A simple and general method is presented herein for the in situ preparations of circularly polarized luminescence (CPL)‐active microcrystals with a large luminescence dissymmetry factor glum, high ...fluorescence quantum efficiency (ΦFL), wide emission color tenability, and well‐ordered morphology. The reactions of pyridine‐containing achiral molecules 1–7 with chiral camphor sulfonic acid ((±)‐CSA) gave crystalline microplates formed by hydrogen bonding interactions between the protonated pyridinium units and the sulfonic anions. The chiral information of CSA are effectively transferred to the microcrystals by hydrogen bonding to afford full‐color CPL from deep‐blue to red with glum in the order of 10−2 and ΦFL up to 80 %. Moreover, organic microcrystals with high‐performance white CPL (ΦFL=46 %; |glum|=0.025) are achieved via the light‐harvesting energy transfer between blue and yellow emitters.
As a result of the efficient hydrogen‐bonding‐mediated chirality transfer and light‐harvesting energy transfer, well‐ordered ionic microcrystals formed between pyridine‐containing achiral molecules and chiral camphor sulfonic acid display full‐color and homogeneously white circularly polarized luminescence (CPL) with ΦFL of up to 80 % and glum in the order of 10−2.
Circularly polarized luminescence (CPL)‐active molecular materials have drawn increasing attention due to their promising applications for next‐generation display and optoelectronic technologies. ...Currently, it is challenging to obtain CPL materials with both large luminescence dissymmetry factor (glum) and high quantum yield (Φ). A pair of enantiomeric N N C‐type Pt(II) complexes (L/D)‐1 modified with chiral Leucine methyl ester are presented herein. Though the solutions of these complexes are CPL‐inactive, the spin‐coated thin films of (L/D)‐1 exhibit giantly‐amplified circularly polarized phosphorescences with |glum| of 0.53 at 560 nm and Φair of ~50 %, as well as appealing circular dichroism (CD) signals with the maximum absorption dissymmetry factor |gabs| of 0.37–0.43 at 480 nm. This superior CPL performance benefits from the hierarchical formation of crystalline fibrillar networks upon spin coating. Comparative studies of another pair of chiral Pt(II) complexes (L/D)‐2 with a symmetric N C N coordination mode suggest that the asymmetric N N C coordination of (L/D)‐1 are favorable for the efficient exciton delocalization to amplify the CPL performance. Optical applications of the thin films of (L/D)‐1 in CPL‐contrast imaging and inducing CP light generation from achiral emitters and common light‐emitting diode lamps have been successfully realized.
The thin films of chiral Pt(II) complexes exhibit giantly‐amplified circularly polarized luminescence (CPL) with |glum| of 0.53 at 560 nm and Φ of ~50 % in air, as a result of the hierarchical formation of crystalline fibrillar networks upon spin coating. These films display promising potentials in CPL‐contrast imaging and inducing circularly polarized light generation from achiral emitters and common LED lamps.
Conventional square‐planar platinum complexes typically form one‐dimensional assemblies as a result of unidirectional metallophilic and/or π⋅⋅⋅π intermolecular interactions. Organoplatinum(II) ...complexes with a cruciform shape are presented herein to construct two‐dimensional (2D) microcrystals with full‐color and white phosphorescence. These 2D crystals show unique monocomponent π⋅⋅⋅π stacking, from either the cyclometalating or noncyclometalating ligand, and the bicomponent alternate π⋅⋅⋅π stacking from both ligands along different facet directions. Anisotropic tri‐directional waveguiding is further implemented on a single hexagonal microcrystal. These results demonstrate the great capability of the organoplatinum(II) cruciform as a general platform to fabricate 2D phosphorescent micro‐/nanocrystals for advanced photonic applications.
