33 results on '"Pedzinski T"'
Search Results
2. Dual behavior of histidine during sensitized photo-oxidation of model compounds and proteins
- Author
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Frąckowiak, K.J., Ignasiak, M.T., Grzechowiak, M., Fuentes-Lemus, E., Gamon, L.F., Pędziński, T., Hägglund, P.M., Jaskolski, M., Davies, M.J., and Marciniak, B.
- Published
- 2024
- Full Text
- View/download PDF
3. Spectroscopic properties of Bi2ZnOB2O6 single crystals doped with Pr3+ ions: Absorption and luminescence investigations
- Author
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Kasprowicz, D., Brik, M.G., Jaroszewski, K., Pedzinski, T., Bursa, B., Głuchowski, P., Majchrowski, A., and Michalski, E.
- Published
- 2015
- Full Text
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4. Synthesis of a novel dinuclear ruthenium polypyridine dye for dye-sensitized solar cells application
- Author
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Zalas, M., Gierczyk, B., Klein, M., Siuzdak, K., Pędziński, T., and Łuczak, T.
- Published
- 2014
- Full Text
- View/download PDF
5. Unusual photobehavior of benzophenone triplets in hexafluoroisopropanol. Inversion of the triplet character of benzophenone
- Author
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Lewandowska-Andralojc, A., Hug, G.L., Hörner, G., Pedzinski, T., and Marciniak, B.
- Published
- 2012
- Full Text
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6. Corrigendum to “Synthesis of a novel dinuclear ruthenium polypyridine dye for dye-sensitized solar cells application” [Polyhedron 67 (2014) 381–387]
- Author
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Zalas, M., Gierczyk, B., Klein, M., Siuzdak, K., Pędziński, T., and Łuczak, T.
- Published
- 2021
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7. Erratum to “Synthesis of a novel dinuclear ruthenium polypyridine dye for dye-sensitized solar cells application” [Polyhedron 67 (2014) 381–387]
- Author
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Zalas, M., Gierczyk, B., Klein, M., Siuzdak, K., Pędziński, T., and Łuczak, T.
- Published
- 2021
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8. Emission lifetime study of fluorescence probes based on G-quadruplex oligonucleotides end-labeled with pyrene moieties
- Author
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Cupane, A., Dembska, A., Pedzinski, T., Takenaka, S., and Juskowiak, B.
- Subjects
Spectroscopy - Abstract
Fluorescence lifetime study of two probes abbreviated as Py-Htelom-Py and Py-TBA-Py, carrying pyrene moieties at both termini and sequences of Human telomere and Thrombin Binding Aptamer, respectively are reported. The effect of potassium ion on the photophysical processes was examined in order to elucidate factors that facilitate the production of excimer emission. Emission kinetics data indicated that the relative orientation of pyrene and neighboring nucleobase (guanine, adenine, thymine) plays a crucial role in determining both the rate of electron-transfer quenching of pyrene excited state and the efficiency of excimer emission.
- Published
- 2010
9. Laser flash photolysis study of the photochemistry of resveratrol in acetonitrile
- Author
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Dzeba, I., primary, Pedzinski, T., additional, and Mihaljevic⁎, B., additional
- Published
- 2012
- Full Text
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10. Emission lifetime study of fluorescence probes based on G-quadruplex oligonucleotides end-labeled with pyrene moieties.
- Author
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Dembska, A., Pedzinski, T., Takenaka, S., and Juskowiak, B.
- Subjects
- *
FLUORESCENCE , *OLIGONUCLEOTIDES , *PYRENE , *TELOMERES , *THROMBIN , *POTASSIUM - Abstract
Fluorescence lifetime study of two probes abbreviated as Py-Htelom-Py and Py-TBA-Py, carrying pyrene moieties at both termini and sequences of Human telomere and Thrombin Binding Aptamer, respectively are reported. The effect of potassium ion on the photophysical processes was examined in order to elucidate factors that facilitate the production of excimer emission. Emission kinetics data indicated that the relative orientation of pyrene and neighboring nucleobase (guanine, adenine, thymine) plays a crucial role in determining both the rate of electron-transfer quenching of pyrene excited state and the efficiency of excimer emission. [ABSTRACT FROM AUTHOR]
- Published
- 2010
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11. Evidence for heterolytic cleavage of C-S bonds in the photolysis of 1,3,5-trithianes
- Author
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Hug, G. L., Edyta Janeba-Bartoszewicz, Filipiak, P., Pedzinski, T., Kozubek, H., and Marciniak, B.
12. Hydrogen bond-mediated conjugates involving lanthanide diphthalocyanines and trifluoroacetic acid (Lnpc2@TFA): Structure, photoactivity, and stability
- Author
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Tomasz Pedzinski, Maja Zakrzyk, Giuseppe Mele, Małgorzata A. Broda, Gabriela Dyrda, Rudolf Słota, Dyrda, G., Zakrzyk, M., Broda, M. A., Pedzinski, T., Mele, G., and Slota, R.
