Syntéza, charakterizace a katalytické využití nových typů zeolitů

The PhD thesis concerns the synthesis of novel zeolite materials, investigation of their properties and their possible use in catalytic application. The work was focused on the two- dimensional zeolites. The thesis was worked out at the Department of Synthesis and Catalysis at J. Heyrovský Institute of Physical Chemistry, AS CR. Germanosilicate UTL (Si/Ge molar ratio 4.0-6.5) was found to undergo unique structural changes in the neutral or acid environment leading to transformation of its three-dimensional framework into two-dimensional layered material denoted IPC-1P. The UTL degradation, so called top-down synthesis, was enabled due to a presence of double-four-units (D4Rs), which can be seen as supporting units/pillars between the rigid layers. The preferential location of Ge in D4Rs makes the units an ideal target for their selective degradation. The interlayer space in lamellar IPC-1P was modified by swelling with long-organic chain surfactant (material IPC-1SW). To keep the interlayer space permanently expanded (up to 3.3 nm) the silica amorphous pillars were subsequently introduced (material IPC-1PI). The integrity of the layers and their preserved UTL character was confirmed in all members of IPC-1 family by HRTEM and electron diffraction measuring. The layers of IPC-1P were condensed back...Předložená disertační práce se zabývá syntézou nových typů zeolitů, jejich charakterizací a možným využitím v katalýze. Disertace byla zaměřena především na zeolity s dvourozměrnou strukturou. Práce byla vypracována na oddělení Syntézy a katalýzy na Ústavu fyzikální chemie J. Heyrovského AV ČR. Germanokřemičitan UTL (s molárním poměrem Si/Ge 4.0-6.5) podléhá unikátním strukturním změnám, ke kterým dochází v neutrálním nebo mírně kyselém prostředí a které způsobují přeměnu jeho třírozměrné krystalické struktury na dvourozměrnou. Vzniklý vrstevnatý materiál byl nazván IPC-1P. Přeměna z třírozměrného na dvourozměrný zeolit, tzv. top-down syntéza, je umožněna díky přítomnosti stavebních jednotek tzv. double-four- ring (D4R), které tvoří pilíře mezi pevnými vrstvami daného zeolitu. D4R jednotky jsou přednostně tvořeny atomy germania a kyslíku a tvoří tak ideální cíl pro jejich selektivní odstranění. Mezivrstevný prostor u lamelárního IPC-1P bylo možno modifikovat interkalací činidla s dlouhým organickým řetězcem. Výsledný materiál byl označen IPC-1SW. Následně byly v meziprostoru vytvořeny pilíře z amorfního oxidu křemičitého, aby vrstvy zůstaly natrvalo oddáleny (až do vzdálenosti 3.3 nm). Materiál byl pojmenován jako IPC-1PI. U všech členů IPC-1 skupiny bylo potvrzeno zachování vrstev a jejich původní...Department of Physical and Macromolecular ChemistryKatedra fyzikální a makromol. chemieFaculty of SciencePřírodovědecká fakult

