Search results for "SINGLE"

showing 10 items of 4920 documents

Effect of filtration conditions on the apparent density of the intercrystalline layers of polyethylene single crystal mats

1969

chemistry.chemical_compoundApparent densityMaterials scienceChemical engineeringchemistrylawGeneral EngineeringMineralogyPolyethyleneSingle crystalFiltrationlaw.inventionJournal of Polymer Science Part B: Polymer Letters
researchProduct

Very fast singlet and triplet energy transfers in a tri-chromophoric porphyrin dyad aided by the truxene platform

2015

A trichromophoric dyad composed of an octa-β-alkyl-palladium(II)porphyrin (donor) and two tri-meso-aryl-zinc(II)porphyrins (acceptors) held by a truxene spacer exhibits very fast rates for triplet energy transfers at 77 (kET(T1) = 1.63 × 108 s-1) and 298 K (kET(T1) = 3.44 × 108 s-1), whereas the corresponding singlet energy transfer rates, kET(S1) = 3.9 × 1010 s-1 (77 K) and kET(S1) = 6.0 × 1010 s-1 (298 K), are also considered fast. The interpretation for these results is that the energy transfer processes proceed via a through bond Dexter mechanism (i.e. double electron exchange) supported by comparison with literature data and evidence for a moderate MO coupling between the donor and ac…

chemistry.chemical_compoundChemistryEnergy transferElectron exchangeGeneral ChemistrySinglet stateChromophorePhotochemistryAcceptorPorphyrinJournal of Porphyrins and Phthalocyanines
researchProduct

Evidence for reverse pathways and equilibrium in singlet energy transfers between an artificial special pair and an antenna

2013

A dyad, 1, built on an artificial special pair (bis(meso-nonyl)zinc(II)porphyrin), [Zn2], a spacer (biphenylene), a bridge (1,4-benzene), and an antenna (di-meso-(3,5-di(t-butyl)phenyl)porphyrin free base), FB, is prepared by Suzuki coupling and is analyzed by absorption and steady state, and time-resolved emission spectroscopy at 298 and 77 K. Using bases from the Förster theory, evidence for two pathways for S 1 energy transfer, FB* → [Zn2], and [Zn2]* → FB, along with their respective rates, k ET ( S 1)1 and k ET ( S 1)-1, are extracted from the comparison of the fluorescence decays monitored at the emission maximum. At 77 K, the unquenched (1.79 ([Zn2]) and 10.6 ns (FB)) and quenched c…

chemistry.chemical_compoundChemistryFree baseGeneral ChemistrySinglet stateEmission spectrumSteady state (chemistry)Atomic physicsBiphenyleneAbsorption (electromagnetic radiation)FluorescencePorphyrinJournal of Porphyrins and Phthalocyanines
researchProduct

Heterodimeric capsules formed by tetratosyl and tetratolyl urea calix[4]arenes

2008

Predictions made by MD simulations for size, shape and guest inclusion of a heterodimer formed by a tetratosyl and a tetratolyl urea calix[4]arene and for its hydrogen bonding system have been entirely confirmed by a single crystal X-ray structure.

chemistry.chemical_compoundChemistryHydrogen bondPolymer chemistryUreaOrganic chemistryGeneral Materials ScienceGeneral ChemistryInclusion (mineral)Condensed Matter PhysicsSingle crystalCrystEngComm
researchProduct

Advances in singlet oxygen chemistry

2005

The authors discuss the advances made in both mechanistic and synthetic aspects of singlet oxygen chem.  Formation and reactions of singlet oxygen in heterogeneous media (such as zeolites, micelles, vesicles, etc.) are discussed.  Cycloaddns. of mol. oxygen to olefins, heteroatom oxidns. via reaction of singlet oxygen with the electron pair at heteroatoms, and photooxygenations of heterocyclic systems by singlet oxygen are also reviewed.

chemistry.chemical_compoundChemistrySinglet oxygenphotooxygenationOrganic ChemistryDrug Discoveryheteroatom oxidationPhotooxygenationGeneral MedicinePhotochemistryBiochemistrysinglet oxygenTetrahedron
researchProduct

A coupled cluster calculation of the spectrum of urea

2001

Several coupled cluster methods have been used to compute the vertical excitation energies and oscillator strengths of the lowest singlet states of urea. Except for one excitation, the results are in good agreement with experiment, but previously non-detected transitions have been found.

chemistry.chemical_compoundCoupled clusterChemistrySpectrum (functional analysis)UreaGeneral Physics and AstronomySinglet statePhysical and Theoretical ChemistryAtomic physicsMolecular electronic transitionExcitationChemical Physics Letters
researchProduct

A Nonanuclear Iron(II) Single-Molecule Magnet

2004

chemistry.chemical_compoundCrystallographyChemistryInorganic chemistrySingle-molecule magnetGeneral ChemistryAzideGeneral MedicineCatalysisAngewandte Chemie
researchProduct

A macrocyclic diurea derived from diphenylether

2010

Abstract A new 16-membered cyclic diurea was synthesized and tested as potential receptor for fluoride. 1 H and 19 F NMR spectroscopy revealed an unexpected deprotonation of both urea groups after initial 1:1 binding. A single crystal X-ray structure shows bifurcated hydrogen bonds to two DMSO molecules.

chemistry.chemical_compoundCrystallographyDeprotonationchemistryHydrogen bondOrganic ChemistryDrug DiscoveryUreaMoleculeNuclear magnetic resonance spectroscopyBiochemistrySingle crystalFluorideTetrahedron Letters
researchProduct

Cover Picture: Insertion of a Single-Molecule Magnet inside a Ferromagnetic Lattice Based on a 3D Bimetallic Oxalate Network: Towards Molecular Analo…

2014

chemistry.chemical_compoundCrystallographyFerromagnetismChemistryMagnetLattice (order)Organic ChemistryX-ray crystallographySingle-molecule magnetGeneral ChemistryBimetallic stripCatalysisOxalateChemistry - A European Journal
researchProduct

Slow Relaxation of the Magnetization in a {Co <sup>III</sup>Mn <sup>III</sup>} Heterometallic Brick-Wall Network

2021

The use of the cyanide-bearing dicobalt(III) complex (PPh 4 ) 2 [Co 2 III (m-2,5-dpp)(CN) 8 ] as a metalloligand towards [Mn(salen)(H 2 O)]ClO 4 afforded the heterobimetallic two-dimensional compound of formula [{Mn III (salen)} 2 {(m-NC) 4 Co 2 III (m-2,5-dpp)(CN) 4 }] n (1) [PPh 4 + = teraphenylphosphonium cation, 2,5-dpp = 2,5-bis(2-pyridyl)pyrazine and H 2 salen = N,N’ -ethylenebis(salicylideneimine)] whose structure has been determined by single crystal X-ray diffraction. Compound 1 exhibits a neutral brick-wall structure, where each [Co 2 III (m-2,5-dpp)(CN) 8 ] 2- unit adopts a tetrakis-monodentate bridging mode towards four {Mn III (salen)} + fragments through four of its eight cyan…

chemistry.chemical_compoundCrystallographyMagnetizationMaterials scienceOctahedronPyrazinechemistryRelaxation (NMR)chemistry.chemical_elementMoleculeManganeseSingle crystalCobaltSSRN Electronic Journal
researchProduct