Archive for the ‘Chemical IT’ Category
Thursday, August 27th, 2015
The anomeric effect is best known in sugars, occuring in sub-structures such as RO-C-OR. Its origins relate to how the lone pairs on each oxygen atom align with the adjacent C-O bonds. When the alignment is 180°, one oxygen lone pair can donate into the C-O σ* empty orbital and a stabilisation occurs. Here I explore whether crystal structures reflect this effect.
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Tags:Alkane stereochemistry, Anomeric effect, Carbohydrate chemistry, Carbohydrates, Carbon–oxygen bond, Chemical bond, Ether, Lone pair, Physical organic chemistry, Quantum chemistry, Stereochemistry, Technology/Internet
Posted in Chemical IT, crystal_structure_mining | No Comments »
Wednesday, August 26th, 2015
Previously, I showed how conjugation in dienes and diaryls can be visualised by inspecting bond lengths as a function of torsions. Here is another illustration, this time of the mesomeric resonance on a benzene ring induced by an electron donating substituent (an amino group) or an electron withdrawing substituent (cyano).
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Tags:chemical bonding, Chemical nomenclature, Hammett equation, Mesomeric effect, Substituent, Substitution reactions, usual search
Posted in Chemical IT, crystal_structure_mining | No Comments »
Thursday, August 20th, 2015
Management of research (data) outputs is a hot topic in the UK at the moment, although the topic has been rumbling for five years or more. Most research-active higher educational establishments have or are about to publish general guidelines, which predominantly take the form of aspirational targets rather than actionable examples or use-cases.‡ Because the concepts remain somewhat abstract, one can encounter questions from researchers such as “how should I go about achieving such RDM (research data management)?” I thought it might be useful for me to here summarise some key features in the form of an FAQ that can help answer that question. I will concentrate purely on the sub-set chemistry about which I know most.
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Posted in Chemical IT | 4 Comments »
Wednesday, August 5th, 2015
I recently received two emails each with a subject line new approaches to research reporting. The traditional 350 year-old model of the (scientific) journal is undergoing upheavals at the moment with the introduction of APCs (article processing charges), a refereeing crisis and much more. Some argue that brand new thinking is now required. Here are two such innovations (and I leave you to judge whether that last word should have an appended ?).
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Tags:10.15200, 143871.12809, Academia, Academic publishing, advocate, Citation, data mining, Digital Object Identifier, Do, Knowledge, knowledge mining, Microattribution, Mobley, original researcher, Peer review, Publishing, scholarly publishing tools, Technology/Internet, the New Reddit Journal, Yogi Berra
Posted in Chemical IT, General | No Comments »
Saturday, July 25th, 2015
I recently followed this bloggers trail; link1 → link2 to arrive at this delightful short commentary on atom-atom bonds in crystals[cite]10.1107/S2052252515002006[/cite] by Jack Dunitz. Here he discusses that age-old question (to chemists), what is a bond? Even almost 100 years after Gilbert Lewis’ famous analysis,[cite]10.1021/ja02261a002[/cite] we continue to ponder this question. Indeed, quite a debate on this topic broke out in a recent post here. My eye was caught by one example in Jack's article: "The close stacking of planar anions, as occurs in salts of croconic acid …far from producing a lowering of the crystal energy, this stacking interaction in itself leads to an increase by several thousand kJ mol−1 arising from Coulombic repulsion between the doubly negatively charged anions" I thought I might explore this point a bit further in this post.
