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Artigos de revistas sobre o tema "Alkaline-Earth metal cations"

Autor: Grafiati
Publicado: 15 de fevereiro de 2025

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1

Ustimova, M. A., A. Yu Lebedeva, Yu V. Fedorov, D. V. Berdnikova e O. A. Fedorova. "FRET-based metal ion sensing by a crown-containing bisstyryl dye". New Journal of Chemistry 42, n.º 10 (2018): 7908–13. http://dx.doi.org/10.1039/c8nj00205c.

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2

Tsuzuki, Seiji, Toshihiko Mandai, Soma Suzuki, Wataru Shinoda, Takenobu Nakamura, Tetsuya Morishita, Kazuhide Ueno et al. "Effect of the cation on the stability of cation–glyme complexes and their interactions with the [TFSA]− anion". Physical Chemistry Chemical Physics 19, n.º 28 (2017): 18262–72. http://dx.doi.org/10.1039/c7cp02779f.

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3

Novikov, G. V., N. V. Lobus, N. A. Shulga e O. Yu Bogdanova. "Adsorption of Rare Earth Metal Cations by Base Metal Sulfides in the Broken Spur and TAG Hydrothermal Fields, Atlantic Ocean". Литология и полезные ископаемые, n.º 1 (1 de janeiro de 2023): 38–49. http://dx.doi.org/10.31857/s0024497x23010068.

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The article presents the results of sorption of rare earth metal cations on samples of deepsea polymetallic sulfides of the hydrothermal fields of the Broken Spur and TAG of the Mid-Atlantic Ridge. The main minerals of these samples were respectively marcasite, pyrrhotine, pyrite, sphalerite and chalcopyrite, pyrite, and marcasite. It has been established that these sulfide minerals of iron, copper and zinc are natural adsorbents. The exchange capacity of sulfide minerals for rare earth metal cations is in the range of 0.006‒0.061 mg-eq/g. The exchange complex of sulfide minerals consists of cations of alkaline, alkaline-earth metals and basic cations of metals of the crystal lattice – Fe, Zn, Cu (in very limited quantities). The mechanism of absorption of rare earth metal cations is ion-exchange, equivalent to the exchange cations of sulfide minerals. It was found that in the composition of sulfide minerals, rare earth metal cations are almost completely in sorbed form (more than 90% of the total amount); The chemically bound form can be, apparently, only for Lu and Dy cations. The mineral composition of sulfide deposits is preserved in the products of exchange reactions, new phases do not appear.
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4

Usenik, Andrea, Matija Modrušan, Katarina Leko, Jakov Borovec, Sven Marinac, Lucija Hok, Nikola Cindro et al. "A Combined Thermodynamic and Computational Study of Alkaline Earth Metal Cations Complexation by a Fluorescent Calix[4]arene Receptor". International Journal of Molecular Sciences 26, n.º 3 (31 de janeiro de 2025): 1264. https://doi.org/10.3390/ijms26031264.

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Complexation of alkaline earth metal cations with fluorescent tertiary-amide lower-rim calix[4]arene derivative bearing two phenanthridine moieties was studied experimentally (UV spectrophotometry, fluorimetry, isothermal microcalorimetry, NMR spectroscopy) and computationally (classical molecular dynamics and DFT calculations) at 25 °C. The complexation reactions were studied in acetonitrile, methanol, and ethanol, whereby the solvent effect on cation-binding processes was particularly addressed. The complex stability constants and standard reaction thermodynamic quantities (Gibbs energies, enthalpies, and entropies) were determined. The receptor exhibited particularly high affinity towards alkaline earth metal cations in acetonitrile, with peak affinity for Ca2+. The stability of all complexes was significantly lower in ethanol and methanol, where the most stable complex was formed with Sr2+. The decrease in cation-binding abilities was a consequence of the differences in solvation of the reactants and products of the complexation reactions (involving inclusion of the solvent molecule in the calixarene cone), cation charge density, as well as the cation–ligand binding site compatibility. The reactions were enthalpically controlled in acetonitrile, whereas in methanol and ethanol, the binding processes were endothermic and thus entropy driven. The results of 1H NMR measurements, MD simulations, and DFT calculations provided an insight into the structure of the complexes and the corresponding adducts with solvent molecules, as well as the structural aspects behind the differences in complexation thermodynamics. Due to the significant increase in its fluorescence upon cation binding, the studied calixarene derivative was proven to be a promising luminescent sensor for alkaline earth metal cations.
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5

Vetrova, Daria A., e Sergey A. Kuznetsov. "Study of alkaline earth metals cations influence on the electrochemical behaviour of the Ti (IV) / Ti (III) redox couple in the CsCl — CsF melt". Transactions of the Kоla Science Centre of RAS. Series: Engineering Sciences 13, n.º 1/2022 (27 de dezembro de 2022): 51–57. http://dx.doi.org/10.37614/2949-1215.2022.13.1.008.

