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[Display omitted] Since the chiral emission of excited states is observed on carbon dots (CDs), exploration towards the design and synthesis of chiral CDs nanomaterials with circularly polarized luminescence (CPL) properties has been at a brisk pace. In this regard, the "host and guest" co-assembly strategy based on the combination of CDs and chiral templates has been of unique interest recently for its convenient operation, multicolor tunable CPL, and wide application of prepared CDs-composited materials in optoelectronic devices and information encryption. However, the existing chiral templates that match perfectly with chiral CDs exhibiting optical activity both in ground and excited states are rather scarce. In this work, we synthesize the chiral CDs that could induce the spontaneous supramolecular self-assembly of N-(9-fluorenylmethox-ycarbonyl) (Fmoc)-protected glutamic acid to form chiral hydrogels with helical nanostructure. The co-assembled hydrogels show powerful chiral template function, which not only enable chiral CDs with a luminescence dissymmetry factor (g lum) up to 10-2, but also have universal chiral transfer to inserted dye molecules, realizing full-color CPL and Förster resonance energy transfer (FRET) CPL as well as the distinction between left and right circularly polarized light. This CPL-active template based on chiral CDs enriches the design scenario of chiral functionalized nanomaterials. [ABSTRACT FROM AUTHOR]

Circularly polarized luminescence (CPL) has numerous applications in optical data storage, quantum computing, bioresponsive imaging, liquid crystal displays, and backlights in three‐dimensional (3D) displays. In addition to their competitive optical properties, carbon dots (CDs) benefit from simple and low‐cost preparation, facile post‐modification, and excellent resistance to photo‐ and chemical bleaching after carbonization. Combining the superior optical performance with polarization peculiarities through hierarchical structure engineering is imperative for the development of CDs. In this study, hydrophobic interactions of aromatic ligands, which participate in the surface‐ligand post‐modification process on the ground‐state chiral carbon core, are employed to drive the oriented assembly. Furthermore, the residual chiral amides on CDs form multiple hydrogen bonds during gradual aggregation, causing the assembled materials to form an asymmetric bending structure. Superficial ligands interfere with the optical dynamics of the exciton radiation transition and stabilize the excited state of the assembled materials to achieve a circularly polarized signal. The linkage ligands overcome the frequent aggregation‐induced quenching phenomenon that present difficulties in conventional CDs, facilitate the assembly of self‐supporting films, and improve chiral optical expression. The full‐color and white CPL are manipulated by simply adjusting the functional groups of the ligands, which also illustrates the versatility of the post‐modification strategy. Finally, large chiral flexible films and multicolor chiral light‐emitting diodes based on the stable chiral powder phosphors were constructed, thereby providing feasible materials and technical support for flexible 3D displays. [ABSTRACT FROM AUTHOR]

Chiral self‐assembly has often been found to be an efficient strategy for the development of high‐performance circularly polarized luminescent (CPL) materials, through the regulation of the ordered helical superstructure blocks in liquid crystal media. Here, the design and synthesis of two pairs of axially chiral emitters (BBXT‐3‐Br and BOHXT‐3‐Br) are reported based on bromoxanthone. And the chiral self‐assembled liquid crystal polymer (LCP) framework (PRM257) is demonstrated by mixing of the emitters with liquid crystal monomer (RM257) through thermal annealing and photoinitiated polymerization. Both BBXT‐3‐Br@PRM257 and BOHXT‐3‐Br@PRM257 exhibited excellent room temperature phosphorescence (RTP) properties. In addition, BBXT‐3‐Br@PRM257 enantiomers showed afterglow with an average lifetime (τ) of 162.41 ms and emitted blue CPL (λem = 450 nm, ΦFL = 1.3%, |gFL| = 0.071), although weak circularly polarized RTP (CP‐RTP) is observed. Interestingly, BOHXT‐3‐Br@PRM257 with a less conjugated system emits red RTP (τ = 98.83 ms) and also intense CP‐RTP (λem = 612 nm, ΦPhos = 0.45%, |gRTP| = 0.057). [ABSTRACT FROM AUTHOR]

The synthesis of a family of chiral and enantiomerically pure pyridyl‐diamide (pda) ligands that upon complexation with europium [Eu(CF3SO3)3] result in chiral complexes with metal centered luminescence is reported; the sets of enantiomers giving rise to both circular dichroism (CD) and circularly polarized luminescence (CPL) signatures. The solid‐state structures of these chiral metallosupramolecular systems are determined using X‐ray diffraction showing that the ligand chirality is transferred from solution to the solid state. This optically favorable helical packing arrangement is confirmed by recording the CPL spectra from the crystalline assembly by using steady state and enantioselective differential chiral contrast (EDCC) CPL Laser Scanning Confocal Microscopy (CPL‐LSCM) where the two enantiomers can be clearly distinguished. [ABSTRACT FROM AUTHOR]

