Search results for "Complex formation"
showing 10 items of 50 documents
Supramolecular complexation for environmental control
2012
Supramolecular complexes offer a new and efficient way for the monitoring and removal of many substances emanating from technical processes, fertilization, plant and animal protection, or e.g. chemotherapy. Such pollutants range from toxic or radioactive metal ions and anions to chemical side products, herbicides, pesticides to drugs including steroids, and include degradation products from natural sources. The applications involve usually fast and reversible complex formation, due to prevailing non-covalent interactions. This is of importance for sensing as well as for separation techniques, where the often expensive host compounds can then be reused almost indefinitely. Immobilization of …
Molecular Association of a Nonionic and an Ionic-Induced Surfactant: Cryptand (221D) NaCl in Water
2003
The cryptand 5-decyl-4,7,13,16,21-pentaoxa-1,10-diazabicyclo-[8.8.5] tricosane [221D] strongly resembles a surfactant in its characteristics: it contains a hydrophilic headgroup, the cryptand unit, and a hydrophobic unit, the decyl chain. It is insoluble in water, but in the presence of an appropriate amount of NaCl, as a consequence of the complex formation between 221D and Na+, it becomes soluble and forms aggregates. The aggregates, depending on the NaCl-221D molar ratio, can be considered as mixed ionic nonionic micelles or ionic micelles. The evolution of the aggregate dimensions and their shape has already been studied at two NaCl-221D molar ratios as a function of the 221D concentra…
Binding of fluoride and carbonate by open chain polyammonium cations
2004
The formation of open chain polyammonium cation-fluoride and -carbonate complexes was studied by potentiometric and calorimetric techniques at t=25 degrees C. Several species of H(i)AL (A=amine; L=F(-), CO(3)(2-)) are formed in both systems with a mean stability log K=1.0zeta (zeta=|z(anion)xz(cation)|) and log K=2.0zeta for fluoride and carbonate, respectively. The comparison with analogous systems (chloride and acetate for fluoride and hydrogenphosphate, sulfate and malonate for carbonate) showed that fluoride and carbonate form the most stable species with open chain polyammonium cations, among low molecular weight anions. The N-alkyl substitution does not play negligible role in the sta…
Complex formation of Tb3+ with glycolate, D-gluconate and α-isosaccharinate in neutral aqueous perchlorate solutions
2003
Summary An electromigration technique was used for measurements of metal-ligand formation constants of non-carrier-free 160Tb3+ with glycolate, D-gluconate and α-isosaccharinate ligands. The overall ion mobilities of Tb at different concentrations of the ligands were measured in chemically inert perchlorate solutions (pH 7 and T= 298.1K) with an overall ionic strength μ = 0.1. The stepwise stoichiometric stability constants are: Tb3+/glycolate: log K 1=2.72(18), log K 2=1.73(19), log K 3= 1.12(17), Tb3+/D-gluconate: log K 1=2.96(11), log K 2=2.60(11), log K 3=1.13(9), Tb3+/α-ISA: log K 1=3.07(8), log K 2 = 2.69(11), log K 3 = 1.80(12).
ChemInform Abstract: Supramolecular Complexation for Environmental Control
2012
Supramolecular complexes offer a new and efficient way for the monitoring and removal of many substances emanating from technical processes, fertilization, plant and animal protection, or e.g. chemotherapy. Such pollutants range from toxic or radioactive metal ions and anions to chemical side products, herbicides, pesticides to drugs including steroids, and include degradation products from natural sources. The applications involve usually fast and reversible complex formation, due to prevailing non-covalent interactions. This is of importance for sensing as well as for separation techniques, where the often expensive host compounds can then be reused almost indefinitely. Immobilization of …
X-Ray and NMR Studies on Host-Guest Inclusion Complex Formation between Crown Ethers and Pyridinium Compounds
1998
Aromatic–aromatic, π–π, and cation–π interactions can be exploited in the preparation of molecular complexes between benzene-substituted crown ethers and pyridium cations. These complexes have been studied in the gas phase, in solution, and in the solid state; the structure of one of the complexes is depicted on the right.
Association of N-(Pyridin-2-yl),N′-substituted Ureas with 2-Amino-1,8-naphthyridines and Benzoates: NMR and Quantum Chemical Studies of the Substitue…
2013
Association of four N-(pyridin-2-yl),N'-R(1)-ureas (R(1) = ethyl, n-butyl, phenyl, and tert-butyl) with substituted 2-amino-1,8-naphthyridines and benzoates were studied by (1)H NMR spectroscopic titrations and quantum chemical calculations. The benzoates and 2-amino-1,8-naphthyridines were selected as representatives of double and triple hydrogen bonding counterparts, respectively. The classical substituent effect on the association was studied. A prerequisite and a crucial step for the complex formation was the breaking of the intramolecular hydrogen bond in urea derivatives. The QTAIM calculation method was employed to explain the hydrogen bonding within complexes. In the case of benzoat…
SALMO and S3M: A Saliva Model and a Single Saliva Salt Model for Equilibrium Studies.
2014
A model of synthetic saliva (SALMO, SALiva MOdel) is proposed for its use as standard medium inin vitroequilibrium and speciation studies of real saliva. The concentrations come out from the literature analysis of the composition of both real saliva and synthetic saliva. The chief interactions of main inorganic components of saliva, as well as urea and amino acids, are taken into account on the basis of a complex formation model, which also considers the dependence of the stability constants of these species on ionic strength and temperature. These last features allow the modelling of the speciation of saliva in different physiological conditions deriving from processes like dilution, pH, a…
Studies on DNA interaction of organotin(IV) complexes of meso-tetra(4-sulfonatophenyl)porphine that show cellular activity.
2016
PubMedID: 27393277 The interaction of the diorgano- and triorganotin(IV) derivatives of meso-tetra-(4-sulfonatophenyl)porphine (Me2Sn)2TPPS, (Bu2Sn)2TPPS, (Me3Sn)4TPPS and (Bu3Sn)4TPPS to natural DNA was analysed (together with free meso-tetra-(4-sulfonatophenyl)porphine (TPPS4 -) for comparison purposes). Particular attention was paid to (Bu3Sn)4TPPS, a species that shows significant cellular action. Preliminary tests were done on the solution properties of the organotin(IV) compounds (pKA and possible self-aggregation). Spectrophotometric and spectrofluorometric experiments showed that all the investigated organotin(IV) derivatives strongly interact with DNA, the binding energy depending …
Complex formation of hypoxanthine and 6-mercaptopurine with Cd(II) ion
1984
Reaction of Cd(II) ion with hypoxanthine (H2 Y) and with 6-mercaptopurine (H2 MP) in dioxane-water (50%) leads to the formation of CdY·2H2O and Cd(HMP)2·2H2O, respectively. In methanolic medium Cd(II) and H2 MP give Cd(MP)·H2O. These compounds have been characterized by chemical analysis, IR spectra and thermogravimetric analysis. The stability constant of CdY complex at 25±0.1 °C and 1M ionic strength with NaClO4 in dioxane-water medium is log β=10.25±0.05.