| dc.contributor.advisor | Mata, Ricardo A. Prof. Dr. | |
| dc.contributor.author | Stolper, Thorsten | |
| dc.date.accessioned | 2018-02-07T10:28:58Z | |
| dc.date.available | 2018-02-07T10:28:58Z | |
| dc.date.issued | 2018-02-07 | |
| dc.identifier.uri | http://hdl.handle.net/11858/00-1735-0000-002E-E346-F | |
| dc.identifier.uri | http://dx.doi.org/10.53846/goediss-6716 | |
| dc.language.iso | eng | de |
| dc.publisher | Niedersächsische Staats- und Universitätsbibliothek Göttingen | de |
| dc.rights.uri | http://creativecommons.org/licenses/by-nc-nd/4.0/ | |
| dc.subject.ddc | 540 | de |
| dc.title | Theoretical Studies of Ru- and Re-based Catalysts for Artificial Photosynthesis | de |
| dc.type | doctoralThesis | de |
| dc.contributor.referee | Mata, Ricardo A. Prof. Dr. | |
| dc.date.examination | 2017-12-08 | |
| dc.description.abstracteng | The conversion of light into energy stored in a sustainable and economic way is one of the main challenges of the 21st century.
Artificial photosynthesis is therefore an active research field in many parts of science.
Molecular catalysts have come a long way in the reduction of carbon dioxide and the oxidation of water to dioxygen.
Although a lot has been learned about the reactivity and stability of these catalysts, many unanswered questions remain.
This thesis hopefully takes a further step towards answering some of these questions.
Since computational studies rely heavily on the investigation of relevant points on the potential hypersurface, the optimisation procedure can become a major bottleneck.
Several approximations have been suggested for the step prediction, second derivatives and coordinates.
The latter have been shown to exhibit a great influence on the efficiency of the minimisation, with approximate decoupling for carefully designed internal coordinates.
Nevertheless, the implementation and thus performance varies widely for different software suites.
A new geometry optimisation software is therefore developed that allows a detailed investigation of each employed algorithm.
The focus is set on the impact of the primitive coordinates, as used in the redundant internals scheme, and tested on the convergence of several drug-like organic molecules.
Some corner-cases of molecular structures and a CO2 reduction catalyst are optimised with several approaches to corroborate the superior performance of the developed procedure.
Investigations into CO2 reduction catalysts have been conducted for some time, with a large number of results reported for rhenium-based complexes.
A recently published dinuclear rhenium catalyst with a proton responsive ligand combines the knowledge gained in those studies and reports a detailed analysis of the occurring reduction intermediates by infrared spectro-electrochemistry.
To achieve a greater insight on the molecular structure of the catalyst in solution, a computational basis for the calculation of infrared frequency shifts is devised.
The calibration of theoretical values to the crystal structure enables further comparison of calculated to the experimental spectra.
An extensive search for possible side-reaction products during reduction is then undertaken to assign each of the experimentally encountered intermediates, which underlines the usefulness of the approach in catalysis investigations.
A novel dinuclear ruthenium catalyst with an activity in the oxidation of water to dioxygen is inspected in the fifth chapter.
It has been proven experimentally to react by a water nucleophilic attack mechanism, contrary to other dinuclear complexes.
The computational examination of this catalyst and its comparison to other molecular systems with a similar active site may thus reveal the subtle structural details that determine the mechanism.
In a first step, the full range of possible reaction pathways is scanned, including all probable multiplicities in two oxidation states.
Fuelled by the failure of some density functionals to reproduce the correct mechanistic preference, a range of different methods and the influence of exact exchange is tested.
With the determined computational protocol the catalyst is compared to two similar water oxidation complexes on the same level of theory, which allows to unearth the difference in their structure and reactivity.
The gained insight suggests further modifications of the ligand structure that could steer the mechanism into one direction or the other. | de |
| dc.contributor.coReferee | Blöchl, Peter E. Prof. Dr. | |
| dc.subject.eng | Artificial Photosynthesis | de |
| dc.subject.eng | Computational Chemistry | de |
| dc.subject.eng | Water Oxidation Catalysis | de |
| dc.subject.eng | Carbon Dioxide Reduction | de |
| dc.subject.eng | Geometry Optimization Algorithms | de |
| dc.identifier.urn | urn:nbn:de:gbv:7-11858/00-1735-0000-002E-E346-F-0 | |
| dc.affiliation.institute | Fakultät für Chemie | de |
| dc.subject.gokfull | Chemie (PPN62138352X) | de |
| dc.identifier.ppn | 1013223276 | |