National Repository of Grey Literature 58 records found  1 - 10nextend  jump to record: Search took 0.00 seconds. 
Structure analysis of molecular crystals
Janíček, Jakub ; Císařová, Ivana (advisor) ; Vojtíšek, Pavel (referee)
Summary: Diploma thesis covers characterization of molecular crystals by X-ray structural analysis. N-carbamimidazoylisonikotinamid and 1-phenylguanidin were chosen, because their potential use in second harmony generation. Their salts with inorganic acids were prepared and determined their structures. Phase transition of 4,6-diaminopyrimidinium nitrate was studied by x-ray diffraction and differential scanning calorimetry. This phase transition is accompanied by thermosalient effect, causing that the crystals jump. Keywords: thermosalient, jumping crystal, X-ray diffraction, non-linear optics, N-carbamimidazoylnikotinamid, 1-phenylguanidin, 4,6diaminopyrmidin.
Applied Mineralogy in Forensic Science field
Kotrlý, Marek ; Matějka, Dobroslav (advisor) ; Kopecká, Ivana (referee) ; Vojtíšek, Pavel (referee)
1 ABSTRACT Surprisingly, applied mineralogy plays an important role in the forensic science field. It is the miner- alogical phases which exist in many kinds of materials and traces but also the mineralogical analysis procedures which are often used in the field of so called trace evidence. For purposes of this study, 4 important fields of forensic microanalysis were chosen. These are those fields in which applied min- eralogy is applied and which characterize the width and heterogeneity of the concerned area. Powder X-ray microdiffraction plays quite an important and irreplaceable role not only in the direct phase analysis of substances in mixtures. The author designed, tested and introduced a set for centra- tion and direct check of the analysed surface during micro-diffraction analysis and also experimentally optimised sensing parameters for the different system configuration. A possibility to calculate the size of the nanoparticles (more precisely the size of a mono crystal domain) was tested. XRD methods ap- plication allows refining organic analysis for example in the case of new synthetic drugs. Micro diffrac- tion was also used for the first complex phase analysis of colour layers of the altar in the chapel in the castle of Křivoklát (dated 1480 - 1490). Forensic analysis of soil phases used to be,...
Complexes of 1,4,7-triazacyclononane derivatives
Kubinec, Jan ; Kubíček, Vojtěch (advisor) ; Vojtíšek, Pavel (referee)
The aim of this thesis was to prepare monoamide of macrocycle H3NOTA, which was prepared by multiple step synthesis. Ligand was characterized by NMR, MS and X-ray difraction analysis. Acid-base properties were studied by potentiometric titrations. Four protonation constants pKa`s were found and these protonation constants are lower than pKa`s of H3NOTA. Coordination properties with selected metal ions from the first row of transition metal, metal ions of biological interest and with lithium ions were investigated by potentiometric titration. Stability constants show that monoethylamide derivative of macrocycle H3NOTA forms complexes with lower stability than diethylamide derivative of macrocycle H3NOTA. Stability constants for complexes which contains amide group are lower than for H3NOTA complexes. Kinetics of Ga3+ complexation was investigated at different pH by 71 Ga NMR. The rate constants of and half-lives of complexation were determined at pH = 1. The rate constant was higher and the half-life of complexation was shorter than for H3NOTA ligand. Key words: macrocyclic complexes, thermodynamic stability, formation kinetics, radiopharmaceutical
Complexes of macrocyclic ligands
Buziková, Michaela ; Hermann, Petr (advisor) ; Vojtíšek, Pavel (referee)
Macrocyclic ligands are compounds well-known and studied for their ability to bind metal ions into complexes possessing high kinetic inertness and thermodynamic stability. These properties make such compounds useful in medicine. This thesis focuses on ligand cis- DO2A2P, which belongs to a series of ligands based on cyclen skeleton with mixed acetate and phosphonate pendant arms. A lot of attention has been paid to the other members of this ligands series, but the information about cis-DO2A2P is still incomplete. In this thesis, the complexation properties of mentioned ligand were studied, as well as properties of its complexes with the lanthanide ions in solution. Key words Macrocycles; polydentate ligands; lanthanides; transition metals; organophosphorus acids
Ligands for Multifunctional Dinuclear Complexes
Králová, Marie ; Vojtíšek, Pavel (advisor) ; Lukeš, Ivan (referee)
Title: Ligands for Multifunctional Dinuclear Complexes Author: Marie Králová Site: Charles University in Prague, Faculty of Science Supervisor: doc. RNDr. Pavel Vojtíšek, CSc. Abstract The aim of this work was to prepare substitued phenols as ligands for binuclear complexes of copper(II), which could be used as anion receptors. Two main sythethic strategies are summarised in the introduction: First is single step Mannich-type reaction of 4-substitued phenol, paraformaldehyde and secondary amine, other includes preparation of substitued bis(halomethy)phenol and it's following reaction with secondary anime. A single step Mannich-type reaction was used for preparations of following known ligands: 2,6-bis[(N-methyl piperazine-1-yl)methyl]-4-formyl phenol (L1), 2,6-bis[(N- methyl piperazine-1-yl)methyl]-4-nitro phenol (L3) and 2,6-bis[(N-phenyl piperazine-1- yl)methyl]-4-nitro phenol (L4). The new ligand, 2,6-bis[(N-phenyl piperazine-1-yl)methyl]- 4-formyl phenol (L2), was prepared in the same way. A structure of this ligand was determined using X-ray. One Pd(II) complex [PdL2Cl2]·1.5MeCN (K3) was prepared and it's structure was determined. UV-VIS spectroscopy was used to study interactions in ligand - metal and ligand - metal - anion systems in order to determine the anion - binding capabilities of the...