- Subjects
Lanthanide ,TFA conjugate ,Pharmaceutical Science ,010402 general chemistry ,Photochemistry ,photostability ,01 natural sciences ,singlet oxygen ,Analytical Chemistry ,lcsh:QD241-441 ,lanthanide diphthalocyanines ,chemistry.chemical_compound ,UV-Vis spectra ,lcsh:Organic chemistry ,TFA conjugates ,Drug Discovery ,Trifluoroacetic acid ,Molecule ,Physical and Theoretical Chemistry ,lanthanide diphthalocyanine ,010405 organic chemistry ,Hydrogen bond ,Singlet oxygen ,Organic Chemistry ,photon upconversion ,Chromophore ,0104 chemical sciences ,chemistry ,Chemistry (miscellaneous) ,Phthalocyanine ,Molecular Medicine ,Density functional theory - Abstract
The interaction between lanthanide diphthalocyanine complexes, LnPc2 (Ln = Nd, Sm, Eu, Gd, Yb, Lu, Pc = C32H16N8, phthalocyanine ligand) and trifluoroacetic acid (TFA) was investigated in benzene, and the stability of the resulting molecular system was assessed based on spectral (UV-Vis) and kinetic measurements. Structural Density Functional Theory (DFT) calculations provided interesting data regarding the nature of the bonding and allowed estimating the interaction energy between the LnPc2 and TFA species. Conjugates are created between the LnPc2 and TFA molecules via hydrogen bonds of moderate strength (>, N∙∙H·, ·, ) at the meso- -bridges of the Pc moieties, which renders the sandwich system to flatten. Attachment of TFA is followed by rearrangement of electronic density within the chromophore system of the macrocycles manifested in considerable changes in their UV-Vis spectra and consequently the color of the studied solutions (from green to orange). The LnPc2@TFA conjugates including Nd, Sm, Eu, and Gd appeared evidently less photostable when exposed to UV radiation than the related mother compounds, whereas in the case of Yb and Lu derivatives some TFA-prompted stabilizing effect was noticed. The conjugates displayed the capacity for singlet oxygen generation in contrast to the LnPc2s itself. Photon upconversion through sensitized triplet&ndash, triplet annihilation was demonstrated by the TFA conjugates of Nd, Sm, Eu, and Gd.
- Published
- 2020
13. Spectroscopic insights into BSA-mediated deaggregation of m-THPC.
- Author
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Kolman A, Pedzinski T, and Lewandowska-Andralojc A
- Subjects
- Animals, Cattle, Porphyrins chemistry, Photochemotherapy methods, Spectrum Analysis, Serum Albumin, Bovine chemistry, Photosensitizing Agents chemistry, Spectrometry, Fluorescence, Singlet Oxygen chemistry, Singlet Oxygen metabolism
- Abstract
Meta-tetra(hydroxyphenyl)chlorin (m-THPC) is among the most potent photosensitizers, known for its high singlet oxygen generation efficiency. However, its clinical effectiveness in photodynamic therapy (PDT) is compromised by its propensity to aggregate in aqueous solutions, adversely affecting its photophysical properties and therapeutic potential. A series of spectroscopic techniques, including UV-Vis absorption, fluorescence spectroscopy, and laser flash photolysis, revealed that m-THPC exhibits significant aggregation, particularly in MeOH-PBS mixtures with MeOH content below 30%. This aggregation adversely affects its photophysical properties leading to reduced fluorescence quantum yield and most importantly reducing its singlet oxygen quantum yield. This study introduces the use of bovine serum albumin (BSA) to counteract the aggregation of m-THPC, aiming to enhance its solubility, stability, and efficacy in physiological settings. Through advanced spectroscopic analyses we demonstrated that the m-THPC@BSA complex exhibits restored photophysical properties characteristic for monomeric form. Notably, the complex showed a significant restoration of the singlet oxygen quantum yield (Φ
Δ = 0.21) compared to aggregated m-THPC. These results underscore the potential of BSA to preserve the monomeric form of m-THPC, mitigating aggregation-induced losses in singlet oxygen production. Our findings suggest that BSA-mediated delivery systems could play a crucial role in optimizing the clinical utility of hydrophobic photosensitizers like m-THPC., (© 2024. The Author(s).)- Published
- 2024
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14. Novel Short PEG Chain-Substituted Porphyrins: Synthesis, Photochemistry, and In Vitro Photodynamic Activity against Cancer Cells.
- Author
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Lazewski D, Kucinska M, Potapskiy E, Kuzminska J, Tezyk A, Popenda L, Jurga S, Teubert A, Gdaniec Z, Kujawski J, Grzyb K, Pedzinski T, Murias M, and Wierzchowski M
- Subjects
- Humans, Photochemistry, Photosensitizing Agents chemistry, Zinc pharmacology, Antineoplastic Agents, Neoplasms, Photochemotherapy methods, Porphyrins chemistry
- Abstract
This work presents the synthesis and characterization of metal-free, zinc (II), and cobalt (II) porphyrins substituted with short PEG chains. The synthesized compounds were characterized by UV-Vis,
1 H and13 C NMR spectroscopy, and MALDI-TOF mass spectrometry. The origin of the absorption bands for tested compounds in the UV-Vis range was determined using a computational model based on the electron density functional theory (DFT) and its time-dependent variant (TD-DFT). The photosensitizing activity was evaluated by measuring the ability to generate singlet oxygen (ΦΔ), which reached values up to 0.54. The photodynamic activity was tested using bladder (5637), prostate (LNCaP), and melanoma (A375) cancer cell lines. In vitro experiments clearly showed the structure-activity relationship regarding types of substituents, their positions in the phenyl ring, and the variety of central metal ions on the porphyrin core. Notably, the metal-free derivative 3 and its zinc derivative 6 exerted strong cytotoxic activity toward 5637 cells, with IC50 values of 8 and 15 nM, respectively. None of the tested compounds induced a cytotoxic effect without irradiation. In conclusion, these results highlight the potential value of the tested compounds for PDT application., Competing Interests: The authors declare no conflict of interest.- Published
- 2022
- Full Text
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15. Sensitized photoreduction of selected benzophenones. Mass spectrometry studies of radical cross-coupling reactions.
