Zinc-[7]helicenocyanine and Its Discrete π-Stacked Homochiral Dimer

In this communication, we demonstrate a novel approach to prepare a discrete dimer of chiral phthalocyanine (Pc) by exploiting the flexible molecular geometry of helicenes, which enables structural interlocking and strong aggregation tendency of Pcs. Synthesized [7]helicene-Pc hybrid molecular structure, zinc-[7]helicenocyanine (Zn-7HPc), exclusively forms a stable dimeric pair consisting of two homochiral molecules. The dimerization constants were estimated to be as high as 8.96x10(6) M-1 and 3.42x10(7) M-1 in THF and DMSO, respectively, indicating remarkable stability of dimer. In addition, Zn-7HPc exhibited chiral self-sorting behavior, which resulted in preferential formation of a homochiral dimer also in the racemic sample. Two phthalocyanine subunits in the dimeric form strongly communicate with each other as revealed by a large comproportionation constant and observation of an IV-CT band for the thermodynamically stable mixed-valence state.

Automated summary

In this study, a novel approach to preparing a discrete dimer of chiral phthalocyanine using the flexible molecular geometry of helicenes was demonstrated. The synthesized [7]helicene-Pc hybrid molecular structure, zinc-[7]helicenocyanine (Zn-7HPc), exclusively forms a stable dimeric pair consisting of two homochiral molecules with high dimerization constants. The study also revealed chiral self-sorting behavior in Zn-7HPc, resulting in preferential formation of a homochiral dimer.