Coordination Compounds as Contrast Agents for 19F-MRI
Špánek, Jiří ; Kotek, Jan (advisor) ; Vojtíšek, Pavel (referee)
Magnetic Resonance Imaging (MRI) is one of noninvasive imaging and diagnostic methods in today's medicine. The most commonly measured nucleus is H1 of the water molecules present in the human body. There are also methods that use signal saturation transfer between the contrast agent and water molecules via exchangeable H1 nuclei, or use a different nucleus like F19 . Compounds that show a high potential in this area are complexes of paramagnetic ions such as Gd3+ , Eu3+ , Co2+ , Cu2+ and Ni2+ , which can affect relaxation times and chemical shifts of other atoms due to their magnetic properties. This Master's thesis focuses on ligands L1 and L2 which were prepared in the Bachelor thesis. The main focus is on preparation of complexes with selected paramagnetic ions and subsequent study of their properties relevant for a potential use as contrast agents for F19 -MRI and CEST methods. Keywords: F19 -MRI, CEST, macrocyclic ligands, coordination chemistry
Homologous ferrocene phosphines
Vosáhlo, Petr ; Štěpnička, Petr (advisor) ; Vojtíšek, Pavel (referee)
Title: Homologous ferrocene phosphines Author: Bc. Petr Vosáhlo Department: Department of Inorganic Chemistry Supervisor: prof. RNDr. Petr Štěpnička, Ph.D., DSc. Abstract: This thesis describes the synthesis and coordination behaviour of ferrocene diphosphines derived from 1,1'-bis(diphenylphosphino)ferrocene (dppf). Dppf is one of the most succesful ferrocene ligands, which can be used in various metal-catalyzed reactions. This study aimed to prepare analogous ligands with one dialkylphosphino substituent and one (diphenylphosphino)methyl group. These ligands were oxidized by KSeCN to afford the corresponding phosphinoselenides. The phosphinoselenides were used to assess sigma-donor abilities by measuring the coupling constant 1 JSeP via 31 P NMR spectroscopy. Lastly, the coordination behaviour of these ligands in palladium complexes was studied. The homologous ligands usually formed a mixtures containing a chelate complex and dimeric species with trans- coordinated ligands. Key words: ferrocene, phosphines, homologous ligands, palladium(II) complexes, structure elucidation.
Synthesis and study of crystalline materials for NLO
Janatková, Tereza ; Němec, Ivan (advisor) ; Vojtíšek, Pavel (referee)
This thesis is focused on preparation and study of new compounds of chosen organic bases with potential use in nonlinear optics. 2-amino-5-nitropyrimidine, 2-amino-4-methylpyrimidine and their salts with inorganic and organic acids are compounds of the main interest. Diffraction and vibrational-spectroscopic methods of characterization were used in combination with quantum chemical calculation methods. Another aim of this thesis was preparation of new salts of chosen pyrimidine derivates with the use of methylsulphonic acid. Part of this section is devoted to completion of pyridinium methylsulphonate phase transition and nonlinear optical property studies.

National Repository of Grey Literature : 58 records found   1 - 10nextend  jump to record:
See also: similar author names
11 VOJTÍŠEK, Petr
11 Vojtíšek, Petr
Interested in being notified about new results for this query?
Subscribe to the RSS feed.