Synthesis and crystal structure of chalcogenide cluster compound

Three new cluster compounds were synthesized from Hg(EPh)2 (E = Se, Te; Ph = phenyl) in organic solvents. Two of these compounds, [Hg2Cl2(SePh)2(PCy3)2], (1), and [Hg2Br2(SePh)2(PCy3)2], (2), were prepared by reaction of Hg(SePh)2, HgX2 (X = Cl, Br) and tricyclohexylphosphine, PCy3, in dimethylformamide. The reaction of Hg(TePh)2 with HgBr2 in tetrahydrofuran using triphenylphosphine or 2,2’-bipyridine as co-ligands gave the polymeric cluster [{Hg5Br3(TePh)7}n] (3), whose dissolution in dimethylsulfoxide yielded the cluster [Hg3Br3(TePh)3]·2dmso. The influence of different ligands, coordinating solvents and reaction stoichiometries on the formation of the title compounds is also discussed. All complexes were characterized by elemental analysis, thermogravimetric analysis and single crystal X-ray diffractometry

Polyelectrolyte and Non-Polyelectrolyte Polyacrylamide Copolymer Solutions: the Role of Salt on the Intra- and Intermolecular Interactions

Poly(acrylamide-co-dihexylacrylamide) (PAHM-0) and poly(acrylamide-co-sodium acrylate-co-dihexylacrylamide) (PAHM-21) were studied through small-angle X-ray scattering (SAXS), light scattering (LS) and rheology. SAXS results highlighted the polyelectrolyte character of PAHM-21, with highly extended conformation in aqueous solution owing to charge repulsion, while the PAHM-0 has a coil conformation. LS measurements indicated that PAHM-0 makes intermolecular clusters in solution, in presence and absence of salt, even with a lower hydrophobic content than that described in the literature to the associative polyacrylamides. However, the rheological results showed that there is not an enhancement of the viscosity although hydrophobic association takes place. LS results for PAHM-21 suggest that this polymer makes intramolecular associations mainly in the presence of salts. Furthermore, the viscosity measurements show that its viscosity decreases due to screening of the charges by the addition of salts

CeIII-promoted oxidation: Efficient aerobic one-pot eco-friendly synthesis of oxidized bis(indol-3-yl)methanes and cyclic tetra(indolyl)dimethanes

Indoles and benzaldehyde derivatives undergo an efficient one-pot smooth condensation and a further atmospheric-pressure aerobic dehydrogenation with CeCl3 in i-PrOH, to afford the corresponding oxidized bis(indol-3-yl)methanes. Use of 2,2-bisindole as the heterocyclic precursor provides cyclic tetra(indolyl)dimethane derivatives, which further undergo partial oxidation to the related calix-shaped macrocycles, carrying an all cis 1,3,7-cyclodecatriene core and supporting a 2,2-biindolylidene moiety. The syntheses of these high value-added compounds is operationally simple and can be performed at room temperature under mild, neutral and environmentally friendly conditions.Fil: Silveira, Claudio C.. Universidade Federal de Santa Maria; BrasilFil: Mendes, Samuel R.. Universidade Federal de Santa Catarina; BrasilFil: Villetti, Marcos A.. Universidade Federal de Santa Maria; BrasilFil: Back, Davi F.. Universidade Federal de Santa Maria; BrasilFil: Kaufman, Teodoro Saul. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Rosario. Instituto de Química Rosario. Universidad Nacional de Rosario. Facultad de Ciencias Bioquímicas y Farmacéuticas. Instituto de Química Rosario; Argentin

Synthesis and characterization of [Cd8Cl2Se(SePh)12(PCy3)2]•2.5CH3OH

Neste artigo estamos apresentando a síntese do composto [Cd8Cl2(μ4-Se)(SePh)12(PCy3)2]·2.5CH3OH pela reação de Cd(SePh)2 com CdCl2 e triciclohexilfosfina em metanol em um reator de aço inoxidável sob condições solvotérmicas a 130 °C. Esse composto corresponde ao último resultado de uma série sistemática de reações e visando ao crescimento de clusters moleculares a partir de Cd(SePh)2 como reagente de partida. A importância desta síntese não está baseada somente nas propriedades do produto preparado, mas também no seu possível uso, por exemplo, no desenvolvimento de novas metodologias via estratégias “bottom up” para a obtenção de clusters a partir de uma mesma classe de reagentes - M(ER)2 (M = metal, E = calcogênio, R  =   alquil ou aril). O composto apresentado neste artigo foi caracterizado por difração de raios X em monocristal, análise elementar, análise termogravimétrica e espectroscopia no UV-Vis. Estes últimos resultados foram correlacionados com dados calculados por DFT, teoria do funcional de densidade.In this article we present the synthesis of the compound [Cd8Cl2Se(SePh)12(PCy3)2]·2.5CH3OH by the reaction of Cd(SePh)2 with CdCl2 and PCy3 in methanol in a stainless steel sealed reactor under solvothermal conditions at 130 °C. This compound represents the latest result of our systematic work on the growth of molecular clusters from Cd(SePh)2 as starting material. Their importance is based not only on the properties of the new compounds, but also by their possible use, for example, in the development of new methods via a ‘‘bottom up” strategy to obtain different clusters from single components like M(ER)2 (M = metal, E = chalcogen, R = alkyl or aryl). The title compound was characterized by single crystal X-ray diffractometry, elemental analysis, thermogravimetrical analysis and the UV-Vis spectroscopy. These results were correlated with data calculated by DFT, density functional theory

