Abstract

Certain molecules (and other objects) exhibit chirality – meaning they have nonsuperimposable (non-overlapping) mirror images. Human hands are a clear example of this – our left and right hands are mirror images of each other but cannot be perfectly superimposed. These non-superimposable pairs of chiral objects are called enantiomers. Just as how your left and right hand will interact with certain objects differently (baseball mitts, scissors, can-openers, etc.), the ‘left-handed’ and ‘right-handed’ enantiomers of chiral molecules can interact differently within an environment that is also chiral. Chiral compounds such as a large proportion of drugs, pesticides, and amino acids can behave differently within the human body depending on which enantiomer is present. Thus, there are often differences between enantiomers with respect to their activity, safety, or effectiveness.

This work involves synthesising porous crystals called metal-organic frameworks (MOFs) to act as sensors for enantiomers. This is achieved by designing and synthesising MOFs that are both chiral and fluorescent. By making the MOFs themselves chiral, they will interact differently with the two enantiomers of a chiral molecule. This will cause the fluorescence of the MOF to change, depending on which enantiomer is present. For example, the ‘left-handed’ enantiomer of a molecule may enhance the fluorescence of the MOF, while the ‘right-handed’ enantiomer may diminish the MOF’s fluorescence. So far, several MOFs have been synthesised which show enantioselectivity for amino acid methyl esters. These MOFs could therefore be used to help control the chirality of various drugs synthesised from amino acid methyl esters.