Intercalation of amino acids and polypeptides into 2H-TaS₂

Abstract

2H-TaS₂ can be intercalated by organic amines and empirical rules have been formulated^1–3 governing the properties that chemical species must possess in order to intercalate. One of these rules is that molecules in which the nitrogen is basic (pKa>4) usually form stable compounds provided the amine does not have bulky substituents. For certain amino acids, the values of pKa are significantly larger than this critical value (for example, glycine pK₂=9.78)⁵ so that if the zwitterion is in a state where it can function as a base, it might be expected that the amino acid would intercalate 2H-TaS₂. This prediction has been verified for a number of amino acids. The discovery of these intercalation reactions provides a new range of intercalated compounds for study and also opens up the possibility of in situ polymerisation.