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The influence of the alkaline earth metal cations (Mg2+, Ca2+, Sr2+ и Ва2+) on the charge transfer kinetics of the Ti (IV) / Ti (III) redox couple in melts of alkali metal halides was studied by cyclic voltammetry method. Standard rate constants of charge transfer have been determined by the Nicholson method. The activation energies of the charge transfer process in the CsCl — CsF (10 wt. %) — K2TiF6 melt with the addition of alkaline earth metal cations were calculated.
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6

Sviben, Igor, Nives Galić, Vladislav Tomišić e Leo Frkanec. "Extraction and complexation of alkali and alkaline earth metal cations by lower-rim calix[4]arene diethylene glycol amide derivatives". New Journal of Chemistry 39, n.º 8 (2015): 6099–107. http://dx.doi.org/10.1039/c5nj00805k.

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The metal-ion extraction abilities of calix[4]arene derivatives1and2are largely dependent on the type of the amide group forming the cation-binding site. Tertiary-amide derivative2was shown to be an excellent extractant for most alkali and alkaline earth cations.
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7

Zhu, Ming, Hongfang Ma, Mingjing Wang, Zhihua Wang e Adel Sharif. "Effects of Cations on Corrosion of Inconel 625 in Molten Chloride Salts". High Temperature Materials and Processes 35, n.º 4 (1 de abril de 2016): 337–45. http://dx.doi.org/10.1515/htmp-2014-0225.

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AbstractHot corrosion of Inconel 625 in sodium chloride, potassium chloride, magnesium chloride, calcium chloride and their mixtures with different compositions is conducted at 900°C to investigate the effects of cations in chloride salts on corrosion behavior of the alloy. XRD, SEM/EDS were used to analyze the compositions, phases, and morphologies of the corrosion products. The results showed that Inconel 625 suffers more severe corrosion in alkaline earth metal chloride molten salts than alkaline metal chloride molten salts. For corrosion in mixture salts, the corrosion rate increased with increasing alkaline earth metal chloride salt content in the mixture. Cations in the chloride molten salts mainly affect the thermal and chemical properties of the salts such as vapor pressure and hydroscopicities, which can affect the basicity of the molten salt. Corrosion of Inconel 625 in alkaline earth metal chloride salts is accelerated with increasing basicity.
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8

Fransen, John R., e Philip J. Dutton. "Cation binding and conformation of octafunctionalized calix[4]resorcinarenes". Canadian Journal of Chemistry 73, n.º 12 (1 de dezembro de 1995): 2217–23. http://dx.doi.org/10.1139/v95-275.

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The preparations of four calix[4]resorcinarene esters and two calix[4]resorcinarene amides are reported. The logarithms of association constants have been determined by the picrate extraction method for a variety of metal cations, including alkali metal, alkaline earth, lanthanum, and silver cations. Strong binding toward silver ion, and selectivity amongst the alkaline earth cations, was observed for the octa-α-(diethyl acetamide) 3c. Flattened cone conformations have been established for both C-undecylcalix[4]resorcinarene octa-α-(methyl acetate), 3a, and octa-α-(diethyl acetamide), 3c, in chloroform solutions at 200 K. Dynamic nuclear magnetic resonance was used to identify rapid conformational interconversions of both 3a and 3c corresponding to pseudorotation between flattened cone conformations. The silver complex of 3c also exhibits pseudorotation; however, the activation barrier was observed to increase from 42 kJ mol−1 in the free ligand to 49 kJ mol−1 in the complex. The NMR data indicate that the metal cation binding occurs in a symmetrical fashion using two pairs of binding sites that are disposed across the macrocyclic ring from one another. Considering these data it is concluded that four carbonyl functions are involved in the binding of a metal cation in a 1:1 complex with the ligand. Key words: resorcinarene, picrate, association constant, dynamic NMR, pseudorotation.
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9

Bortun, Anatoly I., Lyudmila Bortun, Abraham Clearfield, Enrique Jaimez, María A. Villa-García, José R. García e Julio Rodríguez. "Synthesis and Characterization of the Inorganic Ion Exchanger Based on Titanium 2-carboxyethylphosphonate". Journal of Materials Research 12, n.º 4 (abril de 1997): 1122–30. http://dx.doi.org/10.1557/jmr.1997.0155.

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An inorganic ion exchanger based on titanium 2-carboxyethylphosphonate (TiPC) has been synthesized by reaction between solutions of TiCl3 and 2-carboxyethylphosphonic acid at elevated temperature. The solid was characterized by chemical analysis, 31P MAS NMR, x-ray powder diffraction, IR spectroscopy, and TG analysis. It was found that TiPC is a highly crystalline layered solid with the interlayer distance 13.1 Å, and exhibits a high thermal stability. The intercalation of n-alkylamines and the ion exchange properties of TiPC toward alkali, alkaline earth, and some transition metal cations have been studied. The exchanger shows high affinity to alkaline earth metal cations and some di- and trivalent cations.
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10

GUAN, QING-MEI, YAN HAN e ZHONG-ZHI YANG. "MOLECULAR DYNAMICS STUDIES ON Fe2+, Co2+, AND Ni2+ AQUEOUS SOLUTIONS BASED ON ABEEM/MM FLUCTUATING CHARGE MODEL". Journal of Theoretical and Computational Chemistry 07, n.º 06 (dezembro de 2008): 1187–201. http://dx.doi.org/10.1142/s0219633608004519.

