Multifunctional Coordination Compounds: Design and Properties

Cleverly designed molecular building blocks provide chemists with the tools of a powerful molecular-scale construction set. They enable them to engineer materials having a predictable order and useful solid-state properties. Hence, it is in the realm of supramolecular chemistry to follow a strategy for synthesizing materials which combine a selected set of properties, for instance from the areas of magnetism, photophysics and electronics. As a successful approach, host/guest solids which are based on extended anionic, homo- and bimetallic oxalato-bridged transition-metal compounds with two-and three-dimensional connectivities have been investigated. In this report, a brief review is given on the structural aspects of this class of compounds followed by a presentation of a thermal and magnetic study for two distinct, heterometallic oxalato-bridged layer compounds.

Thiolato-bridged dinuclear arene ruthenium complexes and their potential as anticancer drugs

Water-soluble arene ruthenium complexes have been intensively studied as cytotoxic compounds for the last fifteen years, notably owing to the promising in vitro and in vivo evaluations of, respectively, RAPTA-C (η6-p-MeC6H4Pri)Ru(P-pta)Cl2 (pta = 1,3,5-triaza-7-phospha-tricyclo-[3.3.1.1]decane) from Dyson's laboratory, and the (η6-arene)Ru(en)Cl]+ (en = ethylenediamine, RAED) family of compounds from Sadler's laboratory. In this account we describe the discovery of thiolato-bridged dinuclear arene ruthenium complexes and highlight subsequent developments in the field, including their syntheses, structures, and the recent strategies for the design of thiolato-bridged dinuclear arene ruthenium bioconjugates.

Magnetic structure of two- and three-dimensional supramolecular compounds

Supramolecular chiral networks of oxalato-bridged transition metals show either two- or three-dimensional structural features. The magnetic structures of such compounds have been investigated by means of elastic neutron powder diffraction.

Natural Compounds from Saffron and Bear Bile Prevent Vision Loss and Retinal Degeneration

All retinal disorders, regardless of their aetiology, involve the activation of oxidative stress and apoptosis pathways. The administration of neuroprotective factors is crucial in all phases of the pathology, even when vision has been completely lost. The retina is one of the most susceptible tissues to reactive oxygen species damage. On the other hand, proper development and functioning of the retina requires a precise balance between the processes of proliferation, differentiation and programmed cell death. The life-or-death decision seems to be the result of a complex balance between pro- and anti-apoptotic signals. It has been recently shown the efficacy of natural products to slow retinal degenerative process through different pathways. In this review, we assess the neuroprotective effect of two compounds used in the ancient pharmacopoeia. On one hand, it has been demonstrated that administration of the saffron constituent safranal to P23H rats, an animal model of retinitis pigmentosa, preserves photoreceptor morphology and number, the capillary network and the visual response. On the other hand, it has been shown that systemic administration of tauroursodeoxycholic acid (TUDCA), the major component of bear bile, to P23H rats preserves cone and rod structure and function, together with their contact with postsynaptic neurons. The neuroprotective effects of safranal and TUDCA make these compounds potentially useful for therapeutic applications in retinal degenerative diseases.

Magnetism and photophysics in supramolecular transition-metal compounds

Based on a synthetic strategy, extended anionic, homo and bimetallic oxalato-bridged transition-metal compounds with two (2D) and three-dimensional (3D) connectivities can be synthesized and crystallized. Thereby, the choice of the templating counterions will determine the crystal chemistry. Since the oxalato bridge is a mediator for both antiferro and ferromagnetic interactions between similar and dissimilar metal ions, long-range magnetic ordering will occur. Examples of the determination of magnetic structures in 2D and 3D compounds by means of elastic neutron scattering methods will be discussed. In addition, due to the possibility of the variation of different metal ions in varying oxidation states, interesting photophysical processes can be observed within the extended three-dimensional host/guest systems.

Performance evaluation of test dummies with flesh parts produced with substitute foaming compounds. Final report.

National Highway Traffic Safety Administration, Washington, D.C.

Interagency workshop on aquatic monitoring and analysis for organotin compounds /

Sponsored by NOAA/National Ocean Service, National Marine Pollution Program Office.

