Synthesis Of Ruthenium Carbonyl-containing Sawhorse Natural Small Molecule Ligands, Characterization And CO Controlled Release

Engineering CO releasing molecules (CO-RMs) of transition metal carbonyl complexes is emerging as new interdisciplinary advances of inorganic chemistry, biological medicine and materials chemistry. In this dissertation, we devised new sawhorse carbonyl complexes with low toxicity ruthenium as metallic centre, natural carboxylic acids and small organic molecules as two-electron donor ligands. Twenty-two sawhorse-type complexes have been synthesized and fully characterized. Five new single-crystal X-ray structures of sawhorse ruthenium compounds reveal novel Ru-S bonding modes. Horse heart myoglobin assays show that these ruthenium carbonyls release carbon monoxide in well-controlled fashion under physiological conditions. Structure-Releasing kinetic analysis find that axial ligand of sawhorse carbonyl ruthenium is the key factor governing their carbon monoxide release, consistent to proposed releasing mechanism. This thesis is composed of following three parts:1. Two types of sawhorse carbonyl ruthenium complexes, including la-8a with acetic acid bridges and a variety of two-electron axial ligands, and1b-14b with carboxylate bridging ligands and DMSO axial ligands are prepared and characterised respectively. All compounds have been characterised by FT-IR,1H,13CNMR and ESI-Ms, which show that the structures are consistent with expected. Single crystal structures of five compounds (1a,4a,3b,4b,14b) are analyzed by X-ray diffraction and establish new Ru-S coordination modes. Acetate bridged sawhorse ruthenium carbonyl ligated by pyridine (2a), methyl imidazole (7a), triphenylphosphine (5a) exhibite high characteristic carbonyl absorption near2018cm-1, while relevant carbonyl bands of glycine methyl ester (3a) increase to2025cm-1. Sawhorse (6a) with CO as axial ligands exhibits significantly higher CO bands, suggesting weak back-donation bonding of Ru-CO.1H NMR spectroscopy prove that both axial ligands and bridging carboxylate ligands affect the bonding strength of Ru-CO.2. Hydrolyzed and photolytic CO-releasing of sawhorse complexes are assessed using myoglobin assay under in vitro physiological condition. In general, these complexes can slowly delivery CO in a well controlled manner. The CO-releasing kinetics shows that most of complexes have a good ability of photolytic release. While axial ligand are1-methyl imidazole, glycine methyl ester or bridging ligand is methoxy benzoate, the corresponding ruthenium complexes are extreme stable in aqueous media and their CO release can be triggered by UV light. The correlation of infrared data and release kinetics reveals that axial ligand determines their release performance.3. Acetate bridged sawhorse DMSO complex (la) is chosen to investigate the CO release pathway of sawhorse compounds in aqueous solution. The degradation pathway of la is monitored by1H NMR and key intermediates detected by ESI-MS. The experiments find several degradation intermediates, which may form via the hydrolysis of Ru-S bond and sequential CO liberation. In the photolysis test, hydroxyl bridging metallic fragments are tracked, revealing an alternative releasing pathway of HO replacing bridged carboxylate.