Thesis supervisor: Attila Bényei
Location of studies (in Hungarian): Kémia Intézet D16-D18 Abbreviation of location of studies: D16
Description of the research topic:
Symmetry is a very important concept in several fields of science and art. In case of supramolecular analysis of solid state structures determined by X-ray diffraction the symmetry is defined as transformation of coordinates on set of points, i.e. atomic coordinates. So one can study the symmetry of the lattice or symmetry of the repeating unit, molecules or ions. If the symmetry operator gives the exact coordinates of another element of the set, then the lattice or molecule posesses the given symmetry induced by the symmetry operator. If the coordinates do not fit, then the system does not show the given symmetry. However, in real cases the symmetry is broken, match of the coordinates is not exactly fulfilled. Moreover, in chemistry this partial or broken symmetry has also importance. Several spectroscopic, kinetic or thermodynamic properties of the system can be explained with it. Axiomatic description of symmetry is possible and various attempts have been made to describe the broken symmetry, too. One of the approach is based on the continuous symmetry measures theory (H. Zabrodsky, S. Peleg and D. Avnir, 1992: Continuous Symmetry Measures, J. Am. Chem. Soc., 114, 7843-7851). This calculation gives an exact description (number) to characterize the symmetry. For example, a number can be calculated which shows that a broken symmetry octahedral metal complex is how far from the perfectly tetrahedral or octahedral cases. Our research is focused on the application of this theory for the description of hydrogen bond web which is a novel approach in the state of the art. In the literature, metal complexes are investigated using continuous symmetry measures (S. Alvarez and D. Avnir, 2003: Continuous chirality measures of tetracoordinate bis(chelate) metal complexes, Dalton Trans, 562-569, A. Ruiz-Martínez, 2008: Polyhedral Structures with an Odd Number of Vertices: Nine-Coordinate Metal Compounds. Chem. Eur. J. 14, 1291 – 1303). Description pf transitions between the symmetries were also attempted (S. Alvarez, 2015: Distortion Pathways of Transition Metal Coordination Polyhedra Induced by Chelating Topology, Chem. Rev., 2015, 115 (24), pp 13447–13483). However, all of these approaches has the assumption that donor atoms are located on a sphere around the central metal ion that is all donor-metal bond distances are equal and comparison with perfect symmetry species is performed. This equal length of donor-metal bonds is a very strong requirement and it is not true even with octahedral metal aqua complexes either, as it is evidenced by single crystal X-ray diffraction studies. Also on the basis of continuous symmetry measure theory we plan to develop an algorithm and software to compare the given symmetry object with any reference structure.
Required language skills: english Further requirements: Advantage: Computer programing, Matlab (Octave) and Linux
Number of students who can be accepted: 1
Deadline for application: 2022-01-15
2024. IV. 17. ODT ülés Az ODT következő ülésére 2024. június 14-én, pénteken 10.00 órakor kerül sor a Semmelweis Egyetem Szenátusi termében (Bp. Üllői út 26. I. emelet).
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