PubChem
PubChem is the world's largest collection of freely accessible chemical information. Search chemicals by name, molecular formula, structure, and other identifiers. Find chemical and physical properties, biological activities, safety and toxicity information, patents, literature citations and more.
This free chemical database collates structure and property information from both experiments and predictions. Also includes curated list of literature and datasets relating to a chemical.
Public Library of Science (PLoS)
PLoS is a nonprofit organization of scientists and physicians committed to making the world's scientific and medical literature a freely available public resource.