- Author
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Grzyb K, Frański R, and Pedzinski T
- Subjects
- Chromatography, Liquid, Free Radicals chemistry, Hydrogen, Benzophenones chemistry, Tandem Mass Spectrometry
- Abstract
The hydrogen atom transfer reaction (HAT) between selected benzophenones (benzophenone BP, 3-carboxybenzophenone 3CB, and 4-carboxybenzophenone 4CB) and 2-propanol was reinvestigated focusing on stable product analysis. As expected, the primary species of these HAT's are the respective diphenyl and dimethyl ketyl radicals that eventually undergo several radical coupling reactions leading to stable photoproducts. However, the mechanisms of these free radical reactions remain unclear and open to question. In this report, we focus on the detailed analysis of the stable photoproducts of these reactions using liquid chromatography coupled with high-resolution mass spectrometry (LC-ESI-QTOF-MS/MS). Products of photopinacolization (benzpinacol and two diastereoisomers of 4CB and 3CB dimers) and isomeric radical cross-coupling adducts of respective diphenyl and dimethyl ketyl radicals were separated chromatographically, and their structures were determined by high-resolution MS/MS, and the mechanisms of the reactions are discussed., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2022 The Authors. Published by Elsevier B.V. All rights reserved.)
- Published
- 2022
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16. Understanding structure-properties relationships of porphyrin linked to graphene oxide through π-π-stacking or covalent amide bonds.
- Author
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Lewandowska-Andralojc A, Gacka E, Pedzinski T, Burdzinski G, Lindner A, O'Brien JM, Senge MO, Siklitskaya A, Kubas A, Marciniak B, and Walkowiak-Kulikowska J
- Abstract
Two graphene oxide nanoassemblies using 5-(4-(aminophenyl)-10,15,20-triphenylporphyrin (TPPNH
2 ) were fabricated by two synthetic methods: covalent (GO-CONHTPP) and noncovalent bonding. GO-CONHTPP was achieved through amide formation at the periphery of GO sheets and the hybrid material was fully characterized by FTIR, XPS, Raman spectroscopy, and SEM. Spectroscopic measurements together with theoretical calculations demonstrated that assembling TPPNH2 on the GO surface in DMF-H2 O (1:2, v/v) via non-covalent interactions causes changes in the absorption spectra of porphyrin, as well as efficient quenching of its emission. Interestingly, covalent binding to GO does not affect notably neither the porphyrin absorption nor its fluorescence. Theoretical calculations indicates that close proximity and π-π-stacking of the porphyrin molecule with the GO sheet is possible only for the non-covalent functionalization. Femtosecond pump-probe experiments revealed that only the non-covalent assembly of TPPNH2 and GO enhances the efficiency of the photoinduced electron transfer from porphyrin to GO. In contrast to the non-covalent hybrid, the covalent GO-CONHTPP material can generate singlet oxygen with quantum yields efficiency (ΦΔ = 0.20) comparable to that of free TPPNH2 (ΦΔ = 0.26), indicating the possible use of covalent hybrid materials in photodynamic/photothermal therapy. The spectroscopic studies combined with detailed quantum-chemical analysis provide invaluable information that can guide the fabrication of hybrid materials with desired properties for specific applications., (© 2022. The Author(s).)- Published
- 2022
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17. In-Depth Studies of Ground- and Excited-State Properties of Re(I) Carbonyl Complexes Bearing 2,2':6',2″-Terpyridine and 2,6-Bis(pyrazin-2-yl)pyridine Coupled with π-Conjugated Aryl Chromophores.
