Prism[n]arenes macrocycles for chiral recognition in supramolecular sensing

Chiral sensing has gained great interest in the recent years, due to its application in several fields, such as medicinal chemistry, environmental control, and natural products. Among the most promising molecular structures for chiral sensing and recognition are the so-called stereodynamic chiroptical probes.[1] To this family belong polyaromatic host macrocycles having planar chirality, able provide host-guest complexes with chiral guests in which the host exhibits a preferred chiral conformation that correlates with the absolute configuration (AC) of the guest. In 2020 a novel class of macrocyclic hosts named prism[n]arenes have been reported by Gaeta and coworkers.[2] Prismarenes are constituted by 1,5-methylene bridged 2,6-dialkoxynaphthalene units and exhibit a deep π-electron rich aromatic cavity, thus being able to form endo-cavity complexes with ammonium guests stabilized by secondary interactions such as cation⋯π, C–H⋯π, van der Waals, and hydrophobic effect. For these macrocycles, the changes in the chiral conformations of the probe can be easily detected and interpreted by means of Electronic Circular Dichroism (ECD) spectroscopy due to its ability to discriminate between enantiomers (Figure 1).[3] Additionally, Vibrational CD (VCD), provides useful insight on local interaction and conformational stability of the Host-Guest system.[4] In this work, we report the study of the chiral induction and host/guest interactions among different chiral guests and Prism[n]arenes hosts supported by ECD and VCD measurements and their DFT simulation.