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Eluvathingal Devassy Jemmis
Eluvathingal Devassy Jemmis or E. D. Jemmis (born 31 October 1951) is a Professor of theoretical chemistry at the Indian Institute of Science, Bangalore, India. He was the founding Director of Indian Institute of Science Education and Research, Thiruvananthapuram (IISER-TVM). His primary area of research is applied theoretical chemistry with emphasis on structure, bonding and reactivity, across the periodic table of the elements. Apart from many of his contributions to applied theoretical chemistry, an equivalent of the structural chemistry of carbon, as exemplified by the Huckel 4n+2 Rule, benzenoid aromatics and graphite, and tetrahedral carbon and diamond, is brought in the structural chemistry of boron by the Jemmis mno rules which relates polyhedral and macropolyhedral boranes to allotropes of boron and boron-rich solids. He has been awarded Padma Shri in Science and Engineering category (year 2014) by the Government of India. Education Eluvathingal D Jemmis, after obtainin ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Indian Institute Of Science
The Indian Institute of Science (IISc) is a public, deemed, research university for higher education and research in science, engineering, design, and management. It is located in Bengaluru, in the Indian state of Karnataka. The institute was established in 1909 with active support from Jamsetji Tata and thus is also locally known as the ''"Tata Institute"''. It is ranked among the most prestigious academic institutions in India and has the highest citation per faculty among all the universities in the world. It was granted the deemed to be university status in 1958 and the Institute of Eminence status in 2018. History After an accidental meeting between Jamsetji Tata and Swami Vivekananda, on a ship in 1893 where they discussed Tata's plan of bringing the steel industry to India, Tata wrote to Vivekananda five years later: "I trust, you remember me as a fellow-traveller on your voyage from Japan to Chicago. I very much recall at this moment your views on the growth of ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Allotropes Of Boron
Boron can be prepared in several crystalline and amorphous forms. Well known crystalline forms are α-rhombohedral (α-R), β-rhombohedral (β-R), and β-tetragonal (β-T). In special circumstances, boron can also be synthesized in the form of its α-tetragonal (α-T) and γ-orthorhombic (γ) allotropes. Two amorphous forms, one a finely divided powder and the other a glassy solid, are also known. Although at least 14 more allotropes have been reported, these other forms are based on tenuous evidence or have not been experimentally confirmed, or are thought to represent mixed allotropes, or boron frameworks stabilized by impurities. Whereas the β-rhombohedral phase is the most stable and the others are metastable, the transformation rate is negligible at room temperature, and thus all five phases can exist at ambient conditions. Amorphous powder boron and polycrystalline β-rhombohedral boron are the most common forms. The latter allotrope is a very hardVickers hardness comparab ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Boron
Boron is a chemical element with the symbol B and atomic number 5. In its crystalline form it is a brittle, dark, lustrous metalloid; in its amorphous form it is a brown powder. As the lightest element of the ''boron group'' it has three valence electrons for forming covalent bonds, resulting in many compounds such as boric acid, the mineral borax, sodium borate, and the ultra-hard crystals of boron carbide and boron nitride. Boron is synthesized entirely by cosmic ray spallation and supernovae and not by stellar nucleosynthesis, so it is a low-abundance element in the Solar System and in the Crust (geology), Earth's crust. It constitutes about 0.001 percent by weight of Earth's crust. It is concentrated on Earth by the water-solubility of its more common naturally occurring compounds, the borate minerals. These are mined industrially as evaporites, such as borax and kernite. The largest known deposits are in Turkey, the largest producer of boron minerals. Elemental b ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Polyhedral Skeletal Electron Pair Theory