- Author
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Szlapa-Kula A, Małecka M, Maroń AM, Janeczek H, Siwy M, Schab-Balcerzak E, Szalkowski M, Maćkowski S, Pedzinski T, Erfurt K, and Machura B
- Abstract
In the current work, comprehensive photophysical and electrochemical studies were performed for eight rhenium(I) complexes incorporating 2,2':6',2″-terpyridine (terpy) and 2,6-bis(pyrazin-2-yl)pyridine (dppy) with appended 1-naphthyl-, 2-naphthyl-, 9-phenanthrenyl, and 1-pyrenyl groups. Naphthyl and phenanthrenyl substituents marginally affected the energy of the MLCT absorption and emission bands, signaling a weak electronic coupling of the appended aryl group with the Re(I) center. The triplet MLCT state in these complexes is so low lying relative to the triplet
3 ILaryl that the thermal population of the triplet excited state delocalized on the organic chromophore is ineffective. The attachment of the electron-rich pyrenyl group resulted in a noticeable red shift and a significant increase in molar absorption coefficients of the lowest energy absorption of the resulting Re(I) complexes due to the contribution of intraligand charge-transfer (ILCT) transitions occurring from the pyrenyl substituent to the terpy/dppy core. At 77 K, the excited states of [ReCl(CO)3 (Ln -κ2 N )] with 1-pyrenyl-functionalized ligands were found to have predominant3 ILpyrene /3 ILCTpyrene→terpy character. The3 IL/3 ILCT nature of the lowest energy excited state of [ReCl(CO)3 (4'-(1-pyrenyl)-terpy-κ2 N )] was also evidenced by nanosecond transient absorption and time-resolved emission spectroscopy. Enhanced room-temperature emission lifetimes of the complexes [ReCl(CO)3 (Ln -κ2 N )] with 1-pyrenyl-substituted ligands are indicative of the thermal activation between3 MLCT and3 IL/3 ILCT excited states. Deactivation pathways occurring upon light excitation in [ReCl(CO)3 (4'-(1-naphthyl)-terpy-κ2 N )] and [ReCl(CO)3 (4'-(1-pyrenyl)-terpy-κ2 N )] were determined by femtosecond transient absorption studies.- Published
- 2021
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18. Carbazole effect on ground- and excited-state properties of rhenium(i) carbonyl complexes with extended terpy-like ligands.
- Author
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Choroba K, Maroń A, Switlicka A, Szłapa-Kula A, Siwy M, Grzelak J, Maćkowski S, Pedzinski T, Schab-Balcerzak E, and Machura B
- Abstract
The ground- and excited-state properties of three novel complexes [ReCl(CO)
3 (Ln -κ2 N)] bearing 2,2':6',2''-terpyridine, 2,6-di(thiazol-2-yl)pyridine and 2,6-di(pyrazin-2-yl)pyridine functionalized with 9-carbazole attached to the central pyridine ring of the triimine core via phenylene linkage were investigated by spectroscopic and electrochemical methods and were simulated using density functional theory (DFT) and time-dependent DFT. To get a deeper and broader understanding of structure-property relationships, the designed Re(i) carbonyl complexes were compared with previously reported analogous systems - without any groups attached to the phenyl ring and bearing pyrrolidine instead of 9-carbazole. The results indicated that attachment of the N-carbazolyl substituent to the triimine core has less influence on the nature of the triplet excited state of [ReCl(CO)3 (Ln -κ2 N)] than the pyrrolidine group. Additionally, the impact of the ligand structural modifications on the light emission of the Re(i) complexes under external voltage was preliminarily examined with electroluminescence spectra of diodes containing the synthesized new molecules in an active layer.- Published
- 2021
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19. Towards better understanding of the photophysics of platinum(II) coordination compounds with anthracene- and pyrene-substituted 2,6-bis(thiazol-2-yl)pyridines.
- Author
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Maria Maroń A, Choroba K, Pedzinski T, and Machura B
- Abstract
The photophysical properties of platinum(ii) compounds with 4-(9-anthryl)-2,6-bis(thiazol-2-yl)pyridine (1) and 4-(1-pyrenyl)-2,6-bis(thiazol-2-yl)pyridine (2) were widely investigated. In DMSO and MeCN, the triplet emission of (1) and (2) most probably experiences the solvent-induced exciplex quenching and both complexes exhibit ligand-based fluorescence with maxima in the range of 468-570 nm. In non-coordinating dichloromethane, the emission of (1) and (2) shifts to longer wavelengths, and the lifetimes in microseconds are indicative of phosphorescence. The formation of the triplet excited state was further supported by the observation of singlet oxygen photoluminescence in the near-IR at 1270 nm. To explore the nature of the triplet excited state, the emission properties of (1) and (2) in low temperature glasses were analysed in comparison with those for free ligands and appropriate hydrocarbons, as well as transient absorption spectra were recorded in femtosecond and nanosecond regimes. The studies revealed that the lowest energy triplet state of both complexes is an admixture of 3ILCT and 3(π-π*)aryl character, but the contribution of the 3ILCT state in (1) originating from anthracene to 2,6-bis(thiazol-2-yl)pyridine can be determined as rather negligible.
- Published
- 2020
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20. Early Events of Photosensitized Oxidation of Sulfur-Containing Amino Acids Studied by Laser Flash Photolysis and Mass Spectrometry.
- Author
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Pedzinski T, Grzyb K, Kaźmierczak F, Frański R, Filipiak P, and Marciniak B
- Abstract
The mechanism of photooxidation of methionine (N-Ac-Met-NH-CH
3 , 1 ) and methyl-cysteine (N-Ac-MeCys-NH-CH3 , 2 ) analogues by 3-carboxybenzophenone triplet (3CB*) in neutral aqueous solution was studied using techniques of nanosecond laser flash photolysis and steady-state photolysis. The short-lived transients derived from 3CB and sulfur-containing amino acids were identified, and their quantum yields and kinetics of formation and decay were determined. The stable photoproducts were analyzed using liquid chromatography coupled with high-resolution mass spectrometry. Substantial differences in the mechanisms were found for methionine and S -methyl-cysteine analogues for both primary and secondary photoreactions. A new secondary reaction channel (back hydrogen atom transfer from the ketyl radical to the carbon-centered α-thioalkyl radical yielding reactants in the ground states) was suggested. The detailed mechanisms of 3CB* sensitized photooxidation of 1 and 2 are proposed and discussed.- Published
- 2020
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21. Unexpected light emission from tyrosyl radicals as a probe for tyrosine oxidation.