Abstract The synthesis of a family of chiral and enantiomerically pure pyridyl‐diamide (pda) ligands that upon complexation with europium [Eu(CF3SO3)3] result in chiral complexes with metal centered luminescence is reported; the sets of enantiomers giving rise to both circular dichroism (CD) and circularly polarized luminescence (CPL) signatures. The solid‐state structures of these chiral metallosupramolecular systems are determined using X‐ray diffraction showing that the ligand chirality is transferred from solution to the solid state. This optically favorable helical packing arrangement is confirmed by recording the CPL spectra from the crystalline assembly by using steady state and enantioselective differential chiral contrast (EDCC) CPL Laser Scanning Confocal Microscopy (CPL‐LSCM) where the two enantiomers can be clearly distinguished.

Efficient circularly polarized luminescence (CPL) from purely organic molecules holds great promise for applications in displays, sensing, and bioimaging. However, achieving high dissymmetry values (glum) from organic chromophores remains a significant challenge. Herein, we present a bioinspired approach using adenosine triphosphate (ATP)‐triggered supramolecular polymerization of a naphthalene diimide‐derived monomer (ANSG) to induce CPL with a remarkable glum value of 1.1×10−2. The ANSG molecules undergo a templated, chiral self‐assembly through a cooperative growth mechanism in the presence of ATP, resulting in scrolled nanotubes with aggregation‐induced enhanced emission (AIEE) and induced CPL. Furthermore, we demonstrate the concept of chiroptical amplification of induced CPL by efficiently amplifying asymmetry using a mixture of chiral ATP and achiral pyrophosphate. This innovative approach opens numerous opportunities in the emerging field of circularly polarized luminescence. [ABSTRACT FROM AUTHOR]

Light that rotates in a circular spiral when viewed from the front is known as circularly polarized luminescence (CPL), and can be divided into two types, namely, left- and right-rotating light. To emit both left- and right-rotating CPLs, two types of optically active luminophores, namely, enantiomer D- and L-bodies, are generally required. This mini-review mainly discusses our latest study on CPL properties via the control of the pyrene ring as the luminescent unit incorporated into chiral peptides. In this study, optically active peptide–pyrene organoluminescent materials that emit CPL were synthesized by combining a peptide as a frame and two pyrene rings as a luminescent unit. By adjusting the interpyrene distance, external conditions, and absolute chiral configuration (D- or L-configuration), the chiral spatial configuration of the luminescent pyrene ring was precisely controlled. Consequently, the direction of CPL rotation from pyrenylalanine-containing peptides with the same configuration was successfully controlled. [ABSTRACT FROM AUTHOR]

Chiral organometallic emitters hold great promise in potential and practical applications of circularly polarized organic light-emitting diodes (CP-OLEDs). However, developing luminescent earth-abundant organometallic complexes concurrently exhibiting circularly polarized luminescence (CPL) and high quantum efficiency remains a formidable challenge. In this study, we introduced a typical planar chiral skeleton of a [2.2]paracyclophane moiety into earth-abundant copper(I) complexes with the goal of realizing efficient CPL and thermally activated delayed fluorescence (TADF) simultaneously. Two pairs of proof-of-the-concept copper(I) enantiomers, Rp/Sp-MAC*-Cu-CzP and Rp/Sp-MAC*-Cu-CNCzP, were developed using planar chiral [2.2] paracyclophane-based donor ligands in a carbene-metal-amide (CMA) motif. Both panels of enantiomers not only exhibited significant mirror-image CPL signals but also displayed distinct TADF nature with fast reverse intersystem crossing rates of up to 108 s−1. The resultant OLEDs based on the MAC*-Cu-CzP enantiomers manifested efficient circularly polarized electroluminescence with excellent external quantum efficiencies of 13.2% and ultraslow efficiency roll-off (7.7% at 10,000 nits). This article not only demonstrates one of the best performances for CP-OLEDs based on earth-abundant organometallic complexes but also represents the first example of CP-OLEDs from CMA complexes to our knowledge. [ABSTRACT FROM AUTHOR]

