N,N'-Diethylethylenediamine is used in the preparation of 2-imidazolidinecarboxaldehydes and 1,4,6,9-tetraalkyl-1,4,6,9-tetraaza-5,10-dioxaperhydroanthracenes by reacting with glyoxal. It acts as a ligand and form coordination complexes with copper(II), which shows thermochromic properties.