- Author
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Ignasiak M, Frackowiak K, Pedzinski T, Davies MJ, and Marciniak B
- Subjects
- Free Radicals, Oxidation-Reduction, Proteins, Tyrosine metabolism
- Abstract
Tyrosine residues (Tyr) on proteins are a favoured site of one-electron oxidation due to their low one-electron reduction potentials. In this work, light-induced oxidation of Tyr residues was investigated using direct ionisation (via 266 nm light excitation) and sensitized photo-oxidation (by 3-carboxybenzophenone as sensitizer and 355 nm). Light emission (fluorescence) was observed at 410-440 nm as a result of Tyr oxidation. This novel light emission process is shown to be dependent on the solvent and aromatic ring substituents, however it does not depend on pH. It is proposed, that after initial formation of tyrosine phenoxyl radicals (TyrO
● ) by one electron-oxidation, the TyrO● absorbs a second photon to give an excited state species that undergoes subsequent light emission. The intensity of this emission depends on the Tyr concentration, and the detection of this emission can be used to identify and quantify one-electron formation of oxidized Tyr residues on proteins., (Copyright © 2020 The Authors. Published by Elsevier Inc. All rights reserved.)- Published
- 2020
- Full Text
- View/download PDF
22. Unexpected Reaction Pathway of the Alpha-Aminoalkyl Radical Derived from One-Electron Oxidation of S -Alkylglutathiones.
- Author
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Pedzinski T, Bobrowski K, Marciniak B, and Filipiak P
- Subjects
- Alkylation, Lasers, Oxidation-Reduction, Photolysis, Electrons, Glutathione chemistry
- Abstract
Laser flash photolysis and high-resolution mass spectrometry were used to investigate the mechanism of one-electron oxidation of two S -alkylglutathiones using 3-carboxybenzophenone (3CB) as a photosensitizer. This report indicates an unexpected reaction pathway of the α-aminoalkyl radical cation (αN
+ ) derived from the oxidation of S -alkylglutathiones. Instead of a common hydrolysis reaction of αN+ reported earlier for methionine and other sulfur-containing aminoacids and peptides, an intramolecular ring-closure reaction was found for S -alkylglutathiones., Competing Interests: The authors declare no conflict of interest.- Published
- 2020
- Full Text
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23. Fluorescent 2-(Pyridin-2-yl)vinyl Pyridine Dyes and Their Thermocontrolled Release.
- Author
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Witkowska A, Brzezinska J, Pedzinski T, and Chmielewski MK
- Abstract
The generation of unique thermosensitive fluorescent dyes via heteroaromatic Heck cross-coupling and N -pyridin-2-yl nucleophilic substitution was described. To demonstrate thermosensitive properties, the precursor was converted into carbonates or phosphates and heated at various temperatures and for various time periods. Significant changes in the fluorescence intensity and emission wavelengths, between carbonates and the cyclic product, were observed, and it was proved that the dyes may serve as removable fluorescent labels with large Stokes shifts (>80 nm). The application of thermosensitive fluorescent dyes in oligonucleotide labeling has been demonstrated.
- Published
- 2019
- Full Text
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24. Experimental and theoretical studies on fluvastatin primary photoproduct formation.
- Author
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Jarmużek D, Pedzinski T, Hoffmann M, Siodła T, Salus K, and Pluskota-Karwatka D
- Subjects
- Chromatography, High Pressure Liquid, Fluvastatin, Photolysis radiation effects, Quantum Theory, Singlet Oxygen chemistry, Singlet Oxygen metabolism, Spectrophotometry, Ultraviolet, Tandem Mass Spectrometry, Thermodynamics, Ultraviolet Rays, Fatty Acids, Monounsaturated chemistry, Indoles chemistry, Models, Theoretical
- Abstract
Fluvastatin (FLV) belongs to the group of compounds referred to as statins, also known as 3-hydroxy-3-methylglutaryl-coenzyme A (HMG-CoA) reductase inhibitors. Statins act as cholesterol-lowering agents and are among the most frequently prescribed drugs. They upregulate low-density lipoprotein receptors in the liver by binding to the active site of HMG-CoA reductase, which is the key enzyme in cholesterol biosynthesis. Statins have been detected as contaminants in natural waters and are susceptible to degradation upon exposure to light. Fluvastatin is extremely sensitive to light; upon irradiation it forms a range of photoproducts. In this study the fluvastatin molar absorption coefficient and the quantum yield of the drug photodegradation were determined. The FLV photodegradation quantum yield value determined in this work (Φ = 0.13 ± 0.02) was found to be significantly larger than that previously reported in the literature. Our results also showed that the generation of singlet oxygen is not involved in the drug photodecomposition indicating that the excited triplet state of fluvastatin is not populated efficiently. Moreover, experimental methods and DFT calculations were applied to get insight into the possible mechanisms of fluvastatin primary photoproduct formation. Using the transient absorption spectroscopy technique, the transient species formed immediately after the drug excitation were followed, and the scheme for fluvastatin primary photochemistry was suggested. The primary photoproducts were identified on the basis of spectroscopic and spectrometric methods. A new mechanism for photooxygenation leading to the formation of one of the identified photoproducts (FP2) was proposed and a new approach to the formation of the other photoproduct (FP1) was provided. The theoretical mechanistic explanation of the photoproduct formation is in excellent agreement with the experimental data.
