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Henry Rzepa's Blog

Henry Rzepa's Blog
Chemistry with a twist
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Interesting ChemistryCambridgeMolecular WirePhthalocyanineCiencias QuímicasInglés
Publicado

In the previous post I pondered the colour of Monastral blue (copper phthalocyanine). Something did not quite fit, and so I speculated that perhaps some oxidation of the pigment might give a new species. This species (Cambridge code FEGJOQ) comprises two parts of copper phthalocyanine, 1 part of the corresponding cation, and 1 part of triodide anion.

Interesting Chemistry18 Electron AromaticityChemical SerendipityHistoricalHTMLCiencias QuímicasInglés
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The story of Monastral is not about a character in the Magic flute, but is a classic of chemical serendipity, collaboration between industry and university, theoretical influence, and of much else.

Interesting Chemistry6-31G(d)ATAT DuplexB-DNACGCG DuplexCiencias QuímicasInglés
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In this earlier post, I noted some aspects of the calculated structures of both Z- and B-DNA duplexes. These calculations involved optimising the positions of around 250-254 atoms, for d(CGCG) 2 and d(ATAT) 2, an undertaking which has taken about two months of computer time!

Interesting ChemistryAfghanistanBill GriffithLapis LazuliMissouriCiencias QuímicasInglés
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My colleague Bill Griffith has again come up with another colour challenge: that of the ancient semi-precious stone Lapis Lazuli , mined in the mountains of Afghanistan for more than 6000 years and used by painters in some medieval paintings of the Virgin, the Wilton diptych etc.

Acidic SolutionsActivation Free EnergyCalculated Free EnergyCyanohydrinMechanismCiencias QuímicasInglés
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Nucleophilic addition of cyanide to a ketone or aldehyde is a standard reaction for introductory organic chemistry. But is all as it seems? The reaction is often represented as below, and this seems simple enough. Cyanohydrin formation. But attention to detail suggests that, HCN being a weak acid, there will be only a very small concentration of cyanide anion in the presence of HCl.

HypervalencyAlbrecht SalzerFrank PodewilsMartin KauppMetalCiencias QuímicasInglés
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Much like chocolate, some of us metallaholics cannot get enough. So WUQXIP proved an irresistible frolic (DOI: 10.1021/om020789h). Let us start with benzene.  It can have metals added in two ways, whilst preserving its essential aromaticity. Triple metal delight. Making a metal sandwich is of course very well known, ferrocene being the first example where the bonding was identified.

GeneralInteresting ChemistryAugust Von HofmannCharles ReesChemical HeroesCiencias QuímicasInglés
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One of my chemical heroes is William Perkin, who in 1856 famously (and accidentally) made the dye mauveine as an 18 year old whilst a student of August von Hofmann, the founder of the Royal College of Chemistry (at what is now  Imperial College London). Perkin went on to found the British synthetic dyestuffs and perfumeries industries.

Interesting ChemistryDiberylliumEnergyExcited StateHigher EnergyCiencias QuímicasInglés
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Much of chemistry is about bonds, but sometimes it can also be about anti-bonds. It is also true that the simplest of molecules can have quite subtle properties. Thus most undergraduate courses in chemistry deal with how to describe the bonding in the diatomics of the first row of the periodic table.

GeneralChemical LiteratureDNAEminent MathematicianHelixCiencias QuímicasInglés
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In my blogroll, I link to Tim Gowers’ blog. He is a very eminent mathematician, and so it is interesting to see what motivates him to write a blog about mathematics. This latest post goes a large way to explaining why. He starts by speculating about the features of some piece of research that might render it conventionally unpublishable, highlighting two reasons; (1) it is not original and (2) it does not lead anywhere conclusive.