Β-diketone Chelates Research Articles

Vapor pressure-temperature data for various metal β-diketone chelates

Vapor pressure-temperature data, molar heats of sublimation, and sublimation temperatures are given for 29 metal β-diketone chelates. The chelatcs studied were these of Be(II), Al(III), Mn(II), Fe(III), Co(II), Ni(II) and Cu(II) with acetyl-acetone, acetyltrifluoroacctone, benzoylacetone, benzoyltrifluoroacetone, 2-furoyl-trifluoroacetone, and 2-thenoyltrifluoroacetone. The observed difference in volatilities of the various metal chelatcs of a given ligand is the basis for a suggestion that various mixtures of metal ions can be resolved by a fractional sublimation scheme.

Mechanism of Energy Transfer in Some Rare-Earth Chelates

The mechanism of energy transfer in rare-earth chelates is discussed with a view to their application as laser material. It is shown that the optical pumping by energy transfer in some rare-earth β-diketone chelates does not involve any inefficient process, although the energy migration occurs via the lowest triplet level of the ligand.

Photoluminescence of Lanthanide Complexes. III. Synergic Agent Complexes Involving Extended Chromophores

The partial development of an insulating sheath via formation of synergic agent complexes is shown to enhance the photoluminescence of a series of europium β-diketone chelates. Equilibria which may occur in solution are discussed and provide a satisfactory explanation for certain variations in behavior.

Fluorescence Quantum Efficiency of Rare-Earth Chelates*

Fluorescence quantum efficiency of several β-diketone chelates of Tb3+, Eu3+, and Sm3+ in solutions have been measured at 300°K. The highest quantum yield of the solutions investigated is found to be approximately 50%. The quantum efficiency is found to be dependent on the nature of the solvent, but is fairly independent of the wavelength of excitation, or the presence of oxygen. The fluorinated chelates, in general, have higher quantum yield in solutions, and therefore may be considered as possible material for liquid laser operation near room temperatures. The high quantum yield of the fluorinated chelates in solution also indicates that the time required for energy transfer in the chelates is at least an order of magnitude less than the time required for oxygen quenching in the triplet state.

Spectra and quantum states of europium β-diketone chelates in polymethylmethacrylate

An analysis of the absorption spectra of different Eu β-diketone chelates led to a detailed spectroscopic investigation of Eu tris (4,4,4-trifluoro-1,2 thienyl-1,3 butanedione) chelate dissolved in polymethylmethacrylate and other hosts, at different temperatures and concentrations. The mechanism responsible for the line fluorescence is attributed to an intramolecular energy transfer from the triplet states of the organic chelate to the 5 D 0 and 5 D 1 resonance energy levels of the central europium ion. The concentration, temperature and host dependent fluorescence spectrum of Eu chelate have been investigated and interpreted. The absorption and phosphorescence spectra of the identical gadolinium chelate in different hosts were related to the overall transfer mechanism and the lowest-lying triplet states. The “molecular field splitting” effects are observed at low temperatures for the 7 F 0 → 5 D 2 transition and interpreted based on structural criteria. The intramolecular energy transfer has been tentatively formulated based on the admixture of the biradical triplet state of the chelate with the emitting levels of the europium ion.

Electronic transitions in chromium (III) complexes—III: Luminescence quantum yields and lifetimes

The luminescence quantum yields and lifetimes of a group of β-diketone chelates of chromium have been measured. The changes in these quantities with ligand are ascribed to the variation in the non-radiative transition probabilities from the 4 T 2 and 2 E states to the ground state. A wave length dependence is observed in some cases which appears to be correlated with the energy of the lowest ligand triplet state.

Electronic transitions in chromium (III) complexes—I: Absorption spectra of β-diketone chelates

Absorption spectra of solutions of chromium (III) (β-diketone chelates were obtained at 85°K. The effects of substituents on the chelate rings upon the positions of the bands in the 22–40,000 cm −1 region were determined. These shifts are similar for all the bands and in accord with the predictions of molecular orbital theory for π-π ∗ transitions.

