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174 results on '"Cigáň, Marek"'

12. Synthesis of Unsymmetrically Substituted [5]Helicenes by Tandem Arylation of Binaphthyl by Suzuki Coupling and C−H Activation.

Author

Bulko, Filip, Filo, Juraj, Cigáň, Marek, and Putala, Martin

Subjects
SUZUKI reaction, ARYLATION, HELICENES, STERIC hindrance
Abstract

We report a step‐efficient approach for the synthesis of unsymmetrically substituted naphtho[1,2‐g]chrysenes by tandem arylation of 2,2'‐diiodo‐1,1'‐binaphthyl with arylboronic acids, which proceeds through Suzuki coupling followed by intramolecular arylation by C−H activation. Substrate screening examining over 30 meta‐ and/or para‐substituted arylboronic acids showed that this approach provides the desired helicene products most effectively if arylboronic acids have a small acidifying group at the meta‐position. In the case of unsymmetrically substituted arylboronic acids, the regioselectivity of C−H activation is directed by the attached group(s), its effect on the C−H acidity of the adjacent position, its coordination ability, as well as steric hindrance. Interestingly, selected [5]helicenes exhibited attractive deep blue emission with fluorescence lifetimes slightly exceeding 10 ns. [ABSTRACT FROM AUTHOR]

Published
2024
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13. Thermal isomerization of phenylazoindoles: Inversion or rotation? That is the question.

Author

Hegedüsová, Lea, KuteI', Rastislav, Medved', Miroslav, Pašteka, Lukáš Félix, Cigáň, Marek, and Budzák, Šimon

Subjects
ROTATIONAL motion, DENSITY functional theory, ISOMERIZATION
Abstract

Azoheteroarenes represent an attractive group of photochromes exhibiting a large structural variability and tunability of photoswitching characteristics. The thermal back‐isomerization can proceed via inversion or rotation mechanisms, depending on the functionalization and environment. However, the distinction between the two remains a challenge for both experiment and theory. Here, four experimentally fully characterized phenylazoindoles are studied to establish the mechanism of back‐reaction in solvent using density functional theory (DFT), spin‐flip time‐dependent (TD‐)DFT, mixed‐reference TD‐DFT, and restricted ensemble Kohn–Sham approaches as well as CASPT2 and CCSD(T). While the inversion is consistently described by all methods, the rotation mechanism requires multireference approaches including dynamic correlation. The balanced description of both pathways becomes even more important in solvent which apparently affects the mechanism. For the present set, the range‐separated functionals combined with continuum models appear to be the most consistent with experiment in terms of the substitutional and solvent effects on thermal halftimes. [ABSTRACT FROM AUTHOR]

Published
2023
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16. Rigidized 3-aminocoumarins as fluorescent pH probes for strongly acidic environments

Author

Joniak, Jakub, Stankovičová, Henrieta, Budzák, Šimon, Sýkora, Milan, Gaplovská-Kyselá, Katarína, and Cigáň, Marek

Subjects
Turn-on pH probes, Highly acidic conditions, Coumarin, Yeast vacuolar lumen staining, Fluorescence
Abstract

Coumarins remain one of the most important group of fluorescent bio-probes, thanks to their high quantum yields, excellent photostability, efficient cell permeation and low (cyto)toxicity. Herein, we introduce new 3-aminocoumarin turn-on pH probes for strongly acidic conditions, capable of significantly improved yeast vacuolar lumen staining compared to the commercial CMAC derivatives. We present the details of the on-off switching mechanism revealed by the TD-DFT and ab initio calculations complemented by a Franck-Condon analysis of the probes´ emission profiles.

Published
2022

21. Rigidized 3-aminocoumarins as fluorescent probes for strongly acidic environments and rapid yeast vacuolar lumen staining: mechanism and application.

Author

Joniak, Jakub, Stankovičová, Henrieta, Budzák, Šimon, Sýkora, Milan, Gaplovská-Kyselá, Katarína, Filo, Juraj, and Cigáň, Marek

Abstract

Coumarins remain one of the most important groups of fluorescent bio-probes, thanks to their high quantum yields, moderate photostability, efficient cell permeation and low (cyto)toxicity. Herein, we introduce new 3-aminocoumarins as turn-on pH probes under strongly acidic conditions and for indicators capable of significantly improving yeast vacuolar lumen staining compared to the commercial CMAC derivatives. We present the details of the on–off switching mechanism revealed by the TD-DFT and ab initio calculations complemented by a Franck–Condon analysis of the probes' emission profiles. [ABSTRACT FROM AUTHOR]

Published
2023
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26. Dithienylnaphthalenes and quaterthiophenes substituted with electron-withdrawing groups as n-type organic semiconductors for organic field-effect transistors

Author

Feriancova, Lucia, primary, Cigáň, Marek, additional, Kozisek, Jozef, additional, Gmucová, Katarína, additional, Nádaždy, Vojtech, additional, Dubaj, Tibor, additional, Sobota, Michal, additional, Novota, Miroslav, additional, Weis, Martin, additional, and Putala, Martin, additional

Published
2022
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28. Design of High-Performance Pyridine/Quinoline Hydrazone Photoswitches

