1,1′-Binaphthol annulated perylene diimides: Aggregation-induced emission enhancement and chirality inversion

Non-Covalent Self-Assembly Behaviors Based on Racemic Binaphthol Scaffolds

Understanding the fundamental mechanisms involved in the construction and organization of multi-scale structures is crucial for the design and manufacture of complex functional systems with long-range molecular arrangements. In this paper, a series of compounds have been synthesized using racemic binaphthols as the skeleton and a Suzuki coupling reaction for derivatization at the 6,6' positions, which resulted in various structures bearing different functional groups. Control over the self-assembly of these racemic binaphthol derivatives was successfully achieved by adjusting the types and positions of the substituents in the parent binaphthol compound, which revealed the key factors influencing the types of the non-covalent interactions and the self-assembly process. For example, the single-crystal structures of the resulting compounds indicated that assembly structures such as single helix and double helix based on non-traditional hydrogen bond motifs could be obtained, and fascinating non-covalent self-assembly structures such as molecular ladders and catenane discovered.

Deracemization of Atropisomeric Biaryls Enabled by Copper Catalysis

Atropisomeric biaryls have found crucial applications in versatile chiral catalysts as well as in ligands for transition metals. Herein, we have developed an efficient crystallization-induced deracemization (CID) method to access chiral biaryls from their racemates with a chiral ammonium salt under copper catalysis including BINOL, NOBIN, and BINAM derivatives. After being significantly accelerated by its bidentate diamine ligand, the copper catalyst exhibits high efficiency and selectivity in racemizing biaryl skeletons, and the cocrystal complex would be enantioselectively formed together with chiral ammonium salt, which on acid-quenching would directly deliver chiral biaryl without further chromatographic purification. This CID process is easily scalable, and the chiral ammonium salt was nicely recoverable. Ligand effect studies showed that bulky alkyl substitution was an indispensable element to ensure efficient racemization, which probably proceeds via a radical-cation intermediate and further allows axial rotation by forming a delocalized radical.

Circularly Polarized Phosphorescence of Benzils Achieved by Chiral Supramolecular Polymerization

In current approaches for circularly polarized phosphorescent materials, the crystallization of chiral phosphors suffers from poor processability, while integrating them into an amorphous polymer matrix results in unsatisfactory chiroptical signals due to the absence of chirality communication. Here, we have developed an innovative strategy through chiral supramolecular polymerization of benzil phosphors facilitated by intermolecular hydrogen bonds. The inherent film-forming capabilities of non-covalent supramolecular polymers obviate the need for an external polymer matrix. The pronounced helical asymmetry of benzil phosphors resulting from chiral supramolecular polymerization leads to enhanced circularly polarized phosphorescence compared to their non-hydrogen-bonded counterparts. The circularly polarized phosphorescent signals can be further modulated by varying the location of stereogenic centers or introducing halogen bonding to benzils. Incorporation of platinum(II) phosphor into the benzil supramolecular polymers induces both chirality and triplet-to-triplet energy transfer, leading to a change in circularly polarized phosphorescent color from yellow to red. In summary, chiral supramolecular polymerization of phosphors represents a novel and effective approach to circularly polarized phosphorescent materials.