Luminescent and magnetic properties of europium compounds with cinnamic acid

The temperature dependences of the molar magnetic susceptibility of luminescent europium compounds with cinnamic acid [Eu(Cin)₃] _n and Eu(Cin)₃ · 2D · H₂O (where Cin is the cinnamic acid anion and D is phen (1,10-phenanthroline) or dipy (2,2-dipyridyl)) were studied at temperatures from 300 to 2 K. The molar magnetic susceptibility of the compounds increased in the series Eu(Cin)₃ · 2dipy · H₂O < Eu(Cin)₃ · 2phen · H₂O < [Eu(Cin)₃] _n . The energy distances λ_lum between the ⁷ F ₀ ground level and the ⁷ F ₁ state in the luminescence spectra correlated well with λ_magn obtained from magnetochemical data.     

Preparation and properties of yttrium complexes with alkanodicarboxylic acids

Malonate, succinate and glutarate of yttrium were obtained by dissolving Y(OH)₃ in a solution of the corresponding acid and crystallization, whereas adipate, pimelate, suberate, azelate and sebacate in the reaction of YCl₃ with the ammonium salt of the acid. Yttrium alkanodicarboxylates were prepared as crystalline solids with general formula Y₂O₃.nH₂O, wheren=3, 4, 6, 7. On the basis of IR spectra the way of coordination COO^– - Y³⁺ was established. Yttrium malonate, succinate, glutarate, azelate and sebacate heated lose crystallization water and next anhydrous complexes are transformed to Y₂O₃, whereas yttrium adipate, pimelate and suberate on heating lose some water molecules and, the mono- or dihydrates formed are decomposed to Y₂O₃. The properties of the studied complexes change discretely according to odd or even number of carbon atoms in the chain.

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Zusammenfassung Durch Auflösen von Y(OH)₃ in einer Lösung der entsprechenden Säure und anschliessendem Kristallisieren wurden Yttriummalonat,-succinat und -glutarat dargestellt, das Yttriumadipat, -pimelat-, -suberat und -azelainat und sebacate hingegen in der Reaktion von YCl₃ mit dem Ammoniumsalz der Säure. In Form kristalliner Feststoffe wurden Yttriumalkanodicarboxylate der allgemeinen Formel Y₂L₃,nH₂O mitn=3, 4, 6 bzw. 7 hergestellt. Ausgehend von den IR-Spektren konnte die Art der Koordinierung als COO^– y³⁺ festgestellt werden. Beim Erhitzen geben Ytrriummalonat, -succinat, -glutarat, azelainat und -sebazat ihr Kristallwasser ab, aus den anhydratierten Komplexen bildet sich anschliessend Y₂O₃, während Yttriumadipet, pimelat und -suberat einige Wassermoleküle verlieren und die monooder dihydratierten Formen sich dann zu Y₂O₃ zersetzen. Die Eigenschaften der untersuchten Komplexe variieren eindeutig in Abhängigkeit davon, ob sich in der Kette eine gerade oder ungerade Anzahl von Kohlenstoffatomen befindet.

     

Potentiometric and spectroscopic studies on yttrium(III) complexes of dihydroxybenzoic acids

The equilibrium reactions of yttrium(III) ion with dihydroxybenzoic acids (2,3-dihydroxybenzoic acid (2,3-DHBA) and 3,4-dihydroxybenzoic acid (3,4-DHBA)) (H(3)L) were investigated in aqueous solution by means of potentiometric and spectroscopic methods, in 0.1 mol.l(-1) ionic strength medium at 25 degrees C. The stability constants are reported for YL, YL(HL)(2-) and YL(2)(3-)- type mononuclear complexes. 2,3-DHBA can bind Y(III) ion strongly and the salicylate mode is effective over the acidic pH range. But in higher pH range, 2,3-DHBA and 3,4-DHBA act more efficiently through catecholate groups. The complexes of 2,3-DHBA are more stable than the complexes of 3,4-DHBA.     

Electron charges of bonds and spectroscopic characteristics of organic compounds

Conclusions On the basis of the fact that the electronic shielding of the protons should be related to the value of the electronic charge at the corresponding C-H bond, the chemical shifts in the PMR spectra were compared with the electronic charges of the -bonds of CH in alkanes and cycloalkanes. In this case, the variation of the chemical shifts in structurally different bonds of saturated hydrocarbons and the unusual chemical shift of the protons of cyclopropane were explained.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 7, pp. 1543–1549, July, 1968.     

Synthesis, structure and luminescent properties of yttrium benzene dicarboxylates with one- and three-dimensional structure

The synthesis and structure of two yttrium benzene dicarboxylates, 1 is proportional to [[Y2(C12N2H8)2(C8H4O4)3].H2O], I and 3 is proportional to [[Y2(C12N2H8)2(C8H4O4)3]], II with one- and three-dimensional structure has been accomplished employing hydrothermal methods in the presence of 1,10-phenanthroline. While I is formed with phthalic aid (1,2-BDC), II is formed using isophthalic acid (1,3-BDC). Both the structures appear to have comparable building units, an eight-membered ring and a paddle-wheel arrangement, connected through the carboxylic acid. The 1,10-phenanthroline, connected to Y as a secondary ligand, occupies the inter-chain spaces in I, and projects into the channels in II. The channels in II are inter-connected. Photoluminescence studies indicate that both I and II exhibit a bathochromic shift with respect to the acids (1,2-BDC and 1,3-BDC) and a hypsochromic shift with respect to 1,10-phenanthroline. Both the compounds exhibit reasonable pi...pi interactions.     

