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Henry Rzepa's Blog

Henry Rzepa's Blog
Chemistry with a twist
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Chemical ITKimya Bilimleriİngilizce
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The first conference devoted to scientific uses of Wikipedia has just finished; there was lots of fascinating stuff but here I concentrate on one report that I thought was especially interesting. To introduce it, I need first to introduce WikiData. This is part of the WikiMedia ecosystem, and one of the newest. The basic concept is really simple. It is a repository for data objects; 14,757,419 of them as I write this to be precise.

GeneralKimya Bilimleriİngilizce
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Most visitors to London use the famous underground trains (the “tube”) or a* double-decker bus* to see the city (one can also use rivers and canals). So I thought, during the tourism month of August, I would show you an alternative overground circumnavigation of the city using the metaphor of benzene. Benzene you see is a ring, comprising three “HCCH” segments.

Chemical ITCrystal_structure_miningAlkane StereochemistryAnomeric EffectCarbohydrate ChemistryKimya Bilimleriİngilizce
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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.

Chemical ITGeneral10.15200143871.12809AcademiaKimya Bilimleriİngilizce
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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.

Chemical ITCrystal_structure_miningInteresting ChemistryCarbonCationsKimya Bilimleriİngilizce
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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.

HistoricalNaphthaleneOscillationKimya Bilimleriİngilizce
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This is a little historical essay into the electronic structure of naphthalene, presented as key dates (and also collects comments made which were appended to other posts). 1890[cite]10.1039/pl8900600095[/cite]: Henry Armstrong presents the following structure of naphthalene. Three words need translation into modern usage.

Reaction MechanismActivation Free EnergyBasis SetDan SingletonEnergy DifferencesKimya Bilimleriİngilizce
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Previously on the kinetic isotope effects for the Baeyer-Villiger reaction, I was discussing whether a realistic computed model could be constructed for the mechanism. The measured KIE or kinetic isotope effects (along with the approximate rate of the reaction) were to be our reality check.