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Gerard Parkin
Gerard "Ged" F. R. Parkin (born February 15, 1959) is a professor of chemistry at Columbia University. Biography Gerard Parkin attended the English Martyrs School and Sixth Form College before working under Malcolm Green during both his undergraduate and graduate studies at Queens College of Oxford University. His work involved exploring the chemistry of tungsten phosphine derivatives. He obtained a post-doctoral position at the California Institute of Technology working with Professor John Bercaw on tungstenocene reactivity. In 1988, Ged joined the faculty at Columbia University, where he currently investigates a myriad of problems in main group and transition metal chemistry, including: * Calixarene complexes * Retrodative bonding, especially related to boratranes * Group 6 reactivity relating to X-H (X=H, C, O) bond activation, hydrodesulfurization and hydrodenitrogenation * The Tris(mercaptoimidazolyl) borate Tm ligand * Terminal chalcogen metal bondin ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Chemistry
Chemistry is the science, scientific study of the properties and behavior of matter. It is a natural science that covers the Chemical element, elements that make up matter to the chemical compound, compounds made of atoms, molecules and ions: their composition, structure, properties, behavior and the changes they undergo during a Chemical reaction, reaction with other Chemical substance, substances. Chemistry also addresses the nature of chemical bonds in chemical compounds. In the scope of its subject, chemistry occupies an intermediate position between physics and biology. It is sometimes called the central science because it provides a foundation for understanding both Basic research, basic and Applied science, applied scientific disciplines at a fundamental level. For example, chemistry explains aspects of plant growth (botany), the formation of igneous rocks (geology), how atmospheric ozone is formed and how environmental pollutants are degraded (ecology), the properties ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Post-doctoral
A postdoctoral fellow, postdoctoral researcher, or simply postdoc, is a person professionally conducting research after the completion of their doctoral studies (typically a Doctor of Philosophy, PhD). The ultimate goal of a postdoctoral research position is to pursue additional research, training, or teaching in order to have better skills to pursue a career in academia, research, or any other field. Postdocs often, but not always, have a temporary academic appointment, sometimes in preparation for an academic Faculty (academic staff), faculty position. They continue their studies or carry out research and further increase expertise in a specialist subject, including integrating a team and acquiring novel skills and research methods. Postdoctoral research is often considered essential while advancing the scholarly mission of the host institution; it is expected to produce relevant publications in peer-reviewed academic journals or conferences. In some countries, postdoctoral r ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ligand
In coordination chemistry, a ligand is an ion or molecule (functional group) that binds to a central metal atom to form a coordination complex. The bonding with the metal generally involves formal donation of one or more of the ligand's electron pairs, often through Lewis bases. The nature of metal–ligand bonding can range from covalent to ionic. Furthermore, the metal–ligand bond order can range from one to three. Ligands are viewed as Lewis bases, although rare cases are known to involve Lewis acidic "ligands". Metals and metalloids are bound to ligands in almost all circumstances, although gaseous "naked" metal ions can be generated in a high vacuum. Ligands in a complex dictate the reactivity of the central atom, including ligand substitution rates, the reactivity of the ligands themselves, and redox. Ligand selection requires critical consideration in many practical areas, including bioinorganic and medicinal chemistry, homogeneous catalysis, and environmental chemi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tm Ligands
In coordination chemistry, Tm is an abbreviation for anionic tridentate ligand based on three imidazole-2- thione groups bonded to a borohydride center. They are examples of scorpionate ligands. Various ligands in this family are known, differing in what substituents are on the imidazoles. The most common is TmMe, which has a methyl group on the nitrogen. It is easily prepared by the reaction of molten methimazole (1-methylimidazole-2-thione) with sodium borohydride, giving the sodium salt of the ligand. Salts of the TmMe anion are known also for lithium and potassium. Other alkyl- and aryl-group variations are likewise named TmR according to those groups. Ligand characteristics, comparison with Tp− The TmMe anion is a tridentate, tripodal ligand topologically similar to the more common Tp ligands, but the two classes of ligands differ in several ways. TmMe has three "soft" sulfur donor atoms, whereas Tp− has three nitrogen donor atoms. The thioamide sulfur is highly basic ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hydrodenitrogenation
Hydrodenitrogenation (HDN) is an industrial process for the removal of nitrogen from petroleum. Organonitrogen compounds, even though they occur at low levels, are undesirable because they cause poisoning of downstream catalysts. Furthermore, upon combustion, organonitrogen compounds generate NOx, a pollutant. HDN is effected as general hydroprocessing, which traditionally focuses on hydrodesulfurization (HDS) because sulfur compounds are even more problematic. To some extent, hydrodeoxygenation (HDO) is also effected. Typical organonitrogen compounds in petroleum include quinolines and porphyrins and their derivatives. The total nitrogen content is typically less than 1% and the targeted levels are in the ppm range. As described in organic geochemistry, organonitrogen compounds are derivatives or degradation products of the compounds in the living matter that comprised the precursor to fossil fuels. In HDN, the organonitrogen compounds are treated at high temperatures with ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hydrodesulfurization
