽  
Green Emission ◽  
Lanthanide Ions ◽  
Water Molecules ◽  
X Ray Diffraction ◽  
Magnetic Studies ◽  
Slow Magnetic Relaxation ◽  
Metal Organic ◽  
Solvent Molecules

A family of metal–organic frameworks with general formula {[Nd2(ant)2((NH2)2-bdc)(DMF)4]·2DMF}n (1) and {[Ln2(ant)2((NH2)2-bdc)(DMF)4]·2DMF·2H2O}n (Ln = Tb (2), Ho (3), and Er (4)) has been obtained from reactions between 9,10-anthracenedicarboxylic (H2ant) and 2,5-diaminoterephthalic ((NH2)2-H2bdc) acids, and lanthanide ions in dimethylformamide (DMF). These lanthanide–organic frameworks (LnOFs) have been characterized, and their crystal structures have been elucidated by single crystal and powder X-ray diffraction methods (on the basis of a comparative refinement with similar structures), respectively for 1 and 2–4. All LnOFs present three-dimensional structures composed of dinuclear [Ln2(µ-CO2)4] entities linked through both carboxylate ligands that yield open frameworks in which DMF and water molecules are located in the channels. Magnetic studies of these LnOFs have revealed slow relaxation of the magnetization for the Nd-based counterpart. The compounds also acknowledge relevant photoluminescence (PL) emissions in the visible (for the Tb-based homologue) and near-infrared (for the Nd- and Er-based compounds) regions. The strong green emission yielded by compound 2 at room temperature allows its study for photoluminescence (PL) sensing of various solvent molecules, finding a particular discrimination for acetone.

The Anticoagulant Activity of 3.3’-(p-Alkylthio-Benzylidene)-Bis-4-Hydroxycoumarins and Their Oxidation Products

1967 ◽  
Vol 17 (01/02) ◽  
pp. 277-286 ◽  
Author(s):  
Maria Gumińska ◽  
M Eckstein ◽  
Barbara Stachurska ◽  
J Sulko
Keyword(s):  
Biological Activity ◽  
Anticoagulant Activity ◽  
Oxidation Products ◽  
Para Position ◽  
Sulphur Atom ◽  
Group I ◽  
One Step

SummaryThe anticoagulant activity of 3.3’-(benzylidene)-bis-4-hydroxycoumarin derivatives has been estimated by one step Quick’s method. The derivatives contained the following groups in the para position of benzylidene residue: NCS- (I), CH3-S- (II), CH3-SO-(III), CH3-S02- (IV), C2H5-S- (V), C2H5-SO- (VI), C2H5-S02- (VII). All these compounds were much more active than 3.3’-(benzylidene)-bis-4-hydroxycoumarin itself.Compounds possessing the ethyl chain at the sulphur atom (V, VI, VII) were more active than methyl homologues (II, III, IV). Comparison of the activity of the series of thio-, sulphoxy-, and sulphonyl-derivatives showed that among methyl- and ethyl-derivatives those with the sulphoxy grouping (III, VI) displayed the greatest anticoagulant activity. The action of sulphonyl (IV, VII) and thio-derivatives (II, V) was weaker and shortest. The derivative with the NCS-group (I) possessed a relatively the lowest activity among the investigated compounds. 3.3’-(p-Ethylsulphoxybenzyl-idene)-bis-4-hydroxycoumarin (VI), with distinct biological activity reached about ½ of dicoumarol activity.

Growth Kinetics of Quantum Size ZnO Particles

1998 ◽  
Vol 536 ◽  
Author(s):  
E. M. Wong ◽  
J. E. Bonevich ◽  
P. C. Searson
Keyword(s):  
Growth Kinetics ◽  
Ostwald Ripening ◽  
Chemical Potential ◽  
Colloidal Suspensions ◽  
Green Emission ◽  
Blue Shift ◽  
Constant Current ◽  
Mass Model ◽  
Zno Particles ◽  
Kinetics Of

AbstractColloidal chemistry techniques were used to synthesize ZnO particles in the nanometer size regime. The particle aging kinetics were determined by monitoring the optical band edge absorption and using the effective mass model to approximate the particle size as a function of time. We show that the growth kinetics of the ZnO particles follow the Lifshitz, Slyozov, Wagner theory for Ostwald ripening. In this model, the higher curvature and hence chemical potential of smaller particles provides a driving force for dissolution. The larger particles continue to grow by diffusion limited transport of species dissolved in solution. Thin films were fabricated by constant current electrophoretic deposition (EPD) of the ZnO quantum particles from these colloidal suspensions. All the films exhibited a blue shift relative to the characteristic green emission associated with bulk ZnO. The optical characteristics of the particles in the colloidal suspensions were found to translate to the films.

