Re(I), Ir(III) and Au(I) luminescent complexes for imaging, sensing and therapy

This thesis further developed several fluorescent ligand systems and their coordination to transition metals. Their synthesis and coordination chemistry to Re(I), Ir(III)or Au(I) is described, with detailed discussions on the photophysical properties and their potential towards imaging, sensing and therapeutic applications. In Chapters 2–3, N–substituted–1,8–naphthalimide fluorophores were synthesised and their coordination to Re(I) was investigated. Chapter 2 describes a series of fac– [Re(CO)3(N^N)(LX)]BF4 complexes, axially substituted with naphthalimide fluorophores. Chapter 3 builds on work in Chapter 2 by investigating dipicolylamine–appended naphthalimide ligands and corresponding fac–[Re(CO)3(L)]BF4 complexes. The core investigations of both chapters centre on the photophysical properties where subtle changes of the substituents were observed to have profound effects on both the photophysical and physical properties. The feasibility of these compounds as cellular imaging agents, and also for photodynamic therapy in Chapter 2, was assessed. Chapter 4 expands Au(I)! coordination chemistry of alkynyl–derived 1,8–naphthalimide fluorophores. Seven new fluorophores, together with their Au(I) phosphine complexes, are described. These compounds were evaluated for imaging capabilities, via the fluorescent ligand and the inherent toxicity from the Au(I) core was assessed. Selected examples showed outstanding characteristics as potentialoptical/therapeutic agents. Chapter 5 involved the further conjugated anthracene–1,9–dicarboximide core, possessing an additional ringcompared to naphthalimide species in Chapters 2–4. The synthesis and characterisation of two novel anthracene based fluorophores, together with their Re(I) complexes, is described. These new compounds were again assessed as cellular probes and the results gave insight into the possible localisation of structurally related anticancer drugs. Chapter 6 describes the synthesis of three novel cyclometalated Ir(III) complexes of the general form [Ir(C^N)2(N^N)]BF4, where N^N represents a novel, fluorescent! phenylimidazo–phenanthroline ligand, capable of binding to NO. All precursors, ligands and complexes were extensively characterised and the response to NO was determined. The complexes in particular show great promise as effective NO probes

Synthesis and luminescence properties of cyclometalated iridium(III) complexes incorporating conjugated benzotriazole units

The stepwise synthesis of imidazo[4,5-f]-1,10-phenanthroline-based ligands that incorporate conjugated benzotriazole units are described. Corresponding cyclometalated Ir(III) complexes of the type [Ir(CˆN)2(L)]BF4 (where CˆN = cyclometalating ligand; L = phenanthroline type ligand) are reported. The complexes were characterized using a variety of techniques, including IR, NMR, UV-vis. spectroscopies, mass spectrometry and cyclic voltammetry. The [Ir(ppy)2(L)]BF4 complexes display luminescence in the visible region with the benzotriazole variants showing blue shifted emission around 495 nm. Supporting TD-DFT calculations predict that a mixture of MLCT and LLCT character may contribute to the HOMO-LUMO transition of the benzotriazole derivatives

Luminescent 1,8-Naphthalimide-Derived ReI Complexes: syntheses, spectroscopy, X-ray structure and preliminary bioimaging in fission yeast cells

A series of picolyl-functionalised, fluorescent 1,8-naphthalimide ligands (L) have been synthesised and coordi-nated to ReI to form luminescent cationic complexes of the general form fac-[Re(phen)(CO)3(L)]BF4. The complexes were characterised by using a range of spectroscopic and analytical techniques. One example of a complex was also characterised in the solid-state by using single-crystal X-ray diffraction, reveal-ing a distorted octahedral coordination sphere at ReI and Re– C/Re–N bond lengths within the expected ranges. All ligands were shown to be fluorescent, with the 4-amino derivatives showing intramolecular charge transfer in the visible region (511–534 nm). The complexes generally showed a mixture of ligand-centred and/or 3MLCT emission depending upon the na-ture of the coordinated 1,8-naphthalimide ligand. For selected complexes, confocal fluorescence microscopy was undertaken by using fission yeast cells (Schizosaccharomyces pombe) and showed that the structure of the 1,8-naphthalimide ligand influ-ences the uptake and localisation of the rhenium complex

