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Copper Octacarboxyphthalocyanine Aggregation in Buffered Solutions

Suchan A., Nackiewicz J.

Polish Journal of Chemistry

2008

Vol. 82, nr 8

1489-1489

Results of spectral UV-Vis absorption investigations on association of copper octa-carboxyphthalocyanine, CuPcOC, are reported. Influence of pH on association is discussed. In pH < 5.5 only ag gre gates are present. Monomer appears above pH = 5.5 and at pH Greater-than or equal to 6.2 only monomeric Pc forms exist. CuPcOC exhibits higher tendency to wards association in phosphate buffer solutions than in redistilled water. In pH 5.9–6.0 monomers, dimers and trimers coexist in equilibrium in 1.0×10–6 – 1.2×10–5 mol/dm3 concentration range at 25°C. The average assembling number n = 3 was determined for pH 5.6, 5.9 and 6.0 solutions. The spectrum of aggregate was calculated with two maxima at gammamax approx. 600 nm and 630 nm attributed to trimer and dimer band, respectively. Decrease of pH causes an in crease of cumulated association constant Kn. Kn of or der of 109 (dm3/mol)2 was calculated for pH 6.0 and 1010 (dm3/mol)2 for pH 5.9. For pH 5.6 considerably higher Kn was evaluated. A strong influence of pH on CuPcOC spectrum and equilibrium constants suggests that be sides pi-pi inter actions hydrogen bonding between Pc molecules can also occur.

Dimerization of Copper Octacarboxyphthalocyanine in Aqueous Solutions

Suchan A., Nackiewicz J., Hurek J., Wacławek W.

Polish Journal of Chemistry

2005

Vol. 79 / nr 12

1937-1947

Spectral absorption UV-Vis investigations on association of copper(II) octacarboxyphthalocyanine in aqueous solutions are reported. In 5.0x10-7-5.0x10-5 mol/dm3 concentration range monomers and dimers are mainly present. The calculated dimerization constant 106dm3/mol at 25°C and the hypsochromic spectral shift for the dimer 1164 cm-1 (688 nm_ 637 nm) indicate a stack-like association of molecules and suggestpi-pi interactions between Pc macrocycles in dimer and higher aggregates, in contrast to hydrogen bonding between carboxylic groups of adjacent Pc molecules.

Wyznaczanie stałych multimeryzacji kwasów ftalocyjaninowych w roztworach wodnych

Nackiewicz J., Hurek J., Suchan A., Wacławek W.

Chemistry-Didactics-Ecology-Metrology

2002

R. 7, NR 1-2

85--89

Omówiono metody wyznaczania stałych i stopnia multimeryzacji ftalocyjanin z widm absorpcyjnych VIS. Przedstawiono wyznaczanie stałej dimeryzacji molekuł oktakarboksyftalocyjaniny miedzi(II) w roztworze wodnym. Przeprowadzona analiza statystyczna uzyskanego dopasowania widm zmierzonych do „obliczonych” potwierdza poprawność przyjętej metody obliczeniowej dla wyznaczenia stałej dimeryzacji.

The methods of evaluation of both phthalocyanine multimerization constants and multimerization degree from VIS absorption spectra are discussed. The evaluation of dimerization constant of copper(II) octacarboxyphthalocyanine molecules in aqueous solution is presented. Statistical analysis of the experimental and calculated spectra fit confirms the reliability of the calculation method applied for the evaluation of the dimerization constant.