Carbon dots (CDs) due to their excellent photostability, good biocompatibility and multicolor fluorescence, have been preferentially selected as luminescent fluorophores and co-assembled with various chiral host templates in recent years. The as-prepared composites exhibit marvellous circularly polarized luminescence (CPL) activity and show promising potentials in the fields of stereopsis and optoelectronic display, which have drawn increasing attention. However, the fussy assembly procedure and over-reliance on template chirality extremely limit the design and application of CDs-composited materials in the field of CPL. In this work, we directly prepared the CDs-composited G-quartet hydrogels with CPL activity using a one-step microwave-assisted method, and their helical chiral structure and CPL orientation can be arbitrarily switched back and forth between left-handed and right-handed through K+ and formation kinetics. Finally, the CDs-composited G-quartet hydrogels can be applied in anti-counterfeiting printing for encrypted information transfer, and their outstanding thermal cycling stability and CPL dissymmetry factor (g lum) of up to 10−1 demonstrate a wider application potential in CPL active materials based on CDs. [Display omitted] • CDs-composited fluorescent G-quartet hydrogels were directly prepared by a simple one-step microwave method. • Helical chirality and CPL properties of hydrogels can be flexibly regulated by metal ions—K+ and formation kinetics. • The CPL dissymmetry factor (g lum) of hydrogels reached 10−1, which is much higher than that of most CPL materials. • The CDs-composited G-quartet hydrogels can be employed in anti-counterfeiting printing for information encryption. [ABSTRACT FROM AUTHOR]

Multiple heterohelicenes are a unique class of helical nonplanar scaffolds that have attracted great attention due to their appealing shapes, optical and electronic properties, and potential applications in chiral materials. This review describes the recent advances and challenges in the design and synthesis of representative multiple heterohelicenes with intriguing chiral properties. And the corresponding applications are also covered. [ABSTRACT FROM AUTHOR]

Molecular motions are closely associated with the behaviors and properties of organic materials. However, monitoring molecular motions is challenging. Herein, a chiral supramolecular system consisting of L‐/D‐phenylalanine (LPF/DPF) as a chiral inducer and an achiral tetraphenylethene derivative (TPEF) as a molecular rotor has been proposed and explored for real‐time discriminating the supramolecular motions by the visualization of circularly polarized luminescence (CPL) signal variations. Derived from the ordered molecular motions of TPEF induced by LPF/DPF, highly organized aggregates have been progressively assembled in a controlled manner with differentiated morphologies, including spherical particles, one‐dimensional fibers, and floor‐shaped supercrystals. Notably, increasing level of ordered aggregates, in turn, led to quenching emissions, while the CPL signals have been dramatically amplified accompanying by a sharp enhancement of luminescence dissymmetry factors (glum) from nearly 0 to −0.1. The significant amplification of CPL is attributed to the ordered aggregates of supramolecules, leading to the decrease of electric transition dipole moments in supramolecular system. As a result of the chiral supramolecular motions powered by supramolecular crystallization, the supramolecular motions are conveniently discriminated by visual CPL signal variation with an enhancement of glum value from 0 to −0.1 in real time. [ABSTRACT FROM AUTHOR]

Abstract Understanding the precise molecular arrangement of chiral supramolecular polymers is essential not only to comprehend complex superstructures like proteins and DNA but also for the development of next‐generation optoelectronic materials, including materials displaying high‐performance circularly polarized luminescence (CPL). Herein, we report the first chiral supramolecular polymer systems based on hydrazone–pyridinium conjugates comprising alkyl chains of different lengths, which afforded control of the apparent supramolecular chirality. Although supramolecular chirality is governed basically by the remote chiral centers of alkyl chains, helicity inversion was achieved by controlling the conditions under which the hydrazone building blocks underwent aggregation (i.e., solvent compositions or temperature). More importantly, the addition of water to the system led to aggregation‐induced hydrazone deprotonation, which resulted in a completely different self‐assembly behavior. Structural water molecules played an essential role, forming the assembly's channel‐like backbone, around which hydrazone molecules gathered as a result of hydrogen bonding interactions. Further co‐assembly of an achiral hydrazone luminophore with the given supramolecular polymer system allowed the fabrication of a novel CPL‐active hydrazone‐based material exhibiting a high maximum value for the photoluminescence dissymmetry factor of −2.6 × 10−2.