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Based on atom-bond electronegativity equalization method fused into molecular mechanics (ABEEM/MM), the intermolecular potential for transition metal ion Fe 2+, Co 2+, and Ni 2+ cations in water has been derived. Parameters for the effective interaction between a cation and a water molecule were determined by reproducing the ab initio results. Many structural and dynamic properties of Fe 2+(aq.), Co 2+(aq.), and Ni 2+(aq.) were studied using these potential parameters. Strong influences of the twofold charged cations on the structures of the hydration shells and some other properties of aqueous ionic solutions are discussed and compared with the results of a previous study of alkali metal and alkaline-earth metal cations in water. At the same time, comparative study of the hydration properties of each cation is also discussed. This work demonstrates that ABEEM/MM provides a useful tool in the exploration of the hydration of transition metal cations in water.
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11

Vetrova, Daria A., e Sergey A. Kuznetsov. "(Digital Presentation) Charge Transfer Kinetics of the Ti(IV)/Ti(III) Redox Couple in the Cesium Chloride-Cesium Fluoride Melt with Addition of Alkaline Earth Metal Cations". ECS Transactions 109, n.º 14 (30 de setembro de 2022): 95–103. http://dx.doi.org/10.1149/10914.0095ecst.

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The electrochemical behavior of the Ti(IV)/Ti(III) redox couple in the CsCl-CsF(10 wt.%)-K2TiF6 melt was studied. The standard rate constants of charge transfer for the Ti(IV)/Ti(III) redox couple in CsCl-CsF(10 wt.%)-K2TiF6-based melts with additions of alkaline earth metal cations (Mg2+, Ca2+, Sr2+ and Ba2+) were determined by cyclic voltammetry method. The activation energies of charge transfer process were calculated. The linear dependence of charge transfer rate constants on the ionic potential of alkaline earth metal cations was found.
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12

Kudrevatykh, Alexandra A., e Lyubov S. Klimenko. "Synthesis and properties of halogen-containing macrocyclic anthraquinone imines – chemosensors for metal cations". Yugra State University Bulletin 16, n.º 2 (9 de outubro de 2020): 50–56. http://dx.doi.org/10.17816/byusu2020250-56.

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New crown-containing imines of 1-hydroxyanthraquinone with chlorine and fluorine atoms in the anthraquinone nucleus were synthesized. For the first time, the thermal and photochemical stages of synthesis are carried out in the solid state (without a solvent). The features of complexation of new chemosensors with cations of alkaline and alkaline earth metals were studied by spectrophotometry. It is shown that the introduction of halogen atoms in the anthraquinone nucleus leads to a significant spectral response. The obtained compounds are tested as components of test systems for visual determining the presence of alkaline earth metal cations in aqueous media.
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13

Shen, Fang-Fang, Jiang-Lin Zhao, Kai Chen, Jing Xu, Yuan Wang, Zi-Yi Hua, Lu Wu, Min-Dong Chen, Yun-Qian Zhang e Zhu Tao. "Coordination and supramolecular assemblies of mono-hydroxylated octamethylcucurbit[6]uril with alkali and alkaline earth metal ions in the presence of polychloride cadmium anions". CrystEngComm 19, n.º 28 (2017): 4017–24. http://dx.doi.org/10.1039/c7ce00751e.

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14

Fedorova, O. A., Y. V. Fedorov, E. N. Andrjukhina, S. P. Gromov e M. V. Alfimov. "Cation-dependent photochromic properties of novel ditopic receptors". Pure and Applied Chemistry 75, n.º 8 (1 de janeiro de 2003): 1077–84. http://dx.doi.org/10.1351/pac200375081077.

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Novel crown-containing 2-styrylbenzothiazoles were prepared to obtain optical ditopic receptors that can bind alkaline-earth metal cations by a crown ether fragment and could serve as host for the heavy metal cations and proton owing to the presence of the heterocyclic part. Photochemical transformations of the ditopic receptors depend on the type of metal cations present in solution. They include trans–cis-isomerization, [2+2]-cycloaddition, and electrocyclic reaction.
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15

Tsuji, Masamichi, e Yasuo Tanaka. "Spectroscopic study of a cryptomelane-type manganic acid exchanged by divalent transition-metal cations". Journal of Materials Research 16, n.º 1 (janeiro de 2001): 108–14. http://dx.doi.org/10.1557/jmr.2001.0020.

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A cryptomelane-type manganic acid (CMA) exchanged by divalent transition-metal cations was studied by means of x-ray diffraction, electron microscopic observation, electron spin resonance, infrared spectra, and electron spectroscopy for chemical analysis. Especially the last three techniques were decisive for the chemical speciation of manganese oxide systems. The findings clearly eliminated a redox process as the principal process for cation uptake in the α–MnO2 phase. Transition-metal cations are stoichiometrically exchanged on this material on an equivalent basis similarly with alkali and alkaline-earth metal cations, except Fe2+. The last ion is oxidized to Fe3+ through a redox reaction with Mn3+ in the a–MnO2. The CMA is a mixed-valence compound represented by H2Mn2IIIMn6IVO16 2.3H2O. Two moles of tunnel protons are exchangeable to give 2.70 mequiv/g for the calculated ion-exchange capacity.
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16

KOH, K. "Site selectivity of alkaline earth metal cations in zeolite A". Journal of Catalysis 98, n.º 1 (março de 1986): 126–30. http://dx.doi.org/10.1016/0021-9517(86)90302-7.

