Synthesis and characterisation of a series of novel mononuclear and surface active dinuclear ruthenium (II) and osmium (II) polypyridyl complexes

The synthesis, spectroscopic and electrochemical characterisation of a series of mononuclear and dinuclear ruthenium (II) and osmium (II) complexes is described. Chapter 1 provides an introduction to the area of supramolecular chemistry. The complex [Ru(bpy)3]2 , the parent complex of modem supramolecular chemistry is also introduced. Chapter 2 is a general introduction to the physical measurements of the complexes which have been synthesised. The techniques of High Performance Liquid Chromatography (HPLC), Nuclear Magnetic Resonance (NMR), UV/Visible spectroscopy, fluorimetry, spectroelectrochemistry and electrochemistry are all briefly described to provide an insight into the application of these techniques later in the thesis. Chapter 3 provides an introduction to the ligands used to synthesise the complexes described in Chapters 3, 4 and 5. The ligands all contain a fused 5 and 6 membered ring, with the 5 membered ring having an imidazo-type functionality in the case of all the ligands with the exception of one, where the 5 membered ring contains a third nitrogen and becomes a triazotype system. The ’H NMR spectra of the ligands have been assigned where possible, and die photophysics and electro chemistry of the free ligands are discussed. The synthesis of a series of novel ruthenium(II) mononuclear complexes, [Ru(bpy)2(LL)j2 is described as is the synthesis of several deuleraled analogues, [Ruic/s-bpyMLL)]2'. The characterisation of these complexes by X-Ray Crystallography and *H NMR is discussed with an isomerisation effect being discussed in detail using analysis from ’H NMR and HPLC experiments. The characterisation of the complexes is completed with an examination of the photophysical, photochemical and electrochemical properties. Chapter 4 is structured similarly. The synthesis of the osmium(II) bipyridyl complexes using the ligands discussed in Chapter 3 is described. The same isomerisation effect appears for several of the ligands and is again discussed in detail. Again, the characterisation of the complexes is completed with an examination of the photophysical, photochemical and electrochemical properties. The LL7 ligand is used to synthesise a ruthenium(II) monomer as well as a series of homonuclear and heteronuclear ruthenium(II) and osmium(n) dimers. The deuterated analogues of the Ru-Ru homonuclear dimer has also been synthesised. These complexes provide the material for discussion in Chapter 5. The photophysical and electrochemical examination of this series of complexes indicates that little or no communication exists between the metal centres, even in the case of the mixed-metal complex. The spectroelectrochemistry of the complexes agree with this supposition. Chapter 6 introduces a different type of complex and a detailed survey of previous work in this area using the bridging ligands 4,4’bipyridyl, P2P, P3P and PEP precedes the discussion of the synthesis and characterisation of the series of mononuclear ruthenium(II) and osmium(II) complexes. It proved important to understand the properties of these compounds as these monomeric species provide the starting material for the synthesis of the series of dimers discussed in Chapter 7. The synthesis and spectroscopic behaviour of this series of dinuclear complexes is presented. The dinuclear complexes have been synthesised with the intention of attaching them to surfaces. This is described for one of the complexes and a brief examination of the behaviour of the complex confined to a surface is performed. The final chapter, Chapter 8 provides a conclusion to the work carried out on the two projects that make up this thesis. The chapter also suggests further work, which may be carried out in future studies

Modulation of internuclear communication in multinuclear Ruthenium(II) polypyridyl complexes

The syntheses and characterisation of a series of mononuclear and dinuclear ruthenium polypyridyl complexes based on the bridging ligands 1,3-bis-[5-(2-pyridyl)-1H-1,2,4-triazol-3-yl]benzene, 1,4-bis-[5-(2-pyridyl)-1H-1,2,4-triazol-3-yl]benzene, 2,5-bis-[5-(2-pyridyl)-1H-1,2,4-triazol-3-yl]thiophene, 2,5-bis-[5-pyrazinyl-1H-1,2,4-triazol-3-yl]thiophene are reported. Electrochemical studies indicate that in these systems, the ground state interaction is critically dependent on the nature of the bridging ligand and its protonation state, with strong and weak interactions being observed for thiophene- and phenylene-bridged complexes, respectively