Hydrodesulfurization (HDS) is a catalytic chemical process widely used to remove sulfur (S) from natural gas and from refined petroleum products, such as gasoline or petrol, jet fuel, kerosene, diesel fuel, and fuel oils. The purpose of removing the sulfur, and creating products such as ultra-low-sulfur diesel, is to reduce the sulfur dioxide () emissions that result from using those fuels in automotive vehicles, aircraft, railroad locomotives, ships, gas or oil burning power plants, residential and industrial furnaces, and other forms of fuel combustion. Another important reason for removing sulfur from the naphtha streams within a petroleum refinery is that sulfur, even in extremely low concentrations, poisons the noble metal catalysts (platinum and rhenium) in the catalytic reforming units that are subsequently used to upgrade the octane rating of the naphtha streams. The industrial hydrodesulfurization processes include facilities for the capture and removal of the result ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Bond Activation
Bond or bonds may refer to: Common meanings * Bond (finance), a type of debt security * Bail bond, a commercial third-party guarantor of surety bonds in the United States * Chemical bond, the attraction of atoms, ions or molecules to form chemical compounds People * Bond (surname) * Bonds (surname) * Mr. Bond (musician), Austrian rapper Arts and entertainment * James Bond, a series of works about the eponymous fictional character * James Bond (literary character), a British secret agent in a series of novels and films * Bond (band), an Australian/British string quartet ** '' Bond: Video Clip Collection'', a video collection from the band * Bond (Canadian band), a Canadian rock band in the 1970s * ''The Bond'' (2007 book), an American autobiography written by The Three Doctors * ''The Bond'', a 1918 film by Charlie Chaplin supporting Liberty bonds * Bond International Casino, a former music venue in New York City Places Antarctica * Bond Glacier, at the head of Vincenn ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Group 6 Element
Group 6, numbered by IUPAC style, is a group of elements in the periodic table. Its members are chromium (Cr), molybdenum (Mo), tungsten (W), and seaborgium (Sg). These are all transition metals and chromium, molybdenum and tungsten are refractory metals. The electron configuration of these elements do not follow a unified trend, though the outermost shells do correlate with trends in chemical behavior: "Group 6" is the new IUPAC name for this group; the old style name was "''group VIB''" in the old US system (CAS) or "''group VIA''" in the European system (old IUPAC). Group 6 must not be confused with the group with the old-style group crossed names of either ''VIA'' (US system, CAS) or ''VIB'' (European system, old IUPAC). ''That'' group is now called group 16. History Discoveries Chromium was first reported on July 26, 1761, when Johann Gottlob Lehmann found an orange-red mineral in the Beryozovskoye mines in the Ural Mountains of Russia, which he named "Siberian red ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Boratrane
Atranes are a class of tricyclic molecules with three five-membered rings. It is a heterocyclic structure similar to the propellanes. It has a transannular dative bond from a nitrogen at one bridgehead to a Lewis acidic atom such as silicon or boron at the other bridgehead.Voronkov, Mikhail G.; Baryshok, Viktor P. "Atranes - a new generation of biologically active substances" (in Russian) Vestnik Rossiiskoi Akademii Nauk 2010, volume 80, 985-992. The name "atrane" was first proposed by . Nomenclature Various atranes are named depending on the central element, e.g. "silatrane" (E = silicon); "boratrane" (E = boron); "phosphatrane" (E = phosphorus), etc. It is also proposed that when Y = nitrogen, the prefix "aza" be inserted before ''element'' + "atrane" (azasilatrane, for example) because atranes wherein E = silicon and Y = oxygen have been referred to as just "silatranes". Structure and properties Silatranes exhibit unusual properties as well as biological activity ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Calixarene
A calixarene is a macrocycle or cyclic oligomer based on a methylene-linked phenols. With hydrophobic cavities that can hold smaller molecules or ions, calixarenes belong to the class of cavitands known in host–guest chemistry. Nomenclature Calixarene nomenclature is straightforward and involves counting the number of repeating units in the ring and including it in the name. A calix rene has 4 units in the ring and a calix rene has 6. A substituent in the meso position Rb is added to the name with a prefix C- as in C-methylcalix rene The word calixarene is derived from the Greek calix or chalice because this type of molecule resembles a vase (or cup) and from the word arene that refers to the aromatic building block. Synthesis Calixarenes are generally produced by condensation of two components: an electron-rich aromatic compound, classically a 4-substituted phenol, and an aldehyde, classically formaldehyde. *The scope for the aromatic component is broad diverse. The key at ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Main Group
In chemistry and atomic physics, the main group is the group of elements (sometimes called the representative elements) whose lightest members are represented by helium, lithium, beryllium, boron, carbon, nitrogen, oxygen, and fluorine as arranged in the periodic table of the elements. The main group includes the elements (except hydrogen, which is sometimes not included) in groups 1 and 2 (s-block), and groups 13 to 18 (p-block). The s-block elements are primarily characterised by one main oxidation state, and the p-block elements, when they have multiple oxidation states, often have common oxidation states separated by two units. Main-group elements (with some of the lighter transition metals) are the most abundant elements on Earth, in the Solar System, and in the universe. Group 12 elements are often considered to be transition metals; however, zinc (Zn), cadmium (Cd), and mercury (Hg) share some properties of both groups, and some scientists believe they should be inclu ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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