Synthesis, characterization and reactivity study of some cobalt phenanthroline complexes and (salen)ruthenium complexes

含鈷鄰二氮菲配合物和含釕席夫堿配合物的合成, 表徵及反應性能研究

Student thesis: Doctoral Thesis

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Author(s)

  • Kwok Wa IP

Detail(s)

Awarding Institution
Supervisors/Advisors
Award date2 Oct 2015

Abstract

This work is mainly focused on the synthesis, catalytic activity, reactivity and anti-cancer properties of some cobalt and ruthenium complexes. This thesis is divided into four parts. The first part is the design, synthesis and catalytic water oxidation studies of cobalt(II) complexes bearing various functionalized phenanthroline ligands. The second and third parts are about the synthesis and reactivity of cyanamide- and guanidine-ruthenium(III) complexes bearing salen ligands. The fourth part is concerned with studies of the cytotoxicity of some (salen)ruthenium(III) complexes. In the first part, a new class of cobalt(II) complexes bearing various functionalized 1,10-phenanthroline ligands, [CoII(HL1)2(NO3)2] (L1 = 2-hydroxyl-1,10-phenantholine) (1.1), [CoII(HL2)2(NO3)2] (L2 = 2-amino-1,10-phenantholine) (1.2), [CoII(HL3)(NO3)2(H2O)] (L3 = 2,9-di(amino)-1,10-phenantholine) (1.3), [CoII(HL4)2(NO3)2] (L4 = 2,9-di(imidazol-2-yl)-1,10-phenantholine) (1.4) and [CoII(HL2)2(OAc)](ClO4) (1.5) have been prepared. These complexes have been characterized by elemental analysis, IR spectroscopy as well as electrospray ionization mass spectrometry (ESI-MS). The molecular structures of 1.1, 1.3, 1.4 and 1.5 have been determined by X-ray crystallography. Catalytic water oxidation of these complexes have been studied using [RuIII(bpy)3](ClO4)3 as the oxidant. Complex 1.3 shows the highest turnover number (TON) of 79 (in 0.1 M pH 8.0 sodium borate buffer). Photocatalytic water oxidation of complex 1.3 gives TON = 700 (LED λ = 450-495 nm, 15 mM pH 8.0 sodium borate buffer), using [RuII(bpy)3](ClO4)2 as the photo-sensitizer and Na2S2O8 as the sacrificial electron acceptor. Dynamic Light Scattering (DLS) analysis revealed the formation of nano-particles after the photochemical-driven catalytic oxidation, which indicated that complex 1.3 could be a pre-catalyst for water oxidation. In part II, three bis(cyanamide)ruthenium(III) complexes bearing a salen ligand have been synthesized, trans-[RuIII(salchda)(NCNH2)2]ClO4 (2.1b), [RuIII(salchda)(NHCN)(NCNH2)] (2.2), and trans-PPh4[RuIII(salchda)(NHCN)2] (2.3b) (salchda = N,N'-bis(salicylidene)-o-cyclohexyldiamine). These complexes have been characterized by ESI-MS, elemental analysis, IR spectroscopy as well as magnetic measurement. The structures of 2.1b and 2.3b have been determined by X-ray crystallography. The pKa values of 15.28 and 25.44 in acetonitrile for 2.1b and 2.2b have been determined by spectrophotometric titration. Using bis(cyanamide)ruthenium(III) complex as precursor, a new series of guanidine-containing ruthenium(III) complexes, {RuIII(salchda)[NH=C(NH2)2](NH3)}PF6 (3.1), trans-[RuIII(salchda)(NH{C(NH2)R}2)]PF6 [R = NH2 (3.2); NHC3H7 (3.3); NHC4H9 (3.4); NHCH(CH3)2 (3.5); NHC6H11 (3.6); NHC2H4OH (3.7); and Trans-{RuIII(salchda)[NH=C(N(CH3)2)(NHC2H5)]2}PF6 (3.8) have been prepared through nucleophilic addition of various amines to the coordinated cyanamide ligands. All these complexes have been characterized by ESI-MS, CHN elemental analysis, IR spectroscopy and cyclic voltammetry. Some of these complexes have also been structurally characterized by X-ray crystallography. As an extension of the guanidine-ruthenium(III) complexes, analogous amidine-ruthenium(III) complexes, trans-[RuIII(salchda)(NH{C(CH3)R}2)]PF6 [R = NHC3H7 (4.2); NHC4H9 (4.3); NHC2H4NH2 (4.4); NHC6H13 (4.5); NC4H8O (4.6); NHC2H4OH (4.7) have been prepared. All of these complexes have been characterized by ESI-MS, CHN elemental analysis, IR spectroscopy and cyclic voltammetry. Complex 4.7 has been structurally characterized by X-ray crystallography. The guanidine group is a key feature in many biological active species. Recently, guanidinium-rich compounds have received much attention due to their incredible improvement in cell penetrating power of drugs and they can act as molecular transporters for carrying drugs and probes across biochemical barriers. Therefore, incorporating a biologically available guanidine ligand or structurally similar amidine ligand onto a (salen)ruthenium(III) platform may offer effective anticancer activity. Herein, in part IV, the cyctotoxicity of bis(guanidine)ruthenium(III) complexes and bis(amidine)ruthenium(III) complexes have been studied towards in four human cancer cell lines (HeLa, HepG2, MCF-7 and A549). The results demonstrate that these complexes are potentially useful anti-cancer drugs. In general the bis(amidine)ruthenium(III) complexes are more cyctotoxic than the bis(guanidine)ruthenium(III) complexes.

    Research areas

  • Phenanthrene, Cobalt compounds, Ruthenium compounds