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Inventory no. 17631 - Former Display Label


The structure of penicillin was investigated by X-ray analysis as part of the general chemical investigation of this molecule. By a comparative study of the potassium, rubidium and sodium salts of benzylpenicillin, it was found possible to solve the crystal structures and to show in detail how the atoms were arranged in space. This arrangement established the essential chemical structure of the molecule as one including fused thiazolidine and {beta} -lactam rings.
In this model of crystalline potassium benzylpenicillin, the contours showing lines of equal electron density are drawn on perspex sheets which, stacked together, give an impression of the electron density in a volume. The representation is based on the second refinement of the three dimensional calculation of the electron density in the crystal. At this stage of the structure analysis the relative positions of the atoms were clear, and established the fact that they were combined in fused thiazolidine and {beta} -lactam rings. The model here, the first attempt at this type of representation of a three-dimensional electron density distribution, only covers part of the penicillin molecule, including however the thiazolidine and {beta} -lactam rings.
The crystallographic investigation was carried out in Oxford by Dorothy Crowfoot and Barbara Low, and in the laboratories of I.C.I. (Alkali Division) at Northwich by C. W. Bunn and A. Turner-Jones.

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