Posts Tagged ‘spectroscopy’
Thursday, April 18th, 2019
The topic of this post originates from a recent article which is attracting much attention.[1] The technique uses confined light to both increase the spatial resolution by around three orders of magnitude and also to amplify the signal from individual molecules to the point it can be recorded. To me, Figure 3 in this article summarises it nicely (caption: visualization of vibrational normal modes). Here I intend to show selected modes as animated and rotatable 3D models with the help of their calculation using density functional theory (a mode of presentation that the confinement of Figure 3 to the pages of a conventional journal article does not enable).
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References
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J. Lee, K.T. Crampton, N. Tallarida, and V.A. Apkarian, "Visualizing vibrational normal modes of a single molecule with atomically confined light", Nature, vol. 568, pp. 78-82, 2019. http://dx.doi.org/10.1038/s41586-019-1059-9
Tags:anionic metal surface, Cambridge, chemical bonding, Chemistry, dihedral, energy, flat metal surface, Interesting chemistry, metal, Natural sciences, Neutral Quartet, Physical sciences, Raman scattering, Raman spectroscopy, Resonance, spectroscopy, steric repulsion energy
Posted in Uncategorised | No Comments »
Saturday, September 1st, 2018
I am exploring the fascinating diverse facets of a recently published laboratory experiment for undergraduate students.[1] Previously I looked at a possible mechanistic route for the reaction between an enal (a conjugated aldehyde-alkene) and benzyl chloride catalysed by base and a chiral amine, followed by the use of NMR coupling constants to assign relative stereochemistries. Here I take a look at some chiroptical techniques which can be used to assign absolute stereochemistries (configurations).
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References
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M. Meazza, A. Kowalczuk, S. Watkins, S. Holland, T.A. Logothetis, and R. Rios, "Organocatalytic Cyclopropanation of (E)-Dec-2-enal: Synthesis, Spectral Analysis and Mechanistic Understanding", Journal of Chemical Education, vol. 95, pp. 1832-1839, 2018. http://dx.doi.org/10.1021/acs.jchemed.7b00566
Tags:Absolute configuration, Biochemistry, bulk solutions, chemical transformations, Chemistry, Conformational isomerism, difficult energy difference, gas phase, higher energy forms, Interesting chemistry, Isomer, Isomerism, Nature, Physical organic chemistry, Polarization, spectroscopy, stereochemical product, Stereochemistry, Stereoisomerism, Vibrational circular dichroism
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Wednesday, July 18th, 2018
FAIR is one of those acronyms that spreads rapidly, acquires a life of its own and can mean many things to different groups. A two-day event has just been held in Amsterdam to bring some of those groups from the chemical sciences together to better understand FAIR. Here I note a few items that caught my attention.
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Tags:Acronym, Amsterdam, chemical sciences, City: Amsterdam, Interesting chemistry, Queen Mary University of London, spectroscopy, Technology/Internet, text editor, University of London, visualisation tools
Posted in Uncategorised | 3 Comments »
Monday, June 18th, 2018
It was about a year ago that I came across a profusion of colour in my local Park. Although colour in fact was the topic that sparked my interest in chemistry many years ago (the fantastic reds produced by diazocoupling reactions), I had never really tracked down the origin of colours in many flowers. It is of course a vast field. Here I take a look at just one class of molecule responsible for many flower colours, anthocyanidin, this being the sugar-free counterpart of the anthocyanins found in nature.
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Tags:Anthocyanidin, Anthocyanin, Chemistry, Delphinidin, HOMO/LUMO, Interesting chemistry, Major, Molecular electronic transition, Molecule, Nature, PH indicators, Quantum chemistry, spectroscopy, Ultraviolet–visible spectroscopy
Posted in Uncategorised | 4 Comments »
Saturday, January 6th, 2018
The title here is from an article on metalenses[1] which caught my eye.
