Posts Tagged ‘Chemistry’
Wednesday, February 15th, 2017
This post arose from a comment attached to the post on Na2He and relating to peculiar and rare topological features of the electron density in molecules called non-nuclear attractors. This set me thinking about other molecules that might exhibit this and one of these is shown below.
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Tags:Attractor, brief search, Chemistry, Electron, Electron density, Hydrogen, Molecule, Nature, Physics, Quantum chemistry
Posted in Interesting chemistry | 11 Comments »
Tuesday, February 14th, 2017
I analysed the bonding in chlorine trifluoride a few years back in terms of VSEPR theory. I noticed that several searches on this topic which led people to this post also included a query about the differences between it and the bromine analogue. For those who posed this question, here is an equivalent analysis.
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Tags:Bromine, Bromine trifluoride, Chemical elements, Chemistry, Chlorine, Fluorides, Halogens, Interhalogen compounds, Matter, Oxidizing agents, VSEPR theory
Posted in Interesting chemistry | 1 Comment »
Saturday, February 11th, 2017
On February 6th I was alerted to this intriguing article[cite]10.1038/nchem.2716[/cite] by a phone call, made 55 minutes before the article embargo was due to be released. Gizmodo wanted to know if I could provide an (almost)† instant‡ quote. After a few days, this report of a stable compound of helium and sodium still seems impressive to me and I now impart a few more thoughts here.
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Tags:10.1038, Atom, Chemical elements, chemical phenomenon, Chemistry, Company: P. Acucar-CBD, Electride, Electron, Food Retail & Distribution - NEC, helium, Hydrogen, Matter, Oxygen, Physics, social media
Posted in Bond slam, crystal_structure_mining, Interesting chemistry | 11 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[cite]10.1126/science.aal1619[/cite] reports a molecular knot with the remarkable number of eight crossings.
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Tags:Cheminformatics, Chemistry, Drug discovery, Education, π-systems, Matter, Molecule, Nature, spectroscopy, Structure validation
Posted in Interesting chemistry | 3 Comments »
Monday, January 2nd, 2017
Here is an inside peek at another one of Derek Lowe’s 250 milestones in chemistry, the polymorphism of Ritonavir.[cite]10.1023/A:1011052932607[/cite] The story in a nutshell concerns one of a pharma company’s worst nightmares; a drug which has been successfully brought to market unexpectedly “changes” after a few years on market to a less effective form (or to use the drug term, formulation). This can happen via a phenomenon known as polymorphism, where the crystalline structure of a molecule can have more than one form.[cite]10.1021/ar00052a005[/cite],[cite]10.1002/anie.201410356[/cite],[cite]10.1039/D1SC06074K[/cite] In this case, form I was formulated into soluble tablets for oral intake. During later manufacturing, a new less-soluble form appeared and “within weeks this new polymorph began to appear throughout both the bulk drug and formulation areas“[cite]10.1023/A:1011052932607[/cite]
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Tags:Carbamates, Chemistry, Derek Lowe, free energy, high energy process, High-energy rotations, higher energy, higher energy s-trans form, hydrogen bonding network, later manufacturing, Lipid polymorphism, low energy conformational effects, low energy rotations, lower energy rotation, Peek, Polymorphism, Protease inhibitors, Ritonavir, RTT, SN, Software engineering, Thiazoles, Ureas
Posted in Interesting chemistry | No Comments »
Saturday, December 31st, 2016
My holiday reading has been Derek Lowe’s excellent Chemistry Book setting out 250 milestones in chemistry, organised by year. An entry for 1920 entitled hydrogen bonding seemed worth exploring in more detail here.
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Tags:10.1021, aqueous solution, Chemical bond, chemical bonding, Chemistry, Derek Lowe, Hydrogen, Hydrogen bond, Intermolecular forces, Lowe's, Nature, Supramolecular chemistry
Posted in Historical | 2 Comments »
Saturday, December 24th, 2016
The previous posts produced discussion about the dipole moments of highly polar molecules. Here to produce some reference points for further discussion I look at the dipole moment of glycine, the classic zwitterion (an internal ion-pair).
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Tags:aqueous solution, Chemical polarity, Chemistry, dielectric, Dipole, Electric dipole moment, Electromagnetism, Magnetism, Moment, Nature, Physical quantities, Physics, Potential theory, zwitterion
Posted in crystal_structure_mining, Interesting chemistry | 1 Comment »
Monday, December 12th, 2016
Chemical and engineering news (C&EN) is asking people to vote for their molecule of the year from six highlighted candidates. This reminded me of the history of internet-based “molecules of the moment“. It is thought that the concept originated in December 1995 here at Imperial and in January 1996 at Bristol University by Paul May and we were joined by Karl Harrison at Oxford shortly thereafter. Quite a few more such sites followed this concept, differentiated by their time intervals of weeks, months or years. The genre is well suited for internet display because of plugins or “helpers” such as Rasmol, Chime, Jmol and now JSmol which allow the three dimensions of molecular structures to be explored by the reader. Here I discuss a second candidate from the C&EN list; a ferrocene-based Ferris wheel[cite]10.1038/nchem.2553[/cite],[cite]10.5517/CCDC.CSD.CC1JPKYQ[/cite] (DOI for 3D model: 10.5517/CCDC.CSD.CC1JPKYQ) originating from research carried out at Imperial by Tim Albrecht, Nick Long and colleagues.
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Tags:American Chemical Society, Bristol University, Chemical & Engineering News, Chemistry, Engineering, internet display, Karl Harrison, metal centres, Nick Long, Paul May, Tim Albrecht
Posted in crystal_structure_mining, Interesting chemistry | 2 Comments »
Thursday, December 1st, 2016
Following on from a search for long C-C bonds, here is the same repeated for C=C double bonds.
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Tags:Chemical bond, chemical bonding, Chemical nomenclature, Chemistry, Conjugated system, double bond, energy, Nature, Nonmetal, Organic chemistry, Physical organic chemistry, search query, Substituent
Posted in crystal_structure_mining, Interesting chemistry | 2 Comments »