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Synthesis, characterization, spectroscopic and crystallographic investigation of Cobalt(Ⅲ) schiff base complex with two perpendicular diamine coumarin ligands

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Open Journal of Inorganic Chemistry 2012年第2期2卷 33-39页

作者： Imen Ketata Lassad Mechi taicir ben ayed Michal Dusek Vaclav Petricek Rached ben Hassen Unite de Recherche de Chimie des Materiaux et de l’Environnement Universite de Tunis El ManarTunisTunisia INSAT Universite de CarthageTunisTunisia Institute of Physics Academy of Sciences of the Czech RepublicPrahaCzech Republic

New transition metal complex of Cobalt(III) of the ligand (E)-3-(1-(2-aminoethylimino)ethyl)-4-hydroxy-2H-chromen-2-one, derived from condensation of ethylene diamine with 3-acetyl-4-hydroxy-chromene-2-one have been synthesized by reaction of cobalt(III) salt and the ligand, in amounts equal to metal-ligand molar ratio of 1:2. Both the Schiff base and the complex of Co(III) were characterized by IR, UV-Vis, 1H NMR- and 13C NMR-spectroscopy techniques. Single crystal X-ray diffraction investigation, at low temperature T = 120 K, shows that the cobalt complex is triclinic P-1, a = 10.426(5) ?, b = 11.3234(2) ?, c = 15.729(5) ?, α(°) = 70.102(4), β(°) = 86.049(4), γ(°) = 82.497(4), Z = 2, and its structure consists of isolated [Co(III)(C13H13N2O3)2]+ complex cations with distorted octahedral geometry, ClO-4 counter anions, acetone solvent and water molecules. The crystal cohesion is stabilized by hydrogen bonds between ligands and water molecules, and ionic interactions between complex cations and counter anions.

关键词： Hydroxycoumarin Derivative Co^(Ⅲ) Complex ^(1)H NMR UV-Visible Single Crystal X-Ray Diffraction

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Time-varying nexus and causality in the quantile between Google investor sentiment and cryptocurrency returns

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Blockchain(Research and Applications) 2024年第2期5卷 1-12页

作者： Fatma ben Hamadou taicir Mezghani Mouna Boujelbene Abbes Faculty of Economics and Management of Sfax Laboratory URECASfax UniversityBP1169.3029SfaxTunisia

Understanding the interplay between investor sentiment and cryptocurrency returns has become a critical area of ***,this study aims to uncover the role of Google investor sentiment on cryptocurrency returns(including Bitcoin,Litecoin,Ethereum,and Tether),especially during the 2017-18 bubble(January 01,2017,to December 31,2018)and the COVID-19 pandemic(January 01,2020,to March 15,2022).To achieve this,we use two techniques:quantile causality and wavelet ***,the quantile causality test revealed that investors’optimistic sentiments have notably higher cryptocurrency returns,whereas pessimistic sentiments have significantly opposite ***,the wavelet coherence analysis shows that co-movement between investor sentiment and Tether cannot be considered *** result supports the role of Tether as a stablecoin in portfolio diversification *** fact,the findings will help investors improve the accuracy of cryptocurrency return forecasts in times of stressful events and pave the way for enhanced decision-making utility.

关键词： Cryptocurrency COVID-19 pandemic Wavelet coherence Causality-in-quantile approach Google trends

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