Universität zu Köln

Lapić, Tobias ORCID: 0000-0003-3115-6756 (2025). Divalent Lanthanoid Sulfonate Complexes: Design, Stabilization and Properties. PhD thesis, Universität zu Köln.

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Abstract

The subject of this work is the synthesis and investigation of divalent lanthanoid compounds. The focus lies on their stabilization by sulfonate ligands in combination with neutral coordinating partners such as terpyridine and crown ethers. Particular emphasis is placed on the comprehensive characterization of their chemical and physical properties. A central objective was the development of soluble sulfonate ligands. For this purpose, various sulfonates of the cations [PNP]+ (bis(triphenylphosphane)iminium) and [PPh4]+ (tetraphenylphosphonium) were synthesized and thoroughly characterized. These salts exhibit excellent solubility in polar organic solvents, enabling targeted reactions under strictly inert conditions. Building on this preliminary work, divalent lanthanoid sulfonate complexes of the general composition [Ln(BS)2(DB–18–C–6)] (BS = benzenesulfonate, Ln = Eu, Yb, Sm) were prepared for the first time. Their molecular structures were elucidated by single-crystal X-ray diffraction, and their physical properties were studied in detail. These compounds form the basis for a systematic exploration of lanthanoid sulfonate coordination chemistry. In addition, the complex [Eu(PFBS)(OTf)(DB–18–C–6)]2 (PFBS = pentafluorobenzenesulfonate, OTf = triflate) was synthesized for the first time, providing initial insight into the influence of perfluorinated sulfonate ligands compared to their nonfluorinated analogues. Furthermore, additional sulfonate complexes of the compositions [Ln(MS)2(DB–18–C–6)] (MS = methanesulfonate, Ln = Eu, Yb and Sm) and [Ln(N–2–S)2(DB–18–C–6)] (N–2–S = naphthalene–2–sulfonate, Ln = Eu and Sm) were prepared, characterized, and compared. These studies provide a first assessment of the structural and electronic effects of different sulfonate ligands on the properties of divalent lanthanoid complexes. The developed synthetic routes open access to a wide range of further sulfonate ligands, which can be employed in future studies to systematically investigate the impact of ligand substitution on stability and luminescence properties. In addition, lanthanoid terpyridine complexes and the analogous calcium and strontium compounds with the general composition [M(terpy)3](OTf)2 (M = Sr, Ca, Eu, Yb and Sm) were synthesized and examined. For the lanthanoid complexes, a remarkable redox system was identified and characterized in detail using various analytical techniques. In the course of this work, a total of four scientific articles were prepared and published in peer-reviewed journals. These publications focus on the synthesis and characterization of the newly developed soluble sulfonate ligands and form the basis for further investigations into lanthanoid sulfonate chemistry.

Item Type:	Thesis (PhD thesis)
Creators:	Creators Email ORCID ORCID Put Code Lapić, Tobias tobias.lapic@uni-koeln.de https://orcid.org/0000-0003-3115-6756 UNSPECIFIED
URN:	urn:nbn:de:hbz:38-792409
Date:	2025
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 divalent lanthanoid complexes English
Date of oral exam:	14 October 2025
Referee:	Name Academic Title Wickleder, Mathias Prof. Dr. Ruschewitz, Uwe Prof. Dr.
Refereed:	Yes
URI:	http://kups.ub.uni-koeln.de/id/eprint/79240