Ladder-Type Perylene Diimides Linked by Pyrene Bridges at Bay Area

Doubling the Length of the Longest Pyrene-Pyrazinoquinoxaline Molecular Nanoribbons

Molecular nanoribbons are a class of atomically-precise nanomaterials for a broad range of applications. An iterative approach that allows doubling the length of the longest pyrene-pyrazinoquinoxaline molecular nanoribbons is described. The largest nanoribbon obtained through this approach-with a 60 linearly-fused ring backbone (14.9 nm) and a 324-atoms core (C276 N48 )-shows an extremely high molar absorptivity (values up to 1 198 074 M-1  cm-1 ) that also endows it with a high molar fluorescence brightness (8700 M-1  cm-1 ).

Twisted Molecular Nanoribbons with up to 53 Linearly-Fused Rings

The synthesis of three molecular nanoribbons with a twisted aromatic framework is described. The largest one shows a 53 linearly fused rings backbone (12.9 nm) and 322 conjugated atoms in its aromatic core (C₂₉₆N₂₄S₂). This new family of nanoribbons shows extremely high molar absorptivities, reaching 986 100 M^-1 cm^-1, and red-emitting properties.

Stringing the Perylene Diimide Bow

This study explores a new mode of contortion in perylene diimides where the molecule is bent, like a bow, along its long axis. These bowed PDIs were synthesized through a facile fourfold Suzuki macrocyclization with aromatic linkers and a tetraborylated perylene diimide that introduces strain and results in a bowed structure. By altering the strings of the bow, the degree of bending can be controlled from flat to highly bent. Through spectroscopy and quantum chemical calculations, it is demonstrated that the energy of the lowest unoccupied orbital can be controlled by the degree of bending in the structures and that the energy of the highest occupied orbital can be controlled to a large extent by the constitution of the aromatic linkers. The important finding is that the bowing results not only in red-shifted absorptions but also more facile reductions.

Carbocyclization approaches to electron-deficient nanographenes and their analogues

Versatile π-aromatic building blocks and selective coupling transformations enable rapid assembly of complex electron-deficient molecules, useful as n-type organic semiconductors.