Crystal Engineering

Organic multicomponent crystals can alter material properties without changing the covalent structures of their constituent molecules. René de Gelder examines how these crystals can be classified and how chirality affects the resulting classes and subclasses. Thousands of structures in resources such as the Cambridge Structural Database provide the basis for a network-science analysis of structural diversity. The approach seeks principles governing multicomponent crystal formation, ways to predict new combinations, and a map of the transition between cocrystals and salts.

Richard Robson, Susumu Kitagawa and Omar M. Yaghi examine the origins, development and applications of metal–organic frameworks. Robson follows the emergence of coordination polymers and the design of extended molecular structures from pre-organized building blocks, explaining the architectural ideas behind framework construction. Kitagawa describes how coordination chemistry led to porous materials and then to flexible crystalline structures. His discussion of soft porous crystals shows how frameworks can respond to external stimuli, opening and closing as they capture molecules, with implications for gas storage and separation. Yaghi considers how fundamental framework chemistry can connect to industrial and societal applications, including emerging uses of artificial intelligence. Together, the lectures show how complementary approaches to molecular design, porosity and responsive structure developed into a broad materials research field.