Search results for "aqueous solution"
showing 10 items of 1610 documents
[2]Catenanes and inclusion complexes derived from self-assembled rectangular PdII and PtII metallocycles
2012
New inclusion complexes and [2]catenanes were self-assembled from a fluorescent diazapyrenium based ligand, a PdII or PtII complex, and cyclic or acyclic electron rich aromatic guests in aqueous and organic media. The molecular rectangles display a π-deficient cavity suitable to incorporate π-donor aromatic systems. The inclusion complexes between the metallocycles and phenylenic (2a,b) and naphthalenic (3a,b–5a,b) derivatives were studied by NMR, UV-vis and fluorescence spectroscopy. The crystal structure of (3b) ⊂ 1a·6PF(6) confirmed the insertion of the guest into the cavity of the metallocycle. Following the same self-assembly strategy, the use of polyethers 6,7 as π-donors resulted in …
Complexes of molybdenum(VI) with organic diacid ligands: The molybdenum(VI)-malonic acid system
1983
Malonic acid (C3O4H4) and MoVI form in aqueous solution two dinuclear dioxo-complexes of which the stability is a function of the pH of the medium. Both complexes have a 1∶1 metal-ligand stoichiometric ratio, and the interconversion may involve a structural rearrangement. Conditional dissociation constants have been determined spectrophotometrically. Saline cryoscopy supports the spectrophotometric results. Salts of [Co(en)3]3+ have been isolated. The ligand behaviour of malonic acid differs partially from that observed for α-polyhydroxy ligands.
Dendritic octa-CMPO derivatives of calix[4]arenes
2004
Abstract Calix[4]arenes substituted at the narrow or wide rim by eight carbamoylmethyl-phosphine oxide (CMPO) functions in a dendritic manner were synthesised and studied in extraction of Eu 3+ and Am 3+ from aqueous nitric acid into o -nitrophenylhexyl ether. 1 H NMR relaxivity titrations for a wide rim octa-CMPO reveal the clear formation of a solvent-free 1:2 ligand/metal complex, while the wide rim tetra-CMPO formed oligomeric complexes under similar conditions.
Complexation and Extraction of PAHs to the Aqueous Phase with a Dinuclear Pt II Diazapyrenium‐Based Metallacycle
2010
New palladium and platinum metallacycles have been synthesized by reaction between a 2,7-diazapyrenium-based ligand and Pd(II) and Pt(II) complexes. The inclusion complexes between the metallacycles and polycyclic aromatic hydrocarbons (PAHs) in CD(3)NO(2) and D(2)O were studied by NMR spectroscopy. The structures of the inclusion complexes of the Pt metallacycle as host with pyrene, phenanthrene, and triphenylene were confirmed by single crystal X-ray crystallography. The association constants between the Pt metallacycle and the selected PAHs were determined in CH(3)CN following the characteristic charge-transfer band displayed in their UV/Vis absorption spectrum. Although in aqueous solut…
Oxamidato complexes. Part 4. Electrochemical study of the copper(III)/copper(II) couple in monomeric N,N?-bis(substituent)oxamidatocopper(II) complex…
1993
The electrochemical behaviour of a series of monomeric N,N′-bis(substituent)oxamidato copper(II) complexes of formula Na2[Cu(3,5,3′,5′-X4obbz)]·4H2O [X = Cl (1), Br (2), I (3) and obbz = oxamidobis(benzoato)], Na2-[Cu(obbz)]·4H2O (4), Na2[Cu(5,5′-Me2obbz)]·4H2O (5), Na2[Cu(4,5,4,5′-(MeO)4obbz)]·4H2O(6),Na2[Cu(obp)]· 3.5H2O (7) (obp = oxamidobis(propionato)) and Na2[Cu(pba)]·6H2O (8), [pba = propylenebis(oxamate)] has been investigated by cyclic voltammetry, rotating disk electrode and coulometry in water and dimethylsulphoxide (dmso) solutions. NaNO3 (0.1 M) and n-Bu4NPF6 (0.1 M) were used as supporting electrolytes in H2O and dmso respectively, all solutions being thermostatted at 25 °C. I…
Desulfurization processes of thiosemicarbazonecopper(ii) derivatives in acidic and basic aqueous media
