Development of magnetic resonance (MR) imaging of enantiomeric excess (ee), which can be used to monitor in situ or in vivo local ee, ideally with sub-millimetre spatial resolution. The key is the transfer of chiral information from chiral analyte to achiral detector (a porphyrin-type molecule) with subsequent detection by MR. This system is also of note from the point of view that it does not rely on the formation of diastereomers. This is perhaps counterintuitive given the prevailing opinion that formation of diastereomers is required in the NMR analysis of ee. We call this type of achiral porphyrin detectors a pro-chiral solvating agents (pro-CSAs).
Further peripheral modifications by tetraethylene glycol (TEG) or poly(N-isopropylacrylamide) (PNIPAAm) makes the core porphyrin (TPP) molecules water-soluble. This introduces temperature sensitivity through a phase separation phenomenon and subsequent formation of various supramolecular assemblies, such as 1D supramolecular polymers or large spherical globules.