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17

Wankowski, James L., Michael J. Kaul e Mark L. Dietz. "Micelle formation as a factor influencing the mode(s) of metal ion partitioning into N-alkylpyridinium-based ionic liquids (ILs): implications for the design of IL-based extraction systems". Green Chemistry 19, n.º 23 (2017): 5674–82. http://dx.doi.org/10.1039/c7gc02338c.

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In the extraction of alkali and alkaline earth cations by a crown ether into certain N-alkylpyridinium-based ILs, the balance between neutral complex/ion-pair partitioning and ion exchange is significantly altered by the formation of micelles in the aqueous phase involving the IL cation.
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18

Yin, Jun, Ying Hu e Juyoung Yoon. "Fluorescent probes and bioimaging: alkali metals, alkaline earth metals and pH". Chemical Society Reviews 44, n.º 14 (2015): 4619–44. http://dx.doi.org/10.1039/c4cs00275j.

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This review highlights the recent advances that have been made in the design and bioimaging applications of fluorescent probes for alkali metals, alkaline earth metal cations and for pH determination within biological systems.
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19

Koepf, Matthieu, Jesse J. Bergkamp, Anne-Lucie Teillout, Manuel J. Llansola-Portoles, Gerdenis Kodis, Ana L. Moore, Devens Gust e Thomas A. Moore. "Design of porphyrin-based ligands for the assembly of [d-block metal : calcium] bimetallic centers". Dalton Transactions 46, n.º 13 (2017): 4199–208. http://dx.doi.org/10.1039/c6dt04647a.

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20

Wu, L., Y. Zhang, W. W. Su, Y. F. Kong e J. J. Xu. "Structural study of nonlinear optical borates K1−xNaxSr4(BO3)3 (x≤0.5)". Powder Diffraction 25, S1 (setembro de 2010): S11—S16. http://dx.doi.org/10.1154/1.3478412.

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X-ray powder diffraction was used for the structural study of nonlinear optical borates K1−xNaxSr4(BO3)3 (x≤0.5). Results show that up to 50% K+ can be substituted by Na+ in orthorhombic K1−xNaxSr4(BO3)3. Isolated BO3 triangles in the Na-substituted compound constrict to adjust to a local distribution of alkali-metal atoms, which explains the large range of structural homogeneity. An expansion of the c axis in a unit cell with increasing Na substitution was found probably caused by the tilted BO3 triangles and asymmetric distortion of (K/Na)O8 polyhedra. As the ratio of ionic radii of alkaline-earth and alkali-metal cations decreases and the electronegative difference between alkaline-earth and alkali-metal cations increases, the crystal system of MM′4(BO3)3 borates changes from cubic to orthorhombic and then to monoclinic.
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21

Wang, Cheng-Hui, Qing Tang, Jing Zhang, Yu-Qing Yao, Xin Xiao, Ying Huang e Zhu Tao. "Alkaline earth cation-mediated photoluminescent complexes of thioflavin T with twisted cucurbit[14]uril". New Journal of Chemistry 42, n.º 11 (2018): 9244–51. http://dx.doi.org/10.1039/c7nj04115b.

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The introduction of alkaline earth metal cations into the tQ[14]–ThT interaction system leds to the precipitation of solid tQ[14]/ThT/AE2+ interaction products, which emitted strong blue fluorescence.
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22

Yao, Yao, Jin-Ting Ye, Xiang Li, Yuan Zhang, Si-Nan Zhu e Yong-Qing Qiu. "Regulating the NLO response of anthraquinone-supported thiourea-linked crown ether macrocycle by introducing metal cations: A DFT study". Journal of Theoretical and Computational Chemistry 19, n.º 05 (4 de julho de 2020): 2050017. http://dx.doi.org/10.1142/s0219633620500170.

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Recently, an anthraquinone-supported thiourea group linking a 1-aza-18-crown-6 macrocycle L has been the subject of extensive attention due to the perfect affinity towards metal cations. This work systematically researched the effects of different metal cations ([Formula: see text], [Formula: see text], [Formula: see text], [Formula: see text], [Formula: see text] and [Formula: see text]) on the second-order nonlinear optical (NLO) properties of macrocycle L by density functional theory (DFT). DFT calculations revealed that the values of first hyperpolarizabilities ([Formula: see text] decrease significantly when alkaline earth metal cations ([Formula: see text] and [Formula: see text]) were injected into macrocycle L due to the smaller charge transfer (CT) transition and larger transition energy. Conversely, the variations of [Formula: see text] values in alkali metal cations ([Formula: see text] and [Formula: see text] and transition metal cations ([Formula: see text] and [Formula: see text]) derivatives are not obvious compared to the [Formula: see text] value of macrocycle L. Therefore, the NLO properties of macrocycle can be effectively regulated by alkaline earth metal cations. Furthermore, we found that the [Formula: see text] value of anion-controlled complex Na(L)(ClO4) is larger than that of L*Na+ complex because the anion [Formula: see text] improves the planarity of anthraquinone-supported thiourea group leading to the enhancement of the CT ability. In addition, the influence of frequency-dependent on the first hyperpolarizabilities is weak for the current systems. Hence, we look forward to the conception of this work will offer a fundamental guideline and reference for further research for novel NLO materials.
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23

Fan, Li-Tao, Ying Li, Di Wu, Zhi-Ru Li e Chia-Chung Sun. "Structural Characteristics and Large Non-Linear Optical Responses of New Alkaline Earth-Based Alkalides". Australian Journal of Chemistry 65, n.º 2 (2012): 138. http://dx.doi.org/10.1071/ch11334.