In chemistry the polyhedral skeletal electron pair theory (PSEPT) provides electron counting rules useful for predicting the structures of clusters such as borane and carborane clusters. The electron counting rules were originally formulated by Kenneth Wade, and were further developed by others including Michael Mingos; they are sometimes known as Wade's rules or the Wade–Mingos rules. The rules are based on a molecular orbital treatment of the bonding. These notes contained original material that served as the basis of the sections on the 4''n'', 5''n'', and 6''n'' rules. These rules have been extended and unified in the form of the Jemmis ''mno'' rules. Predicting structures of cluster compounds Different rules (4''n'', 5''n'', or 6''n'') are invoked depending on the number of electrons per vertex. The 4''n'' rules are reasonably accurate in predicting the structures of clusters having about 4 electrons per vertex, as is the case for many boranes and carboranes. For such ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Carboranes
Carboranes are electron-delocalized (non-classically bonded) clusters composed of boron, carbon and hydrogen atoms.Grimes, R. N., ''Carboranes 3rd Ed.'', Elsevier, Amsterdam and New York (2016), . Like many of the related boron hydrides, these clusters are polyhedra or fragments of polyhedra. Carboranes are one class of heteroboranes. In terms of scope, carboranes can have as few as 5 and as many as 14 atoms in the cage framework. The majority have two cage carbon atoms. The corresponding C-alkyl and B-alkyl analogues are also known in a few cases. Structure and bonding Carboranes and boranes adopt 3-dimensional cage (cluster) geometries in sharp contrast to typical organic compounds. Cages are compatible with sigma—delocalized bonding, whereas hydrocarbons are typically chains or rings. Like for other electron-delocalized polyhedral clusters, the electronic structure of these cluster compounds can be described by the Wade–Mingos rules. Like the related boron hydrides, the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Aromaticity
In chemistry, aromaticity is a chemical property of cyclic ( ring-shaped), ''typically'' planar (flat) molecular structures with pi bonds in resonance (those containing delocalized electrons) that gives increased stability compared to saturated compounds having single bonds, and other geometric or connective non-cyclic arrangements with the same set of atoms. Aromatic rings are very stable and do not break apart easily. Organic compounds that are not aromatic are classified as aliphatic compounds—they might be cyclic, but only aromatic rings have enhanced stability. The term ''aromaticity'' with this meaning is historically related to the concept of having an aroma, but is a distinct property from that meaning. Since the most common aromatic compounds are derivatives of benzene (an aromatic hydrocarbon common in petroleum and its distillates), the word ''aromatic'' occasionally refers informally to benzene derivatives, and so it was first defined. Nevertheless, many non-be ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hydrogen Bond
In chemistry, a hydrogen bond (or H-bond) is a primarily electrostatic force of attraction between a hydrogen (H) atom which is covalently bound to a more electronegative "donor" atom or group (Dn), and another electronegative atom bearing a lone pair of electrons—the hydrogen bond acceptor (Ac). Such an interacting system is generally denoted , where the solid line denotes a polar covalent bond, and the dotted or dashed line indicates the hydrogen bond. The most frequent donor and acceptor atoms are the second-row elements nitrogen (N), oxygen (O), and fluorine (F). Hydrogen bonds can be intermolecular (occurring between separate molecules) or intramolecular (occurring among parts of the same molecule). The energy of a hydrogen bond depends on the geometry, the environment, and the nature of the specific donor and acceptor atoms and can vary between 1 and 40 kcal/mol. This makes them somewhat stronger than a van der Waals interaction, and weaker than fully covalent ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Organometallic
Organometallic chemistry is the study of organometallic compounds, chemical compounds containing at least one chemical bond between a carbon atom of an organic molecule and a metal, including alkali, alkaline earth, and transition metals, and sometimes broadened to include metalloids like boron, silicon, and selenium, as well. Aside from bonds to organyl fragments or molecules, bonds to 'inorganic' carbon, like carbon monoxide (metal carbonyls), cyanide, or carbide, are generally considered to be organometallic as well. Some related compounds such as transition metal hydrides and metal phosphine complexes are often included in discussions of organometallic compounds, though strictly speaking, they are not necessarily organometallic. The related but distinct term " metalorganic compound" refers to metal-containing compounds lacking direct metal-carbon bonds but which contain organic ligands. Metal β-diketonates, alkoxides, dialkylamides, and metal phosphine complexes are repres ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
