What is it about?

This paper arose from an educational exercise designed to introduce secondary school students to the technique of single-crystal X-ray diffraction and enhance their understanding of primary and secondary bonding. The students were given the opportunity to prepare a series of new alkali metal salts of an organic acid, 4-hydroxybenzoic acid. With the assistance of experienced crystallographers, the students used modern, easy-to-use software to solve and refine X-ray diffraction data collected on the crystalline materials they had prepared. Their investigation yielded nine new compounds and the structures are described in this article.

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Why is it important?

The role of X-ray crystallography in providing detailed representations of molecules is poorly recognized in many secondary school chemistry courses worldwide. This exercise introduced senior secondary school students to this technique. In addition, it proved to be highly successful in demonstrating the fundamental roles of strong and weak bonding interactions in the structure of materials. Whilst the salts are readily synthesized, the structures of most of the compounds prepared in this study have not been reported previously, allowing students to experience genuine scientific discovery and also to appreciate the power, precision and convenience of the technique of X-ray crystallography for structure analysis.


It was a pleasure to work with the students in this study and share the excitement of their discoveries. The publication of a scientific paper based on their research was unexpected, but we quickly realised that the structures of the individual compounds are inherently interesting and collectively they demonstrate the effects of reaction stoichiometry, ion size, hydrogen bonding and the nature of the ligand and solvent in the formation of ionic networks involving metal ions and organic anions.

Christopher Commons
University of Melbourne

Read the Original

This page is a summary of: Alkali metal salts of 4-hydroxybenzoic acid: a structural and educational study, Acta Crystallographica Section C Structural Chemistry, June 2021, International Union of Crystallography,
DOI: 10.1107/s2053229621005465.
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