Understanding the interactions between as emiconducting nanocrystal surface and chiral anchoring molecules could resolve the mechanism of chirality induction in nanoscale and facilitate the rational design of chiral semiconducting materials for chiroptics.N ow,c hiral molybdenum oxide nanoparticles are presented in which chirality is transferred via abio-to-nano approach. With facile control of the amount of chiral cysteine molecules under redox treatment, circular dichroism (CD) signals are generated in the plasmon region and metal-ligand charge-transfer band. The obtained enhanced CD signals with tunable lineshapes illustrate the possibility of using chiral molybdenum oxide nanoparticles as potentials for chiral semiconductor nanosensors,optoelectronics,and photocatalysts. Figure 2. XPS spectra of different l-Cys capped NPs with deconvoluted Mo 3d peaks. Blue, orange, and green peak areas corresponds to three valence states of molybdenum with Mo VI ,M o V ,and Mo IV respectively.
chirality-based light emitting diodes (LEDs), [7,8] and so forth. [9,10] Extensive efforts have been applied to a broad range of organic luminophores up till now. [11] However, only a few CPL-active inorganic nanomaterials have been designed recently due to the complexity of fine controlled chiroptical responses and insufficient theoretical background explaining the origin of chirality. [12,13] Various approaches have been developed to realize CPL from inorganic nanomaterials. For instance, nanocrystals could exhibit CPL behaviors through the π conjugated interaction between chiral capping ligand and achiral cores. [12,14] It is also hypothesized that chiral environment could confer CPL on quantum dots (QDs), which has been evidenced by CdS QDs encapsulated in chiral apoferritin. [15] However, these approaches usually need tedious synthesis procedures, and the induced CPL signal is usually very low with the dissymmetry factor only ≈10 −3 -10 −4 . [12][13][14][15][16] Moreover, it is known that most metal-based nanomaterials are toxic and have the disadvantage of high manufacturing cost, which limit their widespread applications. Under this circumstance, it is urgent to develop environmentally friendly and CPL nanomaterials with high strength and capacity for scalable preparations.Silicon-based nanoparticles have gained extensive attentions owing to their desirable properties such as being comprised of earth-abundant elements, favorable biocompatibility, and excellent photostability. [17][18][19] Fluorescent silicon QDs (Si QDs) have been recognized as a promising material sharing remarkable optical and electronic properties of traditional metal-based semiconductor QDs. In the past decades, considerable efforts have been devoted to investigate their synthetic strategies and practical applications. A variety of green and simple synthetic methods have been developed for preparing this promising material. [17,[20][21][22] Besides, the excellent water stability, high fluorescence, and low toxicity make them suitable for applications in plenty of fields such as bioimaging, photocatalysis, and sensing. [23][24][25] Based on these outstanding properties, Si QDs is undoubtedly a prominent candidate for the implementation of CPL. To the best of our knowledge, conferring CPL on Si QDs has not been reported to date.Cellulose nanocrystals (CNCs) are renewable and biocompatible nanomaterials which could be easily obtained from bulk cellulose by acid-hydrolysis. After treating with sulfuric acid, CNCs could exhibit excellent water dispersibility due to negative charge from the enriched sulfonate groups on the surfaces. [26,27] Circularly polarized luminescent inorganics arouses attentions due to scalable preparation and versatile chiral optoelectronic applications. Here, strong circularly polarized luminescence (CPL) activity has been developed from self-assembled cellulose nanocrystals decorated with blue emitting silicon quantum dots (QDs). The electrostatic attraction promotes the successful incorporation of QDs into chiral ...
Hybrid multifunctional materials have great potential in a wide variety of applications due to their flexible combination of organic and inorganic components. Introducing chiral organic modules into the metal halide frameworks can effectively generate multifunctional materials, achieving new functionalities with noncentrosymmetric structures. Here, by incorporating (R)-or (S)-piperidine-3-carboxylic acid (R/S-PCA) as the templating cation, we report the synthesis and characterization of three pairs of new 2D chiral hybrid Cu(I) halides, namely, (R/S-PCA)CuBr 2 , (R/S-PCA)CuBr 2 •0.5H 2 O, and (R/S-PCA)CuI 2 . These chiral Cu(I) halides crystallize in the noncentrosymmetric space group C2 and belong to a new structural type similar to layered silicates. The optical absorption edges of these chiral materials can be tuned by changing the halide or upon the absorption of water and range from 2.70 to 3.66 eV. A dynamic conversion between (R/S-PCA)CuBr 2 and (R/S-PCA)CuBr 2 •0.5H 2 O occurs through exposure to moisture or vacuum drying along with changes in the reversible bandgap and photoluminescence. Chiroptical properties such as circular dichroism, circular polarized light emission, and second harmonic generation are investigated. Density functional theory calculations (DFT) show the indirect and direct bandgap natures of these Cu(I) halides and reveal the mechanism for the broadband self-trapped exciton emission at the excited state. The fascinating structural type, chiroptical properties, and reversible hydrochromic behavior of these Cu(I)-based halides make them viable candidates for next-generation multifunctional optoelectronic materials.
Stable organic radicals represent a unique type of functional materials for a broad scope of applications in optoelectronic and spintronic devices. A central challenge toward these applications is how to suppress the inter-radical aggregation that often causes aggregation-induced photoluminescence quenching and limits the correlation lifetime of the electron spins from the radicals. Here, we report an effective approach to fine-tuning luminescence and spin dynamics using a series of polyester-tethered single radicals, with a common core of carbazole-triphenylmethyl radical but different chains of polyesters with distinct glass transition temperature and rigidity. The rigidity of the polymeric matrices plays a critical role in tuning the luminescence and electron spin resonance of the radicals. The tunable properties of luminescence and electron spin dynamics as well as the robust photostability of such polymer-tethered single radicals represent important attributes for cutting-edge applications in optoelectronic devices and quantum information technologies.
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