OPEN Repository

Welcome to OPEN - the Repository of Open Scientific Publications, run by the Interdisciplinary Centre for Mathematical and Computational Modelling, University of Warsaw, previously operating as the CeON Repository. The Repository enables Polish researchers from all fields to openly share their articles, books, conference materials, reports, doctoral theses, and other scientific texts.

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22799 archived items

Recent Submissions

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Selective and Controlled Grafting from PVDF-Based Materials by Oxygen-Tolerant Green-Light-Mediated ATRP
(ACS Publications, 2024-05-08) Mocny, Piotr; Lin, Ting-Chih; Parekh, Rohan; Zhao, Yuqi; Czarnota, Marek; Urbańczyk, Mateusz; Majidi, Carmel; Matyjaszewski, Krzysztof; Department of Chemistry, Carnegie Mellon University, Pittsburgh, United States;; Department of Materials Science & Engineering, Carnegie Mellon University, Pittsburgh, United States; Institute of Physical Chemistry, Polish Academy of Sciences; Department of Mechanical Engineering, Carnegie Mellon University, Pittsburgh, United States
Poly(vinylidene fluoride) (PVDF) shows excellent chemical and thermal resistance and displays high dielectric strength and unique piezoelectricity, which are enabling for applications in membranes, electric insulators, sensors, or power generators. However, its low polarity and lack of functional groups limit wider applications. While inert, PVDF has been modified by grafting polymer chains by atom transfer radical polymerization (ATRP), albeit via an unclear mechanism, given the strong C−F bonds. Herein, we applied eosin Y and green-light-mediated ATRP to modify PVDF-based materials. The method gave nearly quantitative (meth)acrylate monomer conversions within 2 h without deoxygenation and without the formation of unattached homopolymers, as confirmed by control experiments and DOSY NMR measurements. The gamma distribution model that accounts for broadly dispersed polymers in DOSY experiments was essential and serves as a powerful tool for the analysis of PVDF. The NMR analysis of poly(methyl acrylate) graft chain-ends on PVDF-CTFE (statistical copolymer with chlorotrifluoroethylene) was carried out successfully for the first time and showed up to 23 grafts per PVDF-CTFE chain. The grafting density was tunable depending on the solvent composition and light intensity during the grafting. The initiation proceeded either from the C−Cl sites of PVDF-CTFE or via unsaturations in the PVDF backbones. The dehydrofluorinated PVDF was 20 times more active than saturated PVDF during the grafting. The method was successfully applied to modify PVDF, PVDF-HFP, and Viton A401C. The obtained PVDF-CTFE-g-PnBMA materials were investigated in more detail. They featured slightly lower crystallinity than PVDF-CTFE (12−18 vs 24.3%) and had greatly improved mechanical performance: Young’s moduli of up to 488 MPa, ductility of 316%, and toughness of 46 × 106 J/m3. .
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Sonocatalytic Activity of Porous Carbonaceous Materials for the Selective Oxidation of 4-Hydroxy-3,5-dimethoxybenzyl Alcohol
(MDPI, 2024-03-23) Hashemi Hosseini, Behdokht; Oliveira, Rafael L.; Łomot, Dariusz; Chernyayeva, Olga; Colmenares Quintero, Juan C.; Wang, Nannan; Institute of Physical Chemistry, Polish Academy of Sciences; Institute of Low Temperature and Research Structure, Polish Academy of Sciences, Wrocław, Poland; Chemistry Department, Federal University of Pernambuco, Recife 50740-560, Brazil
Selective oxidation, which is crucial in diverse chemical industries, transforms harmful chemicals into valuable compounds. Heterogeneous sonocatalysis, an emerging sustainable approach, urges in-depth exploration. In this work, we investigated N-doped or non-doped carbonaceous materials as alternatives to scarce, economically sensitive metal-based catalysts. Having synthesized diverse carbons using a hard-template technique, we subjected them to sonication at frequencies of 22, 100, 500, and 800 kHz with a 50% amplitude. Sonochemical reaction catalytic tests considerably in-creased the catalytic activity of C-meso (non-doped mesoporous carbon material ). The scavenger test showed a radical formation when this catalyst was used. N-doped carbons did not show adequate and consistent sonoactivity for the selective oxidation of 4-Hydroxy-3,5 di-methoxybenzyl alcohol in comparison with control conditions without sonication, which might be associated with an acid–base interaction between the catalysts and the substrate and sonoactivity prohibition by piridinic nitrogen in N-doped catalysts.
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Chromophore hydrolysis and release from photoactivated rhodopsin in native membranes
(National Academy of Sciences USA, 2022-11-02) Hong, John D.; Salom, David; Kochman, Michał Andrzej; Kubas, Adam; Kiser, Philip; Palczewski, Krzysztof; Herbert Eye Institute, Department of Ophthalmology, University of California; Department of Chemistry, University of California; Institute of Physical Chemistry, Polish Academy of Sciences; Department of Physiology and Biophysics, University of California; Department of Clinical Pharmacy Practice, University of California; Research Service, Veterans Affairs Long Beach Healthcare System, Long Beach, USA; Department of Molecular Biology and Biochemistry, University of California
