Supramolecular complexes of podand ligands with xenon

AbstractFormation of stable complexes between xenon and podand polyoxyethylene ligands was ascertained. The complexation process was studied by 129Xe NMR titration, NMR diffusiometry and heteronuclear NOE measurements. The ligands studied form a 1:1 complexes with Xe(0). Their stability constants depend on the ligand structure, i.e., polyoxyethylene chain length, number of complexating polyether units and the topology of the anchoring centre.

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Changes in the Humic Acid–Metal Complexation Characteristics Depending on Humification Degree / Humīnskābju – Metālu Kompleksveidošanās Rakstura Izmaiņas Atkarībā No Humifikācijas Pakāpes

Latvian Journal of Chemistry ◽

10.2478/v10161-012-0012-0 ◽

2012 ◽

Vol 51 (3) ◽

pp. 228-237

Author(s):

D. Dudare ◽

M. Klavins

Keyword(s):

Humic Acid ◽

Stability Constants ◽

Humic Acids ◽

Complex Stability ◽

Peat Layer ◽

Raised Bog ◽

Complexing Capacity ◽

Humification Degree ◽

Complexation Process ◽

Complex Stability Constants

The aim of this study is to determine the Cu(II) complexing capacity and stability constants of Cu(II) complexes of humic acids isolated from two well-characterized raised bog peat profiles in respect to the basic properties and humification characteristics of the studied peats and their humic acids. The complex stability constants significantly change within the studied bog profiles and are well correlated with the age and decomposition degree of the peat layer from which the humic acids have been isolated. Among factors that influence this complexation process, molecular mass and ability to form micellar structures (supramolecules) of humic substances are of key importance.

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Extraction of strontium and barium salts by the nitrobenzene solution of dicarbolide in the presence of glymes

Collection of Czechoslovak Chemical Communications ◽

10.1135/cccc19850581 ◽

1985 ◽

Vol 50 (3) ◽

pp. 581-599 ◽

Cited By ~ 41

Author(s):

Petr Vaňura ◽

Emanuel Makrlík

Keyword(s):

Stability Constants ◽

Organic Phase ◽

Equilibrium Constants ◽

Minor Role ◽

Nitrobenzene Solution ◽

Ligand Structure ◽

Stability Constants Of Complexes ◽

Separation Factors ◽

The Stability ◽

A Minor

Extraction of microamounts of Sr2+ and Ba2+ (henceforth M2+) from the aqueous solutions of perchloric acid (0.0125-1.02 mol/l) by means of the nitrobenzene solutions of dicarbolide (0.004-0.05 mol/l of H+{Co(C2B9H11)2}-) was studied in the presence of monoglyme (only Ba2+), diglyme, triglyme, and tetraglyme (CH3O-(CH2-CH2O)nCH3, where n = 1, 2, 3, 4). The distribution of glyme betweeen the aqueous and organic phases, the extraction of the protonized glyme molecule HL+ together with the extraction of M2+ ion and of the glyme complex with the M2+ ion, i.e., ML2+ (where L is the molecule of glyme), were found to be the dominating reactions in the systems under study. In the systems with tri- and tetraglymes the extraction of H+ and M2+ ions solvated with two glyme molecules, i.e., the formation of HL2+ and ML22+ species, can probably play a minor role. The values of the respective equilibrium constants, of the stability constants of complexes formed in the organic phase, and the theoretical separation factors αBa/Sr were determined. The effect of the ligand structure on the values of extraction and stability constants in the organic phase is discussed.

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