Circularly polarized luminescence (CPL) organic dyes are currently receiving a great interest, but there are still not many reported observations of CPL spectra of hydrophobic dyes from aqueous solution. We have prepared hydrophobic pyrene derivatives and dissolved them into aqueous solutions with γ-cyclodextrin (γ-CD) by using grinding technique. Among these derivatives, (pyrene-1-carbonyl)serine (PySer) forms a spatially restricted dimer in the hydrophobic chiral cavity of γ-CD and exhibits excimer emission with a high quantum yield of Φf = 0.68. In addition, circular dichroism and CPL signals were induced for the complex. The strong gCPL value of gCPL = + 2.2 × 10−3 was obtained, which may be attributed to the interaction between the hydroxyl groups in the side chain of PySer with those of γ-CD and it strengthens the chiral dimeric structure. [ABSTRACT FROM AUTHOR]

Circularly polarized luminescence (CPL) materials hold significant value in various fields, including information storage, secure communication, three-dimensional displays, biological detection, and optoelectronic devices. Using the Langmuir-Schaeffer (LS) assembly technique, we successfully construct a series of large-area flexible optical ultrathin films. Impressively, the inorganic assembled ultrathin films exhibit excellent CPL optical activity covering the visible to near-infrared (NIR) region, with the luminescence asymmetry factor g lum ranging from 0.59 to 0.72. Moreover, such ultrathin films also display outstanding mechanical flexibility, the optical activity of which even after 240 bending cycles shows almost no difference compared to the unbent samples. Owing to the ultra-broadband optical activity and ultra-stable optical activity of such full-inorganic assembled materials on flexible substrates, coupled with their excellent processability and outstanding mechanical flexibility, we anticipate they will find use in many fields such as communication technology and flexible optoelectronics., (© 2024 Wiley-VCH GmbH.)

Recently, scientists have reported a range of chiral fluorescence materials or chiral composites that can emit circularly polarized luminescence. Herein, two achiral metal–organic colloidal solutions were studied, showing active circularly polarized luminescence, which is observed in vortex stirring. The absolute values for glum are 0.05 and 0.03 and the plus or minus sign of glum depends on the colloidal structure and stirring direction, which make the property easy to manipulate. Further, the host–guest interaction study suggests both electrostatic interactions and coordination bonding may influence the chiroptical property from the colloidal solution to the guest molecule. Rhodamine 6G and its carboxylic acid derivative exhibit good quantum yields and acceptable glum values in the colloidal solution. [ABSTRACT FROM AUTHOR]

Spirocyclic Ag9 clusters, as a new form of intrinsically chiral metal clusters, were constructed through vertex‐sharing of two in‐situ‐generated heteroaryl diide‐centered metal rings. Such core‐peripheral type clusters exhibit versatile photoluminescent and chiroptical behavior under different aggregation conditions. In contrast to a ligand‐based fluorescence emission in a diluted solution of the clusters, a solvent polarity‐caused assembly gives rise to new cluster‐based phosphorous luminescence owing to radiative mode switching and aggregation‐induced emission. Assembly of cluster enantiomers leads to micrometer‐long helical nanofibers, whose handedness is determined by absolute configuration of individual spirocyclic clusters. Benefiting from exciton couplings of helical arrangements of chelating ligands at molecular and microscopic levels, the assembled film of cluster enantiomers exhibits circularly polarized luminescence with a high anisotropy factor (0.16). [ABSTRACT FROM AUTHOR]

Next-generation medical and consumer electrical devices require soft, flexible materials. Piezoelectric materials, capable of converting mechanical stress into electrical energy, are of interest across various fields. Chiral nanostructures, with inherent chirality, have emerged as potential piezoelectric materials. Peptide-based materials, known for self-assembly and stimuli responsiveness, hold promise for the utilization of chiral nanostructures. When combined with luminescent chromophores, peptides can generate aggregation-induced chiroptical effects like Circularly Polarized Luminescence (CPL) and Circular Dichroism (CD). In this study, a chiral organogel, L,L-1 is synthesized, and its self-assembly, mechanical properties, and chiroptical features are examined. The organogel exhibits thermo-reversible and thixotropic behavior, forming fibrillar networks and 2D-sheets upon cooling. CD spectroscopy reveals aggregation-induced chirality on pyrene chromophore, resulting in CPL with g lum values of 3.0 (± 0.2) × 10 -3 and 3.1 (± 0.2) × 10 -3 for L,L-1 and D,D-1, respectively. Notably, the 2D-sheets exhibit an enhanced piezoelectric response (d 33 ≈76.0 pm V -1 ) compared to the fibrillar network (d 33 ≈64.1 pm V -1 ). Introducing an electron-deficient molecule into the solution forms a Charge-transfer (CT) complex, modulating the piezoelectric response to d 33 ≈52.44 pm V -1 . This study offers a promising approach to optoelectronics design, presenting a chiral system with both CPL and piezoelectric responses, opening new possibilities for innovative applications., (© 2023 Wiley‐VCH GmbH.)