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References
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M. Khorasaninejad, W.T. Chen, A.Y. Zhu, J. Oh, R.C. Devlin, D. Rousso, and F. Capasso, "Multispectral Chiral Imaging with a Metalens", Nano Letters, vol. 16, pp. 4595-4600, 2016. http://dx.doi.org/10.1021/acs.nanolett.6b01897
Tags:Biochemistry, Biology, Chemistry, Chirality, Circular dichroism, Interesting chemistry, Nature, Pharmacology, Polarization, spectroscopy, Stereochemistry, Ultraviolet, Vibrational circular dichroism
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Tuesday, May 23rd, 2017
This is taking place in the idyllic surroundings of the Niederwald forest, Rüdesheim, Germany. Here I highlight only aspects of the first three talks.
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Tags:article processing charges, Bad Kreuznach, Chemical IT, chemical shift, chemical terms, City: Rüdesheim, Country: Germany, Hesse, Hesse-Nassau, Ian Bruno, Jeremy Frey, Klaus Tochtermann, Leah McEwen, Martin Hicks, metadata tools, Niederwald, Niederwalddenkmal, Quotation, Rüdesheim, Rüdesheim am Rhein, Rüdesheim an der Nahe, Rheingau-Taunus-Kreis, Rhine, Richard Kidd, spectroscopy, States of Germany, Stuart Chalk, Technology/Internet
Posted in Uncategorised | 1 Comment »
Friday, March 31st, 2017
Occasionally one comes across a web site that manages to combine being unusual, interesting and also useful. Thus www.molinsight.net is I think a unique chemistry resource for blind and visually impaired students.
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Tags:Chemistry, Electromagnetic radiation, Infrared, Infrared spectroscopy, Interesting chemistry, Multimodal interaction, Nuclear magnetic resonance, open source chemical structure editors, Sonification, spectroscopy, stereochemical utilities
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Friday, March 10th, 2017
George Olah passed away on March 8th. He was part of the generation of scientists in the post-war 1950s who had access to chemical instrumentation that truly revolutionised chemistry. In particular he showed how the then newly available NMR spectroscopy illuminated structures of cations in solvents such “Magic acid“. The obituaries will probably mention his famous “feud” with H. C. Brown over the structure of the norbornyl cation (X=CH2+), implicated in the mechanism of many a solvolysis reaction that characterised the golden period of physical organic chemistry just before and after WWII.
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Tags:2-Norbornyl cation, aqueous solutions, Chemical bond, chemical instrumentation, Chemistry, George Andrew Olah, George Olah, Interesting chemistry, Ion association, Magic acid, Michael Dewar, Molecule, Nature, Physical organic chemistry, Reactive intermediates, spectroscopy
Posted in Uncategorised | 17 Comments »
Friday, January 20th, 2017
This is one of those posts of a molecule whose very structure is interesting enough to merit a picture and a 3D model. The study[1] reports a molecular knot with the remarkable number of eight crossings.
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References
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J.J. Danon, A. Krüger, D.A. Leigh, J. Lemonnier, A.J. Stephens, I.J. Vitorica-Yrezabal, and S.L. Woltering, "Braiding a molecular knot with eight crossings", Science, vol. 355, pp. 159-162, 2017. http://dx.doi.org/10.1126/science.aal1619
Tags:Cheminformatics, Chemistry, Drug discovery, Education, Interesting chemistry, π-systems, Matter, Molecule, Nature, spectroscopy, Structure validation
Posted in Uncategorised | 3 Comments »
Monday, November 14th, 2016
Chloroform, often in the deuterated form CDCl3, is a very common solvent for NMR and other types of spectroscopy. Quantum mechanics is increasingly used to calculate such spectra to aid assignment and the solvent is here normally simulated as a continuum rather than by explicit inclusion of one or more chloroform molecules. But what are the features of the hydrogen bonds that form from chloroform to other acceptors? Here I do a quick search for the common characteristics of such interactions.
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Tags:chemical shifts, Chloroform, Deuterated chloroform, Deuterated methanol, Hydrogen bond, Nuclear magnetic resonance, spectroscopy
Posted in crystal_structure_mining | 5 Comments »