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81.
Tomasz Koczorowski Wojciech Szczolko Anna Teubert Tomasz Goslinski 《Molecules (Basel, Switzerland)》2021,26(8)
The syntheses, spectral UV–Vis, NMR, and electrochemical as well as photocatalytic properties of novel magnesium(II) and zinc(II) symmetrical sulfanyl porphyrazines with 2-(morpholin-4-yl)ethylsulfanyl peripheral substituents are presented. Both porphyrazine derivatives were synthesized in cyclotetramerization reactions and subsequently embedded on the surface of commercially available P25 titanium(IV) oxide nanoparticles. The obtained macrocyclic compounds were broadly characterized by ESI MS spectrometry, 1D and 2D NMR techniques, UV–Vis spectroscopy, and subjected to electrochemical studies. Both hybrid materials, consisting of porphyrazine derivatives embedded on the titanium(IV) oxide nanoparticles’ surface, were characterized in terms of particle size and distribution. Next, they were subjected to photocatalytic studies with 1,3-diphenylisobenzofuran, a known singlet oxygen quencher. The applicability of the obtained hybrid material consisting of titanium(IV) oxide P25 nanoparticles and magnesium(II) porphyrazine derivative was assessed in photocatalytic studies with selected active pharmaceutical ingredients, such as diclofenac sodium salt and ibuprofen. 相似文献
82.
Marina Huber-Gedert Dr. Michał Nowakowski Dr. Ahmet Kertmen Dr. Lukas Burkhardt Dr. Natalia Lindner Dr. Roland Schoch Dr. Regine Herbst-Irmer Dr. Adam Neuba Lennart Schmitz Tae-Kyu Choi Dr. Jacek Kubicki Prof. Dr. Wojciech Gawelda Prof. Dr. Matthias Bauer 《Chemistry (Weinheim an der Bergstrasse, Germany)》2021,27(38):9905-9918
A new base metal iron-cobalt dyad has been obtained by connection between a heteroleptic tetra-NHC iron(II) photosensitizer combining a 2,6-bis[3-(2,6-diisopropylphenyl)imidazol-2-ylidene]pyridine with 2,6-bis(3-methyl-imidazol-2-ylidene)-4,4′-bipyridine ligand, and a cobaloxime catalyst. This novel iron(II)-cobalt(III) assembly has been extensively characterized by ground- and excited-state methods like X-ray crystallography, X-ray absorption spectroscopy, (spectro-)electrochemistry, and steady-state and time-resolved optical absorption spectroscopy, with a particular focus on the stability of the molecular assembly in solution and determination of the excited-state landscape. NMR and UV/Vis spectroscopy reveal dissociation of the dyad in acetonitrile at concentrations below 1 mM and high photostability. Transient absorption spectroscopy after excitation into the metal-to-ligand charge transfer absorption band suggests a relaxation cascade originating from hot singlet and triplet MLCT states, leading to the population of the 3MLCT state that exhibits the longest lifetime. Finally, decay into the ground state involves a 3MC state. Attachment of cobaloxime to the iron photosensitizer increases the 3MLCT lifetime at the iron centre. Together with the directing effect of the linker, this potentially makes the dyad more active in photocatalytic proton reduction experiments than the analogous two-component system, consisting of the iron photosensitizer and Co(dmgH)2(py)Cl. This work thus sheds new light on the functionality of base metal dyads, which are important for more efficient and sustainable future proton reduction systems. 相似文献
83.
Dr. Julian Heinrich Dr. Karolina Bossak-Ahmad Mie Riisom Dr. Haleh H. Haeri Tasha R. Steel Vinja Hergl Alexander Langhans Corinna Schattschneider Jannis Barrera Dr. Stephen M. F. Jamieson Prof. Matthias Stein Prof. Dariush Hinderberger Prof. Christian G. Hartinger Prof. Wojciech Bal Prof. Nora Kulak 《Chemistry (Weinheim an der Bergstrasse, Germany)》2021,27(72):18093-18102
Redox-active Cu(II) complexes are able to form reactive oxygen species (ROS) in the presence of oxygen and reducing agents. Recently, Faller et al. reported that ROS generation by Cu(II) ATCUN complexes is not as high as assumed for decades. High complex stability results in silencing of the Cu(II)/Cu(I) redox cycle and therefore leads to low ROS generation. In this work, we demonstrate that an exchange of the α-amino acid Gly with the β-amino acid β-Ala at position 2 (Gly2→β-Ala2) of the ATCUN motif reinstates ROS production (•OH and H2O2). Potentiometry, cyclic voltammetry, EPR spectroscopy and DFT simulations were utilized to explain the increased ROS generation of these β-Ala2-containing ATCUN complexes. We also observed enhanced oxidative cleavage activity towards plasmid DNA for β-Ala2 compared to the Gly2 complexes. Modifications with positively charged Lys residues increased the DNA affinity through electrostatic interactions as determined by UV/VIS, fluorescence, and CD spectroscopy, and consequently led to a further increase in nuclease activity. A similar trend was observed regarding the cytotoxic activity of the complexes against several human cancer cell lines where β-Ala2 peptide complexes had lower IC50 values compared to Gly2. The higher cytotoxicity could be attributed to an increased cellular uptake as determined by ICP-MS measurements. 相似文献
84.