Cyclometalated cinchophen ligands on iridium(iii): towards water-soluble complexes with visible luminescence

Eight cationic heteroleptic iridium(III) complexes, [Ir(epqc)2(N^N)]+, were prepared in high yield from a cyclometalated iridium bridged-chloride dimer bearing two ethyl-2-phenylquinoline-4-carboxylate (epqc) ligands. Two X-ray crystallographic studies were undertaken on selected complexes (where the ancillary ligand N^N = 4,4′-dimethyl-2,2′-bipyridine and 4,7-diphenyl-1,10-phenanthroline) each confirming the proposed formulations, showing an octahedral coordination at Ir(III). In general, the complexes are luminescent (620–630 nm) with moderately long lifetimes indicative of phosphorescence. Hydrolysis of the ethyl ester moieties of the epqc ligands gave the analogous cinchophen-based complexes, which were water-soluble and visibly luminescent (568–631 nm). The spectroscopic and redox characterisation of the complexes was complemented by DFT and TD-DFT calculations, supporting the assignment of dominant 3MLCT to the emissive character

A novel cobalt complex for enhancing amperometric and impedimetric DNA detection

In this work we present a novel cobalt complex, [Co(GA)2(aqphen)]Cl that is water-soluble, redox-active and binds to dsDNA. We report that this complex can be used as a signal enhancer when detecting DNA hybridisation using electrochemical impedance spectroscopy (EIS) and differential pulse voltammetry (DPV). The compound mediates its EIS signal enhancement by causing an increase in charge transfer resistance (Rct) when bound to dsDNA. Increased peak currents are also observed with DPV when the compound is incubated with dsDNA as compared with ssDNA. We believe that this compound intercalates specifically with dsDNA and alters the DNA structure to affect the electrostatic barrier to charged redox markers in solution. To our knowledge this is the first example of a single compound that can enhance both amperometric and impedimetric signals for DNA detection. Our findings enable the development of a label-free and multi-modal approach to improve the sensitivity, accuracy and speed of electrochemical DNA detection

The coordination chemistry of substituted anthraquinones: Developments and applications

Anthraquinone has found diverse use within the sphere of coordination chemistry. The sheer breadth of application in this context has been driven by the remarkable physical and biological properties that are known for a wide variety of anthraquinone derivatives. This review discusses three main areas of research and development: (i) the coordination chemistry of substituted anthraquinones, including self-assembled systems, coordination polymers and metal organic frameworks; (ii) the incorporation of anthraquinone into ligand structures and their resultant chemistry with both d- and f-block metal ions; (iii) the application of metal-anthraquinone species to biological and chemosensing disciplines. Key aspects regarding synthetic approaches and physical characteristics are discussed throughout, with particular attention and focus on the electronic and redox properties of the species in question

Recent developments in gold(i) coordination chemistry: luminescence properties and bioimaging opportunities

The fascinating biological activity of gold coordination compounds has led to the development of a wide range of complexes. The precise biological action of such species is often poorly understood and the ability to map gold distribution in cellular environments is key. This article discusses the recent progress in luminescent Au(I) complexes whilst considering their utility in bioimaging and therapeutics

ChemInform Abstract: The Coordination Chemistry of Substituted Anthraquinones: Developments and Applications

Anthraquinone has found diverse use within the sphere of coordination chemistry. The sheer breadth of application in this context has been driven by the remarkable physical and biological properties that are known for a wide variety of anthraquinone derivatives. This review discusses three main areas of research and development: (i) the coordination chemistry of substituted anthraquinones, including self-assembled systems, coordination polymers and metal organic frameworks; (ii) the incorporation of anthraquinone into ligand structures and their resultant chemistry with both d- and f-block metal ions; (iii) the application of metal-anthraquinone species to biological and chemosensing disciplines. Key aspects regarding synthetic approaches and physical characteristics are discussed throughout, with particular attention and focus on the electronic and redox properties of the species in question

Authors reply

The authors reply to the letter written to the editor (JOSEPH M. PIERRE (2009). Letter to the Editor: Naming names: auditory hallucinations, inner speech, and source monitoring. Psychological Medicine, 39, pp. 1578-1580 doi:10.1017/S0033291709990249).2 page(s