Chiral molecules are essential for the development of advanced technological applications in spintronic and photonic. The best systems should produce large circularly polarized luminescence (CPL) as estimated by their dissymmetry factor (glum), which can reach the maximum values of −2 ≤ glum ≤ 2 when either pure right- or left-handed polarized light is emitted after standard excitation. For matching this requirement, theoretical considerations indicate that optical transitions with large magnetic and weak electric transition dipole moments represent the holy grail of CPL. Because of their detrimental strong and allowed electric dipole transitions, popular chiral emissive organic molecules display generally moderate dissymmetry factors (10−5 ≤ glum ≤ 10−3). However, recent efforts in this field show that glum can be significantly enhanced when the chiral organic activators are part of chiral supramolecular assemblies or of liquid crystalline materials. At the other extreme, chiral EuIII- and SmIII-based complexes, which possess intra-shell parity-forbidden electric but allowed magnetic dipole transitions, have yielded the largest dissymmetry factor reported so far with glum ~ 1.38. Consequently, 4f-based metal complexes with strong CPL are currently the best candidates for potential technological applications. They however suffer from the need for highly pure samples and from considerable production costs. In this context, chiral earth-abundant and cheap d-block metal complexes benefit from a renewed interest according that their CPL signal can be optimized despite the larger covalency displayed by d-block cations compared with 4f-block analogs. This essay thus aims at providing a minimum overview of the theoretical aspects rationalizing circularly polarized luminescence and their exploitation for the design of chiral emissive metal complexes with strong CPL. Beyond the corroboration that f–f transitions are ideal candidates for generating large dissymmetry factors, a special attention is focused on the recent attempts to use chiral CrIII-based complexes that reach values of glum up to 0.2. This could pave the way for replacing high-cost rare earths with cheap transition metals for CPL applications.

Graphical abstract Highlights • Planar chiral organosilanes were prepared from dioxacyclophane as a building block. • Absolute configurations were determined by single-crystal X-ray analysis. • (+)-(R)- 2 exhibited circularly polarized luminescence for a small organic molecule. Abstract Planar chiral dioxacyclophanes were designed and synthesized as a key scaffold for materials with circularly polarized luminescence (CPL). Representative planar chiral 1,12-dioxa[12](1,4)naphthaleneophane-derived organosilane compounds (−)-(R)- 1 , (+)-(R)- 2 , and (−)-(R)- 3 were prepared by (+)-sparteine-mediated aryl metalation and an electrophilic reaction with chlorosilanes. The absolute configurations of the planar chirality were determined in the R form by single-crystal X-ray analysis. Optically active compound (+)-(R)- 2 exhibited blue fluorescence and a CPL signal with a dissymmetry factor (g lum value) of 0.001 in solution. The electronic structure was corroborated by DFT and TD-DFT calculations rationalizing the observed spectroscopic properties. [ABSTRACT FROM AUTHOR]

Circularly polarized luminescence (CPL) has attracted significant attention in the fields of chiral photonic science and optoelectronic materials science. In a CPL-emitting system, a chiral luminophore derived from chiral molecules is usually essential. In this review, three non-classical CPL (NC-CPL) systems that do not use enantiomerically pure molecules are reported: (i) supramolecular organic luminophores composed of achiral organic molecules that can emit CPL without the use of any chiral auxiliaries, (ii) achiral or racemic luminophores that can emit magnetic CPL (MCPL) by applying an external magnetic field of 1.6 T, and (iii) circular dichroism-silent organic luminophores that can emit CPL in the photoexcited state as a cryptochiral CPL system.

Abstract: Two new inherently chiral oligothiophenes characterized by the atropisomeric 3,3′‐bithianaphtene scaffold functionalized with fused ring bithiophene derivatives, namely 4H‐cyclopenta[2,1‐b3:4b′]dithiophene (CPDT) and dithieno[3,3‐b:2′,3′‐d]pyrrole (DTP), were synthesized. The racemates were fully characterized and resolved into antipodes by enantioselective HPLC. The enantiomers were analyzed through different chiroptical techniques: electronic circular dichroism (ECD) and vibrational circular dichroism (VCD) were employed to attribute the absolute configuration (AC). Comparison of experimental and calculated VCD spectra confirmed the DFT calculated conformational characteristics. The compound functionalized with two CPDT units was oxidized with FeCl3, and ECD and CPL of the resulting material were measured. Circularly polarized luminescence (CPL) was measured to verify if inherently chiral oligothiophenes could be promising systems for chiral photonics applications. [ABSTRACT FROM AUTHOR]

