Metal-organic frameworks, MOFs, are a relatively recent discovery. They are crystalline three-dimensional materials formed from a regular network of metal ions interlinked by organic molecules. The organic groups act as spacers to keep the metal ions apart, generally giving rise to permanent porosity within the solid. These pores can adsorb a wide range of small molecules, often with a useful degree of specificity and the materials have been touted as safe gas storage materials, greenhouse gas absorbers, molecular sieves for separating different gases, sensors and catalysts. I recently wrote about the latest development with these fascinating materials for my Research Highlights column in the Chemistry Views magazine – http://dx.doi.org/10.1002/chemv.201600095
Dermot O’Hare, of the University of Oxford, UK, and his team have used a real-time technique to analyse one particularly promising class of MOFs that could help in the design of new materials with highly specific functionality for a wide range of applications.
All that said, despite more than two decades of intensive research, the synthesis of MOFs has not yet reached the level of real controlled design, although a few approaches such as the secondary building units route previously led to some successes, says Christian Serre of Paris Research University, France. “Understanding how these tunable architectures form in solution is still of great interest,” he told me. Serre points out that the role of ligands, pH and additives have already been addressed, but the influence of the metal cation over the formation mechanism of MOFs remains largely unexplored. “O’Hare and colleagues have not only proposed a new kinetic model to follow the formation mechanism of MOFs but also have evidence for what most researchers have suspected so far, i.e. how the kinetics and the metal ligand lability are related,” he explains. “This represents a really significant piece of work that will certainly be very useful for MOF researchers to construct more advanced architectures in the near future.”