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Richard M. Hartshorn

Bio: Richard M. Hartshorn is an academic researcher from University of Canterbury. The author has contributed to research in topics: Ligand & Imine. The author has an hindex of 13, co-authored 69 publications receiving 1131 citations. Previous affiliations of Richard M. Hartshorn include Australian National University & University of Copenhagen.


Papers
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Journal ArticleDOI
TL;DR: A series of ruthenium(II) complexes have been prepared which contain two phenanthroline ligands and a third bidentate ligand which is one of a set of derivatives of the parent dipyrido[3,2-a:2',3'c]phenazine (DPPZ) ligand.
Abstract: A series of ruthenium(II) complexes have been prepared which contain two phenanthroline ligands and a third bidentate ligand which is one of a set of derivatives of the parent dipyrido[3,2-a:2',3'c]phenazine (DPPZ) ligand. The spectroscopic properties of these complexes in the presence and absence of DNA have also been characterized. The derivatives have been prepared by condensation of different diaminobenzenes or diaminopyridines with the synthetic intermediate bis(1,10-phenanthroline)(1,10-phenanthroline-5,6-dione)ruthenium(II). [Ru(phen)_2DPPz](2+), like [Ru(bpy)_2DPPz]^(2+), acts as a molecular "light switch" for the presence of DNA, displaying no detectable photoluminescence in aqueous solution but luminescing brightly on binding to DNA. None of the DPPZ derivatives prepared show comparable "light switch" enhancements, since some luminescence may be detected in aqueous solution in the absence of DNA. For some complexes, however, luminescence enhancements of a factor of 20-300 are observed on binding to DNA. For these and the parent DPPZ complexes, the large enhancements observed are attributed to a sensitivity of the ruthenium-DPPZ luminescent charge-transfer excited state to quenching by water; although these complexes show little or no luminescence in water, appreciable luminescence is found in acetonitrile. Other derivatives show little solvent sensitivity in luminescence, and these, like Ru(phen)_3^(2+), display moderate enhancements (20-70%) on binding to DNA. [Ru(phen)_2DPPz]^(2+) and its derivatives all show at least biexponential decays in emission. Two binding modes have been proposed to account for these emission characteristics: a perpendicular mode where the DPPZ ligand intercalates from the major groove such that the metal-phenazine axis lies along the DNA dyad axis, and another, side-on mode where the metal-phenazine axis lies along the long axis of the base pairs.

588 citations

Journal ArticleDOI
TL;DR: This study investigated the influence of the buffering system itself on the in vitro corrosion of Mg and found that the less realistic zwitterion-based buffer did not form the same corrosion layers as the carbonate buffer, and was potentially affecting the behaviour of the hydrated oxide layer that forms on Mg in all aqueous environments.
Abstract: Magnesium (Mg) alloys are being actively investigated as potential load-bearing orthopaedic implant materials due to their biodegradability in vivo. With Mg biomaterials at an early stage in their development, the screening of alloy compositions for their biodegradation rate, and hence biocompatibility, is reliant on cost-effective in vitro methods. The use of a buffer to control pH during in vitro biodegradation is recognised as critically important as this seeks to mimic pH control as it occurs naturally in vivo. The two different types of in vitro buffer system available are based on either (i) zwitterionic organic compounds or (ii) carbonate buffers within a partial-CO2 atmosphere. This study investigated the influence of the buffering system itself on the in vitro corrosion of Mg. It was found that the less realistic zwitterion-based buffer did not form the same corrosion layers as the carbonate buffer, and was potentially affecting the behaviour of the hydrated oxide layer that forms on Mg in all aqueous environments. Consequently it was recommended that Mg in vitro experiments use the more biorealistic carbonate buffering system when possible.

79 citations

Journal ArticleDOI
TL;DR: In this paper, seven phenylpyrimidines have been cyclopalladated with lithium tetrachloropalladium and the products characterised by 1H and 13C NMR studies of their acetylacetonate complexes.

50 citations

Journal ArticleDOI
TL;DR: In this paper, established IUPAC recommendations for the representation of configuration are reviewed briefly, and then methodologies are examined for dealing with regular polyhedra that are typically used when working with coordination numbers greater than 6.
Abstract: Established IUPAC recommendations for the representation of configuration are reviewed briefly, and then methodologies are examined for dealing with regular polyhedra that are typically used when working with coordination numbers greater than 6. More than one method is available and can be used for many such geometries, but the deviations from regular polyhedral geometries that are typically found in such molecules can make it difficult to arrive reproducibly at the same description for a complex using purely objective criteria. Recommendations are made for some geometries of coordination numbers 7, 8, and 9, but not for higher coordination numbers.