Hydrothermal Synthesis and Solid-State Laser Refrigeration of Ytterbium-Doped Potassium Lutetium Fluoride (KLF) Microcrystals

2020 ◽  
Author(s):  
Xiaojing Xia ◽  
Anupum Pant ◽  
Xuezhe Zhou ◽  
Elena Dobretsova ◽  
Alex Bard ◽  
...  
Keyword(s):  
Hydrothermal Synthesis ◽  
Solid State ◽  
Information Science ◽  
Point Group ◽  
Solid State Laser ◽  
Lanthanide Ions ◽  
Group Symmetry ◽  
Luminescence Spectra ◽  
Crystalline Phases ◽  
State Laser

Fluoride crystals, due to their low phonon energies, are attractive hosts of trivalent lanthanide ions for applications in upconverting phosphors, quantum information science, and solid-state laser refrigeration. In this article, we report the rapid, low-cost hydrothermal synthesis of potassium lutetium fluoride (KLF) microcrystals for applications in solid-state laser refrigeration. Four crystalline phases were synthesized, namely orthorhombic K<sub>2</sub>LuF<sub>5</sub> (Pnma), trigonal KLuF<sub>4</sub> (P3<sub>1</sub>21), orthorhombic KLu<sub>2</sub>F<sub>7</sub> (Pna2<sub>1</sub>), and cubic KLu<sub>3</sub>F<sub>10</sub> (Fm3m), with each phase exhibiting unique microcrystalline morphologies. Luminescence spectra and emission lifetimes of the four crystalline phases were characterized based on the point-group symmetry of trivalent cations. Laser refrigeration was measured by observing both the optomechanical eigenfrequencies of microcrystals on cantilevers in vacuum, and also the Brownian dynamics of optically trapped microcrystals in water. Among all four crystalline phases, the most significant cooling was observed for 10%Yb:KLuF<sub>4</sub> with cooling of 8.6 $\pm$ 2.1 K below room temperature. Reduced heating was observed with 10%Yb:K<sub>2</sub>LuF<sub>5</sub>

Bond-length distributions for ions bonded to oxygen: Results for the lanthanides and actinides and discussion of the f-block contraction

2017 ◽  
Author(s):  
Olivier Charles Gagné
Keyword(s):  
Bond Length ◽  
Coordination Number ◽  
Lanthanide Ions ◽  
Lanthanide Contraction ◽  
Trivalent Lanthanide ◽  
Actinide Ions

Bond-length distributions have been examined for eighty-four configurations of the lanthanide ions and twenty-two configurations of the actinide ions bonded to oxygen. The lanthanide contraction for the trivalent lanthanide ions bonded to O<sup>2-</sup> is shown to vary as a function of coordination number and to diminish in scale with increasing coordination number.

Synthesis, Characterization and In vitro Evaluation of N-Substituted- Sulfomoyl-Phenyl-Amino Carboxylic Acid Derivatives as Squalene Synthase Inhibitors

2019 ◽  
Vol 15 (4) ◽  
pp. 415-426
Author(s):  
Avani B. Chokshi ◽  
Mahesh T. Chhabria ◽  
Pritesh R. Desai
Keyword(s):  
Carboxylic Acid ◽  
Cell Line ◽  
Hepatic Cell ◽  
Squalene Synthase ◽  
Lipid Lowering ◽  
Assay Method ◽  
Aromatic Substituent ◽  
Hepatic Cell Line ◽  
Amino Carboxylic Acid

Background:Squalene Synthase is one of the cholesterol biosynthetic pathway enzymes, inhibition of which produces potent lipid lowering action. A variety of chemical classes have been evaluated for its inhibition to provide alternate antihyperlipidemic agents to statins.Methods:A series of N-substituted-sulfomoyl-phenyl-amino carboxylic acid derivatives were designed through pharmacophore modelling as Squalene Synthase inhibitors. We report here the synthesis, characterization and in vitro pharmacological screening of the designed molecules as Squalene synthase inhibitors. The target molecules were synthesized by a simple procedure and each molecule was characterized by IR, Mass, 1HNMR and 13CNMR spectroscopic techniques. As a primary site of action for cholesterol biosynthesis is liver, each of the molecules were first screened for in vitro cytotoxicity over human hepatic cell line (HepG2) by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay method. The enzyme inhibition assay was performed on cell lysates prepared from HepG2 cells by Human Squalene Synthase ELISA kit, where test compounds were added in the nontoxic concentrations only.Results:Compound 5f was found to be most potent with the IC50 value of 11.91 µM. The CTC50 value for 5f on human hepatic cell line was > 1000 µM so it was considered that the compound was relatively safe and might be free of hepatotoxicity.Conclusion:From the results of our studies, it was observed that compounds with poly nuclear aromatic or hetero aromatic substituent on a side chain were more potent enzyme inhibitors and a distance of 4-5 atoms is optimum between amide nitrogen and hydroxyl group of carboxylic acid.

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