Assessment of the various ionization methods in the analysis of metal salen complexes by mass spectrometry
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Beata Słomińska Wojciech Chaładaj Witold Danikiewicz 《Journal of mass spectrometry : JMS》2014,49(5):392-399
Metal salen complexes are one of the most frequently used catalysts in enantioselective organic synthesis. In the present work, we compare a series of ionization methods that can be used for the mass spectral analysis of two types of metalosalens: ionic complexes (abbreviated as Com+X?) and neutral complexes (NCom). These methods include electron ionization and field desorption (FD) which can be applied to pure samples and atmospheric pressure ionization techniques: electrospray ionization (ESI), atmospheric pressure chemical ionization (APCI) and atmospheric pressure photoionization (APPI) which are suitable for solutions. We found that FD is a method of choice for recording molecular ions of the complexes containing even loosely bonded ligands. The results obtained using atmospheric pressure ionization methods show that the results depend mainly on the structure of metal salen complex and the ionization method. In ESI spectra, Com+ ions were observed, while in APCI and APPI spectra both Com+ and [Com + H]+ ions are observed in the ratio depending on the structure of the metal salen complex and the solvent used in the analysis. For complexes with tetrafluoroborate counterion, an elimination of BF3 took place, and ions corresponding to complexes with fluoride counterion were observed. Experiments comparing the relative sensitivity of ESI, APCI and APPI (with and without a dopant) methods showed that for the majority of the studied complexes ESI is the most sensitive one; however, the sensitivity of APCI is usually less than two times lower and for some compounds is even higher than the sensitivity of ESI. Both methods show very high linearity of the calibration curve in a range of about 3 orders of magnitude of the sample concentration. Copyright © 2014 John Wiley & Sons, Ltd. 相似文献
85.
Mariusz Krupiński Beata Krupińska Krzysztof Labisz Zbigniew Rdzawski Wojciech Borek 《Journal of Thermal Analysis and Calorimetry》2014,118(2):1361-1367
In this study, the change of the cooling rate in the range of about 0.1–1 °C s?1 and the addition of Sr on the crystallization kinetics of the cast zinc alloys of the ZnAlCu type, as well as its relation to the microstructure were also investigated. Therefore, the aim of the rapid crystallisation is the achievement of materials with better properties, which can be obtained by refinement of the dendritic or eutectic microstructure, elimination of segregation, or creation of metastable phases and their morphology changes. In the investigated alloys, the change of cooling rate of 1 °C s?1 has caused microstructure’s refinement as well as increase in hardness. Increase in the cooling rate causes also morphology changes of the η + α eutectic, and makes generally a global overcooling of the alloy as well as change in the temperatures at the beginning of crystallization T DN and of the alloy crystallization T S. The presented investigations concerning the electron microscopy methods, including transmission electron microscopy, allow revealing the crystallographic structure, based on the d-spacing changes, as well as the diffraction method used for phase determination, which is a helpful tool for the explanation of the important points in the thermo-derivative analysis curve, where the relation between the amount of phase and the occurrence of new phases can be determined. 相似文献
86.