- Published
- 2017
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25. Structural Aspects of the Antiparallel and Parallel Duplexes Formed by DNA, 2'-O-Methyl RNA and RNA Oligonucleotides.
- Author
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Szabat M, Pedzinski T, Czapik T, Kierzek E, and Kierzek R
- Subjects
- Circular Dichroism, Hydrogen-Ion Concentration, DNA chemistry, Oligonucleotides chemistry, RNA chemistry
- Abstract
This study investigated the influence of the nature of oligonucleotides on the abilities to form antiparallel and parallel duplexes. Base pairing of homopurine DNA, 2'-O-MeRNA and RNA oligonucleotides with respective homopyrimidine DNA, 2'-O-MeRNA and RNA as well as chimeric oligonucleotides containing LNA resulted in the formation of 18 various duplexes. UV melting, circular dichroism and fluorescence studies revealed the influence of nucleotide composition on duplex structure and thermal stability depending on the buffer pH value. Most duplexes simultaneously adopted both orientations. However, at pH 5.0, parallel duplexes were more favorable. Moreover, the presence of LNA nucleotides within a homopyrimidine strand favored the formation of parallel duplexes.
- Published
- 2015
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26. A reevaluation of the photolytic properties of 2-hydroxybenzophenone-based UV sunscreens: are chemical sunscreens inoffensive?
- Author
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Ignasiak MT, Houée-Levin C, Kciuk G, Marciniak B, and Pedzinski T
- Subjects
- Kinetics, Oxidation-Reduction, Phenols chemistry, Photolysis, Spectrometry, Fluorescence, Ultraviolet Rays, Benzophenones chemistry, Sunscreening Agents chemistry
- Abstract
The excited states of a set of popular sunscreen agents (2-hydroxybenzophenone, oxybenzone, and sulisobenzone) are studied by using femto- and nanosecond time-resolved spectroscopy. Upon excitation, the compounds undergo an ultrafast excited-state intramolecular proton transfer (ESIPT) reaction as the major energy-wasting process and the rate constant of this reaction is k=2×10(12) s(-1) . The ESIPT yields a keto conformer that undergoes a fast, picosecond internal conversion decay. However, a photodegradative pathway is a monophotonic HO bond breakage that subsequently leads to trace yields of phenoxyl radicals. Because potentially harmful phenoxyl radicals are formed upon irradiation of sunscreen agents, care should be taken about their reactivity towards biologically relevant compounds., (© 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)
- Published
- 2015
- Full Text
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27. Photosensitized oxidation of methionine-containing dipeptides. From the transients to the final products.
- Author
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Ignasiak MT, Pedzinski T, Rusconi F, Filipiak P, Bobrowski K, Houée-Levin C, and Marciniak B
- Subjects
- Kinetics, Lasers, Oxidation-Reduction, Dipeptides chemistry, Methionine, Photolysis
- Abstract
The Met residue oxidation has been studied for decades. Although many efforts have been made on the identification of free radicals, some doubts remain about their final fates, i.e., the nature of stable oxidation products. The photosensitized oxidation processes of two peptides, methionyl lysine (Met-Lys) and lysyl methionine (Lys-Met), were investigated using 3-carboxybenzophenone (3CB) as a sensitizer. Therefore, not only the transients were characterized but also the final products (by high-performance liquid chromatography and mass spectrometry) together with the quantum yields. As for the transients, the sulfur radical cations stabilized by a two-center three electron bonds with a nitrogen (S.·.N)(+) were identified in the case of Met-Lys. On the other hand, in Lys-Met, the intermolecular (S.·.S)(+) radical cations were found. The peptide-3CB adduct was the only stable product detected and was accompanied neither by sulfoxide formation nor by decarboxylation. It shows that both (S.·.N)(+) and (S.·.S)(+) radicals are converted into the relatively long-lived α-(alkylthio)alkyl radicals, which add to the 3CB-derived radicals. This addition reaction prevented all other oxidation processes such as formation of sulfoxide. The lysine residue was totally protected, which may also be of importance in biological processes.
- Published
- 2014
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28. Photochemical formation of thiirene and thioketene in 1,2,3-thiadiazoles with phenyl substituents studied by time-resolved spectroscopy.
- Author
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Burdzinski G, Sliwa M, Zhang Y, Delbaere S, Pedzinski T, and Réhault J
- Subjects
- Isomerism, Photolysis, Solutions chemistry, Spectrophotometry, Infrared, Spectrophotometry, Ultraviolet, Temperature, Time Factors, Ultraviolet Rays, Ethylenes chemistry, Ketones chemistry, Thiadiazoles chemistry
- Abstract
Photochemistry of 4-phenyl-1,2,3-thiadiazole (PT) and 4,5-diphenyl-1,2,3-thiadiazole (DPT) in solution was studied at room temperature using UV-vis and IR transient absorption spectroscopies (λ(ex) = 266 nm). Ultrafast techniques show a very fast rise (<0.3 ps) of thiirene and thioketene species, formed from 1,2,3-thiadiazoles in the singlet excited state. The remarkable unimolecular stability of thiirenes in solution is observed. On a millisecond time scale thiirenes with phenyl substituents undergo an intermolecular reaction (dimerization of thiirene-thioketene complexes) leading to 1,3-dithiole derivatives.
