- 标题
- 摘要
- 关键词
- 实验方案
- 产品
-
Control of Circularly Polarized Luminescence by Orientation of Stacked π-Electron Systems
摘要： New planar chiral building blocks based on 4,7,12,15-tetrasubstituted [2.2]paracyclophanes were obtained via a synthetic route involving an optical resolution step. Planar chiral enantiomers, comprising of two fluorophores that were stacked to form a V-shaped higher-ordered structure, were synthesized from these building blocks. The V-shaped molecules emitted intense circularly polarized luminescence (CPL). Their chiroptical properties were compared with those of X-shaped molecules bearing the same two fluorophores stacked together. CPL sign of the X-shaped molecule was opposite to that of the V-shaped molecule, which is supported by the theoretical results, indicating that CPL sign can be controlled by the orientation of the stacked fluorophores.
关键词： circularly polarized luminescence,planar chirality,higher-ordered structure,[2.2]paracyclophane
更新于2025-09-23 15:23:52
-
Circularly Polarized Luminescence from Chiral Conjugated Poly(carbazole-ran-acridine)s with Aggregation-Induced Emission and Delayed Fluorescence
摘要： Pure organic materials with circularly polarized luminescence (CPL) and delayed fluorescence have gained increasing interest from academic and technological areas. To enhance the solid-state emission and exciton utilization in chiral optoelectronic devices, a synthetic strategy to impart conjugated polymers with CPL and aggregation-induced delayed fluorescence was proposed. Herein, two conjugated macromolecules with electron-donating poly(carbazole-ran-acridine) backbones, electron-withdrawing dibenzothiophen-2-yl(phenyl)methanone and chiral alanine moieties were designed and synthesized. Their neat films exhibited strong green emission with quantum yields of 6.7% and 10.3% and delayed fluorescence with lifetime of 1.358 μs and 1.366 μs, respectively. Both Cotton effect and CPL with dissymmetry factor of –2.01 × 10–3 and –1.39 × 10–3 were determined in the solid state. Such unique conjugated polymers were employed as solution-processed emitting layers in organic light emitting diodes, which displayed maximum brightness of 1477 cd/m2 and maximum current efficiency of 2.52 cd/A.
关键词： OLEDs,conjugated polymers,aggregation-induced emission,delayed fluorescence,aggregation-induced delayed fluorescence,circularly polarized luminescence
更新于2025-09-23 15:23:52
-
Chiral Sensing Using Circularly Polarized Luminescence of Bis (phenanthroline dicarboxylic acid) Eu(III) Complex Induced by Allosteric-type Interaction with Amino Acid Molecules
摘要： [Eu(pda)2]- and [Eu(bda)2]- (pda = 1,10-phenanthroline-2,9-dicarboxylic acid; bda = 2,2’ bipyridine 5,5’-dicarboxylic acid) have an achiral D2d structure in crystals. These complexes exhibit circularly polarized luminescence (CPL) in water containing chiral amino acids. In this work, induced CPL of [Eu(pda)2]- and [Eu(bda)2]- in water solutions containing a mixture of D- and L- amino acids were examined. Plots of glum values of the induced CPL as a function of mol-fraction of L- and D- arginine reveal that [Eu(pda2]- favors homo-association ([Eu(pda)2]--(L-arginine)2 or [Eu(pda)2]--(D-arginine)2) over hetero-association {[Eu(pda)2]--(L-arginine)?(D-arginine)}. This suggests that association of an arginine molecule induces a structural change in [Eu(pda)2]- to promote chiral selective association to another arginine, i.e., homo-allosteric association. On the other hand, the system of [Eu(pda)2]- with histidine favors hetero-allosteric association over homo-association. No allosteric effect is recognized in CPL from [Eu(bda)2]-.
