Haseloer, Alexander 
ORCID: 0000-0003-0480-7568
(2021).
Complexes of N4 Substituted Thiosemicarbazones with Applications in Medicine and Catalysis.
PhD thesis, Universität zu Köln.
Abstract
The presented work is based on the N4 derivatization of thiosemicarbazones and the influence within medical and catalytical applications. A total of 48 thiosemicarbazones were synthesized and characterized. Chapter 2.1 gives an insight into the electrochemical characteristics of the synthesized ligands and the comparison shows the influence of the substitution patterns. As expected, all thiosemicarbazones get reduced on the imine moiety and oxidized at the sulphur atom during the first electrochemical processes.
To further understand the influence of the substitutions on the metal centre, Ir(III) complexes were synthesized in the chapter 2.2. Herein, the complexes bear several coligand combinations of which the hydride coligand acts as a sensor for the electron density at the metal centre. The influence of a N2 substitution on a metal centre appears is neglectable. Decomposition in DCM yielded oxalate bridged dinuclear iridium complexes which could be determined by single crystal XRD.
2-Pyrdinyl thiosemicarbazones were used to coordinate nickel group metals. A series of Pt(II) chloro complexes were synthesized, characterized, and conjugated to peptides by solid phase peptide synthesis. Antiproliferation studies showed that no toxicity arises from the peptide conjugate and the corresponding complexes.
Since the complex [Pt(dpyTSCLp-sC18)Cl] was instable under HPLC conditions the chlorido coligand was exchanged for NCS− and CN−. The resulting complexes of the nickel group were investigated by NMR, CV and (SEC-)UV/Vis. The coligands did not follow any trend, yet the complex [Pt(dpyTSCLp-sC18)CN] showed high stability under HPLC conditions, was stable in aqueous media, and was not toxic.
Tetradentate thiosemicarbazone complexes of Ni(II), Cu(II), Pd(II) and Pt(II) were synthesized and characterized in Chapter 2.7. The complexes showed high similarity in their electrochemical and photophysical properties, due to mainly ligand centred frontier orbitals with low contributions of the metal ions.
Additionally, the functionalities of the ligands and complexes could be tuned to gain access to cation specific fluorophores, highly active C-C coupling catalysts. Also, the first U(IV) complexes of thiosemicarbazones could be synthesized and characterized in this work.
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