Insights into the Intermolecular Interactions Between Stacked Antiaromatic 24-π Hexaphyrin Macrocycles. Variation of the Magnetic Response Properties

Abstract

The understanding of antiaromatic characteristics and their variations requires the study of medium sized species, towards a generalization of their behavior. In this work, we account for the medium sized hexaphyrin macrocycle, namely naphthorosarin, which features an antiaromatic 24-π electron kernel. The structure exhibits a large deshielding cone behavior, inducing an increased magnetic anisotropy a the center of the structure, confirmed by 1 H-NMR experiments, and calculated data.Furthermore, naphthorosarin is prone to form π-π stacked dimers promoted by dispersion-type interactions, contributed by electrostatic and orbital interactions, which largerly reduces the central deshielding region and the related anisotropy, suggesting that mediums sized stacks are able to build-up a lesser magnetic anisotropic central region, in relation to the parent isolated rings. Thus, the establishment of π-π interactions between medium-sized antiaromatic rings impacts in the characteristics observed for the isolated units, offering valuable guidance and insights into the expected changes in molecular properties when larger aggregates are formed.