Universität zu Köln

Sebastian, Sean S. ORCID: 0000-0002-7092-3308 (2024). Novel MOFs Based on Fluorinated Aromatic Carboxylate-Ligands and Analysis of Host-Guest-Interactions in their Pores. PhD thesis, Universität zu Köln.

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Abstract

This dissertation sets out to investigate the influence of fluorination of organic linkers on the porous materials, such as metal-organic frameworks (MOFs), metal-organic cages (MOCs) and coordination polymers (CPs), assembled from them. Central aspects are the synthesis of the linkers and novel materials, as well as their in depth analysis via single crystal X-ray diffraction and computational methods. Predominantly focusing on fluorinated benzene-1,3,5-tribenzoates (BTB) and its derivatives (BTMB) as linkers, ten new compounds were synthesized and crystallographically explored over the course of this project. These compounds, which utilized divalent transition metals (Mn(II), Co(II), Cu(II) and Cd(II)), the alkaline earth metals (Ca(II)-Ba(II)) and trivalent lanthanides as metal nodes, were studied to reveal how the fluorination affects the geometry of the linker as well as the host-guest interactions therein. Four articles were prepared and submitted to scientific journals within this work, all of which are accepted and published at the time of writing. These contain the highlights of the results from the undertaken studies and report on the structures and material properties of UoC-9(Ca), UoC-9(Sr), UoC-10(3F), UoC-10(6F) and UoC-11. UoC-9 is a 3D MOF with a 1D SBU, that exhibits a reversible temperature induced phase transition and capabilities of acting as a crystal sponge. In the first of the two articles on this framework, the structure and phase transition of the material along with the characteristic interaction with DMF were reported. The second article explores the guest exchange capabilities of the material in detail and focuses on the influence of different guest materials on the lattice and the phase transition. UoC-10 is a Cu paddle-wheel-based MOC, which was synthesized from linkers with two different degrees of fluorination (3F & 6F). The almost spherical cage was shown to crystallize in five different sphere packings, one of them exhibited exceptional rigidity and one of the highest specific surface areas measured for MOCs to date. Further material properties of UoC-10 such as the solubility and capability to remove organic substances from water were also explored. The influence of the fluorine substituents on the linker molecules were further elucidated by computational investigations on the DFT level. The article was published as a Hot Paper in Chemistry - A European Journal. UoC-11 is a Mg based MOF with an interpenetrating structure, similar to UoC-9. It is shown, that F-H contacts between the linker molecules occur predominantly therein suggesting their decisive influence on the crystallization of the compound. The remainder of this work features the structural analysis of all other compounds which were synthesized herein, along with the material properties of some of them. Weak, electrostatic interactions between the organic linker molecules and guest species are systematically studied to give an insight into possible interactions of guests with the inner surface of porous materials assembled from fluorinated linkers. The computational studies from the article on UoC-10 are expanded to include the BTB linker, and supplemented by statistical analysis of crystal structures featuring the unfluorinated congener. These studies may serve to present pathways to and properties of new porous materials as well as to provide a clear description of the various interactions and effects that are formed by fluorinated carboxylate-based linkers. Understanding these interactions may in particular contribute to the field of porous metal-organic materials from the aspects of basic research.

Item Type:	Thesis (PhD thesis)
Translated title:	Title Language Neue MOFs auf Basis fluorierter aromatischer Carboxylat-Liganden und Analyse von Gast-Wirt-Wechselwirkungen in deren Poren German
Creators:	Creators Email ORCID ORCID Put Code Sebastian, Sean S. sean.sebastian@uni-koeln.de orcid.org/0000-0002-7092-3308 UNSPECIFIED
URN:	urn:nbn:de:hbz:38-753728
Date:	2024
Place of Publication:	Köln
Language:	English
Faculty:	Faculty of Mathematics and Natural Sciences
Divisions:	Faculty of Mathematics and Natural Sciences > Department of Chemistry > Institute of Inorganic Chemistry
Subjects:	Chemistry and allied sciences
Uncontrolled Keywords:	Keywords Language Kumulativ UNSPECIFIED Anorganische Chemie UNSPECIFIED Ruschewitz UNSPECIFIED MOF, Metal-Organic Framework UNSPECIFIED MOC, Metal-Organic Cages UNSPECIFIED Röntgenbeugung, X-Ray Diffraction UNSPECIFIED Host-Guest Interactions UNSPECIFIED Wirt-Gast Wechselwirkungen UNSPECIFIED Fluoriert UNSPECIFIED
Date of oral exam:	14 February 2025
Referee:	Name Academic Title Ruschewitz, Uwe Prof. Dr. Bruns, Jörn PD Dr. Harald, Krautscheid Prof. Dr.
Refereed:	Yes
URI:	http://kups.ub.uni-koeln.de/id/eprint/75372