For sustained vision, photoactivated rhodopsin (Rho*) must undergo hydrolysis and release of all-trans-retinal, producing substrate for the visual cycle and apo-opsin available for regeneration with 11-cis-retinal. The kinetics of this hydrolysis has yet to be described for rhodopsin in its native membrane environment. We developed a method consisting of simultaneous denaturation and chromophore trapping by isopropanol/borohydride, followed by exhaustive protein digestion, complete extraction, and liquid chromatography–mass spectrometry. Using our method, we tracked Rho* hydrolysis, the subsequent formation of N-retinylidene-phosphatidylethanolamine (N-ret-PE) adducts with the released all-trans-retinal, and the reduction of all-trans-retinal to all-trans-retinol. We found that hydrolysis occurred faster in native membranes than in detergent micelles typically used to study membrane proteins. The activation energy of the hydrolysis in native membranes was determined to be 17.7 ± 2.4 kcal/mol. Our data support the interpretation that metarhodopsin II, the signaling state of rhodopsin, is the primary species undergoing hydrolysis and release of its all-trans-retinal. In the absence of NADPH, free all-trans-retinal reacts with phosphatidylethanolamine (PE), forming a substantial amount of N-ret-PE (∼40% of total all-trans-retinal at physiological pH), at a rate that is an order of magnitude faster than Rho* hydrolysis. However, N-ret-PE formation was highly attenuated by NADPH-dependent reduction of all-trans-retinal to all-trans-retinol. Neither N-ret-PE formation nor all-trans-retinal reduction affected the rate of hydrolysis of Rho*. Our study provides a comprehensive picture of the hydrolysis of Rho* and the release of all-trans-retinal and its reentry into the visual cycle, a process in which alteration can lead to severe retinopathies.
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A Straightforward Method for the Generation of Hyperpolarized Orthohydrogen with a Partially Negative Line
(Wiley, 2024) Czarnota, Marek; Mames, Adam; Pietrzak, Mariusz; Jopa, Sylwia; Theiß, Franziska; Buntkowsky, Gerd; Ratajczyk, Tomasz; Institute of Physical Chemistry, Polish Academy of Sciences; Faculty of Chemistry, University of Warsaw, Poland; Institute of Physical Chemistry, Technical University Darmstadt, Darmstadt, Germany
The hydrogen molecule, which exists in two spin isomers (ortho- and parahydrogen), is a highly studied system due to its fundamental properties and practical applications. Parahydrogen is used for Nuclear Magnetic Resonance signal enhancement, which is hyperpolarization of other molecules, including biorelevant ones. Hyperpolarization can be achieved by using Signal Amplification by Reversible Exchange (SABRE). SABRE can also convert parahydrogen into orthohydrogen, and surprisingly, in some cases, it has been discovered that orthohydrogen's resonance has the Partially Negative Line (PNL) pattern. Here, an approach for obtaining orthohydrogen with a PNL signal is presented for two catalysts: Ir−IMes, and Ir−IMesBn. The type of solvent in which SABRE is conducted is crucial for the observation of PNL. Specifically, a PNL signal can be easily generated in benzene using both catalysts, but it is more intense for Ir−IMesBn. In acetone, PNL is observed only for Ir−IMesBn. In methanol, no PNL is detected. The PNL effect is only detectable during the initial steps of pre-catalyst activation, and disappears as the activation process progresses. We have proposed a working hypothesis that explains our results. The presented data may facilitate the further investigation of PNL and its applications in material science and catalysis.
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Catalytic Ketonization over Oxide Catalysts (Part XIV): The Ketonization and Cross-Ketonization of Anhydrides, Substituted Acids and Esters
(MDPI, 2024-01-24) Gliński, Marek; Gidzińska, Małgorzata; Czerwiński, Łukasz; Drozdowski, Kasper; Iwanek (nee Wilczkowska), Ewa M.; Ostrowski, Andrzej; Łomot, Dariusz; Huang, Lin; Zhu, Yinghuai; Faculty of Chemistry, Warsaw University of Technology; Institute of Physical Chemistry, Polish Academy of Sciences
A series of 20 wt.% MO2 /S catalysts (where M = Ce, Mn or Zr and S = SiO2 or Al2 O3 ) were prepared using various precursors of the active phases. The resulting catalysts were characterized using different methods (XRD, TPR and SBET ). For the first time, anhydrides were used as potential starting materials for ketone synthesis. This novel reaction was performed on various aliphatic anhydrides in the presence of catalysts within a temperature range of 523–723 K. For all anhydrides, except for pivalic anhydride, the appropriate ketones were obtained with good or very good yields. The vapor-phase catalytic ketonization of esters of benzene-1,x-dicarboxylic acids (x = 2, 3 or 4) with acetic acid were studied in the range of 673–723 K in order to obtain 1,x-diacetylbenzenes. Their yields strongly increased with an increase in the x value (0, 8 and 43% for x = 2, 3 and 4, respectively). The presence of acetophenone as a side product was always noted. In the case of ω-phenylalkanoic acids, their vapor-phase ketonization with acetic acid led to the formation of appropriate ketones with 47–49% yields. Much lower yields of ketones (3–19%) were obtained for acids and ethyl esters containing heterocycle substituents (with O or S atoms) and/or vinyl groups. In the reaction between ethyl 4-nitrophenylacetate and acetic acid, only the products of ester decomposition (p-toluidine and p-nitrotoluene) were determined.