467 research outputs found
Data for: Two Closely Related Polymorphs of Ammonium Trifluorooxovanadate
No full textRaw crystallographic data for the two polymorphs of NH4VOF
Protein targets for anticancer metal based drugs
No full textOwing to the extensive investigations carried out on cisplatin soon after its discovery, anticancer metal-based drugs- as a category - were believed to target nuclear DNA selectively and cause cancer cell death primarily through a direct DNA damage, according to the so called “DNA paradigm.” In contrast to this concept, it is now widely accepted that proteins, beyond nucleic acids, play an essential role in the mode of action of anticancer metal drugs. Notably, for certain classes of metal-based drugs, e.g. the cytotoxic gold and ruthenium compounds, proteins rather than nucleic acids are the nearly exclusive targets, an opposite situation with respect to the DNA paradigm. Investigating proteins as targets for anticancer metallodrugs and elucidating the associated protein metalation processes is not trivial owing to the intrinsic high complexity of the biological systems and of the cellular proteomes. However, thanks to a research strategy recently developed in our laboratory, mostly grounded on the combined use of electrospray ionization mass spectrometry (ESI MS) and X-ray crystallography, it is possible to characterize in the atomic detail the metalation of a variety of individual proteins. A few instructive examples of metallodrug-protein adducts analyzed according to this strategy are herein provided. Protein metalation may result into protein's loss of function triggering a cascade of cellular processes eventually leading to cancer cell death. Yet, describing in detail protein metalation taking place within the real cellular environment where thousands of proteins -instead of a single one- are simultaneously present, remains a very ambitious and challenging goal for researchers. The emerging omics technologies are starting to shed some light on these issues; a few relevant examples featuring the smart implementation of innovative Chemical Proteomics and Metalloproteomics approaches in the search of the true targets for metallodrugs are herein presented. The perspectives for future work in the area are delineated
Synthetic methodologies
No full textThe great variety of inorganic materials and the fact that they comprise elements with widely varying chemistry, drawn from every corner of the periodic table, imply that there will always be the need for myriad ways to make materials. We describe, in this chapter, some general routes for the preparation of inorganic solids, emphasizing recent advances. We particularly emphasize developing an understanding of the preparation of solids through in situ studies, which oftentimes reveal the role of fugitive intermediates phases, that may not be recognized at the outset as playing a role in reaching the target material. Many recent examples of topochemical conversions of solids are also presented. The long-held goal of atom-by-atom control of the preparation of complex materials is bearing fruit, and some examples of these are presented. These atom-by-atom routes show no sign of displacing more traditional preparative methods because of issues of generality and scale
Lanthanides and Actinides in Ionic Liquids
No full textIonic liquids are solvents that consist entirely of ions. These nonvolatile and nonflammable solvents offer interesting opportunities for lanthanide and actinide chemistry. They can replace the organic phase in solvent extraction systems and can be used as nonaqueous electrolytes for electrodeposition of metals. Ionic liquids could find applications in the nuclear fuel cycle. Lanthanide coordination compounds or lanthanide-containing nanoparticles can be obtained via ionothermal or microwave-assisted synthesis in ionic liquids. Lanthanide-doped ionogels are a new type of luminescent hybrid materials. Ionic liquids can serve as solvents for lanthanide-mediated organic reactions, and there are several examples of high reactivity and selectivity.status: Publishe
Solar Fuels: Approaches to Catalytic Hydrogen Evolution
No full textIn response to political and environmental motivations to develop alternative energy resources, researchers have taken a variety of approaches to develop solar energy conversion technologies. Solar fuel production is an area of enormous promise where, in analogy to natural photosynthesis, sunlight drives the conversion of energy-poor molecules (H_2O and CO_2) to energy-rich ones (O_2, H_2, and (CH_2O)_n). To realize a solar-driven water splitting device based on earth-abundant materials, new chemistry is needed, including materials for light harvesting and electrocatalysts for fuel production. In this chapter, we focus on molecular hydrogen production catalysts capable of evolving H_2 at low overpotentials. Recent synthetic advances in catalyst design, detailed electrochemical and photochemical studies, and developments in mechanistic understandings are covered
6.12Asymmetric Epoxidation and Sulfoxidation
No full textBoth epoxides and sulfoxides are important families of compounds, many of which are biologically active or have been applied in the synthesis of biologically active compounds. In many cases, in order to exert its biological activity, there is a requirement that the molecule be optically pure with a defined absolute configuration. Catalytic asymmetric epoxidation of olefins, and catalytic oxidation of sulfides with metal based catalysts are the current methods of choice to access such compounds in these states. This chapter focuses on these methods, in the homogenous phase. Key applications of these methods, particularly in the industrial context, are mentioned. The chapter is written in a systematic fashion, commencing with the epoxidation methods, and being divided up according to the principle metal involved. For both reaction processes, first the more well known catalytic procedures, with more common metal based catalysts (e.g., Titanium, Manganese, Vanadium, and Molybdenum etc) are considered, terminating with applications of less common or novel catalysts (like, those based on alkaline earth oxides, and lanthanoid based systems). The advantage of this method of categorization is that in the context of catalytic epoxidation it leads to a clean division between electrophilic and nucleophilic processes. Both the efficiency and selectivity of the oxidation event are discussed, in terms (generally) of reaction yield and enantioselectivity, as well as a careful discussion of the catalyst structure, synthesis and stability, not to mention a thorough review of the reaction mechanism and/or of the catalytic cycle. In many cases throughout this chapter these aspects are compared between different catalytic systems, highlighting the advantages and disadvantages of each method. Where appropriate, for aspects outside the remit of this chapter, the reader is referred to the most appropriate literature available.
This chapter considers the recent literature on this subject for about a ten year period up until late 2011
Ammonia Synthesis: State of the Bellwether Reaction
No full textCatalytic ammonia synthesis has been judged to be one of mankind's greatest scientific achievements during the twentieth century. The socioeconomic implications of producing ammonia industrially have been a strong driving force, and this development has spurred a range of new discoveries within physics, chemistry, and chemical engineering. In this chapter, we describe how it has been possible in recent years to provide a full understanding of the catalytic ammonia synthesis reaction at the atomic level through the combined use of experiments and quantum mechanical electronic structure calculations, thus clearly showing many of the reasons why ammonia synthesis has been, and still is, the bellwether reaction in heterogeneous catalysis
Noncovalent DNA binding of metal complexes
No full textOver the last 30 years there has been increasing interest in utilizing kinetically inert transition-metal complexes as noncovalent DNA- and RNA-binding agents. Metal complexes can interact with nucleic acids through a variety of different modes, with the particular mode of binding being predictably governed by the metal complex structure. Furthermore, there are an increasing number of studies highlighting the biological applications of a broad range of nucleic acid-binding metal complexes. The aim of this chapter is to provide an up-to-date and comprehensive discussion of the interactions of metal complexes with nucleic acids, with the major emphasis on work published over the last 20 years. So that this chapter can be more readily placed into context, a relatively detailed description of the structure of DNA and RNA is also presented
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