NIR spectroscopic properties of aqueous acids solutions

Acid content is one of the important quality attributes in determining the maturity index of agricultural product, particularly fruits. Despite the fact that much research on the measurement of acidity in fruits through non-destructive spectroscopy analysis at NIR wavelengths between 700 to 1,000 nm has been conducted, the same response towards individual acids is not well known. This paper presents NIR spectroscopy analysis on aqueous citric, tartaric, malic and oxalic solutions through quantitative analysis by selecting a set of wavelengths that can best be used to measure the pH of the solutions. The aquaphotomics study of the acid solutions has generated R2 above 0.9 for the measurement of all acids. The most important wavelengths for pH are located at 918-925 nm and 990-996 nm, while at 975 nm for water.     

Characteristic and spectroscopic properties of the Schiff-base model compounds

Two series of conjugated aromatic imines (Schiff-base model compounds) with different central groups and various side-group substitutions have been synthesized and characterized by elemental analysis, differential scanning calorimetry (DSC) technique, hydrogen nuclear magnetic resonance (¹H NMR), Fourier transform infrared (FTIR) and ultra-violet and visible light (UV–vis) spectroscopy measurements. The UV–vis absorption of solutions of these compounds in dimethylacetamid (DMA), chloroform and methanol was investigated in the optical range from 240 to 450 nm, where two distinct absorption bands: at 250–280 and 315–360 nm with the different level of absorption have been observed. The influence of compound molecular structure and polarity of solvent on the absorption spectra and the possible optical transitions have been discussed. Structure of diamines in the azomethine models fundamentally affected their spectroscopic properties and conjugation of π-electrons.     

Extraction of yttrium with molten monocarboxyl acids

A method has been developed for the determination the fluorine content from the induced activity of the short-lived nuclide²⁰F (T-11.4 s; E_λ=1.63 MeV) formed by the reaction¹⁹F(d,p)²⁰F. The method has been employed to determine fluorine in zirconium using a small-size 3 MeV deuteron accelerator for activation. The lower limit of fluorine detection is 0.5 ppm at the average deteron current of 0.3 μA.     

Formate ion: structure and spectroscopic properties

The formate anion HCOO(-) is present in a multitude of systems of relevance, and it is characterized by its plasticity, adopting several different structures. This work provides a theoretical study of the ion focused on two of these structures, a crystal and an isolated species. Crystals of sodium formate and ammonium formate are studied using CASTEP, a solid-oriented computing package. Individual molecules of the same systems and of the formate and ammonium ions are also studied, using the Gaussian code at the MP2/aug-cc-pvTZ level. All theoretical calculations are contrasted by comparison to observed infrared spectra, recorded by using different techniques. In addition, a topological analysis of the bonding properties of the isolated molecules is presented.     

Some spectroscopic properties of cyclic organolead compounds I

The nuclear magnetic resonance and infrared properties of two new cyclic organolead compounds are discussed.     

Synthesis,crystal structure and properties of copper(II) complexes with triethanolamine and carboxylic acids (succinic,salicylic, cinnamic)

Transition Metal Chemistry - The interaction of triethanolamine (TEA) with Cu(II) salts of salicylic, cinnamic and succinic acids was studied for the first time. The structure of the synthesized...     

Chelation of manganese(II) with quinaldic acids. An NMR relaxation study

Manganese(II) enhanced spin-lattice relaxation rates (1/T_1p) of ¹H and ¹³C nuclei in quinoline-2-carboxylic acid, 8-methoxyquinoline-2-carboxylic acid, 8-hydroxyquinoline-2-carboxylic acid, 8-aminoquinoline-2-carboxylic acid, and 6-(hydroxymethyl)pyridine-2-carboxylic acid were measured in aqueous solution at various temperatures. Relative metal-nucleus distances were calculated from the r^?6 dependence of 1/T_1p. The results indicate that the Mn²⁺ ion in the 8-methoxyquinaldic acid chelate is coordinated to the carboxyl oxygen atom and the nitrogen atom but not t the methoxyl oxygen atom.     

Synthesis,structure, and magnetism of four polyoxomolybdate compounds containing yttrium and ytterbium

Four new polyoxometalate compounds consisting of Anderson-type anions and trivalent rare earth (RE) cations, [RE ₂ (H₂O)₁₄M(OH)₆Mo₆O₁₈][M(OH)₆Mo₆O₁₈]?·?14H₂O, RE?=?Y, M?=?Cr(1), Al(2); RE?=?Yb, M?=?Al(3), Cr(4), have been synthesized in aqueous solution and characterized by elemental analyses, infrared (IR) spectra, thermal gravimetric (TG) analyses, and single crystal X-ray diffraction. [M(OH)₆Mo₆O₁₈]^3? as a bidentate ligand coordinates to two RE ^{3 +} , forming a double-supported cation [RE ₂(H₂O)₁₄M(OH)₆Mo₆O₁₈]³⁺. The cations and other [M(OH)₆Mo₆O₁₈]^3? anions in the crystals are linked via hydrogen bonding interactions tightly, forming four supramolecular compounds. The magnetic properties of 1, 3, and 4 have been examined by measuring their magnetic susceptibilities from 2 to 300?K.     

具有Dawson结构的钼钒磷杂多酸的制备和性质研究

本文报道用改良的分步处理合成方法, 直接制备了五种未见报道的2:18系列钼钒磷杂多酸, 详细考察了它们的生成条件. 经元素分析、电位滴定和差热热重分析确定阴离子的组成分别为[P2Mo17VO62]^7^-,[P2Mo16V2O62]^8^-,[P2Mo15V3O62]^9^-, [P2Mo14V4O62H2]^8^-, [P2Mo13V5O62H2]^9^-. 对五种杂多酸的热化学性质和碱度进行了讨论. 根据紫外、红外及X射线衍射结果讨论了它们的结构, 表明都属于具有Dawson结构的杂多化合物.