Octopus[5]arene from Pagoda[5]arene by Macrocycle-to-Macrocycle Conversion.

Macrocycle-to-macrocycle conversion is an effective strategy to construct new macrocyclic arenes with specific structures. Herein, a new class of chiral macrocyclic arene, namely, octopus[5]arenes (Oc5s), cannot be synthesized by the direct approach from the corresponding chiral monomers but can be successfully achieved by a macrocycle-to-macrocycle conversion strategy utilizing racemic pagoda[5]arenes as the starting materials. It was found that enantiomeric Oc5s showed fixed conformations and stable chiral structures and exhibited significant chiral recognition toward chiral diamines.

Self-Assembled Chiral Polymers Exhibiting Amplified Circularly Polarized Electroluminescence.

Circularly polarized electroluminescence (CPEL) is highly promising in realm of 3D display and optical data storage. However, designing a groundbreaking chiral material with high comprehensive CPEL performance remains a formidable challenge. In this work, a pair of chiral polymers with self-assembled behavior is designed by integrating a chiral BN-moiety into polyfluorene backbone, named R-PBN and S-PBN, respectively. The chiral polymers show narrowband emission centered at 490 nm with full-width half maximum (FWHM) of 29 nm and high photoluminescence quantum yield (PLQY) of 79%. After thermal annealing treatment, the chiral polymers undergo self-assembly, exhibiting amplified circularly polarized luminescence (CPL) with asymmetry factor (|glum|) of up to 0.11. Moreover, the solution-processed nondoped CP-OLEDs based on the chiral polymers as emitting layers exhibit maximum external quantum efficiency (EQEmax) of 9.8%, intense CPEL activities with |gEL| of up to 0.07, and small FWHM of 36 nm, simultaneously. This represents the first case of self-assembled chiral polymers that combines high EQE, large gEL value and narrowband emission.

Single-Molecule White Circularly Polarized Photoluminescence and Electroluminescence from Dual-Emission Enantiomers.

The strategy of integrating conformational isomerization donors and chiral acceptors in a single molecule was proposed to construct white circularly polarized luminescence (WCPL) materials in this work. Consequently, a pair of dual-emission enantiomers, namely (R/S)-DO-PTZ, were designed and synthesized, which displayed white emission with blue and yellow dual-emission bands in solution and solid films with Commission Internationale de l'Eclairage (CIE) coordinates of (0.30, 0.33) and (0.33, 0.35), respectively. Meanwhile, (R/S)-DO-PTZ exhibited a high PLQY of up to 67 % in doped films and clear mirror-image WCPL signals with a |glum| value of 3.0×10-3. Moreover, white circularly polarized electroluminescence (WCPEL) based on organic light-emitting diodes (OLEDs) with (R/S)-DO-PTZ as emitters were also achieved with CIE coordinates of (0.32, 0.37) and EQEmax of 4.7 %, representing the state-of-the-art level of white OLEDs based on single-molecule purely organic emitters. By optimizing the device structure, warm WCPEL devices were further obtained with a |gEL| value of 2.8×10-3, CIE coordinates of (0.37, 0.48) and EQEmax of up to 15.6 %. To our knowledge, this is the first report of CP-WOLEDs based on single-molecule purely organic emitters.

Synthesis and properties of an O-doped aromatic belt.

A new macrocyclic arene, dibenzofuran[3]arene, was synthesized, which could be conveniently transformed to an O-doped aromatic belt with a rigid ring-shaped structure and deep cavity. Moreover, the O-doped aromatic belt also showed a high HOMO energy and a narrow HOMO-LUMO gap experimentally and theoretically.

Macrocycle-Based Charge Transfer Cocrystals with Dynamically Reversible Chiral Self-Sorting Display Chain Length-Selective Vapochromism to Alkyl Ketones.

Chirality-driven self-sorting plays an essential role in controlling the biofunction of biosystems, such as the chiral double-helix structure of DNA from self-recognition by hydrogen bonding. However, achieving precise control over the chiral self-sorted structures and their functional properties for the bioinspired supramolecular systems still remains a challenge, not to mention realizing dynamically reversible regulation. Herein, we report an unprecedented saucer[4]arene-based charge transfer (CT) cocrystal system with dynamically reversible chiral self-sorting synergistically induced by chiral triangular macrocycle and organic vapors. It displays efficient chain length-selective vapochromism toward alkyl ketones due to precise modulation of optical properties by vapor-induced diverse structural transformations. Experimental and theoretical studies reveal that the unique vapochromic behavior is mainly attributed to the formation of homo- or heterochiral self-sorted assemblies with different alkyl ketone guests, which differ dramatically in solid-state superstructures and CT interactions, thus influencing their optical properties. This work highlights the essential role of chiral self-sorting in controlling the functional properties of synthetic supramolecular systems, and the rarely seen controllable chiral self-sorting at the solid-vapor interface deepens the understanding of efficient vapochromic sensors.

