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Study of Complex Formation between Iodoquinol (IQ) and Co2,+ Mn2+, Cd2+, Pb2+ and Zn2+ Cations in DMF/EtOH Bi nary Solvent Mixtures Us ing Spectrophotometry

Nezhadali A., Hosseini H. A., Langara P.

Polish Journal of Chemistry

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2009

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Vol. 83, nr 4

573-580

EN

The complexation reactions between iodoquinol and Co2+, Mn2+, Cd2+, Pb2+ and Zn2+ cations were studied in different DMF/EtOH binary mixtures at the ionic strength of 0.1 M sodium nitrate. The spectrophotometric method was used for the determination of stability constants and stoichiometries of complexes. Job’s and moleratio methods evidenced a 1:1 stoichiometry in all of the cases. It was found that the stability constants of the complex formed between the ligand (IQ) and the cations in all cases in crease with in creasing of EtOH per cent in binary mixtures. In the most cases the maximum formation constant for Zn2+–IQ complex was found.

2

Spectrophotometric complexation study of 4-(2-thiazolylazo) resorcinol and Zn2+, Cd2+, Pb2+ and Cu2+ in 50% DMSO/water solution

Ghasemi J. B., Zohrabi P.

Chemia Analityczna

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2009

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Vol. 54, No. 5

1035-1049

EN

A multiwavelength spectrophotometric titration method was applied to determine protona-tion constants of 4-(2-thiazolylazo) resorcinol (TAR) and stability constants of complexes between TAR and Zn2+, Cd2+, Pb2+ and Cu2+ ions in 50% v/v mixtures of DMSO/H2O of 0.1 mol L-1 ionic strength using global analysis at 25°C. UV-VIS absorption spectra of TAR and metal-TAR complexes were recorded in the course of pH-metric titration of acidic solutions of TAR and metal-TAR with standard base solution. In spectrophotometric titra-tions, linear or near-linear concentration profiles and the existence of minor species could cause difficulties in data evaluation. In the second-order global analysis, a number of spectrophotometric titrations starting from different initial concentrations were simultaneously performed. This way, conditions for the abundant formation of all species could be reached and consequently the concentration matrix was augmented to the full rank. Stability constants of different TAR-metal complexes at various molar ratios were estimated using SQl JAD and EQU1SPEC programmes.

PL

Miareczkowanie spektrofotometryczne przy wielu długościach fali zastosowano do wyznaczenia stałych protonowania 4-(2-tiazoliloazo) rezorcyny (TAR) oraz stałych trwałości kompleksów TAR z jonami Zn2+, Cd2+, Pb2+ i Cu2+ w 50% v/v mieszaninach DMSO-11,O przy sile jonowej 0,1 mol L-1 w temperaturze 25°C stosując analizę globalną. Widma absorpcyjne UV-VIS TAR i kompleksów metal-TAR zapisywano \v trakcie miareczkowania pehametrycznego kwaśnych roztworów TAR i mieszanin metal-TAR za pomocą standardowych roztworów zasady. W miareczkowaniach spektrofotometrycznych liniowe lub prawie liniowe profile stężeniowe oraz istnienie mniejszościowych indywiduów mogą utrudniać opracowanie danych. W analizie globalnej drugiego rzędu wykonano jednocześnie szereg miareczkowań spektrofotometrycznych zaczynając od różnych stężeń początkowych. W ten sposób można uzyskać warunki, w których występują w odpowiednich ilościach wszystkie indywidua i zgodnie z tym można uzupełnić do pełnej liczności matryce stężeniową. Stosując programy SQUAD i EQUISPEC oszacowano stałą trwałości różnych kompleksów TAR-metal przy rozmaitych stosunkach molowych.

3

Experimental Evidence, Stability and Proposed Structure of Protonated Tetramethyl p-tert-Butylcalix[4]arene Tetraketone

Makrlík E., Dybal J., Budka J., Vaoura V.

Polish Journal of Chemistry

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2008

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Vol. 82, nr 7

1441-1441

EN

From extraction experiments and gamma-activity measurements, the extraction constant corresponding to the equilibrium H3O+(aq) + 1×Na+(nb) 1.H3O+ (nb) + Na+(aq) taking place in the two-phase water–nitrobenzene system (1 = tetramethyl p-tert-butylcalix[4]arene tetraketone; aq = aqueous phase, nb = nitrobenzene phase) was evaluated as log Kex(H3O+,1.Na+) = –0.6š0.1. Fur ther, the sta bil ity con stant of the 1×H3O+ complex in water saturated nitrobenzene corresponding to the equilibrium 1(nb) + H3O+(nb) 1×H3O+ (nb) was calculated for a temperature of 25°C as log beta nb (1×H3O+) = 9.7š0.2. Finally, by means of DFT cal cu la tions, three dif fer ent struc tures of this com plex spe cies were in di cated. The cal culated stabilization energy of 1×H3O+, –406.7 kJ mol–1, is the same for of all three optimized structures.

4

The Silver(I) – Complexes of Cyclic Polyamines with Pendant-arm Modification

Wyrwa J., Kira J., Pankiewicz R., Schroeder G.

Polish Journal of Chemistry

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2006

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Vol. 80, nr 10

1633-1644

EN

The complex formation for two different groups of cyclic polyamines with four or six nitrogen atoms and with pendant-arm modification and silver(I) ions in propylene carbonate has been studied by electron spray ionization mass spectrometry (ESI MS), potentiometric and Austin Model 1 (AM1d) semiempirical methods. The stability constants of complexes are determined by potentiometric method. The structure of those complexes are visualised by AM1d semiempirical calculations.

5

The stoichiometry and stability of beta-cyclodextrin complexes of some aromatic ketones and thioketones

Milewski M., Urjasz W., Maciejewski A., Augustyniak W.

Polish Journal of Chemistry

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1998

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Vol. 72, nr 11

2405-2417

EN

Stoichiometry and stability constants of beta-cyclodextrin (beta-CD) complexes of several aromatic ketones and the corresponding thioketones were determined by the spectrophotometric and solubility methods. The solubility method with high-performance liquid chromatography (HPLC) detection of the solute concentration proved to be very convenient in determination of the stability constant for the least soluble thioketone. The formation constants were correlated with 1-octanol-water partition cefficients, which vary over more than five orders of magnitude for compounds studied. The hydrophobic interaction and dispersion forces were found to be the most important sources of the complex stability. Relatively strong hydrogen bonds between the ketone molecules and water destabilize their beta-cyclodextrin complexes. Stoichiometry of all beta-cyclodextrin complexes studied was found to be 1:1. The synthesis of a new alkyl derivative of 4H-1-benzopyran-4-one and 4H-1-beznopyran-4-thione was described.