Archive for the ‘Interesting chemistry’ Category
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 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 19th, 2016
I am completing my survey of the vote for molecule of the year candidates, which this year seems focused on chemical records of one type or another.
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Tags:chemical publishing, chemical records, human chemical perception, Matter, metal, Molecule, Nature, search query, search software, Voting
Posted in crystal_structure_mining, Interesting chemistry | 2 Comments »
Friday, December 16th, 2016
Here is a third candidate for the C&EN “molecule of the year” vote. This one was shortlisted because it is the first example of a metal-nitrogen complex exhibiting single, double and triple bonds from different nitrogens to the same metal[cite]10.1039/c5sc04608d[/cite] (XUZLUB has a 3D display available at DOI: 10.5517/CC1JYY6M). Since no calculation of its molecular properties was reported, I annotate some here.
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Tags:10.14469, chemical shifts, expert chemical knowledge, metal, metal-nitrogen complex exhibiting single, search query
Posted in crystal_structure_mining, Interesting chemistry | 10 Comments »
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 »
Wednesday, November 30th, 2016
In an earlier post, I searched for small C-C-C angles, finding one example that was also accompanied by an apparently exceptionally long C-C bond (2.18Å). But this arose from highly unusual bonding giving rise not to a single bond order but one closer to one half! How long can a “normal” (i.e single) C-C bond get, a question which has long fascinated chemists.
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Tags:Aviation, Bond order, Carbon–carbon bond, Chemical bond, chemical bonding, naive search, search query, single bond
Posted in crystal_structure_mining, Interesting chemistry | No Comments »