Comparison of in vitro methods for the study of cytotoxicity

Charles University Faculty of Pharmacy in Hradec Králové Department of Pharmacology and Toxicology Student: Pavla Eliášová Supervisor: RNDr. Jana Maixnerová, Ph.D. Title of diploma thesis: Comparison of in vitro methods for the study of cytotoxicity People are exposed to a growing number of toxic substances from the environment. Endocrine disrupting chemicals (EDCs) are a broad category of molecules that are thought to cause adverse effects on the endocrine system by interfering with the synthesis, transport, degradation or action of endogenous ligands. One of the aims of this thesis was to determine the in vitro toxicity of 17 selected endocrine disruptors on the human hepatocellular carcinoma HepG2 cell line. Cell viability was determined using the CellTiter96® AQueous One Solution Cell Proliferation Assay colorimetric method, the principle of which is the reduction of MTS to the colored product formazan by mitochondria in viable cells. The cytotoxic potential of the compounds was expressed by using the toxicological parameter IC50, which was measured in three time intervals (6, 12 and 24 hours). For 14 substances: Atrazine, DHEP, Bisphenol A, Carbofuran, 3-hydroxycarbofuran, Cypermethrin, DDE, DES, MEHP, PCB 118, PCB 153, PFOA, PFOS, Propiconazole, IC50 > 100 µM (respectively > 250 µM) was...Univerzita Karlova Farmaceutická fakulta v Hradci Králové Katedra farmakologie a toxikologie Studentka: Pavla Eliášová Školitel: RNDr. Jana Maixnerová, Ph.D. Název diplomové práce: Porovnání in vitro metod pro studium cytotoxicity Lidé jsou vystaveni stále většímu počtu toxických látek z životního prostředí. Chemikálie narušující endokrinní systém (EDC) jsou širokou třídou molekul, u kterých se předpokládá, že způsobují nepříznivé účinky na endokrinní systém tím, že interferují se syntézou, transportem, degradací nebo působením endogenních ligandů. Jedním z cílů této práce bylo stanovení in vitro toxicity 17 vybraných endokrinních disruptorů na buněčné linii lidského hepatocelulárního karcinomu HepG2. Viabilita buněk byla stanovena pomocí kolorimetrické metody CellTiter96® AQueous One Solution Cell Proliferation Assay, jejíž principem je redukce MTS na barevný produkt formazan pomocí mitochondrií v životaschopných buňkách. Cytotoxický potenciál látek byl vyjádřen pomocí toxikologického paramatru IC50, který byl měřen ve třech časových intervalech (6, 12 a 24 hodin). U 14 látek: Atrazin, DHEP, Bisphenol A, Carbofuran, 3-hydroxycarbofuran, Cypermethrin, DDE, DES, MEHP, PCB 118, PCB 153, PFOA, PFOS, Propiconazol bylo stanoveno IC50 > 100 µM (resp. > 250 µM), což znamená, že tyto látky jsou netoxické...Department of Pharmacology and ToxicologyKatedra farmakologie a toxikologieFaculty of Pharmacy in Hradec KrálovéFarmaceutická fakulta v Hradci Králov

Hierarchical MTW zeolites in tetrahydropyranylation of alcohols : comparison of bottom-up and top-down methods

Authors thank the Czech Science Foundation for financial support (17-06524Y). H.P. and J.Y. thank to the 111 project of the Ministry of Education of China (B17020). M.M. and S.M.V. acknowledge the support of EPSRC grant EP/K025112/1 and Capital for Great Technologies Grant EP/L017008/1.Despite a widespread application of zeolites in catalysis, these microporous materials still suffer from a low accessibility of active sites located deep in crystals due to limited size of channels (< 1 nm). Here, we prepared a series of micro-mesoporous zeolites with MTW topology and similar Si/Al molar ratio (50). Two topical approaches were applied here: i. bottom-up synthesis with a surfactant-SDA leading to so-called nanosponge material; ii. top-down desilication of bulk crystals by NaOH solution in the presence of tetraalkylammonium cations (TAA+). Prepared materials were characterized by powder X-ray diffraction, sorption of nitrogen, adsorption of pyridine and di-tert-butyl-pyridine followed by FTIR, solid state 27Al NMR, ICP-OES, SEM, TEM, and STEM-EDS. It was found that the desilication of MTW in the presence of TAA+ proceeds in different pathway compared to well-studied MFI. This variance was attributed to the different dimensionality of their channel systems (1D vs. 3D). Materials were tested in tetrahydropyranylation of alcohols differing in a chain length and degree of branching. The nanosponge MTW shows generally very good performance. Nevertheless, in cases of the branched alcohols MTW materials desilicated in the presence of TAA+ exhibited comparable or even higher activity than nanosponge based on TOF values. Therefore, desilicated MTW presents cheaper and equally or more effective catalyst compared to nanosponge material with the same topology.PostprintPeer reviewe

The preparation route and final form of V-MXenes override the effect of the O/F ratio on their magnetic properties

This work was supported by OP VVV “Excellent Research Teams” project no. CZ.02.1.01/0.0/0.0/15_003/0000417 – CUCAM. P. E. would like to also acknowledge the Czech Science Foundation for the ExPro project (19-27551X). Computational resources and low-temperature infrastructure were supplied by the projects “e-Infrastruktura CZ” (e-INFRA CZ LM2018140) and MGML (LM2023065) supported by the Ministry of Education, Youth and Sports of the Czech Republic.Transition metal carbides and nitrides (MXenes) show a high potential for electrochemical energy storage in batteries and supercapacitors and for electrocatalysis. Their excellent electronic and magnetic characteristics have been highlighted in several theoretical studies. However, experimental research on MXenes is yet to confirm their predicted properties as candidates for controllable magnetic 2D materials. Here, we report our theoretical and experimental study of V2CTx MXenes (T = O, OH, F), providing key insights into their magnetism. Based on our density functional theory (DFT) analysis, we predicted ferromagnetic (FM) and antiferromagnetic (AFM) states of V2CTx, which are determined by the O/F ratio of surface functional groups. Accordingly, we prepared V2CTx MXenes in the form of multilayered powders and thin films with different O/F ratios. No experimental evidence of FM or AFM properties was found in any material. Nevertheless, powders and films with almost identical chemical compositions (in terms of O/F ratio) displayed different magnetic properties, whereas films with disparate chemical compositions revealed a similar magnetic character. Therefore, the preparation route and form of the final V2CTx material override the effect of the O/F ratio, which is often overestimated in theoretical studies. Moreover, these findings underscore the importance of preparing MXene materials to experimentally confirm their theoretically predicted properties.Peer reviewe