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A series of M2+(H5Aza222)–M′– (M = Be, Mg, Ca; M′ = Li, Na, K) alkalides that contain alkaline earth metal cations complexed by the H5Aza222– cage have been investigated using the CAM-B3LYP method. These alkaline earth-based alkalides not only present unusual structural features but also exhibit extraordinarily large static first hyperpolarizabilities (β0) up to 1.98 × 105 au. By comparing the β0 values among alkalides with various complexants, the Aza222 cage is found to be preferable to the previously investigated calix[4]pyrrole and n6adamanzane (n = 2, 3) complexants in enhancing the first hyperpolarizabilities of alkalides. In addition, the relationships between the β0 values of M2+(H5Aza222)–M′– and the atomic number of the M′– anion, the atomic number of the M2+ cation, and the M–M′ distance are explored.
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Wang, Guangyu, Ao-Jin Wang e Kun-Sheng Hu. "Tryptophan fluorescence quenching by alkaline earth metal cations in deionized bacteriorhodopsin". Journal of Photochemistry and Photobiology B: Biology 59, n.º 1-3 (dezembro de 2000): 38–41. http://dx.doi.org/10.1016/s1011-1344(00)00132-9.

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25

Meng, Lingbiao, e Zijing Lin. "Complexations of alkali/alkaline earth metal cations with gaseous glutamic acid". Computational and Theoretical Chemistry 1039 (julho de 2014): 1–10. http://dx.doi.org/10.1016/j.comptc.2014.04.016.

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Inouye, Masahiko, e Yoshiyuki Noguchi. "Selective Coloration of Cryptand - Type Spirobenzopyran for Alkaline - Earth - Metal Cations". Molecular Crystals and Liquid Crystals Science and Technology. Section A. Molecular Crystals and Liquid Crystals 246, n.º 1 (maio de 1994): 187–89. http://dx.doi.org/10.1080/10587259408037811.

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Vasil’ev, V. G., M. I. Buzin, G. G. Nikiforova, N. M. Belomoina, E. G. Bulycheva e V. S. Papkov. "Modification of sulfonated polyphenylquinoxaline by alkali and alkaline earth metal cations". Doklady Physical Chemistry 466, n.º 2 (fevereiro de 2016): 29–31. http://dx.doi.org/10.1134/s0012501616020019.

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28

Anantanarayan, Ashok, e Thomas M. Fyles. "Polycarboxylate diaza crown ethers derived from R,R-(+)-tartaric acid: synthesis and complexation of metal ions". Canadian Journal of Chemistry 68, n.º 8 (1 de agosto de 1990): 1338–51. http://dx.doi.org/10.1139/v90-206.

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The synthesis and complexation properties of polycarboxylate diaza crown ethers based on R,R-(+)-tartaric acid are described. Cesium carbonate mediated macrocyclization of a bis-tosylamide precursor with a bis-tosylate precursor provided the protected crown ethers. Photochemical deprotection of the tosylamides and hydrolysis of the carboxamides yielded dicarboxylic and tetracarboxylic acid derivatives of 1,10-diaza-18-crown-6. N-Methylenecarboxylate (N-acetate) derivatives were prepared by N-alkylation with bromoacetic acid. The synthetic and purification procedures developed provide samples of the ligands in a metal-free form. Acidity and stability constants for complexation of alkali metal, alkaline earth, late- and post-transition metal cations were determined by potentiometric titration. The ligands form complexes which show enhancement of stability by charge–charge and chelate interaction with the carboxylates. In comparison with crown ether polycarboxylates these aza crown ethers showed a selectivity for softer metal ions relative to alkali and alkaline earth metal ions. N-Methylenecarboxylate chelate ligands were found to bind almost all types of metal ions, due to a highly co-operative array of charge–charge, chelate and crown ether interactions. Keywords: aza crown ether synthesis, tartaric acid, potentiometric titration, cation complexation, aminocarboxylate complexone.
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29

Jimenez-Lopez, A., A. L. Garcia-Ponce e L. Moreno-Real. "Intercalation of cations into niobyl-vanadyl phosphate by redox reactions". Canadian Journal of Chemistry 68, n.º 9 (1 de setembro de 1990): 1616–20. http://dx.doi.org/10.1139/v90-249.

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Mixed niobyl-vanadyl phosphate, Nb0.86V0.14OPO4•2.7H2O, intercalates various alkali, NH4+ alkaline earth, Zn2+, Cd2+, transition metal, and H+ cations by topotactic redox reactions. All the intercalates thus obtained are tetragonal (a = b = 6.44 Å, c lower than in the precursor solid). The degree of hydrolysis of the mixed phosphate in the intercalate in the redox reactions is always lower than 1%. Upon reduction, the cation exchange capacity (CEC) of the intercalates is 71 mequiv. per 100 g of solid calcined at 1000 °C. Keywords: mixed niobyl-vanadyl phosphate, layered compounds, redox intercalation.
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30

Kang, Kevin, Jack Fuller, Alexander H. Reath, Joseph W. Ziller, Anastassia N. Alexandrova e Jenny Y. Yang. "Installation of internal electric fields by non-redox active cations in transition metal complexes". Chemical Science 10, n.º 43 (2019): 10135–42. http://dx.doi.org/10.1039/c9sc02870f.