Ewelina Lipiec Dr. Ryo Sekine Dr. Jakub Bielecki Prof. Dr. Wojciech M. Kwiatek Assoc. Prof. Bayden R. Wood 《Angewandte Chemie (International ed. in English)》2014,53(1):169-172
DNA double strand breaks (DSBs) are deadly lesions that can lead to genetic defects and cell apoptosis. Techniques that directly detect DNA DSBs include scanning electron microscopy, atomic force microscopy (AFM), and fluorescence based approaches. While these techniques can be used to identify DSBs they provide no information on the molecular events occurring at the break. Tip‐enhanced Raman scattering (TERS) can provide molecular information from DNA at the nanoscale and in combination with AFM provides a new way to visualize and characterize the molecular structure of DSBs. DSBs result from cleavage at the 3’‐ and 5’‐bonds of deoxyribose upon exposure to UVC radiation based on the observation of P? O? H and methyl/methylene deformation modes enhanced in the TERS spectra. It is hypothesized that strand fragments are hydrogen‐terminated at the lesion, indicating the action of free radicals during photon exposure. 相似文献
87.
Water‐Stable Zirconium‐Based Metal–Organic Framework Material with High‐Surface Area and Gas‐Storage Capacities
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Dr. Oleksii V. Gutov Dr. Wojciech Bury Dr. Diego A. Gomez‐Gualdron Dr. Vaiva Krungleviciute Dr. David Fairen‐Jimenez Dr. Joseph E. Mondloch Dr. Amy A. Sarjeant Salih S. Al‐Juaid Prof. Dr. Randall Q. Snurr Prof. Dr. Joseph T. Hupp Prof. Dr. Taner Yildirim Prof. Dr. Omar K. Farha 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(39):12389-12393
We designed, synthesized, and characterized a new Zr‐based metal–organic framework material, NU‐1100 , with a pore volume of 1.53 ccg?1 and Brunauer–Emmett–Teller (BET) surface area of 4020 m2g?1; to our knowledge, currently the highest published for Zr‐based MOFs. CH4/CO2/H2 adsorption isotherms were obtained over a broad range of pressures and temperatures and are in excellent agreement with the computational predictions. The total hydrogen adsorption at 65 bar and 77 K is 0.092 g g?1, which corresponds to 43 g L?1. The volumetric and gravimetric methane‐storage capacities at 65 bar and 298 K are approximately 180 vSTP/v and 0.27 g g?1, respectively. 相似文献
88.
Prof. Wojciech Grochala 《Angewandte Chemie (International ed. in English)》2014,53(14):3680-3683
The relative stability of graphite and diamond is revisited with hybrid density functional theory calculations. The electronic energy of diamond is computed to be more negative by 1.1 kJ mol?1 than that of graphite at T=0 K and in the absence of external pressure. Graphite gains thermodynamic stability over diamond at 298 K only because of the differences in the zero‐point energy, specific heat, and entropy terms for both polymorphs. 相似文献
89.
Thioridazine is a well-known dopamine-antagonist drug with a wide range of pharmacological properties ranging from neuroleptic to antimicrobial and even anticancer activity. Thioridazine is a critical component of a promising multi-drug therapy against M. tuberculosis. Amongst the various proposed mechanisms of action, the cell membrane-mediated one is peculiarly tempting due to the distinctive feature of phenothiazine drug family to accumulate in selected body tissues. In this study, we employ long-scale molecular dynamics simulations to investigate the interactions of three different concentrations of thioridazine with zwitterionic and negatively charged model lipid membranes. Thioridazine partitions into the interfacial region of membranes and modifies their structural and dynamic properties, however dissimilarly so at the highest membrane-occurring concentration, that appears to be obtainable only for the negatively charged bilayer. We show that the origin of such changes is the drug induced decrease of the interfacial tension, which ultimately leads to the significant membrane expansion. Our findings support the hypothesis that the phenothiazines therapeutic activity may arise from the drug–membrane interactions, and reinforce the wider, emerging view of action of many small, bioactive compounds. 相似文献
90.
Natalia CZUMA Wojciech FRANUS Pawe BARAN WIK Agnieszka Katarzyna ZARBSKA 《Turkish Journal of Chemistry》2020,44(1):155
In the presented study, the sulfur dioxide sorption properties of fly ash zeolite X were investigated. Sorption tests were performed on fly ash zeolite samples that were not prepared specially for sorption, in addition to dried samples and samples in the presence of water vapor. The samples saturated with water vapor showed the highest sorption capacity. The sorption capacity of the samples additionally dried prior to the sorption experiment was higher than that of the samples that were not specially prepared for the sorption test. Regeneration tests indicated relatively good regeneration properties. The obtained results were described with the use of Langmuir, Sips, and Dubinin–Astakhov models, with the Dubinin–Astakhov model providing the best fit. 相似文献