Self-Assembly of Cone-Shaped Subphthalocyanines: A Theoretical Insight

Abstract

Compared to planar phthalocyanines, cone-shaped subphthalocyanines (SubPcs) exhibit axial dipole moments, giving rise to polarly ordered materials when piled up in columns, and become intrinsically chiral when properly substituted. Furthermore, owing to their rigid conic structure, SubPcs display a convex side (a head) and a concave side (a tail) and their intermolecular stacking interactions may lead to centrosymmetric head-to-head and tail-to-tail and to noncentrosymmetric head-to-tail aggregation geometries.In this contribution, we perform a theoretical study on the aggregation modes of the C 3-symmetric boron SubPc 1, in which the central boron atom is substituted with a small, highly electronegative fluorine atom and the SubPc core is decorated with arilamide groups giving rise to 1P and 1M enantiomers (Figure 1). Depending solely on the solvent nature (aromatic or aliphatic), π-conjugated SubPc 1 can self-assemble either in a tail-to-tail dimer (regime A) or in a head-to-tail columnar stack (regime B), formed via a nucleation-elongation polymerization mechanism.1 Furthermore, 1P and 1M enantiomers give rise to homochiral assemblies with opposite helicities.2 Calculations indicate that whereas the SubPc enantiomers socially self-sort in the polymer regime, showing an alternate columnar stacking order, they reveal narcissistic self-sorting in the dimer regime, each enantiomer disclosing a strong preference to associate with itself.