Although chiral 1,1′-binaphthalene-2,2′-diyl- O , O -bis( N , N -dimethylthiocarbamate) ( 1 ) revealed no circularly polarized luminescence (CPL) signals, Newman–Kwart rearrangement of O -thiocarbamate groups at 1 yielded clear CPL signals from 1,1′-binaphthalene-2,2′-diyl- S , S -bis( N , N -dimethylthiocarbamate) ( 2 ), which acts as a CPL-gen molecule. [ABSTRACT FROM AUTHOR]

Abstract: The photoexcited and ground state chiralities of enantiopure oligopeptides bearing two pyrenyl groups (DD‐2/LL‐2: four methylene spacer between two pyrenyl groups and DD‐1/LL‐1: no methylene spacer thereof) in eight common organic solvents (CHCl3, CH2Cl2, MeOH, CH3CN, DMF, NMP, DMAc, and acetone) were investigated by means of circularly polarized luminescence (CPL) and circular dichroism (CD) spectroscopies. It was found that chiroptical signs of pyrene‐origin CPL and CD signals largely depend on the nature of solvents and are susceptible to the methylene spacer. Actually, the excimer‐origin CPL signs at 450–510 nm of DD‐1/LL‐1 in DMF were (–)/(+), respectively, while those in other solvents were oppositely (+)/(–), respectively. On the other hand, in DD‐2/LL‐2, the excimer‐origin CPL signs were (–)/(+) in CH2Cl2 (and CHCl3), respectively, and (+)/(–) in MeOH/DMF/NMP/DMAc, respectively. The solvent dependent and the methylene spacer dependent CD sign inversion of DD‐1/LL‐1 and DD‐2/LL‐2 were also found. These results led to conclude that the solvent molecule and the methylene spacer collaboratively affect both the ground state chirality and the photoexcited chirality. [ABSTRACT FROM AUTHOR]

For the selective emission of positive- and negative-sign circularly polarized luminescence (CPL), two chiral organic luminophores with opposing chirality are generally needed. In this study, the solution-state CPL sign of an axially chiral binaphthylacetic acid organic luminophore was successfully controlled by changing the solvent from chloroform (or methanol) to dimethylformamide (or acetonitrile). [ABSTRACT FROM AUTHOR]

We review the present status of experiments and calculations for circularly polarized luminescence (CPL) of simple organic molecules and of stimuli-responsive organic molecules. Together with the historical report of the main instrumental approaches, a few crucial points about experiments are tackled, with the aim of defining measurement protocols, in view of the wide availability of commercial apparatuses in the near future. The calculations aimed at interpreting the CPL spectra, mostly based on time-dependent Density Functional Theory (TD-DFT) calculations, which started around 2010, are reviewed, limiting the discussion to small to mid-sized molecules. Some applications of CPL spectra of organic molecules-based systems are presented, with a focus especially on two fields: material science and biology. Chirality 28:696-707, 2016. © 2016 Wiley Periodicals, Inc. [ABSTRACT FROM AUTHOR]

The photoluminescence (PL) and circularly polarized luminescence (CPL) of (( R )-1-phenyl- N -(pyren-1-ylmethyl)ethanamine) P - R were successfully modulated via fine-tuning and precise control of excited conformation of dimer/excimer by external stimuli. The resulting aggregation-induced emission (AIE)-active material ( P - R ) exhibited CPL with a low dissymmetry factor (∼10 −4 ) in monomeric form, while demonstrating a prominent CPL signal with a higher dissymmetry factor (∼10 −3 ) in thin solid films even without annealing processes. [ABSTRACT FROM AUTHOR]

Multiple heterohelicenes involving one or more heteroatoms in the helical backbone, in light of the importance of their spanning disciplines of the chemical and material sciences, have thus attracted significant interest from various research fields. This review summarizes the current progress in the chemistry of multiple heterohelicenes, especially of those with boron, nitrogen, oxygen, silicon, sulfur, or phosphorus atoms fused into their skeletons over the past decade (2012–2022). For each of multiple heterohelicenes, their synthesis, structural features, electronic and chiroptical properties, as well as examples of their applications, are collected (DOI: 10.1002/chem.202202069). [ABSTRACT FROM AUTHOR]