Author

Mravec, Bernard, primary, Budzák, Šimon, additional, Medved’, Miroslav, additional, Pašteka, Lukáš F., additional, Slavov, Chavdar, additional, Saßmannshausen, Torben, additional, Wachtveitl, Josef, additional, Kožíšek, Jozef, additional, Hegedüsová, Lea, additional, Filo, Juraj, additional, and Cigáň, Marek, additional

Published
2021
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38. Photoswitching hydrazones based on benzoylpyridine

Author

Mravec, Bernard, primary, Filo, Juraj, additional, Csicsai, Klaudia, additional, Garaj, Vladimír, additional, Kemka, Miroslav, additional, Marini, Anna, additional, Mantero, Mariachiara, additional, Bianco, Andrea, additional, and Cigáň, Marek, additional

Published
2019
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41. Front Cover: Enhancing the Potential of Fused Heterocycle‐Based Triarylhydrazone Photoswitches (Chem. Eur. J. 8/2024).

Author

Hegedüsová, Lea, Blaise, Nadine, Pašteka, Lukáš F., Budzák, Šimon, Medveď, Miroslav, Filo, Juraj, Mravec, Bernard, Slavov, Chavdar, Wachtveitl, Josef, Grabarz, Anna M., and Cigáň, Marek

Subjects
HYDROGEN bonding, THERMAL stability, PHOTOISOMERIZATION
Abstract

A new class of triarylhydrazone photoswitches has been developed, which aims to control the strength of a hydrogen bond between the photo-active hydrazone part and a heteroaryl substituent. By introducing a benzothiazole moiety, the photoswitches exhibit high thermal stability, absorption above 365 nm, and satisfactory photoconversion rates. Through calculations and spectroscopy, the electronic transitions and photoisomerization mechanism of the photoswitches have been elucidated. For more information, readers can refer to the Research Article by A. M. Grabarz, M. Cigáň, and their colleagues. [Extracted from the article]

Published
2024
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45. Effect of the ethynylene linker on the properties and carrier mobility of naphthalene derivatives with hexylbithienyl arms

Author

Mišicák, Róbert, primary, Stříteský, Stanislav, additional, Vala, Martin, additional, Weiter, Martin, additional, Cigáň, Marek, additional, Gmucová, Katarína, additional, Végsö, Karol, additional, Weis, Martin, additional, Kožíšek, Jozef, additional, Pavúk, Milan, additional, and Putala, Martin, additional

Published
2016
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46. Keď molekuly svetielkujú.

Author

Jurdáková,, Helena, Cigáň, Marek, and Górová, Renáta

Abstract

In this paper, the authors try to bring the reader closer to understanding the concept of LUMINISCENCE of organic compounds from a physico-chemical point of view. The structure of luminiscent substances, called luminophores, as well as various luminiscence subtypes according to source of excitation energy are described. Interesting application fields, including firefly lightening, laundry brightening or detection of blood traces in criminalistics, are explained. Moreover, the phenomenon of luminiscence in determination of biomarkers and identification of pathogens in diagnostics of diseases is mentioned. [ABSTRACT FROM AUTHOR]

Published
2018

48. Photostability of D--A nonlinear optical chromophores containing a benzothiazolium acceptor

Author

Cigáň, Marek, Gáplovský, Anton, Sigmundová, Ivica, Zahradník, Pavol, Dědic, Roman, Hromadová, Magdaléna, Institute of Chemistry, Faculty of natural sciences, Comenius University, Department of Organic Chemistry, Department of Chemical Physics and Optics [Prague], Charles University [Prague] (CU), Department of Molecular Electrochemistry, and J. Heyrovský Institute of Physical Chemistry of ASCR, v.v.i

Subjects
Physical Sciences
Abstract

International audience; For the practical application of second-order NLO materials, not only a high molecular quadratic hyperpolarizability  but also good thermal, chemical and photochemical stabilities are required. Most of the state-of-the-art chromophores with high NLO response cannot be put to use because they are photochemically highly unstable. Good thermal and photochemical stabilities with preserved high hyperpolarizabilities can be achieved by replacement of an aromatic ring with easily delocalizable heteroaromatics, e.g. with benzothiazole. Furthermore, desirable modifications of the benzothiazole fragment lead to improvement in  values. Here we report results of a comprehensive investigation of the photochemical stability of seven D--A push-pull molecules based on a N-methylbenzothiazolium acceptor and a N,N-dimethylaminophenyl donor with a different length of conjugated bridge and different acceptor strength. The quantum yield () and the kinetic parameters of photoreactions were determined for existing photodegradation pathways on irradiation at 300-850 nm in MeOH. Trans¬-cis photoisomerization is proposed as a fast but inefficient photobleaching mechanism for these irradiation wavelengths. Self-sensitized photooxidation by 1O2 makes very slow parallel photodegradation pathway and, albeit to small value of Ф, plays a dominant role in the photodegradation of the compounds investigated. Both structural modifications (extension of conjugated bridge and an additional acceptor group bonded to heterocycle) resulting in an increase of NLO response led to a decrease in photostability due to the self-sensitized 1O2 photooxidative attack. Thus a compromise should be found between an increase in NLO response and a decrease in photostability to make a choice of studied compounds for practical applications.

Published
2010
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