PubChem PubChem mostly contains small molecules, but also larger molecules such as nucleotides, carbohydrates, lipids, peptides, and chemically-modified macromolecules. Information is collected on chemical structures, identifiers, chemical and physical properties, biological activities, patents, health, safety, toxicity data, and many others. Since its launch in 2004, PubChem has become a key chemical information resource for scientists, students, and the general public.