Acceptor Copolymerized Axially Chiral Conjugated Polymers with TADF Properties for Efficient Circularly Polarized Electroluminescence.

Chiral conjugated polymer has promoted the development of the efficient circularly polarized electroluminescence (CPEL) device, nevertheless, it remains a challenge to develop chiral polymers with high electroluminescence performance. Herein, by the acceptor copolymerization of axially chiral biphenyl emitting skeleton and benzophenone, a pair of axially chiral conjugated polymers namely R-PAC and S-PAC are synthesized. The target polymers exhibit obvious thermally activated delayed fluorescence (TADF) activities with high photoluminescence quantum yields of 81%. Moreover, the chiral polymers display significant circularly polarized luminescence features, with luminescence dissymmetry factor (|glum|) of nearly 3 × 10-3. By using the chiral polymers as emitters, the corresponding circularly polarized organic light-emitting diodes (CP-OLEDs) exhibit efficient CPEL signals with electroluminescence dissymmetry factor |gEL| of 3.4 × 10-3 and high maximum external quantum efficiency (EQEmax) of 17.8%. Notably, considering both EQEmax and |gEL| comprehensively, the device performance of R-PAC and S-PAC is the best among all the reported CP-OLEDs with chiral conjugated polymers as emitters. This work provides a facile approach to constructing chiral conjugated TADF polymers and discloses the potential of axially chiral conjugated luminescent skeletons in architecting high-performance CP-OLEDs.

B,N-Embedded Hetero[9]helicene Toward Highly Efficient Circularly Polarized Electroluminescence.

The intrinsic helical π-conjugated skeleton makes helicenes highly promising for circularly polarized electroluminescence (CPEL). Generally, carbon helicenes undergo low external quantum efficiency (EQE), while the incorporation of a multi-resonance thermally activated delayed fluorescence (MR-TADF) BN structure has led to an improvement. However, the reported B,N-embedded helicenes all show low electroluminescence dissymmetry factors (gEL), typically around 1×10-3. Therefore, the development of B,N-embedded helicenes with both a high EQE and gEL value is crucial for achieving highly efficient CPEL. Herein, a facile approach to synthesize B,N-embedded hetero[9]helicenes, BN[9]H, is presented. BN[9]H shows a bright photoluminescence with a maximum at 578 nm with a high luminescence dissymmetry factor (|glum|) up to 5.8×10-3, attributed to its inherited MR-TADF property and intrinsic helical skeleton. Furthermore, circularly polarized OLED devices incorporating BN[9]H as an emitter show a maximum EQE of 35.5 %, a small full width at half-maximum of 48 nm, and, more importantly, a high |gEL| value of 6.2×10-3. The Q-factor (|EQE×gEL|) of CP-OLEDs is determined to be 2.2×10-3, which is the highest among helicene analogues. This work provides a new approach for the synthesis of higher helicenes and paves a new way for the construction of highly efficient CPEL materials.

Naphth[4]arene: Synthesis, Conformations, and Application in Color-Tunable Supramolecular Crystalline Assemblies.

Although the chemistry of macrocyclic arenes has seen rapid development in recent years, the synthesis of new macrocyclic arenes from aromatic rings with no directing groups remains a challenge. In this work, a new macrocyclic arene, naphth[4]arene (NA[4]A), composed of four naphthalene rings bridged by methylene groups, was synthesized using macrocycle-to-macrocycle conversion. NA[4]A shows 1,3-alternate and 1,2-alternate conformations in the solid state, which can be selectively obtained. By supramolecular co-assembly of NA[4]A and 1,2,4,5-tetracyanobenzene (TCNB) in different concentrations and temperatures, two conformation-dependent crystalline luminescent co-assemblies 1,2-NTC and 1,3-NTC can be selectively prepared. Interestingly, the two charge-transfer crystalline assemblies containing NA[4]A with different conformations show bright yellow and green fluorescence, and also display high photoluminescence quantum yields (PLQYs) of 45 % and 43 %. Furthermore, they exhibit color-tunable two-photon excited upconversion emission.

Data-driven criterion for the solid-liquid transition of two-dimensional self-propelled colloidal particles far from equilibrium.

We establish an explicit data-driven criterion for identifying the solid-liquid transition of two-dimensional self-propelled colloidal particles in the far from equilibrium parameter regime, where the transition points predicted by different conventional empirical criteria for melting and freezing diverge. This is achieved by applying a hybrid machine learning approach that combines unsupervised learning with supervised learning to analyze a huge amount of the system's configurations in the nonequilibrium parameter regime on an equal footing. Furthermore, we establish a generic data-driven evaluation function, according to which the performance of different empirical criteria can be systematically evaluated and improved. In particular, by applying this evaluation function, we identify a new nonequilibrium threshold value for the long-time diffusion coefficient, based on which the predictions of the corresponding empirical criterion are greatly improved in the far from equilibrium parameter regime. These data-driven approaches provide a generic tool for investigating phase transitions in complex systems where conventional empirical ones face difficulties.