Abstract
<jats:title>Abstract</jats:title> <jats:p>The strongly interacting lactam functional group in both γ‐ and ε‐lactams makes them of considerable interest in the formation of multicomponent solids including a hugely diverse range of cocrystals, coordination complexes with lactam ligands and coamorphous phases. This chapter reviews both crystalline and amorphous multicomponent materials based on small‐molecule mono‐ and bislactams with a focus on the interactions between the lactam component and the molecules or ions with which it binds. The lactam amide group is a highly polar organic functional group, and the property dominates much of the chemistry and applications of lactam derivatives. N‐Methyl pyrrolidone is an important industrial substance and is produced on a 20 000‐30 000‐ton scale annually by ester‐to‐amide conversion, treating butyrolactone with methylamine. The chapter deals with molecular cocrystals of the systems while looks at their properties as ligands for metal ion complexation within the context of metal coordination by polyvinylpyrrolidone in particular.</jats:p>