Henry Rzepa's Blog Chemistry with a twist

May 16, 2018

Ten years on: Jmol and WordPress.

Ten years are a long time when it comes to (recent) technologies. The first post on this blog was on the topic of how to present chemistry with three intact dimensions. I had in mind molecular models, molecular isosurfaces and molecular vibrations (arguably a further dimension). Here I reflect on how ten years of progress in technology has required changes and the challenge of how any necessary changes might be kept “under the hood” of this blog.


January 2, 2017

Ritonavir: a look at a famous example of conformational polymorphism.

Here is an inside peek at another one of Derek Lowe’s 250 milestones in chemistry, the polymorphism of Ritonavir.[1] 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.[2],[3] 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[1]



  1. J. Bauer, S. Spanton, R. Henry, J. Quick, W. Dziki, W. Porter, and J. Morris, "Array", Pharmaceutical Research, vol. 18, pp. 859-866, 2001. http://dx.doi.org/10.1023/A:1011052932607
  2. J.D. Dunitz, and J. Bernstein, "Disappearing Polymorphs", Accounts of Chemical Research, vol. 28, pp. 193-200, 1995. http://dx.doi.org/10.1021/ar00052a005
  3. D. Bučar, R.W. Lancaster, and J. Bernstein, "Disappearing Polymorphs Revisited", Angewandte Chemie International Edition, vol. 54, pp. 6972-6993, 2015. http://dx.doi.org/10.1002/anie.201410356

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