Spectra and quantum states of europium β-diketone chelates in polymethylmethacrylate

Spectra and quantum states of europium β-diketone chelates in polymethylmethacrylate

Chelates of β-Diketones. V. Preparation and Properties of Chelates Containing Sterieally Hindered Ligands

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTChelates of β-Diketones. V. Preparation and Properties of Chelates Containing Sterieally Hindered LigandsGeorge S. Hammond, Derek C. Nonhebel, and Chin-Hua S. WuCite this: Inorg. Chem. 1963, 2, 1, 73–76Publication Date (Print):February 1, 1963Publication History Published online1 May 2002Published inissue 1 February 1963https://doi.org/10.1021/ic50005a021RIGHTS & PERMISSIONSArticle Views1396Altmetric-Citations207LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (481 KB) Get e-Alerts Get e-Alerts

Complexing Behavior of Kojic Acid with Metal Ions. I. Mg(II) and Mn(II) Chelates

Abstract Chelating tendencies of kojic acid toward divalent magnesium and manganese ions have been investigated in aqueous media at 25.0±0.1°C and 0.10 m of ionic strength. In spite of the difference in their electronic configurations, both metal ions formed similar chelate compounds and indicated an optimum coördination number of four. Both metal ions formed kojate chelates whose stabilities are nearly equal to the corresponding metal chelates of β-diketones of the same acidity.

The rate of solvent extraction of some zinc β-diketone chelates

The rate of solvent extraction of some zinc β-diketone chelates

Adducts of copper(II) β-diketone chelates with heterocyclic bases

Equilibrium constants have been determined at room temperature for the 1:1-addition of heterocyclic bases to copper(II) β-diketone chelates in three solvents. Irrespective of changes in the other two variables, the stability of the adducts increases in the order: 1. (a) 2:6:dimethyl-pyridine < 2:methyl-pyridine < pyridine < 4:methyl-pyridine 2. (b) acetylacetonate < benzoylacetonate < ethyl-acetoacetate 3. (c) chloroform < acetone < benzene Variations of stability of the adducts due to changing bases are attributed in part to changes in donor power and in part to steric effects. Variations from one copper compound to another are related to the residual positive charges on the copper atoms of the chelates and solvent affects are thought to be due mainly to changes in the solvation energies of the bases. The addition compounds (CH 3CO·CH·CO 2C 2H 5) 2Cu(C 6H 7N) 2, (CH 3CO·CH·CO 2C 2H 5) 2Cu (C 5H 5N) 2, (C 6H 5CO·CH·COCH 3) 2Cu(C 6H 7N), (C 6H 5CO·CH·COCH 3) 2Cu(C 5H 5N) and (CH 3CO ·CH·COCH 3) 2Cu(C 6H 7N) have been isolated by crystallisation of the β-diketonates from pyridine or 4:methyl-pyridine. Infra-red and visible region absorption spectra indicate a 5:co-ordinated structure for all of these compounds, the 1:2-adducts of bis(ethyl-acetoacetato)copper(II) having the additional molecule of heterocyclic base free in the crystal lattice. The magnetic properties of these adducts are normal, the moment of the copper atom being 1·81–1·85β.

Volatile Characteristics of Some Cobalt(III) and Iron(II) β-Diketone Chelates.

Volatile Characteristics of Some Cobalt(III) and Iron(II) β-Diketone Chelates.

STRUCTURAL DEPENDENCE OF ABSORPTION SPECTRA OF β-DIKETONE CHELATES. II. ULTRAVIOLET1

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTSTRUCTURAL DEPENDENCE OF ABSORPTION SPECTRA OF β-DIKETONE CHELATES. II. ULTRAVIOLET1J. Charette, G. Neirynck, and Ph. TeyssiéCite this: J. Phys. Chem. 1961, 65, 5, 735–739Publication Date (Print):May 1, 1961Publication History Published online1 May 2002Published inissue 1 May 1961https://doi.org/10.1021/j100823a008RIGHTS & PERMISSIONSArticle Views89Altmetric-Citations11LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (600 KB) Get e-Alerts

Structural dependence of absorption spectra of β-diketone chelates—I: Infra-red

The infra-red and ultra-violet spectra of series of β-diketone chelates were recorded and the variations interpreted in terms of type of the bonding involved. The infra-red shifts were related to the stability constants of the complexes formed as measured by Bjerrum's potentiometric method, whereas the ultra-violet spectra seem to depend on the spatial configuration of the orbitals involved. Assignments are proposed for the different absorption bands of the spectra, and resonance effects through the chelate ring are discussed.

Chelates of β-Diketones. I. Enolization, Ionization and Spectra

Chelates of β-Diketones. I. Enolization, Ionization and Spectra

The Infrared Spectra of Some metal Chelates of β-Diketones

The Infrared Spectra of Some metal Chelates of β-Diketones