scholarly journals Synthesis and properties of fluorescent 4′-azulenyl-functionalized 2,2′:6′,2″-terpyridines

2016 ◽  
Vol 12 ◽  
pp. 1812-1825 ◽  
Author(s):  
Adrian E Ion ◽  
Liliana Cristian ◽  
Mariana Voicescu ◽  
Masroor Bangesh ◽  
Augustin M Madalan ◽  
...  
Keyword(s):  
Quantum Yield ◽  
Aqueous Solutions ◽  
Crystal Structures ◽  
Fluorescence Quantum Yield ◽  
Membered Ring ◽  
Methyl Groups ◽  
Redox Behavior ◽  
Fluorescent Emission ◽  
Tddft Calculations ◽  
Oxidation Reduction

4′-Azulenyl-substituted terpyridines were efficiently synthesized following the Kröhnke methodology via azulenylchalcone intermediates. These azulenyl-containing terpyridines showed fluorescent emission with a fluorescence quantum yield varying from 0.14, in the case of parent terpyridine, to 0.64 when methyl groups are grafted on the azulenyl seven-membered ring. According to the crystal structures and TDDFT calculations, different twisting of the aromatic constituents is responsible for the observed fluorescent behavior. The electrochemical profile contains one-electron oxidation/reduction steps, which can only be explained on the basis of the redox behavior of the azulene unit. The ability of the 4′-azulenyl 2,2′:6′,2″-terpyridine to bind poisoning metal cations was studied by UV–vis titrations using aqueous solutions of Hg(II) and Cd(II) chlorides as illustrative examples.

scholarly journals Estimation of quantum yields of weak fluorescence from eosin Y dimers formed in aqueous solutions

2018 ◽  
Vol 17 (6) ◽  
pp. 793-799 ◽  
Author(s):  
Masami Enoki ◽  
Ryuzi Katoh
Keyword(s):  
Quantum Yield ◽  
Aqueous Solutions ◽  
Fluorescence Quantum Yield ◽  
Quantum Yields ◽  
Eosin Y

A weak fluorescence from eosin Y dimers can be observed. The fluorescence quantum yield was estimated to be 0.005.

A Study of the Optical Properties of Triazene-Cinnamic Acid Polymeric Fluorescent Brighteners

2012 ◽  
Vol 184-185 ◽  
pp. 868-871
Author(s):  
Jing Liu
Keyword(s):  
Optical Properties ◽  
Quantum Yield ◽  
Aqueous Solutions ◽  
Cinnamic Acid ◽  
Fluorescence Quantum Yield ◽  
Solvent Polarity ◽  
Polymerization Reaction ◽  
Dimethyl Formamide ◽  
Coating Application ◽  
Light Stability

Series of the triazene-cinnamic acid polymeric fluorescent brighteners were synthesized through three-step condensation reactions and polymerization reaction with styrene under replacing one of amino compounds of traditional fluorescent brighteners by cinnamic acid. The optical properties in aqueous solutions and N,N’- dimethyl formamide as well as paper coating application test were evaluated. The results showed that the light stability and fluorescence quantum yield of polymeric fluorescent brighteners was improved obviously and photoinduced isomerization was lower. Meanwhile the optical properties of polymeric fluorescent brightener were affected by concentration and solvent polarity, fluorescence quantum yield increasing and hypochromatic shift of fluorescence emmission wavelength with the decrease of solvent polarity. When the concentration was over 1 10-4 g/mL, the fluorescence was quenched.

THE EFFECT OF DIMETHYLSULFOXIDE ON THE FLUORESCENCE PROPERTIES OF SOME 4-HYDROXYQUINOLINES

2021 ◽  
Vol 55 (2 (255)) ◽  
pp. 112-117
Author(s):  
Karine R. Grigoryan ◽  
Hasmik A. Shilajyan ◽  
Iskuhi L. Aleksanyan ◽  
Zara L. Grigoryan ◽  
Lilit P. Hambardzumyan
Keyword(s):  
Charge Transfer ◽  
Quantum Yield ◽  
Aqueous Solutions ◽  
Electron Density ◽  
Aromatic Ring ◽  
Fluorescence Quantum Yield ◽  
Tautomeric Equilibrium ◽  
Fluorescence Properties ◽  
Fluorescence Efficiency ◽  
Dmso Concentration

