Search results for "aqueous solution"
showing 10 items of 1610 documents
A Molecular Dynamics Study of the Structure of an Aqueous KC1 Solution
1986
A molecular dynamics simulation of a 2.2 molal aqueous KCl solution has been performed using the ST2 water model. The simulation extended over 5ps at an average temperature of 288 K. The basic box has a side length of 18.74 A and contained 200 water molecules, 8 cations and 8 anions. The structure of the solution is discussed by radial distribution functions, the orientation of the water molecules, and their geometrical arrangement in the first hydration shells. The first shells of K+ and Cl- extend up to 3.52 and 3.84 A, respectively, with the corresponding hydration numbers 7.8 and 7.6. The results are compared with recent neutron and X-ray diffraction data and with findings of previous M…
Spin Crossover in a Supramolecular Fe4II [2×2] Grid Triggered by Temperature, Pressure, and Light
2000
A multiplex electronic switch on the molecular level has been realized by using a tetranuclear FeII complex of the [2×2] grid type. The four metal ions can be switched stepwise between their high-spin and low-spin states by temperature, pressure, and light, thus representing a triple level, triple switch system as illustrated in the picture.
Design, synthesis and biological evaluation of novel stilbene-based antitumor agents
2008
A series of novel stilbene derivatives has been synthesized and studied with the main goal to investigate SAR of the amino compound 1a, as well as to improve its water solubility, a potentially negative aspect of the molecule that could be a serious obstacle for a pre-clinical development. We have obtained derivatives with good cytotoxic activity, in particular, the derivatives 5c and 6b could represent two novel leads for further investigation. Compound 8b, a morpholino-carbamate derivative, prodrug of 1a, has a very good solubility in water, and is active in suppressing growth of tumor cells at a concentration of 5000 nM, which is a concentration 100 times higher than the parent stilbene …
Cyclopentadienylmolybdenum(VI) and molybdenum(V) oxo chemistry: New synthetic and structural features
2002
International audience; Convenient syntheses for Cp, Cp*, and related cyclopentadienyl derivatives (4Cp = C5HiPr4; Cp′′′ = C5H2tBu3-1,2,4) of formula [(Ring)2Mo2O5] are described. Compound [Cp2Mo2O5] was produced in good yields by the rapid oxidation of red [CpMoO2]4 with PhIO in CH2Cl2. [Cp*2Mo2O5] was obtained by CH3COOH acidification of aqueous solutions of [Cp*MoO3]−Na+, the latter being generated in a single step from [Cp*MoCl4] and more than 5 equiv. of aqueous NaOH in air. Minor quantities of [Cp*MoO2]2 were also isolated from this reaction, although the formation of this by-product may be reduced by using a two-step basic hydrolysis procedure. Extension of the latter strategy also a…
Heats and Entropies of Reaction of Transition Metal Ions with Ethylenediamine
1960
THE heats of formation of complexes between ligands and metal ions are very important to further the ligand field-theory and check its implications. Until now, only the heats of hydration of the first transition group ions have been used for this purpose1 as the thermochemical data on the complexes formed by ligands other than water are very incomplete. The transition metal complexes of ethylenediamine, which have a very nearly octahedral configuration, could also be fruitfully studied in terms of ligand field-theory. Unfortunately only the thermal data on nickel (II), copper (II) and zinc (II) complexes are known2, and so the formation constants have been used instead of the values of enth…
Hydrolysis of Monomethyl-, Dimethyl-, and Trimethyltin(IV) Cations in Fairly Concentrated Aqueous Solutions at I = 1 mol L-1 (NaNO3) and T = 298.15 K…
2011
The hydrolysis of methyltin(IV) cations at fairly high concentrations was investigated to evaluate the formation of polynuclear species in aqueous solution. The hydrolysis of monomethyltin(IV), dimethyltin(IV), and trimethyltin(IV) was studied by potentiometry at T = 298.15 K and at I = 1 mol L-1 in NaNO3 aqueous solutions. The results obtained gave evidence for the formation of the following polynuclear species, in addition to the mononuclear species already reported, which were also considered in the models proposed for the three systems investigated: [(CH3)Sn(OH)3]0, [(CH3)Sn(OH)4]-, [((CH3)Sn)2(OH)4]2+, [((CH3)Sn)2(OH)5]+, [((CH3)Sn)2(OH)7]-, [((CH3)Sn)3(OH)5]4+, [((CH3)Sn)3(OH)7]2þ, [(…
Magnetic hybrid TiO 2 /Alg/FeNPs triads for the efficient removal of methylene blue from water
2018
A new adsorbent material with combined adsorption, photocatalytic, and magnetic properties has been suc- cessfully synthesized and tested for the efficient dye removal from methylene blue (MB) contaminated water. A facile non-thermal method was applied to synthesize a hybrid nanocomposite consisting of TiO2/calcium algi- nate (TiO/Alg) and magnetite (Fe3O4) nanoparticles (FeNPs). The potential of the adsorbent Alg as a barrier to prevent direct contact between the magnetic core and TiO2 was experimented by varying the synthesis condi- tions. The performance of four differently synthesized TiO2/Alg/FeNPs samples (TiO2/Alg/FeNPs-1, TiO2/Alg/ FeNPs-2, TiO2/Alg/FeNPs-3, and TiO2/Alg/FeNPs-4) wa…
Supramolecular capping-ligand effect of lamellar silica mesostructures for the one-pot synthesis of highly dispersed ZnO nanoparticles
2006
ZnO?SiO2 lamellar nanocomposites with high zinc content (5?Si/Zn?50) have been synthesized through a one-pot surfactant-assisted procedure from aqueous solution and starting from molecular atrane complexes of Zn and Si as inorganic hydrolytic precursors. This approach allows optimization of the dispersion of the ZnO nanodomains in the silica sheets. The nature of the layered silica materials has been confirmed by x-ray diffraction. Spectroscopic (ultraviolet?visible and photoluminescence) study of these layered silica materials shows that, regardless of the Si/Zn ratio, Zn atoms are organized in well-dispersed, uniform ZnO nanodomains (about 1.2?nm) partially embedded within the silica shee…
Biomolecular conjugation inside synthetic polymer nanopores via glycoprotein-lectin interactions
2011
We demonstrate the supramolecular bioconjugation of concanavalin A (Con A) protein with glycoenzyme horseradish peroxidase (HRP) inside single nanopores, fabricated in heavy ion tracked polymer membranes. Firstly, the HRP-enzyme was covalently immobilized on the inner wall of the pores using carbodiimide coupling chemistry. The immobilized HRP-enzyme molecules bear sugar (mannose) groups available for the binding of Con A protein. Secondly, the bioconjugation of Con A on the pore wall was achieved through its biospecific interactions with the mannose residues of the HRP enzyme. The immobilization of biomolecules inside the nanopore leads to the reduction of the available area for ionic tran…
Evaluation of adsorption ability of Cyclodextrin-Calixarene Nanosponges towards Pb2+ ion in aqueous solution
2021
Abstract Different cyclodextrin-calixarene nanosponges (CyCaNSs) have been characterized by means of FFC-NMR relaxometry, and used as sorbents to remove Pb2+ ions from aqueous solutions. Considering that the removal treatments may involve polluted waters with different characteristics, the adsorption experiments were performed on solutions without and with the addition of background salts, under different operational conditions. The adsorption abilities and affinities of the nanosponges towards Pb2+ ions were investigated by measuring the metal ion concentration by means of Inductively Coupled Plasma Emission Spectroscopy (ICP-OES) and Differential Pulse Anodic Stripping Voltammetry (DP-ASV…