Chiral and circularly polarized luminescence (CPL) materials with multiple stimuli responses have become a focus of attention. Meanwhile, elastomers have found substantial applications in a wide variety of fields. However, how to design and construct chiral elastomers, in particular CPL-active elastomers, still remains an academic challenge. In the present study, chiral helical substituted polyacetylene is chemically bonded with polydimethylsiloxane (PDMS) by hydrosilylation to form a chiroptically active elastomer. A CPL-active film was further fabricated by adding achiral fluorophores. Compared with the corresponding chiral helical polymer, the chiral films show much enhanced thermal stability in terms of chiroptical properties. The films also demonstrate reversible tunability in optical activity and CPL property when being subjected to a stretching-restoring process and exposed to a solvent like toluene. Further, noticeable chiral amplification is observed when the chiral PDMS film is superimposed with a pure PDMS film. This interesting finding is proposed to be due to the photoreflectivity of PDMS. This study provides an alternative strategy to exploit novel CPL-active elastomer materials with multiple stimuli responsivity and tunability, which may open up new opportunities for developing novel chiroptical devices.

Highlights: [•] We have reviewed N-donor heterocycles as sensitizers of lanthanide ion emission. [•] Terpyridine-based sensitizers are among the most studied and the published work deals increasingly with applications in bioimaging and sensing. [•] Work published with other N-donor ligands still involves mostly exploratory structure-property research. [Copyright &y& Elsevier]

ABSTRACT UV, circular dichroism (CD), fluorescence and circularly polarized luminescence (CPL) spectra were recorded for a set of four related [2.2.1] bicyclic compounds ((1 S,4 S)-and (1 R,4 R)-1,7,7-trimethylbicyclo[2.2.1]heptan-2-one, namely (1 S)- and (1 R)-camphor ( 1), (1 S,4 R)-4,7,7-trimethylbicyclo[2.2.1]hept-5-en-2-one, (1 S)-dehydro-epicamphor ( 2), (1 S,4 S)-1,7,7-trimethylbicyclo[2.2.1]heptane-2,5-dione, (1 S)-5-oxocamphor ( 3), (1 S,4 R)- and (1 R,4 S)-1,7,7-trimethylbicyclo[2.2.1]heptane-2,3-dione, (1 S)- and (1 R)-camphorquinone ( 4)) and a set of three related [2.2.2] bicyclic compounds (1 S,4 S)-bicyclo[2.2.2]octan-2,5-dione (saturated diketone ( 5)), (1 R,4 R)-bicyclo[2.2.2]oct-7-en-2,5-dione (unsaturated diketone ( 6)), ((1 S,4 S)-bicyclo[2.2.2]oct-7-en-5( S)-ol-2-one (which we refer to as unsaturated hydroxy-ketone ( 7)). For the latter three compounds also mid-IR vibrational circular dichroism (VCD) spectra were recorded and are presented. Time-Dependent Density Functional (TD-DFT) calculations provide a satisfactory interpretation of both absorption and emission chiroptical spectra and permit insight into ground and excited state electronic properties. We discuss the applicability of the octant rule or of other approximated models to rationalize the observed sign of the CPL. Chirality 25:589-599, 2013. © 2013 Wiley Periodicals, Inc. [ABSTRACT FROM AUTHOR]

Abstract: The circularly polarized luminescence (CPL) property of (R)-(−)-1,1′-binaphthyl-2,2′-diyl hydrogen phosphate with axial chirality has been previously reported, unfortunately, CPL from (R)-(−)-3,3′-bis(4-nitrophenyl)-1,1′-binaphthyl-2,2′-diyl hydrogen phosphate with a 4-nitorobenzene group could not be observed in this work. However, CPL from the naphthalene unit was observed for (R)-(−)-3,3′-bis[3,5-bis(trifluoromethyl)phenyl]-1,1′-binaphthyl-2,2′-diyl hydrogen phosphate with a bis(trifluoromethyl)phenyl group. Interestingly, in (R)-3,3′-bis(9-anthracenyl)-1,1′-binaphthyl-2,2′-diyl hydrogen phosphate with an anthracene group, CPL was emitted from the anthracene unit due to efficient intramolecular chiral transfer. [Copyright &y& Elsevier]

ABSTRACT Ultraviolet (UV), Circular Dichroism (CD), Fluorescence, and Circularly Polarized Luminescence (CPL) spectra were recorded for mixed chloroform/methanol and chloroform/butanol solutions of regioregular poly[3-(( S)-2-methylbutyl)-thiophene]. An evaluation of the chiral and nonchiral components in solution is proposed on the basis of the UV and CD spectra. The fluorescence and CPL spectra are observed in a wavelength range where some UV and CD activity still appears. For this reason, the observed CPL features are strongly influenced by CD. A general procedure for evaluating true CPL spectra is proposed, when absorption and emission coexist. Chirality 24:725-730, 2012. © 2012 Wiley Periodicals, Inc. [ABSTRACT FROM AUTHOR]

