Coverage induced switching of chirality in surface self-assemblies of prochiral molecules

Symbolbild zum Artikel. Der Link öffnet das Bild in einer großen Anzeige.

When molecules adsorb on surfaces many interesting phenomena arise. One is the occurrence of chirality (handedness) from molecules that a achiral in the gas phase. These so called “prochiral” molecule can adsorb in two mirror symmetric ways on a surface and become chiral, since the two configurations cannot be superimposed by translation or rotation. By suitable molecule-molecule interaction they may form supramolecular self-assemblies. These self-assemblies can then be either enantiopure (e.g. only containing the left- or right-handed molecule) or racemic, i.e. containing a mixture of both molecular configurations.

In our paper that appeared in the ACS Journal of Physical Chemistry C we investigated the behaviour of a particular, metallated porpyhrin molecule on the copper (111) surface. We found that upon increasing the molecular coverage on the surface a transition from enantiopure chain-like self-assemblies towards racemic networks occurred. We could show that this is due to subtle details of the molecule-molecule interaction and potentially to the fact that the molecules may switch their chirality when adsorbed on the surface.

Feifei Xiang and M. Alexander Schneider, Coverage-Induced Chiral Transition of Co(II)-5,15-Diphenylporphyrin Self-Assemblies on Cu(111), J. Phys. Chem. C (2022), 126, 15, 6745–6752