Leszek Fiedor

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In contrast to porphyrins and chlorins, the direct metalation of bacteriochlorins is difficult. Nevertheless, Cu 2+ and Zn 2+ can be introduced into bacteriopheophytin in acetic acid, whereas Cd 2+ can be inserted in dimethylformamide. The former reactions depend on the substituents of the isocyclic ring: they are facilitated if enolization of the-ketoester(More)
Changes in the electronic transition energies and redox potentials because of metal substitution in bacteriochlorophyll a justify the recently suggested correlation between electronegativity M , covalent radius, and an effective charge, Q M , at the metal atom center. A simple electrostatic theory in which Q M modifies the energies of the frontier molecular(More)
Bacteriochlorophyll (BChl) derivatives (with central Mg replaced by metal "M") ([M]-BChl with M = 2H, Mg, Zn, Pd, Cu) have been investigated for their photodynamic capacity and stability toward photodegradation in organic solvents and aqueous micellar solution. A protocol has been developed for screening new sensitizers. BChl and [Zn]-BChl are efficient(More)
The effect of carotenoids on stability of model photosynthetic pigment-protein complexes subjected to chemical oxidation with hydrogen peroxide or potassium ferricyanide was investigated. The oxidation of carotenoid-less and carotenoid-containing complexes was conducted in the presence or absence of ascorbic acid. The progress of the reactions was monitored(More)
Practical applications of photosynthesis-inspired processes depend on a thorough understanding of the structures and physiochemical features of pigment molecules such as chlorophylls and bacteriochlorophylls. Consequently, the major structural features of these pigments have been systematically examined as to how they influence the S1 state energy,(More)
The effects of energetic decoupling of phycobiliproteins (PBP) from photosystems in Nostoc sp. on the emission characteristics and fluorescence profiles of cyanobacterial photosynthetic apparatus and its components were studied using steady-state and time-resolved fluorescence emission. The steady-state measurements show a rise in fluorescence from PBP(More)
This work presents spectroscopic studies of the keto–enol equilibrium induced by solvent polarizability in 4-[5-(naphthalen-1-ylmethyl)-1,3,4-thiadiazol-2-yl]benzene-1,3-diol a strong antiproliferative and anticancer thiadiazol derivative. Electronic absorption, steady state and time resolved fluorescence, and infrared spectroscopies were applied to(More)
Lung adenocarcinoma is a leading human malignancy with fatal prognosis. Ninety percent of the deaths, however, are caused by metastases. The model of subcutaneous tumor xenograft in nude mice was adopted to study the growth of control and photodynamically treated tumors derived from the human A549 lung adenocarcinoma cell line. As a side-result of the(More)
The choice between bare and coated capillaries is a key decision in the development and use of any methods based on capillary electrophoresis. In this work several permanently and dynamically coated capillaries were successfully implemented in a previously developed micellar electrokinetic chromatography (MEKC) assay of the plant membrane enzyme(More)
Water binding to several Mg(2+) chelates, ethylenediamine, ethylenediamine-N,N'-diacetate, porphyrin, chlorophyll a and bacteriochlorophyll a, to form five- and six-coordinate complexes is studied by means of density functional theory. The results obtained for magnesium chelates are compared with the properties of the respective aqua complexes and the(More)
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