Users of the Molecular Foundry have created a sort of nanoscale display case that enables new atomic-scale views of hard-to-study chemical and biological samples. Their work could help to reveal new structural details for a range of challenging molecules—including complex chemical compounds and potentially new drugs—by stabilizing them inside sturdy structures known as metal-organic frameworks (MOFs).
The researchers introduced a series of different molecules that were chemically bound inside these porous MOFs, each measuring about 100 millionths of a meter across, and then used X-ray techniques to determine the precise molecular structure of the samples inside the MOFs.
The samples ranged from a simple alcohol to a complex plant hormone, and the new method, dubbed “CAL” for covalent alignment (the molecules form a type of chemical bond known as a covalent bond in the MOFs), enables researchers to determine the complete structure of a molecule from a single MOF crystal that contains the sample molecules in its pores.
The MOFs in the study, which are identical and are easy to manufacture in large numbers, provided a sort of backbone for the sample molecules that held them still for the X-ray studies—the molecules otherwise can be wobbly and difficult to stabilize. The researchers prepared the samples by dipping the MOFs into solutions containing different molecular mixes and then heating them until they crystallized.
The users studied the MOFs using a technique called nuclear magnetic resonance (NMR) at the Molecular Foundry and determined the atomic structure of the MOFs and the bound molecules with X-rays at the Advanced Light Source (ALS).