Heteroassembly Ability of Dicationic Ionic Liquids and Neutral Active Pharmaceutical Ingredients

Extensive investigation of interactions and aggregation properties of IL + API systems is necessary to apply ionic liquids (ILs) with different hydrophobic characteristics to drug delivery or in active pharmaceutical ingredient (API) formulations. Therefore, this study aims to investigate the heteroassembly between dicationic ILs ([BisOct­(MIM)₂]­[2X], in which X is Br or BF₄, and [BisOct­(BnIM)₂]­[2Br]), both in the absence and the presence of neutral APIs (salicylic acid, ibuprofen, and paracetamol) with different functional groups. Isothermal titration calorimetry results demonstrate that IL–API associations occur at very low concentrations of IL. These results were reinforced by electrospray ionization mass spectrometry with variable collision-induced dissociation, in which the IL dication interactions with APIs were detected. The strength of the dication–API interaction was determined from <i>E</i>_cm,1/2 data. The aggregation parameters (cac, Δ<i>G</i>_agg^°, and <i>K</i>) between ILs and APIs were evaluated by conductivity. The ¹H NMR data showed that differences in chemical shifts provided relevant insights about interaction sites in both components

Ionic liquids based on carboxylate anions: Auto and hetero assembly with methylcellulose in diluted and semi-diluted regime

This study explores the impact of carboxylate ionic liquids (ILs) on the phase transition properties of methylcellulose (MC) in the diluted and semi-diluted regime. Conductivity measurements were used to examine the aggregation of ILs 1-decyl-3-methylimidazolium butanoate ([C10MIM][BUT]), 1-decyl-3-methylimidazolium crotonate ([C10MIM][CRO]), and 1-decyl-3-methylimidazolium pentanoate ([C10MIM][PEN]) in the presence and absence of MC. The interaction between ILs and MC was confirmed using 1H NMR spectroscopy. The effect of ILs on the phase transition of MC was investigated through UV–vis spectroscopy and oscillatory rheometry. Results indicated that the carboxylate ILs studied tend to interact with MC, reducing polymer-polymer interactions and the apparent viscosity of MC solutions. Furthermore, carboxylate ILs were observed to modulate the sol-gel transition temperature of MC to higher temperatures, while weakening the resulting gel compared to pure MC gels

Elucidating Anion Effect on Nanostructural Organization of Dicationic Imidazolium-Based Ionic Liquids

This work reports the influence of anion structure (Br^–, NO₃^–, BF₄^–, and SCN^–) in the aggregation process of ionic liquids (ILs), derived from 1,8-bis­(3-methylimidazolium-1-yl)­octane, in 4.75% ethanol–water solution (v/v). The aggregation behavior was investigated using small-angle X-ray scattering (SAXS), nuclear magnetic resonance (NMR), dynamic light scattering (DLS), and transmission electron microscopy (TEM). Spin–lattice relaxation times (T1), obtained by NMR, indicated that the molecular mobility of the ILs changed when aggregates are formed. ¹H NMR showed distinct chemical shifts as a function of the concentration of [BisOct­(MIM)₂]­[2X] (in which X = Br, NO₃, SCN, and BF₄) in solution. This change was associated with different chemical environments experienced by the hydrogen atoms when the aggregation process occurs. This behavior was characterized by the different types of interactions in the aggregates, in accordance with the anion of the IL structure. The SAXS measurements demonstrated that the distance between two molecules, which function as scattering centers, was dependent on the anion hydrophobicity. Less hydrophobic anions resulted in shorter distances between scattering centers due to their better solvating ability. Due to the lower solvating ability of hydrophobic anions, a larger distance between two scattering centers was observed. Furthermore, ILs with more hydrophobic anions (e.g., BF₄^–) resulted in closely packed aggregates