Universität zu Köln

Anthony, Eric Tobechukwu ORCID: 0000-0002-0217-7585 (2025). Synthesis, Characterization, and Functionalization of Bis-Thiosemicarbazones: Applications in Metal Binding, Catalysis and As Single-Source Precursor. PhD thesis, Universität zu Köln.

PDF (Pentadentate Bis-thiosemicarbazone Nanoparticle Conjugates) AK_Anthony_Eric_Tobechukwu_PhD_Thesis_unsigned.pdf - Accepted Version Download (11MB)

Abstract

Pentadentate Bis-thiosemicarbazones (BTSC) of class S^N^N^N^S binding sites have been known for their therapeutic activities. Thus, investigation of pentadentate BTSC in other fields besides biological activities is often scarce or lacking. Pentadentate BTSC ligand of type S^N^N^N^S comprises a dicarbonyl backbone, N^S core and a diamine tail. Pentadentate BTSC is appealing because the dicarbonyl backbone and the diamine tail can be derivatized, functionalized and conjugated with a nanoparticle (NP) or other molecules, thus potentially expanding the applications of pentadentate BTSC. Thus, the study commenced with the synthesis of various pentadentate BTSC ligands and their metal complexes to expand the library of BTSC. Single crystal XRD showed that Pd2+ and Zn2+ conform to a distorted square planar geometry. Pd2+ bind through Sthiol^Nimine^Npyridinic^Namide, exhibiting a thione/thiol character. Zn2+ is coordinated through Sthiol^Nimine^Nimine^Sthiol showing only thiol characters. Cu2+ coordinate through Sthiol^Nimine^Npyridinic^Nimine^Sthiol, resulting in a bipyramidal geometry. The reaction between pentadentate BTSC and the linkers (dopamine hydrochloride and (3-aminopropyl)-triethoxysilane) was first carried out and to establish a new route to conjugate BTSC with NPs. 1H NMR spectroscopy revealed the new amide bond, confirming the successful conjugation of BTSC with (3-aminopropyl)-triethoxysilane) or dopamine. Magnetic Fe3O4 conjugate of BTSC was first synthesized using the well-established NHS/EDC coupling route. The Fe3O4 was first coated with SiO2, followed by the deposition of (3-aminopropyl)-triethoxysilane to afford amine functionalized Fe3O4 (Fe3O4@SiO2–APTES) and subsequent conjugation with BTSC (Fe3O4@SiO2–APTES–BTSC). The magnetic material (Fe3O4@SiO2–APTES–BTSC) exhibit a high adsorption capacity for binding Pd2+. The unusual high uptake of Pd2+ was attributed to different adsorbed species contributing to the uptake of Pd2+ ions, as revealed by different characterization techniques, including DFT calculations. The newly developed route was employed to conjugate BTSC with different NP (SiO2 and Fe2O3). SiO2 was conjugated with BTSC at the dicarbonyl backbone, and Fe2O3 was conjugated with BTSC at the diamine tail part of the BTSC. SiO2 was initially pre-functionalized with (3-aminopropyl)-triethoxysilane, and Fe2O3 was pre-functionalized with dopamine, and the subsequent reaction with BTSC at room temperature affords SiO2@APTES–BTSC or Fe2O3–Dopamine–BTSC. SiO2@APTES–BTSC was further coordinated with Pd2+ ions and employed as a heterogeneous catalyst in the - 6 - Suzuki-Miyaura cross-coupling reaction. X-ray Photoelectron Spectroscopy investigation of SiO2@APTES–BTSC–Pd revealed that palladium is predominantly Pd0, thus, an invaluable catalyst for coupling aryl compounds. Metal complexes of pentadentate BTSC were also used as single-source precursors for synthesizing metal sulfides NPs. The metal sulfide NP particles were obtained by microwave-assisted decomposition of metal complexes of pentadentate BTSC. Thus, pure Cu7.2S4, Pd16S7, and ZnS metal sulfides NPs were synthesized.

Item Type:	Thesis (PhD thesis)
Creators:	Creators Email ORCID ORCID Put Code Anthony, Eric Tobechukwu UNSPECIFIED orcid.org/0000-0002-0217-7585 UNSPECIFIED
URN:	urn:nbn:de:hbz:38-781772
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 Pentadentate English bis-thiosemicarbazone English Nanoparticle conjugate English
Date of oral exam:	25 April 2025
Referee:	Name Academic Title Klein, Axel Prof. Dr.
Refereed:	Yes
URI:	http://kups.ub.uni-koeln.de/id/eprint/78177