Helical Self-Assembly of Optically Active Phthalocyanine Derivatives Bearing Four Optically Active (S)-2-Methylbutoxy Moieties at the α Position of the Phthalocyanine Ring

Recent Progress in Optically-Active Phthalocyanines and Their Related Azamacrocycles

Optically-active phthalocyanines (Pcs) and related macrocycles reported in the 2010-2020 period are introduced in this review. They are grouped into several categories: (1) chiral binaphthyl-containing Pcs, (2) optically active alkyl chain-containing Pcs, (3) chiral axial ligand- coordinated or -linked Pcs, (4) chiral subphthalocyanines (SubPcs), and (5) related azamacrocycles. For each compound, the structure and important characteristics are summarized.

Helical Self-Assembly of Optically Active Glycoconjugated Phthalocyanine J-Aggregates

Four galactoconjugated zinc(II) phthalocyanines (Pcs) have been prepared and fully characterized. The carbohydrate-containing phthalonitrile precursors of the Pcs were synthesized through a copper-catalysed azide-alkyne cycloaddition (CuAAC). The Pcs show a remarkable aggregation behaviour in solution, depending on the nature of the solvent, the temperature and the substitution position on the phthalocyanine. Solvent-dependent CD-spectroscopy experiments show that these Pcs aggregate as chiral helices in solution. Crystal structure data of a phthalocyanine bearing two carbohydrate units substantiate the properties shown by CD spectroscopy. Furthermore, the 1,2,3-triazole moieties of the Pcs play a decisive role in the formation of supramolecular aggregates. The glycoconjugated zinc(II) phthalocyanines described here show molar extinction coefficients ϵ_max >10⁵  M^-1  cm^-1 and absorption maxima λ_max >680 nm, which make them attractive photosensitizers for Photodynamic Therapy (PDT).

Helical Nanostructures with Circularly Polarized Luminescence from the Multicomponent Assembly of π-Conjugated N-terminal Amino Acids

Self-assembled structures with circularly polarized luminescence (CPL) have attracted great attention in recent years. π-conjugated N-terminal amino acids with chiral amino acid residues and luminophores are capable of forming self-assembled structures at hierarchical levels, whereby chirality can be transferred to the macroscopic scale with easily modulated CPL properties. Due to the presence of multiple noncovalent binding sites, including hydrogen bonding and aromatic interactions, π-conjugated N-terminal amino acids are emerging core candidates for incorporation into multicomponent self-assembled architectures, accomplishing rational control over supramolecular chirality as well as showing rich chiroptical properties. In this Minireview, we provide a brief summary of multiple-component coassembled systems comprising π-conjugated N-terminal amino acids, small organic species and metal ions. The synthesis of helical structures and manipulation of supramolecular chirality by controlling the self-assembled species is introduced, and the CPL properties of multiple-component π-conjugated N-terminal amino acids are also briefly summarized.