2013
This work provides structural evidence for different desulfurization processes in aqueous solutions of [CuL]+ derivatives (HL = pyridine-2-carbaldehyde thiosemicarbazone). Structural resolution has been achieved for the [{CuL(SH)}2] (1), [CuLCl]2[Cu(pic)2] (pic− = picolinato, pyridine-2-carboxilato) (2) and [Cu(HL)(NCS)](NO3) (4) compounds, together with a derivative of 4 with formula [Cu(HL)(NCS)][Cu(HL)(NCS)0.72(NO3)0.28](NO3)2 (5), whose HS−, pic− and NCS− ligands come from thiosemicarbazone breakage. The behaviour of the [CuL]+ species in basic aqueous solutions or water under reflux has been compared with that exhibited by iron(III), cobalt(III), zinc(II) and lead(II) derivatives of th…
Palladium(II) Complexes of Aminopolycarboxylic Ligands in Aqueous Solution
2011
Thebindingcapacityof fiveaminopolycarboxylicligands(APCs)(nitrilotriacetate(NTA),ethylenediamine-N,N,N 0 , N 0 -tetraacetate (EDTA), (S,S)-ethylenediamine-N,N 0 -disuccinic acid (S,S-EDDS), diethylenetriamine-N,N,N 0 ,N 00 ,N 00 -pentaacetate (DTPA), and triethylenetetraamine-N,N,N 0 ,N 00 ,N 000 ,N 000 -hexaacetate (TTHA)) toward the palladium(II) ion was studied by potentiometric titrations (ISE-H + electrode) in NaNO3 and in NaClO4/NaI (at different molar ratios) solutions and by spectrophotometric titrations (only in NaClO4), at I = 0.1 mol 3 kg � 1 and at T = 298.15 K. The high stability of Pd 2+ -complexones species inhibits the formation of sparingly soluble hydroxo species until pH …
Interaction of methyltin(IV) compounds with carboxylate ligands. Part 2: Formation thermodynamic parameters, predictive relationships and sequesterin…
2008
Thermodynamic data of mono-, di- and tri-methyltin(IV)-carboxylate complexes (acetate, malonate, succinate, oxydiacetate, diethylenetrioxydiacetate, malate, citrate, 1,2,3-tricarballylate, 1,2,3,4-butanetetracarboxylate, 1,2,3,4,5,6-benzenehexacarboxylate) in aqueous solution are reported at t = 25 °C and I = 0 mol l−1. Thermodynamic parameters obtained were analysed to formulate empirical predictive relationships as a function of different parameters, such as the number of carboxylate groups of the ligand and the charge of the alkyltin(IV) cation. Sequestration diagrams of citrate and 1,2,3-tricarballylate towards alkyltin(IV) cations at different pH values are also reported and discussed.…
Ab Initio Liquid Water Dynamics in Aqueous TMAO Solution
2015
Ab initio molecular dynamics (AIMD) simulations in trimethylamine N-oxide (TMAO)-D2O solution are employed to elucidate the effects of TMAO on the reorientational dynamics of D2O molecules. By decomposing the O-D groups of the D2O molecules into specific subensembles, we reveal that water reorientational dynamics are retarded considerably in the vicinity of the hydrophilic TMAO oxygen (O(TMAO)) atom, due to the O-D···O(TMAO) hydrogen-bond. We find that this reorientational motion is governed by two distinct mechanisms: The O-D group rotates (1) after breaking the O-D···O(TMAO) hydrogen-bond, or (2) together with the TMAO molecule while keeping this hydrogen-bond intact. While the orientatio…
Apparent molar volumes of lithium nitrate in 1-propanol + water in the temperature range from 288.15 to 318.15 K
2002
Abstract Densities of 1-propanol+water+lithium chloride mixtures have been measured with an oscillating-tube densimeter over a large range of concentrations of the salt and 1-propanol at 288.15, 298.15, 308.15, and 318.15 K. From these densities, apparent molar volumes of lithium chloride in 1-propanol+water mixtures have been calculated for each temperature, and apparent molar volumes at infinite dilution have been evaluated. An empirical correlation for partial molar volumes of lithium chloride in 1-propanol+water mixtures with solvent composition and temperature has been derived.