关键词： allosteric effect,amino acid,lanthanide complex,circularly polarized luminescence,chiral sensing
更新于2025-09-23 15:22:29
-
Aggregation-amplified circularly polarized luminescence from axial chiral boron difluoride complexes
摘要： The development of small organic molecules with intense and switchable circularly polarized luminescence (CPL) is currently attracting great interest due to their promising applications in chiroptical devices and sensors. In this paper, CPL-active BF2-bridged azaanthracene dimers (BA1 and BA2) were facilely synthesized by incorporating boron difluoride unit to the bi-naphthalene. BA1 and BA2 show moderate CPL in diluted solutions, however, BA2 exhibited aggregation-amplified red CPL with large dissymmetry factor up to 1.6×10?2. Moreover, acid-/base-triggered CPL switch off/on were also realized via disaggregation/aggregation of BA2 in tetrahydrofuran (THF)/water binary solvents.
关键词： aggregation-induced emission,bodipy,circularly polarized luminescence,switch,dyes and pigments
更新于2025-09-23 15:22:29
-
Self-Assembly of Amphiphilic Schiff Base and Selectively Turn on Circularly Polarized Luminescence by Al3+
摘要： We designed glutamide-derived amphiphilic Schiff bases containing three different aldehyde moieties for the fabrication of circularly polarized luminescence (CPL) emitting materials. Upon self-assembly in acetonitrile, Schiff bases featuring 4-(dimethylamino)-2-hydroxylbenzaldehyde and 1-hydroxy-2-naphthaldehyde groups form supramolecular gels with twist and fiber structures, respectively, while Schiff bases featuring 2-hydroxy-1-naphthaldehyde groups forms precipitation with flakes structures. Although emission and circular dichroism (CD) signals can be detected from the supramolecular gels formed by amphiphilic Schiff bases, none of them exhibits circularly polarized luminescence (CPL). While Mg2+, Zn2+ and Al3+ can both significantly enhance the fluorescence of the Schiff bases, interestingly, only Al3+ ion is able to turn on the CPL emission. This study on the one hand provides a simple method to the fabrication of CPL emitting supramolecular materials, and on the other hand offers a novel way to the sensing of aluminum ion with supramolecular materials.
关键词： Self-assembly,Schiff bases,Circularly polarized luminescence,Al3+,Supramolecular gels
更新于2025-09-23 15:21:21
-
<i>l</i> -Stercobilin-HCl and <i>d</i> -Urobilin-HCl. Analysis of Their Chiroptical and Conformational Properties by VCD, ECD, CPL Experiments and MD, DFT Calculations
摘要： Vibrational circular dichroism (VCD) and IR spectra of dichloromethane solutions of l-stercobilin and d-urobilin hydrochlorides have been recorded in the mid-IR region. The spectra are best interpreted by combining molecular dynamics (MD) calculations and DFT calculations within the QM/MM ONIOM-type framework, and the combined predicted results are better and more informative than the more standard analysis provided by DFT calculations. The same approach also sheds light on the Cotton effect sign inversion of room temperature versus low temperature electronic CD (ECD) spectra of the same compounds in methanol-glycerol solution. Finally, circularly polarized luminescence (CPL) spectra for l-stercobilin in chloroform solution provide information on the excited state geometry of this molecule.
关键词： Vibrational circular dichroism,electronic CD,molecular dynamics,IR spectra,QM/MM ONIOM-type framework,Cotton effect,circularly polarized luminescence,DFT calculations
更新于2025-09-23 15:21:21
-
Non-classically Controlled Sign in a 1.6 Tesla Magnetic Circularly Polarized Luminescence of Three Pyrenes in a Chloroform and a PMMA Film
摘要： Molecular pyrene, 1-hydroxylpyrene, and 2-hydroxypyrene in chloroform and embedded in poly(methyl methacrylate) film reveal mirror-image magnetic circularly polarized luminescence (MCPL) when south (S)-up or north (N)-up direction of the longitudinal external magnetic field of 1.6 T to unpolarized incident light (Faraday geometry) is employed. The |gMCPL| magnitude is on the order of 10–3 T–1 in 374–416 nm. The sign of MCPL is controlled by the S-up and N-up geometry and by the position (1- or 2-) of the hydroxy group.