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Experimental and computational study quantifying internal electric fields in synthetic systems using transition metal Schiff base complexes functionalized with a crown ether unit containing a mono- or dicationic alkali or alkaline earth metal ion.
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31

Mokhtari, Bahram, e Kobra Pourabdollah. "Extraction of s-block metals by nano-baskets of calix[4]crown-3". Canadian Journal of Chemistry 90, n.º 6 (junho de 2012): 560–66. http://dx.doi.org/10.1139/v2012-020.

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Three kinds of nano-baskets including 1,2-alternate and cone conformers of di-ionizable p-tert-butylcalix[4]arene-1,2-crown-3 and the cone conformer of p-tert-butylcalix[4]arene-1,2-thiacrown-3 were synthesized and the competitive solvent extractions of alkali and alkaline earth metal cations were studied. The novelty of this study is including three binding units of the calixarene’s bowl, the crown ether’s ring, and electron-donor ionizable moieties in a unique scaffold, in which their sizes were selected based upon their complexation ability to show equal binding tendency towards the cations. The objective of this work is to assess the extraction efficiency, selectivity, and pH1/2 of such complexes. The results of solvent extraction experiments indicated that these compounds were effective extractants of alkali and alkaline earth metal cations. Their selectivities were greatly influenced by the acidity of the solution and the conformations of the calixcrown. One conformer was highly selective to Na+ and the other to Ba2+ in acidic and basic solutions, respectively.
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32

Tsukube, Hiroshi, Hayamitsu Adachi e Shiro Morosawa. "Multiarmed macrocyclic polyamines exhibiting unique cation-binding and cation-transport properties toward alkali-metal and alkaline-earth-metal cations". Journal of Organic Chemistry 56, n.º 25 (dezembro de 1991): 7102–8. http://dx.doi.org/10.1021/jo00025a028.

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33

Clegg, William, e Gary S. Nichol. "Investigating the Competitive Factors of Metal–Anion Coordination, Coordination by Water, and Hydrogen Bonding in Complexes of Cyanuric Acid with the Alkaline Earth Metals". Crystals 14, n.º 1 (22 de janeiro de 2024): 98. http://dx.doi.org/10.3390/cryst14010098.

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A survey of the trends in metal–ligand coordination and hydrogen bonding has been carried out on complexes of singly deprotonated cyanuric acid CY− and alkaline earth metals, synthesised from aqueous solution and characterised by X-ray crystallography. The involvement of cyanurate in metal coordination increases from Mg through Ca and Sr to Ba relative to coordination by water, in parallel with increasing ionic radius and coordination number. The incidence of the bridging of metal centres by both water and cyanurate also increases in this series. The Mg complex [Mg(H2O)6][CY]2·2H2O contains hexaaqua-coordinated cations, uncoordinated CY− anions, and additional water molecules. The Ca and Sr complexes {[Ca(CY)(H2O)3][CY]}∞ and {[Sr(CY)2(H2O)4]}∞ feature polymeric chains of coordinated metal ions, the Ca complex with uncoordinated anions and the Sr complex with all potential ligands coordinated. The Ba complex {[Ba(CY)2(H2O)2]}∞ has a two-dimensional coordination network. Extensive hydrogen bonding plays a key role in generating a three-dimensional network in all four structures. The competition between cyanurate and water for coordination to the alkaline earth metal cations, and that between coordination and the hydrogen bonding propensities of the cyanurate anion, appear to be finely balanced, with the structural outcomes depending on the relative sizes and degrees of hardness of the four cations of the group.
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34

Toel, Jun-Ichi. "Separation of alkaline earth metal cations on low capacity chemically bonded cation exchange silica gels". Journal of High Resolution Chromatography 10, n.º 2 (fevereiro de 1987): 111–12. http://dx.doi.org/10.1002/jhrc.1240100217.

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35

Harrowfield, JM, BW Skelton e AH White. "Structural Studies of Alkaline Earth Metal Picrates". Australian Journal of Chemistry 48, n.º 7 (1995): 1333. http://dx.doi.org/10.1071/ch9951333.

