National Repository of Grey Literature 17 records found  1 - 10next  jump to record: Search took 0.00 seconds. 
Synthesis of helical aromatics for applications in enantioselective catalysis and nanoscience
Klívar, Jiří ; Stará, Irena (advisor) ; Hrdina, Radim (referee) ; Církva, Vladimír (referee)
The aim of this work was to explore the scope and limitations of [2+2+2] co- cyclotrimerization of cyanodiynes in the preparation of conformationally stable and optionally optically pure azahelicenes, helically chiral bipyridines and helicenes laterally extended by a pyridine unit. As a key reaction for the construction of a helical skeleton, crucial [2+2+2] (co-)cyclotrimerization mediated by various transition metal complexes was chosen for the preparation of racemic azahelicenes. Oligoynes as key intermediates were prepared by a sequence of Sonogashira and Suzuki-Miyaura coupling. For optically pure azahelicenes and bispyridohelicenes, a sequence of Sonogashira and Suzuki-Miyaura coupling and Mitsunobu reaction was used. Importantly, the Mitsunobu reaction was used for its extraordinary ability to transfer chirality from the starting chiral alcohol to the early helicene precursor without configurational scrambling. It is worth noting that optical purity of the key oligoynes have crucial role in the chirality transfer to final azahelicenes or bispyridohelicenes. An in situ generated Ni(0) catalyst was used for bispyridohelicenes with a connection in the 2,2'-position, which enabled both [2+2+2] cyclotrimerization and Ullmann-type coupling. The conformationally stable racemic aza[6]- and...
Development of a synthetic methodology for the preparation of advanced cycloarenes and their analogues
Bambas, Daniel ; Stará, Irena (advisor) ; Míšek, Jiří (referee)
This Bachelor's Thesis deals with a design and preparation attempts leading to building blocks suitable for macrocycle construction with further utilization in cycloarene synthesis. In Theoretical Background methods for preparation of [n]circulenes and kekulene-like structures are summarized with focus on the final ring-closing steps. In Results and Discussion chapter efforts to prepare the selected advanced building block as a starting compound for macrocyle construction whose transformation using [2+2+2] cyclotrimerization as a ring-forming reaction might provide the selected cycloarene are described. Part Proposed alternatives of synthesis and discussion of further approach is about future possible development of this study. Experimental Part provides practical information about undertaken experiments and characterizations of the prepared compounds.
Synthesis and properties of complex π-electron systems with helical chirality
Houska, Václav ; Stará, Irena (advisor) ; Machara, Aleš (referee)
Planar shape-persistent macrocycles have been known for a long time and are routinely synthesized today. Non-planar 3D structures, however, still remain challenging synthetic targets in many cases. The objective of this Thesis was to develop a synthetic route to shape-persistent macrocycles containing dibenzo[5]helicene or its derivatives as structural units employing alkene and alkyne metathesis. The Introduction focuses on various methods of the macrocycle synthesis, on alkyne metathesis, and synthesis of helicenes is shortly reviewed as well. Then, the first part of Results and discussion describes the synthesis of 3,16-dichlorodibenzo[5]helicene and its derivatives. In the second part, the macrocycle synthesis from these dibenzohelicenes is discussed. The Experimental part provides a detailed description of performed experiments along with characterization of all new compounds prepared.
Ion spectroscopy of reaction intermediates
Škríba, Anton ; Roithová, Jana (advisor) ; Stará, Irena (referee) ; Martinů, Tomáš (referee)
The combination of mass spectrometry, infrared action spectroscopy and quantum-chemical calculations provides a great tool for the study of the structures, properties and reactivities of molecules in the gas phase. This thesis is divided into two main parts. The first part reviews some of the experimental (ESI-MS, ion spectroscopy) and theoretical (DFT) methods used in this thesis and gives a brief description on instrumentation. Second part is presenting four practical applications of gas phase studies in organic and organometallic chemistry: (1) Describing the influence of two functional groups of para-aminophenol on the protonation site. (2) Presenting how the structure and conformation of diethylmalonate is affected by the coordination with silver and gold. (3) Showing the possibility to distinguish between the isobaric complexes and identifying the key intermediates of ruthenium catalyzed C-C coupling. (4) Discussing the possible use of He-tagging infrared spectra not only for structure determination but also for the benchmarking of DFT methods.
Synthesis of thiophenohelicenes and their physico-chemical properties
Palata, Ondřej ; Stará, Irena (advisor) ; Veselý, Jan (referee)
The objective of this Thesis was to prepare thiophenohelicenes by [2+2+2] cyclotrimerization of aromatic triynes, namely dithiopheno[5]helicene, dithiopheno[6]helicene and trithiopheno[6]helicene. The Theoretical part illustrates which heteroatoms can be embedded into helicene backbone and provides few representative syntheses of such heterohelicenes along with some examples of their utilization. The Results and discussion part and Experimental part deal with the synthesis of dithiopheno[5]helicene, dithiopheno[6]helicene and (dihydro)-trithiopheno[6]helicene from commercially available compounds by the [2+2+2] cyclotrimerization of corresponding aromatic triynes as the key step in the synthesis. The UV/Vis and fluorescence spectral analyses and electrochemical measurements of the dithiopheno[5]helicene and dithiopheno[6]helicene were performed. The enantiomers of configurationally stable dithiopheno[6]helicene were separated and CD spectra as well as optical rotation of each enantiomer were measured. A barrier of racemization for dithiopheno[6]helicene was also determined.
Mathematical method for submolecular resolution of helicene-based macrocycles by atomic force microscopy in air
Ukraintsev, Egor ; Houska, Václav ; Vacek, Jaroslav ; Starý, Ivo ; Stará, Irena G. ; Rezek, B.
We introduce a straightforward mathematical method for improving the AFM image resolution, applied to image analysis of helicene-based macrocycles adsorbed on HOPG. The method reveals structural details from insufficiently resolved AFM images and attributes them to internal structure and ordering of the macrocycles. Our findings are also corroborated by molecular mechanics simulations, validating that the structure provided by the method has lower potential energy compared to other tested macrocycle arrangements.
Ion spectroscopy of reaction intermediates
Škríba, Anton ; Roithová, Jana (advisor) ; Stará, Irena (referee) ; Martinů, Tomáš (referee)
The combination of mass spectrometry, infrared action spectroscopy and quantum-chemical calculations provides a great tool for the study of the structures, properties and reactivities of molecules in the gas phase. This thesis is divided into two main parts. The first part reviews some of the experimental (ESI-MS, ion spectroscopy) and theoretical (DFT) methods used in this thesis and gives a brief description on instrumentation. Second part is presenting four practical applications of gas phase studies in organic and organometallic chemistry: (1) Describing the influence of two functional groups of para-aminophenol on the protonation site. (2) Presenting how the structure and conformation of diethylmalonate is affected by the coordination with silver and gold. (3) Showing the possibility to distinguish between the isobaric complexes and identifying the key intermediates of ruthenium catalyzed C-C coupling. (4) Discussing the possible use of He-tagging infrared spectra not only for structure determination but also for the benchmarking of DFT methods.

National Repository of Grey Literature : 17 records found   1 - 10next  jump to record:
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2 Stará, Irena G.
7 Stará, Iveta
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