08 June

Reticular Chemistry

Friday 08 June 2018, 04:30pm

Sala d'Actes i Reunions - C1/178 - Facultat de Ciències i Biociències, UAB

By Prof. Omar M. Yaghi - Department of Chemistry, Kavli Energy NanoScience Institute, Berkeley Global Science Institute, University of California, Berkeley, California, USA

Short abstract: Linking molecular building units by strong bonds to make crystalline extended structures (Reticular Chemistry) has given rise to metal–organic frameworks (MOFs) and covalent organic frameworks (COFs), thus bringing the precision and versatility of covalent chemistry beyond the atoms and molecules. The key advance in this regard has been the development of strategies to overcome the “crystallization problem”, and the use of metal-oxide clusters as secondary building units to impart unprecedented structural robustness, high surface area, and permanent porosity. To date, thousands of MOFs and COFs are made as crystalline materials. The molecular units thus reticulated become part of a new environment where they have (a) lower degrees of freedom because they are fixed into position within the framework; (b) well-defined spatial arrangements where their properties are influenced by the intricacies of the pores; and (c) ordered patterns onto which functional groups can be covalently attached to produce chemical complexity. The notion of covalent chemistry beyond molecules is further strengthened by the fact that covalent reactions can be carried out on such frameworks, with full retention of their crystallinity and porosity. MOFs are exemplars of how this chemistry has led to porosity with designed metrics and functionality, chemically-rich sequences of information within their frameworks, and well-defined mesoscopic constructs in which nanoMOFs enclose inorganic nanocrystals and give them new levels of spatial definition, stability, and functionality. The advent of COFs extends the field of organic chemistry beyond discrete molecules (0D) and polymers (1D) into “infinite” two and three dimensions. Molecular weaving, the mutual interlacing of long threads at the molecular level, was first accomplished in COF to make the true woven material. This discovery combines the porosity and robustness of frameworks with mechanically deformable and stretchable capability.