New Perspectives in Science Education

Pedersen discovered crown ethers rather by coincidence in the early 1960s [1]. Crown ethers are macrocyclic polyethers which complex particularly alkali metal cation guests in their interior via non-covalent bonds [1,2], enclose them lipophilically and thus make them transferable into organic solvents [3]. The cyclic ethers are able to molecularly recognise cations of a suitable size and selectively bind them. Corresponding recognition processes also take place during the interaction of enzymes with substrates or antigens with antibodies [5]. Almost 20 years after his discovery, Pedersen was awarded the Nobel Prize in Chemistry for ‘the development and use of molecules with structure-specific interactions of high selectivity’ [5]. His discovery led to the field of supramolecular chemistry [6], which focusses on the selective aggregation of molecules with other ions or molecules of suitable size or geometry [2]. Unfortunately, crown ethers have so far only been partially used in school, e.g. [7]. In particular, the use of chloroform, benzene or dichloromethane, in which crown ethers dissolve particularly well, or the use of salts of the toxic, explosive picric acid to demonstrate molecular recognition processes [3] have so far made their use in schools problematic and rather uninteresting. At the conference in Florence, it will therefore be shown how various biochemical processes such as the lipophilic masking of cations, molecular recognition or the transport of ions through biomembranes can be demonstrated in simple experiments in a model-like and successful manner through the skilful choice of solvents and coloured salts.

 

Keywords: High School, biochemistry, demonstration, transport properties, molecular recognition

 

REFERENCES

[1] Pedersen, C.J., Angew. Chem. lnt. Ed. Engl. 1988, 27, 1021-1027.

[2] Steed, J. W., Turner, D. R., & Wallace, K. J. (2007): Core concepts in supramolecular chemistry and nanochemistry, John Wiley & Sons.

[3] Weber, E., PdN-Ch. 1996, 45 (4), p. 7-16.

[4] Bruice, P. Y. (2011). Organische Chemie: Studieren kompakt. Deutschland: Pearson Studium.

[5] https://www.nobelprize.org/ prizes/chemistry/1987/pedersen/facts [last accessed: 10.12.2024].

[6] Gokel, G. (1991): Crown Ethers and Cryptands, published by Stoddart, J.F.: Monographs in Supramolecular Chemistry, The Royal Society of Chemistry.

[7] Friedrich, J.; Oetken, M. (2013), PdN– Chem. in der Schule, 62 (8), p. 29-34.