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Tags:Carbon, Cations, Chemical bond, control search, Croconic acid, crystal energy, crystal structure search, Gilbert Lewis, intermolecular search, Jack Dunitz, overall energy balance, Proton
Posted in Chemical IT, crystal_structure_mining, Interesting chemistry | 1 Comment »
Friday, June 26th, 2015
Open principles in the sciences in general and chemistry in particular are increasingly nowadays preached from funding councils down, but it can be more of a challenge to find innovative practitioners. Part of the problem perhaps is that many of the current reward systems for scientists do not always help promote openness. Jean-Claude Bradley was a young scientist who was passionately committed to practising open chemistry, even though when he started he could not have anticipated any honours for doing so. A year ago a one day meeting at Cambridge was held to celebrate his achievements, followed up with a special issue of the Journal of Cheminformatics. Peter Murray-Rust and I both contributed and following the meeting we decided to help promote Open Chemistry via an annual award to be called the Bradley-Mason prize. This would celebrate both “JC” himself and Nick Mason, who also made outstanding contributions to the cause whilst studying at Imperial College. The prize was initially to be given to an undergraduate student at Imperial, but was also extended to postgraduate students who have promoted and showcased open chemistry in their PhD researches.
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Tags:Cambridge, chemical data, Chemistry Central, Collective intelligence, Crowdsourcing, Doctor of Philosophy, Education, European Union, France, GITHUB INC., Imperial College, Jean Claude Bradley, lab on a chip, Lyon, Nick Mason, Nonprofit technology, Open content, Peter Murray-Rust, reward systems, Technology/Internet, Tom Arrow, Tom Phillips, Wikimedia Foundation, wikipedia, World Wide Web, young scientist
Posted in Bradley-Mason Prize for Open Chemistry, Chemical IT | 1 Comment »
Saturday, June 20th, 2015
The university sector in the UK has quality inspections of its research outputs conducted every seven years, going by the name of REF or Research Excellence Framework. The next one is due around 2020, and already preparations are under way! Here I describe how I have interpreted one of its strictures; that all UK funded research outputs (i.e. research publications in international journals) must be made available in open unrestricted form within three months of the article being accepted for publication, or they will not be eligible for consideration in 2020.
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Tags:Academia, Academic publishing, Archival science, author, Data management, Digital library, EPrints, Institutional repository, Knowledge, Knowledge representation, Library science, metadata, Open access, PDF, personal web page, Preprint, Publishing, Repository, researcher, ROMEO GREEN, Science, Technology/Internet, United Kingdom, web server
Posted in Chemical IT | No Comments »
Saturday, May 30th, 2015
I am on a mission to persuade my colleagues that the statistical analysis of crystal structures is a useful teaching tool. One colleague asked for a demonstration and suggested exploring the classical Jahn-Teller effect (thanks Milo!). This is a geometrical distortion associated with certain molecular electronic configurations, of which the best example is illustrated by octahedral copper complexes which have a d9 electronic configuration. The eg level shown below is occupied by three electrons and which can therefore distort in one of two ways to eliminate the eg degeneracy by placing the odd electron into either a x2-y2 or a z2 orbital. Here I explore how this effect can be teased out of crystal structures.
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Tags:basic search, Chemical bond, chemical bonding, Chemistry, classical Jahn-Teller, clear Jahn-Teller, Coordination chemistry, Coordination complex, Copper(II) nitrate, dynamic Jahn-Teller, Edward Teller, Inorganic chemistry, Jahn-Teller, Jahn–Teller effect, Metal ions in aqueous solution, search criteria, Technology/Internet, Transition metals
Posted in Chemical IT, crystal_structure_mining | 1 Comment »
Friday, May 22nd, 2015
As I have noted elsewhere, Gilbert N. Lewis wrote a famous paper entitled “the atom and the molecule“, the centenary of which is coming up.[cite]10.1021/ja02261a002[/cite] In a short and rarely commented upon remark, he speculates about the shared electron pair structure of acetylene, R-X≡X-R (R=H, X=C). It could, he suggests, take up three forms. H-C:::C-H and two more which I show as he drew them. The first of these would now be called a bis-carbene and the second a biradical.
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Tags:Carbene, Carbenes, Chemistry, Cluster chemistry, food, Functional groups, Gilbert N. Lewis, Non-Kekulé molecule, Organic chemistry, Organic compounds
Posted in Chemical IT, Historical, Interesting chemistry | 1 Comment »