Twisted Perylene Stereodimers Reveal Chiral Molecular Assembly Codes

Abstract

Unique perylene diastereomeric linear and cyclic dimers were synthesized from twisted perylene monomers, revealing that pi-stacking stereoisomerism imparted specific intermolecular self-assembly and intramolecular folding. Only the homochiral twisted tetrachloroperylene monomers cyclized via a cooperative reaction, forming the homochiral diastereomers. The heterochiral tetrachloroperylene monomers proceeded through a stepwise reaction and yielded a linear heterochiral dimer, which equilibrated with the linear homochiral dimers. The linear homochiral dimers cyclized to produce the same cyclic homochiral diastereomers. These results demonstrated that homochiral and heterochiral self-assemblies were two distinct molecular codes, directing two specific chemical pathways. The homochiral cyclic dimers remain isomerically pure at -20 degrees C but can be interconverted to the heterochiral cyclic dimer meso compound at room temperature. The diastereomers were readily separated by HPLC. While driven by solvophobic forces, foldable linear dimers synthesized from the same twisted monomers using phosphoramidite chemistry folded into homodimer and heterodimer, confirming the inherent molecular codes, which were dictated by the perylene chirality, ultimately gauged the weak pi-stack forces, and directed self-assembly and folding.

Synthesis of Biocompatible Glycodendrimer based on Fluorescent Perylene Bisimides and Its Bioimaging

“…It is well known that the aggregation (or lack thereof) of perylene bisimides could be determined by comparing the A 0–0 /A 0–1 ratio . At the lower concentration of 1 × 10 −6 m , the A 0–0 /A 0–1 ratio of PBI‐Man was 1.39, indicating non‐aggregated state or a very weakly aggregated state in line with a literature report . However, upon gradually increasing the concentration, the apparent absorption coefficients ( ε ) of 0–0 (535 nm) and 0–1 (497 nm) electronic transitions decreased, while that of the 0–2 (466 nm) electronic transition increased, concurrently a new shoulder at about 560 nm appeared, and the A 0–0 /A 0–1 ratio reduced to 0.70 at the higher concentration of 1.5 × 10 −4 m , reflecting the electronic coupling with a face‐to‐face stacking arrangement.…”

“…[ 32,33 ] At the lower concentration of 1 × 10 −6 M , the A 0-0 /A 0-1 ratio of PBI-Man was 1.39, indicating nonaggregated state or a very weakly aggregated state in line with a literature report. [ 34 ] However, upon gradually increasing the concentration, the apparent absorption coeffi cients ( ε ) of 0-0 (535 nm) and 0-1 (497 nm) electronic transitions decreased, while that of the 0-2 (466 nm) electronic transition increased, concurrently a new shoulder at about 560 nm appeared, and the A 0-0 / A 0-1 ratio reduced to 0.70 at the higher concentration of 1.5 × 10 −4 M , refl ecting the electronic coupling with a face-to-face stacking arrangement. Furthermore, the aggregation constant ( K agg ) of PBI-Man in water was obtained as 6.9 × 10 4 M −1 (Figure S14, Supporting Information) using a nonlinear least-square regression analysis [Equation (S1), Supporting Information] of the concentration-dependent UV-vis spectral data by the isodesmic or equal-K model.…”

Tunable Molecular Assembly Codes Direct Reaction Pathways

“…[14,15] From homogenous mixtures of reactive monomers, planar 11 formed monomer ring 13, dimer ring 14, and concatenated rings 15, while highly twisted compound 12 only yielded homochiral or heterochiral dimer ring 16. The next natural step was to test whether such molecular codes can direct chemical reactions to form specific products.…”

Perylene Bisimide Dye Assemblies as Archetype Functional Supramolecular Materials

“…200 Notably, PBI dimer 2-24 with strongly core twisted chromophore units was only formed if the homochiral isomer (P-or M-enantiomer) of the respective monomer building blocks prevails, whereas for heterochiral monomers the open-chained, linear dimer was formed exclusively. 199 A synthetic strategy toward larger PBI macrocycles consisting of three and more chromophore units (2-26a−d, see Chart 7) was developed by Wurthner and co-workers. 201,202 In-depth photophysical investigations of such PBI macrocyles with varying ring sizes from trimer (2-26a) to hexamer (2-26d) by steadystate and time-resolved spectroscopy provided profound insights into their optical properties and excitation energy migration processes.…”