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Room-temperature, single-crystal X-ray structure determinations are recorded for alkaline earth metal picrates , M( pic )2.nH2O(M = Mg, Sr , Ba ; Hpic = 2,4,6-trinitrophenol, HOC6H2(NO2)3), all crystallized from aqueous solution. Magnesium picrate ,shown to be the nonahydrate, Mg( pic )2.9H2O, forms monoclinic crystals, space group P21/c, a 15.023(3), b 6.718(4), c 26.516(2) Ǻ, β 109.55(1)°, Z = 4 f.u .,conventional R on |F| was 0.049 for No = 4062 'observed' (I > 3σ(I)) reflections. The structure, unusually among the main group metal picrates studied so far, has no coordinative interaction between the metal and the picrate anion; the complex may be formulated as [Mg(OH2)6] ( pic )2.3H2O, with the metal present as the hexaaqua species (Mg-O 2.043(2)-2.077(2)Ǻ). The picrate ions are stacked end to end, presumably as a result of charge-transfer interactions, parallel to b, with side-by-side stacks forming a sheet along ab, and successive sheets are interleaved by layers of cations and water molecules. The strontium salt is a pentahydrate , monoclinic, C2/c, a 24.515(6), b 10.142(6), c 17.932(4) Ǻ, β 98.76(2)°, Z = 8 f.u .; R was 0.046 for No 2731. The complex is a linear polymer, [(H2O)3Sr(O,O′- pic )2(μ-OH2)](∞|∞).H2O, with eight-coordinate (SrO8) strontium. The barium salt is a hexahydrate , also a linear polymer [(H2O)5Ba(O,O′-pic )( O,O′,μ-O″-pic )]∞|∞).H2O, the ten-coordinate (BaO10) barium environment comprising the five water molecules, a pair of picrates, bidentate /chelating via the phenolic oxygen and a 2-nitro group oxygen, with one of the picrates from an adjacent metal atom offering an additional 4-nitro group oxygen, this bridging successive barium atoms. The complex is triclinic, Pī , a 15.120(5), b 11.633(3), c 6.766(3) Ǻ, α 87.24(3), β 79.16(3), γ 84.88(2)°, Z = 2 f.u .; R was 0.027 for No 3904. Repeated attempts to obtain crystals of beryllium picrate suitable for an X-ray structure determination were unsuccessful.
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36

Sarazin, Yann, Bo Liu, Thierry Roisnel, Laurent Maron e Jean-François Carpentier. "Discrete, Solvent-Free Alkaline-Earth Metal Cations: Metal···Fluorine Interactions and ROP Catalytic Activity". Journal of the American Chemical Society 133, n.º 23 (15 de junho de 2011): 9069–87. http://dx.doi.org/10.1021/ja2024977.

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37

Shahangi, Fereshte, Alireza Najafi Chermahini, Hossein Farrokhpour e Abbas Teimouri. "Selective complexation of alkaline earth metal ions with nanotubular cyclopeptides: DFT theoretical study". RSC Advances 5, n.º 3 (2015): 2305–17. http://dx.doi.org/10.1039/c4ra08302d.

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The interaction of alkaline earth metal cations including Be2+, Mg2+, Ca2+, Sr2+ and Ba2+ with cyclic peptides containing 3 or 4 (S) alanine molecules (CyAla3 and CyAla4) was investigated by density functional theory (DFT-CAM-B3LYP and DFT-B3LYP).
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38

Izatt, R. M., R. L. Bruening e M. B. Borup. "Heavy Metal Removal Using Bound Macrocycles". Water Science and Technology 23, n.º 1-3 (1 de janeiro de 1991): 301–8. http://dx.doi.org/10.2166/wst.1991.0428.

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Aza macrocycles bound to silica gel beads were found to selectively remove heavy metal cations such as Pb2+, Cd2+, Ag+, and Hg2+ from aqueous solutions. These bound macrocycles have a virtually infinite selectivity of binding with heavy metals over alkali and alkaline earth cations. The material is very stable and can be reused hundreds of times. Columns may be regenerated using an acidic eluent solution. Equilibrium constants were determined by column tests. Removal of heavy metals was demonstrated in bench scale tests using a synthetic contaminated water and in pilot scale tests using a naturally contaminated river water. Heavy metal concentrations could be effectively reduced to the µg/L level using the process.
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39

Othman*, Amel Ben, Imen Ben Fredj e Rym Abidi. "Extracting and complexing properties of di-, tri- and tetra ThiaCalix [4] arenes". International Journal of Bioassays 5, n.º 10 (1 de outubro de 2016): 4948. http://dx.doi.org/10.21746/ijbio.2016.10.007.

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In the present work, the focus is the study of complexing and extracting properties of three nanoscale derivatives namely multicalixarenes 2C, 3C and 4C which the latter structure is a dendrimer structure of first generation. The metal cations included in this study are the alkali metal, alkaline earth metal, some transition metals, heavy metals and lanthanides. This study was conducted essentially in methanol to determine the stoichiometry of the complexes formed, or the location of the coordination sites, and finally to evaluate selectivity's. These studies have been conducted by UV-visible spectrophotometry, conductivity and proton NMR. The liquid-liquid extraction picrates metal cations followed by UV-visible showed strong selectivity dicalixarenic derived for sodium. The solid liquid extraction of metal picrates followed by 1H-NMR shows an intra- or intermolecular exchange of cations within the calixarene units studied nanocomposites.
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40

TATULIAN, Suren A. "Binding of alkaline-earth metal cations and some anions to hosphatidylcholine liposomes". European Journal of Biochemistry 170, n.º 1-2 (dezembro de 1987): 413–20. http://dx.doi.org/10.1111/j.1432-1033.1987.tb13715.x.