Synthesis and characterisation of ruthenium complexes containing a pendent catechol ring

A series of [Ru(bipy)₂L]⁺ and [Ru(phen)₂L]⁺ complexes where L is 2-[5-(3,4-dimethoxyphenyl)-4H-1,2,4-triazol-3-yl]pyridine (HL1) and 4-(5-pyridin-2-yl-4H-1,2,4-triazol-3-yl)benzene-1,2-diol (HL2) are reported. The compounds obtained have been characterised using X-ray crystallography, NMR, UV/Vis and emission spectroscopies. Partial deuteriation is used to determine the nature of the emitting state and to simplify the NMR spectra. The acid-base properties of the compounds are also investigated. The electronic structures of [Ru(bipy)₂L1]⁺ and Ru(bipy)₂HL1]²⁺ are examined using ZINDO. Electro and spectroelectrochemical studies on [Ru(bipy)₂(L2)]⁺ suggest that proton transfer between the catechol and triazole moieties on L2 takes place upon oxidation of the L2 ligand

Lawson criterion for ignition exceeded in an inertial fusion experiment

For more than half a century, researchers around the world have been engaged in attempts to achieve fusion ignition as a proof of principle of various fusion concepts. Following the Lawson criterion, an ignited plasma is one where the fusion heating power is high enough to overcome all the physical processes that cool the fusion plasma, creating a positive thermodynamic feedback loop with rapidly increasing temperature. In inertially confined fusion, ignition is a state where the fusion plasma can begin "burn propagation" into surrounding cold fuel, enabling the possibility of high energy gain. While "scientific breakeven" (i.e., unity target gain) has not yet been achieved (here target gain is 0.72, 1.37 MJ of fusion for 1.92 MJ of laser energy), this Letter reports the first controlled fusion experiment, using laser indirect drive, on the National Ignition Facility to produce capsule gain (here 5.8) and reach ignition by nine different formulations of the Lawson criterion

Synthesis and Characterization of Dinuclear Ruthenium(II) Complexes Based on 4,4'-Bipyridyl Type Bridging Ligands

The synthesis, spectroscopic, electrochemical and photophysical characterization of a series of dinuclear ruthenium(II) complexes of the type [(bpy)2Ru(NnN)2RuCl(bpy)2](PF6)3, where NnN = 4,4'-bipyridyl (N0N), 1,2-bis(4-pyridyl)ethylene (NEN), 1,2-bis(4-pyridyl)ethane (N2N), and 4,4'-trimethylenedipyridine (N3N) are reported. The photophysical and electrochemical properties are discussed with particular emphasis on the ability of the bridging ligands to support intercomponent interaction.

Routes to Regioselective Deuteriation of Heteroaromatic Compounds

A systematic approach to the deuteriation of polypyridyl type ligands is reported. A range of isotopologues of heteroaromatic compounds containing pyrazyl, pyridyl, 1,2,4-triazole, thienyl, methyl, and phenyl moieties, have been prepared in a cost-effective manner, using a range of methods based on subcritical aqueous media. Selectively and fully deuteriated ligands are characterized by mass spectrometry and 1H, 2D, and 13C NMR spectroscopy. The application of deuteriation to supramolecular chemistry is discussed.

Probing inter-ligand excited state interaction in homo and heteroleptic ruthenium(II) polypyridyl complexes using selective deuteriation

The effect of deuteriation on the photophysical properties of two series of regioselectively deuteriated Ru(II) complexes ([Ru(bipy)x(ph2phen)3-x]2+, where x = 0–3 and ph2phen is 4,7-diphenyl-1,10-phenanthroline and [Ru(bipy)2(dcbipy2-)], where H2dcbipy is 4,4'-dicarboxy-2,2'-bipyridyl) is reported. Although overall, deuteriation results in an increase in emission lifetime for all complexes, the effect of substitution of hydrogen for deuterium shows strong regioselectivity both in terms of the ligand and the position on individual ligands that are exchanged.