Supramolecular chirogenesis is a fundamentally novel interdisciplinary field of research being a smart combination of supramolecular/nano chemistry and chiral science. Supramolecular chirogenesis deals with the phenomenon of “symmetry breaking” in achiral multi- or unimolecular host systems by chiral guests (and vice versa), and is achieved by the rational application of specific non-covalent interactions via a chirality information transfer mechanism.

Recently, we have discovered a novel and very efficient supramolecular chirogenic system based upon an achiral ethane-bridged bis(metallo- or free base octaethylporphyrin).^1-6 Upon interaction with the corresponding chiral guests, there are ligand induced structural deformations in the achiral host, resulting in a asymmetric orientation of the two porphyrin units and subsequent pronounced and easily detectable spectral changes monitored by various spectroscopies. Particularly, through-space exciton coupling between the porphyrin electronic transitions induces bisignate Cotton effects in the circular dichroism (CD) spectra. Significantly, the sign of the observed CD couplet is unequivocally correlated with the absolute configuration of the chiral ligand used, allowing us to develop an absolute configuration sensor for enantiopure amines, alcohols, acids. This system possesses a high degree of chiroptical activity, which allows the differentiation of one of the smallest homologous elements of organic chemistry, i.e. the methylene subunit, such as between methyl and ethyl groups attached to the asymmetric carbon; further, it is able to sense a remote chiral center at a position beta to the binding group. It was also found that this system is highly sensitive to various internal and external controlling factors such as the structure of guest molecules, stoichiometry, number of binding sites, solvent, temperature and phase transition.

Further developments and prospects toward new chirogenic systems on the basis of heterometallic bis- and multi-porphyrin structures will be discussed.

1. V. Borovkov, Symmetry 2014, 6, 256.
2. V. Borovkov, Symmetry 2010, 2, 184.
3. V. Borovkov, Y. Inoue, Eur. J. Org. Chem. 2009, 189.
4. G. A. Hembury, V. V. Borovkov, Y. Inoue, Chem. Rev. 2008, 108, 1
5. V. V. Borovkov, Y. Inoue, Top. Curr. Chem. 2006, 265, 89.
6. V. V. Borovkov, G. A. Hembury, Y. Inoue, Acc. Chem. Res. 2004, 37, 449.