This document discusses different types of polynuclear hydrocarbons including isolated and condensed systems. It provides details on the preparation, properties, and reactions of several isolated polynuclear hydrocarbons including diphenyl, diphenylmethane, triphenylmethane, and stilbene. The key reactions used to synthesize these compounds involve Friedel-Crafts alkylation, Grignard reactions, and reductions. Atropisomerism is also discussed for substituted diphenyls.