30 citations

Journal ArticleDOI
TL;DR: The adoption of a nomenclatura quimica consensuada is a herramienta clave for la comunicación eficiente en las ciencias quimicas, for the busqueda con ordenadores en bases de datos and con fine regulatorios, tales como los asociados a la salud y la seguridad o a la actividad comercial as discussed by the authors.
Abstract: INTRODUCCION La adopcion universal de una nomenclatura quimica consensuada es una herramienta clave para la comunicacion eficiente en las ciencias quimicas, para la busqueda con ordenadores en bases de datos y con fines regulatorios, tales como los asociados a la salud y la seguridad o a la actividad comercial. La Union Internacional de Quimica Pura y Aplicada (IUPAC en sus siglas inglesas) ofrece recomendaciones sobre la naturaleza y el uso de la nomenclatura quimica. Los fundamentos de esta nomenclatura se muestran aqui y en los documentos complementarios sobre los sistemas de nomenclatura de quimica organica y polimeros, con hipervinculos a los documentos originales. Un resumen general de la nomenclatura quimica se puede encontrar en Principles of Chemical Nomenclature. Detalles mayores se pueden hallar en Nomenclature of Inorganic Chemistry coloquialmente conocido como el Libro Rojo, y en las publicaciones relacionadas con compuestos organicos (el Libro Azul) y polimeros (el Libro Purpura). Cabe senalar que muchos compuestos pueden tener nombres no-sistematicos o semi-sistematicos (algunos de los cuales no son aceptados por la IUPAC, por ejemplo, porque son ambiguos) y las reglas IUPAC permiten dar mas de un nombre sistematico a un compuesto en muchos casos. La IUPAC esta elaborando la identificacion de los nombres individuales preferidos a efectos de regulacion (Preferred IUPAC Names o PINs). Nota: En este documento, el simbolo ‘=’ se utiliza para dividir los nombres que resultan ser demasiado largos para el formato de la columna, a menos que ya haya un guion presente en el nombre. Los limites entre compuestos ‘organicos’ e ‘inorganicos’ son difusos. Los tipos de nomenclatura descritos en este documento son aplicables a los compuestos, moleculas e iones que no contienen carbono y tambien a muchas estructuras que contienen carbono (Seccion 2), principalmente los que contienen elementos de los grupos 1−12. La mayoria de los compuestos de boro se tratan mediante una nomenclatura especial. 8

29 citations


Cited by
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Journal ArticleDOI
TL;DR: A more complete understanding of how to target DNA sites with specificity will lead not only to novel chemotherapeutics but also to a greatly expanded ability for chemists to probe DNA and to develop highly sensitive diagnostic agents.
Abstract: The design of small complexes that bind and react at specific sequences of DNA becomes important as we begin to delineate, on a molecular level, how genetic information is expressed. A more complete understanding of how to target DNA sites with specificity will lead not only to novel chemotherapeutics but also to a greatly expanded ability for chemists to probe DNA and to develop highly sensitive diagnostic agents.

1,769 citations

Journal ArticleDOI
TL;DR: There remains growing interest in magnesium (Mg) and its alloys, as they are the lightest structural metallic materials Mg alloys have the potential to enable design of lighter engineered systems, including positive implications for reduced energy consumption as mentioned in this paper.

1,173 citations

Journal ArticleDOI
12 Nov 1993-Science
TL;DR: The stacked aromatic heterocycles of the DNA duplex therefore serve as an efficient medium for coupling electron donors and acceptors over very long distances.
Abstract: Rapid photoinduced electron transfer is demonstrated over a distance of greater than 40 angstroms between metallointercalators that are tethered to the 5' termini of a 15-base pair DNA duplex. An oligomeric assembly was synthesized in which the donor is Ru(phen)2dppz2+ (phen, phenanthroline, and dppz, dipyridophenazine) and the acceptor is Rh(phi)2phen3+ (phi, phenanthrenequinone diimine). These metal complexes are intercalated either one or two base steps in from the helix termini. Although the ruthenium-modified oligonucleotide hybridized to an unmodified complement luminesces intensely, the ruthenium-modified oligomer hybridized to the rhodium-modified oligomer shows no detectable luminescence. Time-resolved studies point to a lower limit of 10(9) per second for the quenching rate. No quenching was observed upon metallation of two complementary octamers by Ru(phen)3(2+) and Rh(phen)3(3+) under conditions where the phen complexes do not intercalate. The stacked aromatic heterocycles of the DNA duplex therefore serve as an efficient medium for coupling electron donors and acceptors over very long distances.

910 citations

Journal ArticleDOI
TL;DR: The challenges to bringing PDT into mainstream cancer therapy are summarized, the chemical and photophysical solutions that transition metal complexes offer are considered, and the multidisciplinary effort needed to bring a new drug to clinical trial is put into context.
Abstract: Transition metal complexes are of increasing interest as photosensitizers in photodynamic therapy (PDT) and, more recently, for photochemotherapy (PCT). In recent years, Ru(II) polypyridyl complexes have emerged as promising systems for both PDT and PCT. Their rich photochemical and photophysical properties derive from a variety of excited-state electronic configurations accessible with visible and near-infrared light, and these properties can be exploited for both energy- and electron-transfer processes that can yield highly potent oxygen-dependent and/or oxygen-independent photobiological activity. Selected examples highlight the use of rational design in coordination chemistry to control the lowest-energy triplet excited-state configurations for eliciting a particular type of photoreactivity for PDT and/or PCT effects. These principles are also discussed in the context of the development of TLD1433, the first Ru(II)-based photosensitizer for PDT to enter a human clinical trial. The design of TLD1433 arose from a tumor-centered approach, as part of a complete PDT package that includes the light component and the protocol for treating non-muscle invasive bladder cancer. Briefly, this review summarizes the challenges to bringing PDT into mainstream cancer therapy. It considers the chemical and photophysical solutions that transition metal complexes offer, and it puts into context the multidisciplinary effort needed to bring a new drug to clinical trial.

740 citations

Journal ArticleDOI
TL;DR: Recent experiments in the laboratory aimed at the design and study of octahedral metal complexes that bind DNA non-covalently and target reactions to specific sites are reviewed.

692 citations