Building ordered polymers with metal

Polymers, the essential materials surrounding us, have typically been chaotic assemblages of intertwined atomic chains. However, since the early 1990s, chemists have pioneered methods to create polymers with meticulously defined structures, known as metal-organic frameworks (MOFs). These innovative frameworks possess unique chemical characteristics, including large pores that facilitate gas filtration and storage, as well as catalytic centers embedded within the polymer itself. In a recent announcement, the Nobel Prize Committee recognized the groundbreaking contributions of three scientists in the field of MOFs. Richard Robson was awarded for his pivotal demonstration of the first MOF, while Susumu Kitagawa and Omar Yaghi were honored for their efforts in fully realizing the potential of these structures. Traditionally, polymers are constructed from individual molecules linked by flexible bonds, resulting in a convoluted arrangement once formed into everyday items like plastic bags or bicycle tires. While some control over the polymer's properties can be achieved by adjusting bulk characteristics or selecting different base molecules, the chemistry options have been limited. The introduction of MOFs changes that paradigm. The metal components in these frameworks function as central hubs, allowing for the precise arrangement of rigid organic molecules that extend outward in various directions. Due to the nature of metal orbitals, each metal can bond with a specific number of organic molecules, creating fixed angles between those bonds. By carefully selecting the metal involved, researchers can engineer distinct three-dimensional structures, alternating between metals and organic components, thus opening new avenues for material science.