Sarah L. Heath

[Ru(η6-p-cymene)Cl2(pta)] (pta = 1,3,5-triaza-7-phosphatricyclo- [3.3.1.1]decane): a water soluble compound that exhibits pH dependent DNA binding providing selectivity for diseased cells

The water soluble complex n[Ru(η6-p-cymene)Cl2(pta)] (pta = n1,3,5-triaza-7-phosphatricyclo[3.3.1.1]decane), exhibits pH dependent DNA ndamage; the pH at which damage is greatest correlates well to the pH nenvironment of cancer cells.

Synthesis, structure, and magnetism of a novel alkoxide bridged nonacopper(II) (Cu9O12) [3 3] square grid generated by a strict self-assembly process

The nonanuclear copper complex [Cu9(2paop-H)6](NO3)12�9H2O (2paop = I) was prepd. and its crystal structure detd. The complex forms a [3 � 3] square grid of copper atoms with the ligand bonding in a heptadentate manner by five nitrogen atoms and two bridging oxygen atoms. Variable temp. magnetic susceptibility and magnetization data show that the complex displays predominantly ferromagnetic behavior at low temp., but a small intramol. antiferromagnetic exchange component may be present. [on SciFinder(R)]

Strategies for producing cluster-based magnetic arrays

Chelating ligands based on the iminodiacetic acid moiety can be used to control the solvolysis reactions of paramagnetic transition metal ions and allow various cluster-based magnetic materials to be isolated and characterised. This paper discusses the strategies that can be used to favour certain types of supramolecular interaction with the ultimate goal of engineering arrays of single molecule magnets. Ten different systems, which have been crystallographically characterised, are presented to illustrate the approach.

Polyiron(III) Oxyhydroxide Clusters: The Role of Iron(III) Hydrolysis and Mineralization in Nature

Abstract The compounds which form in aqueous solutions containing iron(III) and chelating ligands are considered and the control of iron(III) hydrolysis as a synthetic strategy for the preparation of iron(III) species of different nuclearities is explained. The relevance of such complexes to naturally occurring iron species is discussed. Hydroxide, oxide, carboxylate and alkoxide bridged iron(III) aggregates are compared to iron(III) clusters in Nature with particular attention paid to the way in which their formation can aid in understanding the biomineralization of iron. The structures of trapped mineralized iron(III) oxyhydroxide clusters are proposed as good models for the iron storage protein ferritin, which itself is best regarded as a cluster species. Synthetic strategies for producing clusters of different shapes and sizes are suggested.

X-ray structural analysis of biologically relevant aluminium(III) complexes

Abstract The X-ray crystal structures of selected aluminium compounds which may be of relevance to understanding aluminium binding in biological contexts are described. These fall into four main categories: (a) those complexes where the metal is in a mononuclear environment, as would be found in siderophore and similar chelating agent complexes, exemplified by the structures observed with oxygen donors and with N/O donors; (b) polynuclear aluminium complexes which are possibly important species in hydrolysing environments and relevant to aluminium uptake and bioavailability; (c) aluminium in environments found in metalloproteins; and (d) aluminium minerals relevant to bioavailability and to aluminium biomineralization and storage.

A linear trinuclear mixed oxidation state cobalt(III/II/III) complex with pyrazolate bridging ligands

A linear, trinuclear Co complex with pyrazolate bridges, Co3L2(py)4.6H2O (H4L = 1,3-bis(5-methylpyrazole-3-carboxamido)propane), was prepd. and structurally characterized. The outer Co center is low spin, octahedral Co(III) and is coordinated by a tetra-anionic tetradentate ligand. Two of these outer Co(III) complexes act as bidentate chelating ligands to the central Co(II) ion, which adopts a distorted, flattened, tetrahedral geometry. [on SciFinder(R)]

Synthesis and Characterisation of Tetrathiafulvalenyl- and Ferrocenyl-Triphenylenes

The synthesis, electrochem. and mesogenic properties of novel tetrathiafulvalenyl- (e.g., I, R = R = hexyl) and ferrocenyl-triphenylenes are described. In all cases the juxtaposition of the hexa-alkyloxytriphenylene with a tetrathiafulvalene or ferrocene unit failed to give rise to derivs. displaying a discotic mesophase. Soln. electrochem. of derivs. I (R = hexyl, R = hexyl, Me) revealed an interaction occurs between the dicationic state of the TTF moiety and the triphenylene nucleus. [on SciFinder(R)]

A bioinspired approach to control over size, shape and function of polynuclear iron compounds

Abstract Transition metal centres, clusters and aggregates are common in biological systems and fulfil a variety of functions. Nature has the ability to tailor the properties of such species by controlling the molecular and supramolecular environment of the metal centres through the influence of additional structure-directing chemical species. We have been inspired by this to develop synthetic methods which explore the effects of such templating species on the structure and properties of coordination compound aggregates. We have found that chelating ligands can be used to manipulate the hydrolysis of transition metal ions and direct structure and properties both at the molecular and supramolecular levels. Results for a series of iron(III) compounds formed with ligands based around the iminodiacetate moiety are presented.

Diversity in the reactions of unsymmetric dinucleating Schiff base ligands with CuII and NiII

A diversity of reaction products have been found in the reactions of two related unsymmetrical Schiff base dinucleating ligands, HL1 and HL2, derived from 3-chloromethyl-5-methylsalicylaldehyde 1, with copper(II) and nickel(II) salts. The ligands remain intact in the copper(II) complexes to give the homodinuclear complexes [Cu2L1Br3] 2 and [Cu2L2(OH)(ClO4)]ClO43, the crystal structures of which have been solved. The reactions of HL1 and HL2 with nickel perchlorate led to hydrolysis of the imine bond. With HL1 the homodinuclear complex [NiLA(OH2)]2[ClO4]2·4H2O was formed and with HL2 hydrolysis was followed by elimination of C2H4 from the terminal NEt2 of the iminic side arm to leave an NHEt group and the dinuclear complex [NiLC(OH2)]2[ClO4]2·3CH3OH. The crystal structures of the two nickel complexes are also reported.

μSR studies of organic and molecular magnets

Muon-spin rotation and relaxation (μSR) experiments have been performed on a variety of novel organic and molecular magnetic systems. In these experiments, implanted muons are used to study the magnitude, distribution and dynamics of the local field at the muon site. Calculations of the spatial dependence of the dipole-field inside the unit cell are used to interpret the data and determine the muon site in certain cases. We describe and review muon experiments on nitronyl nitroxide organic ferromagnets and antiferromagnets. We discuss a muon study of the spin crossover phenomenon which has been studied in Fe(PM-PEA)2(NCS)2, and which shows Gaussian and root-exponential muon relaxation in the high-spin and low-spin phases, respectively. The effects of high temperature annealing on TDAE-C60 have also been studied with μSR. Experiments on a disc-shaped molecular complex containing Fe19 (with spin 31/2) reveal the effects of fluctuations of magnetization and allow an estimate of the fluctuation rate. These experiments demonstrate the wide range of problems which can be tackled using the μSR technique.