Crystallisation of Dianin's compound (DC) together with two organic amines (piperazine and piperidine) produces co-crystals of 2 : 1 DC–piperazine and 1 : 1 DC–piperidine, respectively. The structures of these adducts contrast sharply with that of the well-known clathrate structure of DC in which organic guests are generally included in ratios of 3 : 1 or 6 : 1 DC–guest.