Abstract: The chiroptical signs in circularly polarized luminescence (CPL) and circular dichroism (CD) spectra of chiral binaphthyl fluorophores in solution were found to be controllable by changing the dihedral angle of the binaphthyl unit regardless of the same axial chirality. [Copyright &y& Elsevier]

Abstract: Solid-state chiral supramolecular thiophene fluorophore has been successfully prepared by using chiral (R)-1-(2-naphthyl)ethylamine and 5-bromothiophene-2-carboxylic acid. This chiral supramolecular thiophene fluorophore is formed by assembling chiral 21-helical columnar network structures composed of (R)-1-(2-naphthyl)ethylamine and 5-bromothiophene-2-carboxylic acid. This supramolecular organic fluorophore exhibits circularly polarized luminescence (CPL) even in the solid state. [Copyright &y& Elsevier]

Abstract: It is important to first determine the solid-state chiral optical properties of basic fluorescence supramolecular building blocks that can form a network structure via intermolecular interactions. Although the circularly polarized luminescence (CPL) properties of (R)-1,1′-binaphthyl-2,2′-dicarboxylic acid with axial chirality could not be measured in either the solution or solid states, those of (R)-1,1′-binaphthyl-2,2′-diyl hydrogen phosphate with axial chirality were successfully measured in both states. The solid-state CPL originates from the intramolecular interaction of single molecule, rather than intermolecular interactions in the crystal. [Copyright &y& Elsevier]

This paper proposes a new approach for generating strong circularly polarized luminescence (CPL), based on the complexation of non-chiral, non-functionalized fluorophores with chirally-assembled nanotemplate. The observed CPL intensities of anthracene and pyrene bound to the nanotemplate reached -1.4 x 10-2 and -0.85 x 10-2 (dissymmetry factor), respectively. [ABSTRACT FROM AUTHOR]

The construction of circularly polarized luminescence (CPL) materials with high porosity and high rigidity is still challenging. Herein, we propose a chiral reticular chemistry strategy to prepare the homochiral porous metal-organic frameworks (MOFs) as CPL-active materials. Two pairs of enantiomeric MOFs are synthesized through the self-assembly of chiral D/L-cam (DL-camphorates) and achiral fluorescent ligand TPB (1,2,4,5-tetra(pyridin-4-yl)benzene). The g lum values of Cd-CMOF-D and Cd-CMOF-L were up to 0.010 and 0.009; the high g lum values could be compared to those of the partially pure multicomponent self-assembly systems obtained by the complicated process. We further trace the generation and transfer of the hierarchical chirality from chiral molecule to 3D framework, demonstrating that the CPL was dominated by the original molecular chirality rather than the global chirality of the hierarchical structure. Moreover, the single-phase white-light materials with nearly ideal CIE coordinates (0.33, 0.33) were constructed through the introduction of dye emitters into Zn-CMOF (Zn-based chiral MOF). This work provided not only an insightful view of the chirality transfer and disappearance mechanism but also an efficient method for the preparation of the highly porous CPL materials.

Chiral supramolecular gels have been widely reported and applied in asymmetric catalysis, chiral recognition and circularly polarized luminescence (CPL). Guanosine, a biomolecule with both hydrogen bond donors and receptors on their purine rings, can self-assemble to form chiral G-quadruplexes, providing a good template for building CPL materials. Herein, we constructed the quadruplex-based ionogels in the absence of metal ions via dissolving a certain amount of guanosine into an ionic liquid, ethylammonium nitrate (abbreviated as EAN), where the cations of EAN worked as stabilizers of the G-quadruplexes. The introduction of K+ or Sr2+ reduced the guanosine concentration required to form G-quadruplex-based gels in EAN. The Sr2+ was found to disturb the homopolar stacking of G-quartets and triggered the heteropolar stacking, and thereby overturned the chirality of G-quadruplexes. All ionogels were CPL-active without additional luminescent materials, producing the left-handed CPL for K+ and right-handed CPL for Sr2+, respectively. Regulating the proportion of metal ions could modulate the chirality and CPL of the hybrid G-quadruplexes. The chiral-controllable ionogels in this work are easy to prepare and are promising to provide potential applications for constructing polarized light-emitting devices. [Display omitted] [ABSTRACT FROM AUTHOR]