- Published
- 2013
- Full Text
- View/download PDF
29. Sensitized photooxidation of s-methylglutathione in aqueous solution: intramolecular (S∴O) and (S∴N) bonded species.
- Author
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Filipiak P, Hug GL, Bobrowski K, Pedzinski T, Kozubek H, and Marciniak B
- Subjects
- Benzophenones chemistry, Electrons, Glutathione chemistry, Hydrogen-Ion Concentration, Kinetics, Nitrogen chemistry, Oxidation-Reduction, Oxygen chemistry, Peptides chemistry, Photolysis, Quantum Theory, Sulfur chemistry, Glutathione analogs & derivatives, Water chemistry
- Abstract
Nanosecond laser flash photolysis was used to generate sulfur radical cations of the thioether, S-methylglutathione (S-Me-Glu), via the one-electron oxidation of this thioether by triplet 4-carboxybenzophenone. The purpose of this investigation was to follow the neighboring group effects resulting from the interactions between the sulfur radical cationic sites and nearby lone-pair electrons on heteroatoms within the radical cation, especially the electron lone-pairs on heteroatoms in the peptide bonds. The tripeptide, S-Me-Glu, offers several possible competing neighboring group effects that are characterized in this work. Quantum yields of the various radicals and three-electron bonded (both intramolecular and intermolecular) species were determined. The pH dependence of photoinduced decarboxylation yields was used as evidence for the identification of a nine-membered ring, sulfur-nitrogen, three-electron bonded species. The mechanisms of the secondary reactions of the radicals and radical cations were characterized by resolving their overlapping transient-absorption spectra and following their kinetic behavior. In particular, sulfur-oxygen and sulfur-nitrogen three-electron bonded species were identified where the oxygen and nitrogen atoms were in the peptide bonds.
- Published
- 2013
- Full Text
- View/download PDF
30. Efficient photochemical oxidation of anisole in protic solvents: electron transfer driven by specific solvent-solute interactions.
- Author
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Lewandowska A, Hug GL, Hörner G, Pedzinski T, Filipiak P, and Marciniak B
- Abstract
The dynamics of the bimolecular quenching of triplet excited benzophenone by anisole was studied by nanosecond flash photolysis. We carried out a detailed study of the solvent dependence of the reaction rates and efficiencies in a number of protic and non-protic solvents. These studies were augmented by theoretical modelling and experimental investigation of solute/solvent interactions in the triplet excited and the ground state, respectively. The triplet quenching that follows Stern-Volmer kinetics in all cases is profoundly dependent on the nature of the solvent, with the highest reactivity being consistently found in protic solvents. The results in non-protic solvents are compatible with unproductive quenching via a charge-transfer state, whereas the generally fast quenching in protic solvents is accompanied by efficient formation of free-radical products. Analysis of the solvent dependence in terms of Marcus theory reveals the impact of specific solvation of benzophenone by protic solvents on the ET driving force and kinetics. Specific solvation is found to support efficient free radical ion formation in media of moderate and low polarity as well.
- Published
- 2010
- Full Text
- View/download PDF
31. Photocycloaddition of the T1 excited state of thioinosine to uridine and adenosine.
- Author
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Wenska G, Filipiak P, Burdziński G, Pedzinski T, Hug GL, and Gdaniec Z
- Subjects
- Absorption, Acetylation, Oxygen chemistry, Temperature, Adenosine chemistry, Photochemical Processes, Thioinosine chemistry, Uridine chemistry
- Abstract
Novel photoadducts were obtained by irradiation of thioinosine (6-thiopurine riboside, TI) in deaerated aqueous solution without and in the presence of uridine and adenosine. Excitation (lambda > 300 nm) of TI to its excited S2 state yields a single bimolecular photoproduct. It is a purine-pyrimidine diriboside in which the purine ring is attached to the amide nitrogen of 6-amino-4-thioxo-5-formamidopyrimidine. When TI was irradiated in the presence of an excess of adenosine, two photoproducts were isolated: diribosides of N-(4,6-diaminopirymidin-5-yl)-N-formyl-6-aminopurine and N-(4-amino-6-formylamino-pyrimidin-5-yl)-6-aminopurine, both containing a purine and a formylaminopyrimidine (Fapy) fragment. The photoreaction of TI with uridine gave two regioisomeric photoproducts identified as diribosides containing either 5- or 6-(purin-6-yl)uracil as aglycones. A multistep mechanism leading to the stable photoproducts is proposed. In the first step of the mechanism, the C=S group of the excited TI undergoes a [2 + 2] cycloaddition regioselectively to the N(7)=C(8) bond of the purine ring or adds in a non-regioselective manner to the C(5)=C(6) bond of uracil. The unstable photoproducts thus formed undergo a series of dark reactions at room temperature. The photocycloaddition reactions originate from the excited T1 state of TI. This conclusion is supported by a combination of evidence from reaction quenching studies using both steady-state quantum yield determinations and kinetics results from nanosecond laser flash photolysis. The T1 state of TI is quenched by other TI molecules in their S0 state (self-quenching) and also by uridine and adenosine, all with large rate constants (0.8-5) x 10(9) M(-1) s(-1). The quantum yields of the reactions are in general very low (phi(R) < or = 8 x 10(-3)). The sources of the inefficiency in the photocycloaddition of TI to uridine and adenosine are discussed. The photoproducts containing the Fapy residue undergo deformylation and isomerization of the ribosyl moiety (anomerization, furanose/pyranose transformation) upon heating in aqueous solution. Products of the transformations were identified.
