Search results for "supramolecular synthon"
showing 6 items of 6 documents
Energetic study of bifurcated hydrogen bonds in secondary structures of salts composed with dicarboxylic acids and ethylamine
2020
Abstract The nature of bifurcated hydrogen bonds prompted us to analyze the energy of supramolecular motifs on the example of new structures of carboxylic acids salts with amines, which guarantee a multitude of such interactions. Experimental and theoretical studies of four dicarboxylic salts with primary amine: ethylammonium succinate hydrate (1), tartrate hydrate (2) phthalate hydrate (3) and terephthalate (4) has been investigated along with study of the strength of interactions between the anions and cations. The complete topological analysis of the charge density for all new structures allowed designation of the estimated Cumulative Dissociation Energy (eCDE).
Self-assembly mechanism based on charge density topological interaction energies
2017
The packing interactions have been evaluated in the context of the self-assembly mechanism of crystal growth and also for its impacts on the aromaticity of the trimesate anion. The structure of ethylammonium trimesate hydrate (1) measured at 100 K and a charge density model, derived in part from theoretical structures, is reported. Theoretical structure factors were obtained from the geometry-optimized periodic wave function. The trimesic acid portion of 1 is fully deprotonated and participates in a variety hydrogen bonding motifs. Topological analysis of the charge density model reveals the most significant packing interactions and is then compared to a complementary analysis performed by …
Development of ultrasound-assisted digestion methods for the determination of toxic element concentrations in ash samples by ICP-OES
2011
The present thesis introduces several ultrasound-assisted digestion methods developed for the determination of toxic element concentrations in ash samples by inductively coupled plasma optical emission spectrometry (ICP-OES). Ultrasound-assisted digestion is a quite new technique used for sample pre-treatment purposes, especially in difficult sample matrixes. Elements determined are As, Ba, Co, Cr, Cu, Ni, Pb, Sb, Sr, V, and Zn. Most of the elements determined exist at a trace or ultra trace level in ashes and most are potential risks in the environment or human body even at low concentrations. Most of the selected elements can be determined directly by ICP-OES, but for the determination of…
Crystalline forms of selected agrochemical actives : design and synthesis of cocrystals
2012
The research described in this disseration covers the crystal form screening of two analogous agrochemical actives, thiophanate-methyl and thiophanate-ethyl, as well as the discovery of seven 4-hydroxybenzoic acid cocrystals of selected agrochemical actives. Polymorphs are crystal forms of a compound that have the same composition, but a different arrangement of molecules. Cocrystals are molecular crystals composed of two or more compounds, and refer mainly to crystals which contain compounds that are solids at standard conditions. Solvates are forms that have molecules of solvent in the crystal lattice and these include hydrates, in which the solvent is water. The crystal forms of organic …
Co-crystals of an agrochemical active – A pyridine-amine synthon for a thioamide group
2011
Five novel co-crystals of thiophanate-ethyl (TE), an agrochemical active, with di(2-pyridyl)ketone (1), 2-benzoylpyridine (2), 3-benzoylpyridine (3), 4-phenylpyridine (4) and biphenyl (5) were found and crystal structures of four of them (TE1–TE3, TE5) solved by single crystal X-ray diffraction. Three of the co-crystals (TE1–TE3) form by way of a reliable pyridine-amine hydrogen bond synthon and one (TE5) because of close packing effects. The fifth co-crystal was identified by X-ray powder diffraction. The work demonstrates the usage of a reliable supramolecular synthon for crystal engineering, while concurrently reminds that the close packing of even very similar molecules cannot be fully …
Packing incentives and a reliable N–H⋯N–pyridine synthon in co-crystallization of bipyridines with two agrochemical actives
2011
The co-crystallization of agrochemical actives thiophanate-methyl and thiophanate-ethyl with 2,2′-bipyridine, 4,4′-bipyridine and 1,2-bis(4-pyridyl)ethane was investigated with conventional crystallization, the slurry method and liquid-assisted grinding. Co-crystals of both thiophanates with all bipyridines were found and the structures solved with single crystal X-ray diffraction. Whereas the 2,2′-bipyridine co-crystals seem to form because of a combination of weak interactions, and in the case of the thiophanate-methyl, partly because of close packing incentives, the 4,4′-bipyridine and 1,2-bis(4-pyridyl)ethane co-crystals form mainly because of a favourable N–H···N–pyridine hydrogen bond…