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Chiral separation of modifiers: summary research report II (VJ01010065-V3)
Storch, Jan
Preliminary result (VJ01010065-V2) of the project Express and portable detection of banned compounds with using innovative techniques: flexible and chiral SERS, selective surface extraction, neural networks (VJ01010065), provides detailed information on the chiral resolution of modifiers - helicenes to individual optically pure forms, which will be used for modification of SERS active surfaces in the future project.\nThe report is an output of the WP2a stage, which was carried out in the period 1/2022 - 12/2022 according to project documentation. The modifiers prepared under WP1b were separated during this year using chiral HPLC to optically pure forms. Since these compounds, are mostly newly prepared, a completely new method of chiral separation had to be developer for each molecule. First in the analytical scale, then at the preparative scale.\n
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The synthesis of π-electron systems suitable for transfer and retention of charges
Nejedlý, Jindřich ; Starý, Ivo (advisor) ; Tobrman, Tomáš (referee) ; Storch, Jan (referee)
The aim of my Thesis was to develop a general synthetic methodology for the preparation of long helicenes equipped with suitable functional groups that control their solubility or serve as anchoring groups for attachment to metallic surfaces, especially gold. The well-established transition metal catalyzed [2+2+2] cyclotrimerization of triynes was selected as the key scaffold-forming transformation in the synthesis of long helicenes because of its high regioselectivity, atom efficiency, functional group tolerance and general robustness. A modular approach was used for the preparation of the starting oligoynes, thus enabling a high level of their structural diversity. Individual resorcinol- based aromatic building blocks were interconnected by Sonogashira cross-coupling reactions, providing complex cyclization precursors encompassing up to twelve alkyne units pre-arranged for the multiple [2+2+2] cycloisomerization to produce three six- membered rings from each set of three neighboring alkyne units. Thus, a small series of long helicenes with up to 19 rings constituting the helical scaffold was synthesized. The quadruple cyclization leading to the longest oxahelicene prepared to date was performed in a high-temperature-high-pressure flow reactor at 250 řC in the presence of CpCo(CO)2. The set of...
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The synthesis of π-electron systems suitable for transfer and retention of charges
Nejedlý, Jindřich
The aim of my Thesis was to develop a general synthetic methodology for the preparation of long helicenes equipped with suitable functional groups that control their solubility or serve as anchoring groups for attachment to metallic surfaces, especially gold. The well-established transition metal catalyzed [2+2+2] cyclotrimerization of triynes was selected as the key scaffold-forming transformation in the synthesis of long helicenes because of its high regioselectivity, atom efficiency, functional group tolerance and general robustness. A modular approach was used for the preparation of the starting oligoynes, thus enabling a high level of their structural diversity. Individual resorcinol- based aromatic building blocks were interconnected by Sonogashira cross-coupling reactions, providing complex cyclization precursors encompassing up to twelve alkyne units pre-arranged for the multiple [2+2+2] cycloisomerization to produce three six- membered rings from each set of three neighboring alkyne units. Thus, a small series of long helicenes with up to 19 rings constituting the helical scaffold was synthesized. The quadruple cyclization leading to the longest oxahelicene prepared to date was performed in a high-temperature-high-pressure flow reactor at 250 řC in the presence of CpCo(CO)2. The set of...
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The synthesis of π-electron systems suitable for transfer and retention of charges
Nejedlý, Jindřich ; Starý, Ivo (advisor) ; Tobrman, Tomáš (referee) ; Storch, Jan (referee)
The aim of my Thesis was to develop a general synthetic methodology for the preparation of long helicenes equipped with suitable functional groups that control their solubility or serve as anchoring groups for attachment to metallic surfaces, especially gold. The well-established transition metal catalyzed [2+2+2] cyclotrimerization of triynes was selected as the key scaffold-forming transformation in the synthesis of long helicenes because of its high regioselectivity, atom efficiency, functional group tolerance and general robustness. A modular approach was used for the preparation of the starting oligoynes, thus enabling a high level of their structural diversity. Individual resorcinol- based aromatic building blocks were interconnected by Sonogashira cross-coupling reactions, providing complex cyclization precursors encompassing up to twelve alkyne units pre-arranged for the multiple [2+2+2] cycloisomerization to produce three six- membered rings from each set of three neighboring alkyne units. Thus, a small series of long helicenes with up to 19 rings constituting the helical scaffold was synthesized. The quadruple cyclization leading to the longest oxahelicene prepared to date was performed in a high-temperature-high-pressure flow reactor at 250 řC in the presence of CpCo(CO)2. The set of...
