Search results for "Complex formation"

Polymerisation von acrylnitril, methylmethacrylat und einigen substituierten acrylnitrilen mit anorganischen nitraten. Zur polymerisation von acryini…

1968

Die radikalische Polymerisation von Acrylnitril (AN), Methacrylnitril, α-Chloracrylnitril, Crotonsaurenitril und Methylmethacrylat wird unter Bestrahlung bei 60°C in An wesenheit von AgNo3 untersucht, und die Polymerisationsgeschwindigkeiten werden verglichen. Unterschiede in der Polymerisationsfahigkeit einzelner Monomerer lassen sich teilweise auf Komplexbildung mit AgNO3 zurackfahren. Es werden einige andere anorganische Nitrate als Initiatoren eingesetzt; ihre Aktivitat entspricht der Stellung der Kationen in der Spannungsreihe. Als Teil der Initiierungsreaktion wird eine Reduktion des Metallions angenommen; daher kann eine Abnahme der Kationenkonzentration bei AgNO3 und besonders bei C…

The complex formation equilibria between Cd(II), Pb(II) and iminodiacetic acid in NaClO4 0.93 Mw at 25°C

2010

Speciation of organic matter in natural waters. Interaction of polyacrylates with the major cation components of seawater

2004

The speciation of some high molecular weight polycarboxylates was studied in different ionic media. Polyacrylates here investigated (W=2.0, 5.1 and 20.0 kDa) form weak species with alkali metal cations (K=102 mol l1, t=25 jC, I=0 mol l1) and quite stable complexes with alkaline earth metal cations (K>106 mol l1, t=25 jC, I=0 mol l1). Results are reported from experiments performed in a multicomponent electrolyte solution simulating the major composition of seawater (artificial seawater). Protonation constants in this medium are expressed as a polynomial function of S1/2 (S=salinity) and the sharp lowering with respect to values obtained in non-interacting aqueous tetraalkylammonium salts ca…

Increased conformational rigidity of humic substances by oxidative biomimetic catalysis

2005

A synthetic water-soluble meso-tetra(2,6-dichloro-3-sulfonatophenyl)porphyrinate of iron(III) chloride, Fe(TDCPPS)Cl, was employed as a biomimetic catalyst in the oxidative coupling of terrestrial humic materials. High-performance size-exclusion chromatography (HPSEC), solid-state nuclear magnetic resonance (CPMAS-(13)C NMR), electron paramagnetic resonance (EPR), and diffuse reflectance infrared spectroscopy (DRIFT) were used to follow conformational and structural changes brought about in different humic materials by the oxidative coupling. Increase in apparent weight-average molecular weight (Mw(a)) occurred invariably for all humic substances with the oxidative polymerization catalyzed …

Equilibrium Studies in Natural Fluids. A Chemical Speciation Model for the Major Constituents of Seawater.

1994

AbstractThe speciation of CI−, OH− and SO42- in synthetic sea water has been studied by Potentiometric measurements (pH-metric and ISE-Na methods) and by literature data analysis, using a well tested complex formation model. Stability constants, together with distribution of hypothesised species in synthetic sea water, as a function of temperature and salinity, are reported. The speciation model proposed in this work is discussed on the basis of chemical and statistical considerations. Comparison with some literature sea water models is given.

Diorganotin(IV) complexes ofD-galacturonic acid: solid-state and solution-phase structural study

2003

Three diorganotin(IV) complexes of D-galacturonic acid (H2GalA; R = Me, n-Bu, Ph), two of which are new derivatives (R = Me, Ph), have been synthesized and their solid-state and solution-phase investigated by IR, Mossbauer, 1H, 13C and 119Sn NMR spectroscopy. The FTIR data suggest that H2GalA, in the dialkyltin derivatives, behaves as a dianionic ligand, coordinating the tin(IV) atom through an ester-type carboxylate and deprotonated alcoholic hydroxo groups, whereas a bridging carboxylate occurs in the diphenyltin(IV) complex. Octahedral and trigonal bipyramidal local geometries on tin(IV) atoms are proposed for dialkyltin(IV)GalA and diphenyltin(IV)GalA complexes respectively on the basis…

Speciation of organotin compounds in NaCl aqueous solution. Interaction of mono-, di- and triorganotin(IV) cations with nucleotides 5’ monophosphates

2004

Formation constants for complex species of mono-, di- and tri-alkyltin(IV) cations with somenucleotide 5-monophosphates (AMP, UMP, IMP and GMP) are reported, atT=25◦CandatI=0.16 mol l−1(NaCl). The investigation was performed in the light of speciation of organometalliccompounds in natural fluids in the presence of nucleotides whose biological importance is wellrecognized. The simple and mixed hydrolytic complex species formed in all the systems investigatedin the pH range 3–9 are (L=nucleotide; M=organotin cation RxSn(4−x)+, withx=1to3):ML+,ML(OH)0and ML(OH)2−for the system CH3Sn3+–L (L=AMP, IMP, UMP); ML0and ML(OH)−for the system (C2H5)2Sn2+–L (L=AMP, IMP, UMP); ML−, ML(OH)2−,MLH0and M2L(O…

Speciation of dimethyltin(IV) – and trimethyltin(IV) – carbocysteinate and – glutamate systems in aqueous media

2008

The formation of complex species in the dimethyltin(IV) and trimethyltin(IV)-carboxymethyl-L-cysteinate (carbocysteinate) systems in NaClaq, at different ionic strengths, and in a multicomponent Na+, K+, Ca2+, Mg2+, Cl- and SO42- medium representative of the seawater major composition, is discussed. Experimental results give evidence for the formation of the following species (L¼carbocysteinate): [(CH3)2Sn(L)]0, [(CH3)2Sn(HL)]+, [(CH3)2Sn(OH)(L)]-, [(CH3)2Sn(OH)2(L)]2- in the DMT–CCYS system, and [(CH3)3Sn(HL)]0, [(CH3)3Sn(L)]- and [(CH3)3Sn(OH)(L)]2- in the TMT-CCYS system. The ionic strength dependence of formation constants was taken into account by an extended Debye Huckel type equation…

Complex formation of copper(II) and cadmium(II) with pectin and polygalacturonic acid in aqueous solution. An ISE-H + and ISE-Me 2+ electrochemical s…

2012

The acid-base properties of pectin and its ability to complex with copper(II) or cadmium(II) were quantitatively determined in order to define the ability of this natural polyelectrolyte to sequester metal ions. Potentiometric measurements carried out at different ionic strengths (0.1 - 0.7 mol L-1, in Na+ ionic medium) allowed us to define the acid-base properties of pectin together with the dependence of the protonation constants on ionic strength and to calculate the protonation constant at infinite dilution. The formation of complex species between pectin and copper(II) or cadmium(II) was investigated potentiometrically (using H+, Cu2+ and Cd2+ Ion Selective Electrodes, ISEs) in NaNO3 a…

A Theoretical and Experimental Investigation of the Spectroscopic Properties of a DNA-Intercalator Salphen-Type ZnIIComplex

2014

The photophysical and DNA-binding properties of the cationic zinc(II) complex of 5-triethylammonium methyl salicylidene ortho-phenylenediiminato (ZnL 2 + ) were investi- gated by a combination of experimental and theoretical methods. DFT calculations were performed on both the ground and the first excited states of ZnL 2 + and on its possi- ble mono- and dioxidation products, both in vacuo and in selected solvents mimicked by the polarizable continuum model. Comparison of the calculated absorption and fluores- cence transitions with the corresponding experimental data led to the conclusion that visible light induces a two-elec- tron photooxidation process located on the phenylenediimi- nato…