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41

Nakatsuji, Yohji, Michiyuki Matsumoto, Araki Masuyama e Toshiyuki Kida. "Synthetic noncyclic ionophores with multiple carboxylate groups for alkaline earth metal cations". Journal of Inclusion Phenomena and Molecular Recognition in Chemistry 18, n.º 4 (1994): 377–83. http://dx.doi.org/10.1007/bf00707386.

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42

You, Ming-Hua, Meng-Hua Li, Hao-Hong Li, Yong Chen e Mei-Jin Lin. "The impact of metal cations on the photochemical properties of hybrid heterostructures with infinite alkaline-earth metal oxide clusters". Dalton Transactions 48, n.º 46 (2019): 17381–87. http://dx.doi.org/10.1039/c9dt04104d.

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Two hybrid heterostructures with infinite alkaline-earth metal oxide clusters exhibited diametrically opposite photochromic sensitivities and photocatalytic activities, which are mainly related to the HOMO levels of inorganic clusters.
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43

Hou, Yujiao, Haiyan An, Baojun Ding e Yanqin Li. "Evans–Showell-type polyoxometalate constructing novel 3D inorganic architectures with alkaline earth metal linkers: syntheses, structures and catalytic properties". Dalton Transactions 46, n.º 26 (2017): 8439–50. http://dx.doi.org/10.1039/c7dt01302g.

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Two 3D frameworks and two 2D networks with an excellent catalytic effect of cyanosilylation were successfully obtained, originating from Evans–Showell-type polyoxoanions [Co2Mo10H4O38]6− and alkaline earth metal cations (Sr2+, Ba2+).
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44

Azar, Ayda, e Lothar Wondraczek. "Effect of Cation Exchange on the Kinetics of Thermal Amorphization of Zeolite X". Glass Europe 2 (17 de dezembro de 2024): 165–79. https://doi.org/10.52825/glass-europe.v2i.2538.

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Thermal collapse of crystalline zeolites offers a way to obtain glasses in chemical regimes that are inaccessible by classical melt quenching. Thereby, the charge-balancing cations located within the zeolitic framework play an important role in determining structural stability and the dynamics of collapse. Here, we use ion exchange in aqueous solution to create a consistent variety of alkali, alkaline earth and transition-metal containing derivatives of the faujasitic Zeolite X. We subsequently explore the effect of cation species on the thermal stability and the collapse dynamics, revealing a systematic decrease of zeolite stability with increasing cation electronegativity, but a more complex correlation for the apparent activation energy of the collapse reaction.
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45

Vetrova, D. A., e S. A. Kuznetsov. "Composition of outer sphere cations and the charge transfer kinetics of the Ti (IV)/Ti (III) redox couple in the KCl—KF melt." Transaction Kola Science Centre 11, n.º 3-2020 (25 de novembro de 2020): 33–38. http://dx.doi.org/10.37614/2307-5252.2020.3.4.006.

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The charge transfer kinetics for the redox couple Ti(IV)/Ti(III) in the KCl —KF (10 wt. %) —K2TiF6was studied by cyclic voltammetry method. The influence of strongly polarizing Mg2+, Ca2+, Sr2+and Ba2+cations on the kinetics of charge transfer for the Ti(IV)/Ti(III) redox couple upon their introduction into the initial melt, was studied. The activation energies of the charge transfer process for the initial melt and for the melt with the addition of alkaline earth metal cations were calculated.
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46

FUKUSHI, Keiichi, Shinya MINAMI, Motokazu KITAKATA, Masaya NISHIJIMA, Kuriko YOKOTA, Sahori TAKEDA e Shin-ichi WAKIDA. "Determination of Ammonium Cations and Alkali and Alkaline Earth Metal Cations in Jellyfish by Capillary Zone Electrophoresis". Analytical Sciences 22, n.º 8 (2006): 1129–33. http://dx.doi.org/10.2116/analsci.22.1129.

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47

Kim, Jong Seung, Sang Chul Lee, Eun Tae Kim, Jae Hoon Cho, Moon Hwan Cho e Joung Hae Lee. "Studies on Complexation of Alkaline Earth Metal Cations with Acyclic Polyether Dicarboxylic Acids". Journal of Chemical & Engineering Data 43, n.º 6 (novembro de 1998): 1072–75. http://dx.doi.org/10.1021/je980058h.

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48

Godber, John, Mark D. Baker e Geoffrey A. Ozin. "Far-IR spectroscopy of alkali-metal and alkaline-earth cations in faujasite zeolites". Journal of Physical Chemistry 93, n.º 4 (fevereiro de 1989): 1409–21. http://dx.doi.org/10.1021/j100341a047.

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49

Markova, N. V., e V. P. Vasiliev. "Thermochemistry of 18C6 complexation with alkali, alkaline earth metal cations and ammonium ion". Journal of Thermal Analysis 45, n.º 4 (outubro de 1995): 695–701. http://dx.doi.org/10.1007/bf02548884.

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50

Agnihotri, Pragati, Subrata Patra, Eringathodi Suresh, Parimal Paul e Pushpito K. Ghosh. "Selective Precipitation of Alkaline Earth Metal Cations with Dipicrylamine Anion: Structure–Selectivity Correlation". European Journal of Inorganic Chemistry 2006, n.º 23 (dezembro de 2006): 4938–44. http://dx.doi.org/10.1002/ejic.200600666.

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