关键词： magnetic circularly polarized luminescence,pyrene,chirality,fluorescence
更新于2025-09-23 15:21:01
-
Circularly Polarized Rooma??Temperature Phosphorescence and Encapsulation Engineering for MOFa??Based Fluorescent/Phosphorescent WLEDs
摘要： Optical materials with circularly polarized luminescence and room temperature phosphorescence currently attract great attention owing to their unique optoelectronic properties. Herein, via the coordination-induced assembly strategy, a homochiral metal–organic framework (MOF) 1 with high stability and porosity is successfully synthesized by using the achiral triphenylamine-based molecule as the building block. Remarkably, MOF 1 shows circularly polarized luminescence and phosphorescence at room temperature simultaneously, also with excellent anisotropic optical properties. Furthermore, MOF 1 can serve as a nanocontainer to construct dye-encapsulated host–guest systems. Importantly, the multicolor emissions including white-light emission can be achieved. The corresponding color rendering index and correlated color temperature values of light emitting device are 73 and 5541 K, when using dye-loaded MOF 1?RhB 10 (CIE: 0.33, 0.33) as single-phase white light-emitting phosphor. This study first reports circularly polarized phosphorescence based on MOF without precious metals under ambient conditions, and also is first time for phosphorescent polarized materials with high porosity. These results will open up a new pathway to the design of porous chiroptical materials and white-light materials.
关键词： circularly polarized luminescence,host–guest system,room temperature phosphorescence,white light emitting devices,metal–organic frameworks
更新于2025-09-23 15:21:01
-
Planar Chiral [2.2]Paracyclophanes: Optical Resolution and Transformation to Optically Active π-Stacked Molecules
摘要： In this article, recent our results on practical optical resolution methods of disubstituted and tetrasubstituted [2.2]paracyclophane compounds and their transformations are described. The obtained enantiopure [2.2]paracyclophane compounds have been used as chiral building blocks to prepare optically active π-stacked molecules. π-Stacked molecules construct optically active second-ordered structures, such as V-, N-, M-, X-, triangle-shaped, and one-handed double helical structures, due to the orientation of stacked π-electron systems. They emit circularly polarized luminescence (CPL) by photo-excitation. [2.2]Paracyclophane-based chiral π-stacked molecules in this article emit brightly owing to good photoluminescence (PL) quantum efficiencies as well as large molar extinction coefficients. In particular, emission is of course CPL with the large disymmetry factor (glum value). It is basically difficult to achieve CPL with high brightness, high PL efficiency, and large glum value by using other chiral scaffolds; therefore, planar chiral [2.2]paracyclophane is the ideal scaffold to be an excellent CPL emitters.
关键词： [2.2]Paracyclophane,Planar chirality,Circularly polarized luminescence
更新于2025-09-23 15:21:01
-
Gap plasmons inducing strong plasmonic chirality in planar metallic nanostructures
摘要： In this paper, an observation of chiral gap plasmons that induce strong optical chirality, spectroscopic circular dichroism (CD), and near-field enhancement in a planar metallic nanostructure is reported. The resulting chiral nanostructure consists of artificial gold nanoscale elements which are periodically fabricated on a glass substrate. The measured extinctions of the structure under linearly polarized light illumination are in good agreement with numerical calculations of extinction cross-sections. The dissymmetry of the extinctions under left- and right-handed circular polarization is correlated to the far-field CD of the chiral nanostructure that yields a strong CD of up to 0.02. Near-field enhancement of up to 20 times and a large local optical chirality is numerically found at a plane 5 nm above the chiral nanostructure. The finding of chiral gap plasmons that induce strong optical chirality is experimentally demonstrated to enhance interaction between achiral dye molecule and chiral gap plasmon, emitting circularly polarized luminescence with a dissymmetry factor of up to 0.15.
关键词： optical chirality,chiral nanostructures,circularly polarized luminescence,circular dichroism,gap plasmon
更新于2025-09-23 15:19:57