The controllable preparations of two‐dimensional phosphorescent crystals remain a challenging task. In stark contrast to the conventional one‐dimensional assemblies of square‐planar platinum complexes, organoplatinum(II) complexes with a cruciform shape form two‐dimensional microcrystals with full‐color and white phosphorescence by unique molecular stackings, opening a new avenue for the preparations of phosphorescent micro/nanostructures for advanced photonic applications.
The development of circularly polarized electroluminescence (CPEL) is currently hampered by the high difficulty and cost in the syntheses of suitable chiral materials and the notorious chirality ...diminishment issue in electrical devices. Herein, diastereomeric IrIII and RuII complexes with chiral (±)‐camphorsulfonate counteranions are readily synthesized and used as the active materials in circularly polarized light‐emitting electrochemical cells to generate promising CPELs. The addition of the chiral ionic liquid (±)‐1‐butyl‐3‐methylimidazole camphorsulfonate into the active layer significantly improves the device performance and the electroluminescence dissymmetry factors (≈10−3), in stark contrast to the very weak circularly polarized photoluminescence of the spin‐coated films of these diastereomeric complexes. Control experiments with enantiopure IrIII complexes suggest that the chiral anions play a dominant role in the electrically‐induced amplification of CPELs.
By using a chiral anion strategy, electrically amplified circularly polarized luminescence (CPL) is realized in light‐emitting electrochemical cells of readily obtained diastereomeric ionic transition‐metal complexes. The addition of a chiral ionic liquid (IL) into the active layer significantly improves the device performance and the electroluminescence dissymmetry factors.
The development and applications of materials with efficient circularly polarized luminescence (CPL) have become an interdisciplinary frontier research topic. We summarize herein the recent advance ...in the development and applications of CPL‐active aggregates based on metal‐ligand coordination materials (termed as “coordination aggregates”). The materials surveyed are classified as aggregates of small‐molecular metal complexes, which include monocomponent assemblies of Pt(II) complexes and other complexes and binary aggregates of metal complexes, and CPL‐active metal‐ligand coordination helicates, polymers, and frameworks. The efforts in improving the dissymmetry luminescence factors and quantum yields of these materials and the use of the aggregation strategy in enhancing the performance of isolated molecules are discussed. The recent applications of chiral metal complexes in circularly polarized organic light‐emitting diodes (OLEDs) based on solution‐ or evaporation‐processed procedures are surveyed. In addition, the uses of lanthanide complexes in CPL‐contrast imaging and as CPL probes are highlighted. The common discussion on the mechanism of aggregation‐enhanced CPLs and a perspective on future works of CPL‐active coordination aggregates are finally given.
The recent progress in the development of circularly polarized luminescence (CPL)‐active aggregates of metal‐ligand coordination materials is summarized, including those based on discrete chiral metal complexes, chiral metal‐ligand helicates, and coordination polymers and frameworks. The applications of these materials in circularly polarized organic light‐emitting diodes and CPL‐contrast imaging and probes are further discussed.
Nano‐ and micromaterials with anisotropic photoluminescence and photon transport have widespread application prospects in quantum optics, optoelectronics, and displays. But the nature of the ...polarization information of the out‐coupled light, with respect to that of the source luminescence, has never been explored in active optical‐waveguiding organic crystals. Herein, three different modes (selective, anisotropic, and consistent) of polarized‐photon out‐coupling are proposed and successfully implemented in a set of 2D organic microcrystals with highly linearly‐polarized luminescence. It is found that the polarization direction and degree of the luminescence out‐coupled through different waveguiding channels can either be essentially retained or distinctly changed with respect to those of the original luminescence, depending on the molecular arrangement and the orientation of transition dipole moments of the crystal. This work demonstrates the promising potential of 2D emissive microcrystals in multi‐channel polarized photon transport.
Multichannel selective, anisotropic, or consistent polarized‐photon out‐coupling has been realized in a set of 2D organic microcrystals, with the polarization direction and degree being either varied or retained with respect to the source luminescence. The molecular arrangement and spatial distribution of the transition dipole moments are found to play prominent roles in determining the polarization properties of the source and out‐coupled emissions.