- Published
- 2009
- Full Text
- View/download PDF
32. Head-to-tail interactions in tyrosine/benzophenone dyads in the ground and the excited state: NMR and laser flash photolysis studies.
- Author
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Hörner G, Hug GL, Pogocki D, Filipiak P, Bauer W, Grohmann A, Lämmermann A, Pedzinski T, and Marciniak B
- Subjects
- Hydrogen chemistry, Magnetic Resonance Spectroscopy, Molecular Structure, Solvents chemistry, Tyrosine chemistry, Benzophenones chemistry, Lasers, Photolysis
- Abstract
The formation of head-to-tail contacts in de novo synthesized benzophenone/tyrosine dyads, bp logical sum Tyr, was probed in the ground and excited triplet state by NMR techniques and laser flash photolysis, respectively. The high affinity of triplet-excited ketones towards phenols was used to trace the geometric demands for high reactivity in the excited state. A retardation effect on the rates with increasing hydrogen-bond-acceptor ability of the solvent is correlated with ground-state masking of the phenol. In a given solvent the efficiencies of the intramolecular hydrogen-atom-transfer reaction depend strongly on the properties of the linker: rate constants for the intramolecular quenching of the triplet state cover the range of 10(5) to 10(8) s(-1). The observed order of reactivity correlates to a) the probability of close contacts (from molecular-dynamics simulations) and b) the extent of the electronic overlap between the pi systems of the donor and acceptor moieties (from NMR). A broad survey of the NMR spectra in nine different solvents showed that head-to-tail interactions between the aromatic moieties of the bp logical sum Tyr dyads already exist in the ground state. Favourable aromatic-aromatic interactions in the ground state appear to correspond to high excited-state reactivity.
- Published
- 2008
- Full Text
- View/download PDF
33. Effect of hydroxylic solvent on the fluorescence behavior of some bioactive 9-oxo-imidazo[1,2-a]purine derivatives.
- Author
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Wenska G, Koput J, Pedzinski T, Marciniak B, Karolczak J, and Golankiewicz B
- Subjects
- Alcohols chemistry, Hydrogen Bonding, Hydroxylation, Molecular Structure, Photochemistry, Solutions, Spectrometry, Fluorescence, Imidazoles chemistry, Purines chemistry, Solvents chemistry
- Abstract
The spectral and photophysical behavior of four fluorescent 9-oxo-imidazo[1,2-a]purine derivatives containing pyridyl, pyridylphenyl, phenyl, and biphenylyl substituents at the C(6) position of the tricyclic skeleton is described. The studies were performed in several aprotic and protic organic solvents using absorption spectroscopy as well as steady-state and time-resolved fluorescence spectroscopy. The results are also presented of TDDFT calculations on singlet-singlet excitation energies and oscillator strengths for two models of 9-oxo-imidazo[1,2-a]purine, with phenyl or pyridyl substituents, both in the gas phase and in methanol solution. While the derivatives with aryl substituents did not show any significant dependence of their static and dynamic fluorescence properties on the nature of the solvent, the compounds containing a pyridine residue exhibited a remarkable reduction of their fluorescence quantum yields and lifetimes in the alcoholic solutions. The solute-solvent hydrogen-bonding interaction in the first excited singlet state is responsible for the fast radiationless decay rates determined for pyridyl- and pyridylphenyl-substituted compounds in protic solvents. The results of experimental and theoretical studies show that the hydrogen of the alcohols' hydroxyl group and the nitrogen atom of the pyridine moiety are involved in the interaction. The fluorescence-quenching experiments performed for the pyridyl-substituted 9-oxo-imidazo[1,2-a]purine derivative using trifluoroethanol, methanol, and butanol as quenchers revealed that the quenching efficiencies, expressed by the Stern-Volmer quenching constants, correlate with the H-bond donating abilities of the alcohols. The quenching is a dynamic process, and the H-bonded complex formed is nonfluorescent. The experimentally determined and the calculated values of the dipole moment change associated with the electronic excitation indicate that the excited S(1) states of all of the molecules studied in this work have an intramolecular charge-transfer character and that electronic charge is transferred to the C(6) substituent upon excitation. Thus, the ability of the pyridyl substituent nitrogen atom to act as an H-bond acceptor in the excited S(1) state is enhanced. The 6-pyridyl-9-oxo-imidazo[1,2-a]purine presents a novel fluorophore, which, besides its medical applications, may be useful as a sensor of hydroxyl groups in microorganized systems.
- Published
- 2006
- Full Text
- View/download PDF
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