Fluorescence properties of 4-hydroxy-2-methylquinoline (1) and 2-(5-mercapto-1,3,4-oxadiazol-2-yl)-6-methylquinoline-4-ol (2) were studied in dimethylsulfoxide (DMSO) aqueous solutions. The fluorescence properties of 1 and 2 exhibit substantial dependence on the DMSO concentration. The fluorescence quantum yield $(\Phi_f)$ of 1 decreases upon adding DMSO due to the shift in the keto-enol (E) tautomeric equilibrium toward E form․ On the contrary 2 demonstrates a tendency of increase of $\Phi_f$ upon adding DMSO due to intermolecular charge transfer from DMSO to the aromatic ring of quinoline, which increases the electron density on the ring and hence the fluorescence efficiency.

Effect of solution acidity on the crystallization of polychromates in uranyl-bearing systems: synthesis and crystal structures of Rb2[(UO2)(Cr2O7)(NO3)2] and two new polymorphs of Rb2Cr3O10

2021 ◽  
Vol 236 (1-2) ◽  
pp. 11-21
Author(s):  
Evgeny V. Nazarchuk ◽  
Oleg I. Siidra ◽  
Dmitry O. Charkin ◽  
Stepan N. Kalmykov ◽  
Elena L. Kotova
Keyword(s):  
Crystal Structure ◽  
Aqueous Solutions ◽  
Crystal Structures ◽  
Hydrothermal Treatment ◽  
Ambient Conditions ◽  
Screw Axis ◽  
3D Framework ◽  
Solution Acidity

Abstract Three new rubidium polychromates, Rb2[(UO2)(Cr2O7)(NO3)2] (1), γ-Rb2Cr3O10 (2) and δ-Rb2Cr3O10 (3) were prepared by combination of hydrothermal treatment at 220 °C and evaporation of aqueous solutions under ambient conditions. Compound 1 is monoclinic, P 2 1 / c $P{2}_{1}/c$ , a = 13.6542(19), b = 19.698(3), c = 11.6984(17) Å, β = 114.326(2)°, V = 2867.0(7) Å3, R 1 = 0.040; 2 is hexagonal, P 6 3 / m $P{6}_{3}/m$ , a = 11.991(2), c = 12.828(3) Å, γ = 120°, V = 1597.3(5) Å3, R 1 = 0.031; 3 is monoclinic, P 2 1 / n $P{2}_{1}/n$ , a = 7.446(3), b = 18.194(6), c = 7.848(3) Å, β = 99.953(9)°, V = 1047.3(7) Å3, R 1 = 0.037. In the crystal structure of 1, UO8 bipyramids and NO3 groups share edges to form [(UO2)(NO3)2] species which share common corners with dichromate Cr2O7 groups producing novel type of uranyl dichromate chains [(UO2)(Cr2O7)(NO3)2]2−. In the structures of new Rb2Cr3O10 polymorphs, CrO4 tetrahedra share vertices to form Cr3O10 2− species. The trichromate groups are aligned along the 63 screw axis forming channels running in the ab plane in the structure of 2. The Rb cations reside between the channels and in their centers completing the structure. The trichromate anions are linked by the Rb+ cations into a 3D framework in the structure of 3. Effect of solution acidity on the crystallization of polychromates in uranyl-bearing systems is discussed.

scholarly journals Synthesis of carbon nitride oligomer as a precursor of melon with improved fluorescence quantum yield

2021 ◽  
Vol 2 (18) ◽  
pp. 6083-6093
Author(s):  
Yuto Miyake ◽  
Goichiro Seo ◽  
Kotaro Matsuhashi ◽  
Noriyuki Takada ◽  
Kaname Kanai
Keyword(s):  
Optical Properties ◽  
Quantum Yield ◽  
Fluorescence Quantum Yield ◽  
Carbon Nitride

Melem tetramer, the newly synthesized carbon nitride compound is composed of oligomers with four melem units, is stable in air, and has improved optical properties compared to melon.

scholarly journals Density functional theory (DFT) calculations of VI/V reduction potentials of uranyl coordination complexes in non-aqueous solutions