The synthesis, characterization, and temperature-responsive properties of two fluorescent organoplatinum(II) metallacycles are reported. Metallacycles M1 and M2 were prepared via the ...coordination-driven self-assembly of a 120° triarylamine ligand L1 and a 120° diplatinum(II) acceptor Pt-1 or 180° diplatinum(II) acceptor Pt-2, respectively. M1 and M2 are hexagonal metallacycles, comprising of three or six freely rotating anthracene pendants on their periphery, respectively. In response to the temperature variation between −20 and 60 °C, the ligand displays irregular emission changes, whereas both metallacycles show reversible absorption and emission spectral changes in THF. The changes in their green emission intensity also exhibit a linear correlation with the temperature variation, with an average sensitivity of −0.67% and −0.77% per °C for M1 and M2, respectively. Furthermore, in coordinating solvents, such as DMF and CH3CN, M1 and M2 show different behaviors: in the lower temperature range, i.e., below 30 °C, their spectral changes are similar to those observed in THF; however, at a higher temperature the metallacycles were presumably destroyed by the solvents and displayed ratiometric fluorescent responses, including a cyan emission of the ligand L1.
Ecological niches remain central to explaining community structure, and niche-based studies have helped us to better understand species interactions, distributions, coexistence and associated ...mechanisms. Quercus wutaishansea populations on Loess Plateau are currently expanding their dominance in natural secondary forest types. In the present paper, we focused on the dynamic changes of niches and interspecific association among different changed stages. The overall interspecies association of the three communities exhibited positive association for Variance Ratio (VR) >1; the value of χ
significance test further revealed that the overall association had reached the level of significant association. Among the total of 45 species pairs composed of 10 dominant species, in the Pinus tabulaeformis forest, the ratio of positive and negative associations was below 1, which 19 pairs showing positive association, 25 pairs showing negative association, and 1 pair showing no association; in contrast, in another forests, the ratios of positive and negative associations were above 1. The timing and consequences of these associations may illuminate how interaction mechanisms such as competition and alleopathy, structure changes. Then differences of species features in niches and associations should receive greater attention when planning forest management and developing restoration strategies.
In this study, we for the first time applied a joint geodynamic‐geophysical inversion approach to oceanic plateau subduction models, and compared the subduction style and corresponding topography and ...Bouguer gravity of two representative subduction scenarios with passive or active collision. We showed that the case of passive collision of the Ontong Java Plateau (OJP) crust better explains the topography, gravity, and seismic data than the active collision scenario. This implies that the OJP did not control the regional dynamics during the collisional process. We conclude that previous studies may have overestimated the role of the OJP in triggering subduction initiation, subduction polarity reversal, and even Pacific Plate rotation.
Plain Language Summary
The effect of the Ontong Java Plateau (OJP), the largest oceanic plateau on Earth, on subduction dynamics remains controversial. Proposed models for the evolution of the OJP range from dominantly “soft docking” that generates shallow subduction and little impact on nearby regions, to strong and active collision that results in deep plateau subduction, extensive accretion, subduction polarity reversal, and even major plate reorganization. Determining the subduction depth and accretion volume of OJP is the key to resolving this dispute. In the former, the oceanic plateau undergoes shallow subduction with its upper and middle crusts slightly accreted into the island arc, leading to relatively low topography and a flat Bouguer gravity profile, consistent with observation. The latter case leads to deep subduction of the plateau lithosphere, resulting in high topography, low Bouguer gravity, and crustal structures that all violate observation.
Key Points
The joint geodynamic‐geophysical inversion approach can help distinguish ambiguous dynamic behaviors of oceanic plateau subduction
The Bouguer gravity and other observations of Ontong Java Plateau (OJP) favor the passive collision model over the active collision model
OJP should have played a passive role in the collision process, implying the overestimation in previous studies
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