Molecular sensors for biological applications

The PhD thesis centres on designing, synthesising, and fine-tuning the novel symmetric and asymmetric ligands derived from the ethylenediamine backbone to form molecular compounds. Some of the novel asymmetric molecular compounds were investigated for their sensing potentials using fluorescence spectroscopy, and results obtained show that they can selectively sense for the presence of Cu2+ and Fe3+ in an aqueous medium; the next chapter highlights the novel synthesis of chiral molecular compounds and their corresponding zinc complexes for sensing biologically important chiral amines, the mechanism of sensing was studied using 19FNMR spectroscopy, other novels symmetric and asymmetric molecular compounds were synthesis. Their corresponding zinc and yttrium complexes were used to sense for the presence of HMPs and Neurotransmitters, respectively, for the two other chapters and results presented and discussed. Chapter 1 This aims to showcase to the reader the motivation, drive, design and development of the chemical concepts and literature discussed throughout the thesis; it further introduces some key concepts and considerations in coordination chemistry related to multiple ligand design and complex development. The second section introduces the reader to the ligand scaffolds and relevant areas of the research in this thesis. Chapter 2 showcases a novel synthetic methodology for the synthesis of novel fluorescent asymmetric salan ligands. It investigates their sensing ability towards first-row transition elements with fluorescence. Computational studies underscore the selective sensing mechanism. Chapter 3 presents the design, synthesis and characterisation of novel fluorine-based salan ligands and corresponding zinc complexes. The latter were used for chiral amine sensing with 19F-NMR. Computational and solution state studies are also presented, and their sensing mechanism towards different analytes are discussed. Chapter 4 presents the ligand design and synthesis of a new asymmetric water-soluble inexpensive heptandentate H4oct(p-OCF3)salox ligand and the corresponding Yttrium complex [Yoct(p-OCF3)salox]-. The latter has been used for neurotransmitter sensing. The process has been monitored using 19F-NMR, Fluorescence and UV-Vis spectroscopy. DFT calculations were also conducted providing useful insights regarding the interaction mechanism. Chapter 5 presents the ligand design and the synthesis of a family of symmetric and asymmetric fluorine-based novel salan ligands and their corresponding zinc complexes. The latter entities were used as molecular fluorine-based probes for detecting heavy metal ions in DMSO-H2O solution. Chapter 6 This shows the overall conclusion of this thesis and enlightens on the contributions that the presented thesis has made to their relevant fields. Suggested potential future directions in the relevant research areas are also discussed. Chapter 7 contains the experimental designs and synthetic procedures. The bibliography of this work is presented in Chapter 8.