Compact CPL emitters based on a [2.2]paracyclophane scaffold: recent developments and future perspectives

Abstract

Due to their unique three-dimensional framework and intriguing electronic properties, [2.2]paracyclophanes have been employed over the years as building blocks in materials science for the development of organic light-emitting diodes...

Stereogenic π-Conjugated Macrocycles: Synthesis, Structure, and Chiroptical Properties Including Circularly Polarized Luminescence

“…Therefore, [2.2]PC with substituents at specific positions on the phenylene rings have planar chirality. Additionally, [2.2]PCs are often used as chiral ligands for asymmetric synthesis, [21][22][23] chiroptical materials, 20,[24][25][26][27][28] and stereogenic units in supramolecular chemistry. 29,30 The optical resolution of planar chiral [2.2]PC can be achieved via the diastereomeric crystallization method developed by Morisaki et al 31 or via the recycling HPLC method, which uses a chiral stationary phase, i.e., a chiral column.…”

Integration of fine-tuned chiral donor with hybrid long/short-range charge-transfer for high-performance circularly polarized electroluminescence

“…2 Within the scope of CPL emitters, circularly polarized thermally activated delayed fluorescence (CP-TADF) materials exhibit compatibility with structural diversity, budget constraints, and the unique ability to utilize both singlet and triplet excitons, making them a promising option for high-performance CP-OLEDs compared to the pure fluorescence or phosphorescence CPL emitters. 3 Typically, there are two prevailing methodologies for constructing CP-TADF emitters: one involves the spontaneous generation of inherently chiral chromophores, 4 while the other comprises functionalizing chromophores with natural chirality groups, a concept referred to as chiral perturbation. 5 Notably, the latter approach offers advantages in terms of meeting commercial demands for large-scale synthesis and economic feasibility compared to the former approach, as CP-TADF features can be derived from readily available enantiopure substrates, thus circumventing challenging chiral resolution processes.…”

Supramolecular Chirality Achieved by Assembly of Small π-Molecules of Octahydrobinaphtols with Axial Chirality

“…Many chiral molecules can be constructed by incorporating asymmetric carbon atoms, as exemplified by biorelated molecules (e.g., amino acids, saccharides, and lipids) and pharmaceuticals. Unlike molecules with point chirality, the axial, planar, and helical chiralities of biaryl, cyclophane, and helicene molecules, respectively, are constructed based on their π electronic systems, and these molecules are promising candidates for chiroptically functional materials. − The circular dichroism (CD) and circular polarized luminescence (CPL) signals for these compounds are in the UV–vis range and are thus of particular recent interest for device applications such as sensing or emitting circularly polarized light. − Other types of chiral π-units are more difficult to envision, so novel chiral π-conjugated molecules are often achieved by tethering a variety of achiral π-conjugated chromophores to the chiral π-unit. − An alternative strategy for creating chirality in π electronic systems is to achieve helical chirality from supramolecular aggregates of helically stacked planar π-conjugated molecules. − The assembly of such an arrangement requires that the π-conjugated skeleton of the molecule be decorated with side groups bearing point or axial chirality. The advantage of targeting supramolecular aggregates is that they can potentially amplify the molecular chirality as the aggregate increases in size. ,− A key issue is thus how to spatially arrange π-conjugated molecules so that their transition dipole moments effectively interact with each other.…”