Molecular mixed-valence cyanide bridged Co-III-Fe-II complexes

Cyano-bridged mixed-valence compounds have been known for a long time, i.e., Prussian Blue polymeric solids. Nevertheless, the interest in discrete complexes having a well-defined molecular nuclearity has emerged more recently. There are numerous examples of cyano-bridged mixed-valence complexes in the recent literature, as they show promising and useful applications in electrochromism, molecular magnetism and molecular electronics. In this paper, the reactivity, synthetic and structural chemistry, as well as some physical and chemical properties, of a series of discrete dinuclear mixed-valence cyano-bridged complexes of general formulae [LnCoIII(mu NC)Fe-II(CN)(5)](-) (L = pentadentate macrocyclic ligand) are reviewed. Special emphasis is given to the synthetic strategy, redox properties and metal-to-metal-charge-transfer (MMCT) band energy. Tuning the MMCT transition energy has been possible by changing the redox potential of the metal centers, both through structural and outer-sphere changes. The redox processes that involve the appearance and disappearance of these MMCT bands in the visible region have been dealt with in relation to the possible uses of the complexes. (c) 2004 Elsevier B.V. All rights reserved.

Carboplatin administration in sulphur-crested cockatoos (Cacatua galerita): Clinical observations

To determine the clinical effect of systemic carboplatin administration in birds, 6 sulphur-crested cockatoos (Cacatua galerita) were anesthetized and infused intravenously or intraosseously with carboplatin at 5 mg/kg over 3 minutes. Four birds were euthanatized 96 hours after infusion and 2 birds given an intravenous dose were euthanatized 21 days after dosing. All birds tolerated the anesthesia and carboplatin infusion and recovered uneventfully. At 24 hours after dosing, all birds were bright and active. Within 12 hours of dosing, feed intake was reduced and 3 birds vomited, but these signs abated by 48 hours after dosing. Mean body weight decreased by 4% at 24 hours after dosing and continued to decrease, but not significantly, until 96 hours after dosing. Changes in packed cell volume (PCV) and plasma total solids reflected blood loss caused by sampling. The mean PCV decreased significantly by 6 hours after dosing, and the concentration of plasma total solids decreased significantly at 1 hour after dosing and continued to decrease until 12 hours after dosing before progressively and significantly increasing toward baseline values by 96 hours after dosing. At necropsy, myelosuppression was not observed in any bird and no evidence of carboplatin toxicity was found. These results provide veterinarians with useful data for formulating efficacious and safe protocols for platinum-containing compounds when treating neoplasia in parrots and other companion birds.

Dinuclear cyano-bridged Co-III-Fe-II complexes as precursors for molecular mixed-valence complexes of higher nuclearity

The preparation and characterization of a series of trinuclear mixed-valence cyano-bridged Co-III-Fe-II-Co-III compounds derived from known dinuclear [{LnCoIII(mu-NC)}Fe-II(CN)(5)](-) complexes (L-n = N-5 or N3S2 n-membered pendant amine macrocycle) are presented. All of the new trinuclear complexes were fully characterized spectroscopically (UV-vis, IR, and C-13 NMR). Complexes exhibiting a trans and cis arrangement of the Co-Fe-Co units around the [Fe(CN)(6)](4-) center are described (i.e., cis/trans-[{LnCoIII(mu-NC)}(2)Fe-II(CN)(4)](2+)), and some of their structures are determined by X-ray crystallography. Electrochemical experiments revealed an expected anodic shift of the Fe-III/II redox potential upon addition of a tripositively charged {(CoLn)-L-III} moiety. The Co-III/II redox potentials do not change greatly from the di- to the trinuclear complex, but rather behave in a fully independent and noncooperative way. In this respect, the energies and extinction coefficients of the MMCT bands agree with the formal existence of two mixed-valence Fe-II-CN-Co-III units per molecule. Solvatochromic experiments also indicated that the MMCT band of these compounds behaves as expected for a class II mixed-valence complex. Nevertheless, its extinction coefficient is dramatically increased upon increasing the solvent donor number.