8 July 2015
“Crystal Engineering with Metal- Organic Frameworks”
Promotores: Prof.dr. F. Kapteijn, Prof.dr. J. Gascon (Delft University of Technology)
After the successful defense of his PhD thesis on July, 8th 2015, Maarten Goesten was awarded the doctor title with distinction (cum laude), something reserved only for the top 5% at the Delft University of Technology. His promotors were prof. dr. Jorge Gascon and Prof. dr. Freek Kapteijn. In Maarten’s thesis, entitled ‘ Crystal Engineering with Metal Organic Frameworks’, it is shown that coordination chemistry effectively rules out the element of ‘crystal design’ in MOF crystal engineering. However, it is also shown that by combining theory and spectroscopy, such complex pathways occuring in MOF crystallization can be resolved.
The synthesis of materials with tailored functionality is increasingly demanded in the 21st century, where grand challenges in energy conversion and storage await. One of the most important strategies in the synthesis of such materials is Crystal Engineering: the self-assembly of crystals with well-defined, pre-specified chemical properties. Metal-Organic Frameworks (MOFs), porous coordination polymers built from metal complexes and organic ligands, realize the concept of crystal engineering to such extent that chemists are increasingly much invoking the term “design”.
Indeed, MOFs feature world record values in gas and vapour adsorption and some tailored properties seem ideal for application in catalysis, heat conversion, luminescence, magnetism or other fields. Yet, the element of design is grossly overestimated, and many MOF materials appear as a result of serendipitous discovery, rather than premeditated synthesis. The reason for this lies in the fact that the physical chemistry that governs the interaction between the molecular building blocks is too pervasive and unpredictable to allow for “true” design.
The described research investigates the viability of Crystal Engineering. Firstly, by observing and studying the local physical chemistry, the complexity of molecular coordination chemistry around MOF crystallisation is documented. Then, methods are presented which show that a combination of theory and spectroscopy techniques can resolve the complex chemistry, and post-synthetic functionalization can overcome many other limitations.
In conclusion, a realistic perspective towards the future is presented: a priori design remains unreal, also for MOF chemistry, but a sensible and patient approach allows for a certain degree of Crystal Engineering to be realized.