Potreba - temeljni parametar čovjekovih aktivnosti

Dosad zanemaren kompleksni fenomen potreba, kako u teorijskim, tako i u praktičnim razmatranjima, zahtjeva nužno promjenu. Jer potreba, predstavlja i početnu i završnu točku i proizvodnje i potrošnje. Relativno je prirodom neograničen i beskonačan broj potreba koji čovjek posjeduje. Razvojem proizvodnje i humanizacijom potrošnje on se geometrijskom progresijom povećava. Ne sagledavanje ovog fenomena u svoj svojoj kompleksnosti, važnosti i dinamičnosti uzrokuje višestruke gubitke čije dimenzije su u svim svojim granicama teško sagledive. Stoga se pred ekonomsku politiku (makro i mikro) postavlja staro-novi problem čije dubinsko sagledavanje je temeljna pretpostavka ostvarivanja željenih pravaca i dinamike razvoja

Synthesis of ‘unfeasible’ zeolites

R.E.M. thanks the Royal Society and the E.P.S.R.C. (Grants EP/L014475/1, EP/K025112/1 and EP/K005499/1) for funding work in this area. J.Č. and P.N. acknowledge the Czech Science Foundation for the project of the Centre of Excellence (P106/12/G015) and the European Union Seventh Framework Programme (FP7/ 2007-­‐2013) under grant agreement n°604307. The research leading to these results has received funding from the European Union Seventh Framework Programme under Grant Agreement 312483 – ESTEEM2 (Integrated Infrastructure Initiative–I3). We thank Professor Wuzong Zhou and Dr. Fengjiao Yu for their expertise in TEM and Daniel Dawson for help with NMR.Zeolites are porous aluminosilicate materials that have found applications in many different technologies. However, although simulations suggest that there are millions of possible zeolite topologies, only a little over 200 zeolite frameworks of all compositions are currently known, of which about 50 are pure silica materials. This is known as the zeolite conundrum - why have only so few of all the possible structures been made? Several criteria have been formulated to explain why most zeolites are unfeasible synthesis targets. Here we demonstrate the synthesis of two such 'unfeasible' zeolites, IPC-9 and IPC-10, through the assembly-disassembly-organization-reassembly mechanism. These new high-silica zeolites have rare characteristics, such as windows that comprise odd-membered rings. Their synthesis opens up the possibility of preparing other zeolites that have not been accessible by traditional solvothermal synthetic methods. We envisage that these findings may lead to a step change in the number and types of zeolites available for future applications.PostprintPeer reviewe

Synthesis, characterization and catalytic application of novel zeolites

The PhD thesis concerns the synthesis of novel zeolite materials, investigation of their properties and their possible use in catalytic application. The work was focused on the two- dimensional zeolites. The thesis was worked out at the Department of Synthesis and Catalysis at J. Heyrovský Institute of Physical Chemistry, AS CR. Germanosilicate UTL (Si/Ge molar ratio 4.0-6.5) was found to undergo unique structural changes in the neutral or acid environment leading to transformation of its three-dimensional framework into two-dimensional layered material denoted IPC-1P. The UTL degradation, so called top-down synthesis, was enabled due to a presence of double-four-units (D4Rs), which can be seen as supporting units/pillars between the rigid layers. The preferential location of Ge in D4Rs makes the units an ideal target for their selective degradation. The interlayer space in lamellar IPC-1P was modified by swelling with long-organic chain surfactant (material IPC-1SW). To keep the interlayer space permanently expanded (up to 3.3 nm) the silica amorphous pillars were subsequently introduced (material IPC-1PI). The integrity of the layers and their preserved UTL character was confirmed in all members of IPC-1 family by HRTEM and electron diffraction measuring. The layers of IPC-1P were condensed back..