2019 ◽  
Vol 21 (6) ◽  
pp. 3227-3241 ◽  
Author(s):  
Krishnamoorthy Arumugam ◽  
Neil A. Burton
Keyword(s):  
Density Functional Theory ◽  
Dft Calculations ◽  
Aqueous Solutions ◽  
Density Functional ◽  
Coordination Complexes ◽  
Dft Study ◽  
Redox Behavior ◽  
Functional Theory ◽  
Reduction Potentials ◽  
Uranium Complexes

Of particular interest within the +6 uranium complexes is the linear uranyl(vi) cation and it forms numerous coordination complexes in solution and exhibits incongruent redox behavior depending on coordinating ligands. This DFT study predicts VI/V reduction potentials of a range of uranyl(vi) complexes in non-aqueous solutions within ∼0.10−0.20 eV of experiment.

Cyclisierung von Di(tert-butyl-methyl)ketazin zu 1,2-Diaza-3-bora- und 1,2-Diaza-3-sila-cyclopent-5-enen / Cyclization of Di(tert-butyl-methyl)ketazine to 1,2-Diaza-3-bora- and 1,2-Diaza-3-sila-cyclopent-5-enes

2006 ◽  
Vol 61 (10) ◽  
pp. 1261-1274 ◽  
Author(s):  
Florian Armbruster ◽  
Nina Armbruster ◽  
Uwe Klingebiel ◽  
Mathias Noltemeyer ◽  
Stefan Schmatz
Keyword(s):  
Crystal Structures ◽  
Quantum Chemical Calculations ◽  
Chlorine Atom ◽  
Quantum Chemical ◽  
Membered Ring ◽  
Substitution Product ◽  
Tert Butyl ◽  
Isomeric Structures

The results of quantum chemical calculations on lithium ketazides suggest mainly four isomeric structures with different modes of lithium coordination (A-D). A monolithium ketazide thf-adduct (1) was isolated supporting the results of the quantum chemical calculations. In reactions of the lithiated di(tert-butyl-methyl)ketazine with BCl3 and Cl2BPh, 1,2-aza-azonia-3-borata-cyclopent-5-enes (2, 3) were isolated. Substitution of a chlorine atom of 2 and 3 with t-BuLi leads to the formation of derivatives 4 and 5. HCl elimination from 2 with Et3N gives - via a diazaboracyclopentene (6) - a bicyclus 7. In the reaction of the dilithiated ketazine with F2BN(SiMe3)2, the diaza-boracyclopentene 8 is obtained while with Cl4Si, F3SiN(SiMe3)2, and Cl2SiMe2 the diazasilacyclopentenes 9 - 11 are generated. SiF4 reacts with the dilithium ketazide to give a spirocyclus (12). The monolithium ketazide and Cl2SiMe2 react at 30 °C to give a four-membered ring isomer of the substitution product which is formed via a 1,3-chlorine shift from silicon to carbon (13). A tetrameric silanolate was isolated as a by-product in this reaction. It gives evidence for the structure of lithium ketazide A. Crystal structures of 5, 7, 10, and 14 are reported.

Oxidation-reduction chemistry of hydrogen peroxide in aprotic and aqueous solutions

1979 ◽  
Vol 18 (7) ◽  
pp. 1971-1973 ◽  
Author(s):  
Mark M. Morrison ◽  
Julian L Roberts ◽  
Donald T. Sawyer
Keyword(s):  
Hydrogen Peroxide ◽  
Aqueous Solutions ◽  
Oxidation Reduction

UV-Trained and Metal-Enhanced Fluorescence of Biliverdin and Biliverdin Nanoparticles

Nanoscale ◽  
2021 ◽  
Author(s):  
Parinaz Fathi ◽  
Ayman Roslend ◽  
Kritika Mehta ◽  
Parikshit Moitra ◽  
Kai Zhang ◽  
...  
Keyword(s):  
Quantum Yield ◽  
Fluorescence Quantum Yield ◽  
Biomedical Imaging ◽  
Enhanced Fluorescence ◽  
Metal Enhanced Fluorescence

Increasing the fluorescence quantum yield of fluorophores is of great interest for in vitro and in vivo biomedical imaging applications. At the same time, photobleaching and photodegradation resulting from continuous...

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