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Synthesis and application of helicene-based N-heterocyclic carbene ligands
Gay Sánchez, Isabel ; Starý, Ivo (advisor) ; Veselý, Jan (referee) ; Pour, Milan (referee)
The aim of my PhD Thesis was to explore the potential of helically chiral N-heterocyclic carbene (NHC) ligands in asymmetric catalysis. Helicenes and helicene-like molecules are inherently chiral. Their application in this field has been rather limited. To date, only a few examples of enantiopure helically chiral NHCs have been described in the literature. Using a well-established method based on the diastereoselective metal catalysed [2+2+2] cycloisomerisation of centrally chiral triynes as the key step, I have synthesised a series of optically pure 2H-pyran based penta- and hexahelicenes bearing an amino group on the terminal benzene ring. The triynes were prepared by a sequence of Sonogashira and Mitsunobu coupling reactions using the commercially available (S)-but-3-yn-2-ol as the source of chirality. The resulting aminooxa[5]- and aminooxa[6]helicenes were then converted into the corresponding 1,3-disubstituted imidazolium salts, from which, upon deprotonation, the helically chiral N- heterocyclic carbenes were generated. To evaluate the performance of the new helically chiral ligands, the enantioselective Ni0 - catalysed [2+2+2] intramolecular cycloisomerisation of prochiral triynes to nonracemic dibenzohelicenes was chosen as a model reaction. All the synthesised imidazolium salts provided,...
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Modification of Metal Surfaces by Optically Active [7]Helicene Derivatives for Molecular Sensing.
Walaská, Hana ; Kalachyova, Y. ; Elashnikov, R. ; Storch, Jan ; Žádný, Jaroslav ; Lyutakov, O.
New derivatives of 9-(pyridylethynyl)[7]helicenes were firstly prepared and fully characterized in this study. Consequently, they were successfully separated to their (P)- and (M)-enantiomers using a preparative HPLC with chiral stationary phase. These optical antipodes were advantageously used for modification of silver plasmon active nanogratings suitable for a SERS-based detection of (bio)molecules. Properties of such nanostructures were studied using different spectro- and microscopic techniques. As proved by UV-Vis spectrometry, a change of plasmon resonance wavelength position and intensity was observed and indicated the appearance of chiral surface plasmon polarization.
Fulltext: content.csg -  PDF
Plný tet: SKMBT_C22018110615053 - PDF
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Photochemical Derivatization of Helicenes.
Jakubec, Martin ; Ghosh, I. ; Storch, Jan ; König, B.
This work is focused on the use of simple helicene derivatives as substrates for modern photochemical methods. Halogen containing substrates are transformed in the reductive pathway to helicenyl radicals, before being trapped by different radical traps. In the oxidative pathway, activated alkoxyhelicenes undergo photoredox catalyzed reactions, yielding various carbon-carbon, as well as carbon-heteroatom containing compounds.\n
Fulltext: content.csg - PDF
Plný tet: SKMBT_C22018110615051 - PDF
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The synthesis of extended helical aromatics
Trávníková, Veronika ; Starý, Ivo (advisor) ; Míšek, Jiří (referee)
Helicenes are inherently chiral polycyclic aromatic molecules. Laterally extended helicenes have their outer rim extended by one or more aromatic rings, which gives them unique optical and electron properties and makes them hot candidates for applications in asymmetric catalysis or molecular electronics, for instance. However, the larger the outer rim is, the more difficult the synthesis of wide helicenes becomes. Frequently bad solubility of laterally extended helicenes, as well as their intermediates, requires comprehensive optimisation of the reaction conditions, which are commonly used in helicene synthesis. In my Bachelor Thesis, I focus on synthesis of a laterally extended helicene with two hexabenzocoronene moieties incorporated in its structure. One of the essential intermediates, bromoiodohexaphenylbenzene derivative, was prepared by Diels-Alder reaction. Optimised conditions of this reaction enabled the synthesis of crucial intermediates necessary for further steps in the target helicene synthesis. Key words: helicene, hexabenzocoronene, hexaphenylbenzene, Diels-Alder, polyaromatics
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Chiral Carbon-rich Materials – From Single Molecule to Functional Layers.
Žádný, Jaroslav ; Storch, Jan ; Strašák, Tomáš ; Krbal, M. ; Hrbáč, J. ; Vacek, J.
Comprehensive study of two different carbon-rich materials properties – [6]helicene and 1-butyl-3-(2-methyl[6]helicenyl)imidazolium bromide – and their thin films is presented. Because of different solubility, diverse preparation approaches had to be employed – electropolymerization and spin-coating. Spectroscopic and electrochemical properties were investigated along with examples of their practical use as detectors of biomolecules (e.g. DNAs). A high application potential of helicene-based carbon-rich materials in development of new optoelectronic devices is demonstrated.
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