JNCASR
The Jawaharlal Nehru Centre for Advanced Scientific Research (JNCASR) is a multidisciplinary research institute located at Jakkur, Bangalore, India. It was established by the Department of Science and Technology of the Government of India, to mark the birth centenary of Pandit Jawaharlal Nehru, the first prime minister of independent India. It is considered one of the most prestigious research institutes in India. In 2019, JNCASR was ranked #7 among the world's top ten research institutes by ''Nature'' journal in a normalised ranking of small research institutes with high quality output. Academics Researchers at the centre are divided into seven units: Chemistry and Physics of Materials, Engineering Mechanics, Evolutionary and Organismal Biology, Molecular biology and Genetics, New Chemistry, Theoretical Sciences, Education Technology and Geodynamics. There are two off-campus units: Chemical Biology and Condensed Matter Theory. JNCASR has a faculty-to-student ratio of about ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Australian National University
The Australian National University (ANU) is a public research university located in Canberra, the capital of Australia. Its main campus in Acton encompasses seven teaching and research colleges, in addition to several national academies and institutes. ANU is regarded as one of the world's leading universities, and is ranked as the number one university in Australia and the Southern Hemisphere by the 2022 QS World University Rankings and second in Australia in the ''Times Higher Education'' rankings. Compared to other universities in the world, it is ranked 27th by the 2022 QS World University Rankings, and equal 54th by the 2022 ''Times Higher Education''. In 2021, ANU is ranked 20th (1st in Australia) by the Global Employability University Ranking and Survey (GEURS). Established in 1946, ANU is the only university to have been created by the Parliament of Australia. It traces its origins to Canberra University College, which was established in 1929 and was integrated into ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Roald Hoffmann
Roald Hoffmann (born Roald Safran; July 18, 1937) is a Polish Americans, Polish-American theoretical chemistry, theoretical chemist who won the 1981 Nobel Prize in Chemistry. He has also published plays and poetry. He is the Frank H. T. Rhodes Professor of Humane Letters, Emeritus, at Cornell University, in Ithaca, New York. Early life Escape from the Holocaust Hoffmann was born in Złoczów, Second Polish Republic (now Zolochiv, Ukraine), to a Polish-Jewish family, and was named in honor of the Norway, Norwegian explorer Roald Amundsen. His parents were Clara (Rosen), a teacher, and Hillel Safran, a civil engineer. After Germany invaded Poland and occupied the town, his family was placed in a labor camp where his father, who was familiar with much of the local infrastructure, was a valued prisoner. As the situation grew more dangerous, with prisoners being transferred to extermination camps, the family bribed guards to allow an escape. They arranged with a Ukrainian neighbor ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
University Of Munich
The Ludwig Maximilian University of Munich (simply University of Munich or LMU; german: Ludwig-Maximilians-Universität München) is a public research university in Munich, Germany. It is Germany's List of universities in Germany, sixth-oldest university in continuous operation. Originally University of Ingolstadt, established in Ingolstadt in 1472 by Louis IX, Duke of Bavaria, Duke Ludwig IX of Bavaria-Landshut, the university was moved in 1800 to Landshut by Maximilian I Joseph of Bavaria, King Maximilian I of Bavaria when the city was threatened by the French, before being relocated to its present-day location in Munich in 1826 by Ludwig I of Bavaria, King Ludwig I of Bavaria. In 1802, the university was officially named Ludwig-Maximilians-Universität by King Maximilian I of Bavaria in honor of himself and Ludwig IX. LMU is currently the second-largest university in Germany in terms of student population; in the 2018/19 winter semester, the university had a total of 51,606 m ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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