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Manipulating plasmonic chirality has shown promising applications in nanophotonics, stereochemistry, chirality sensing, and biomedicine. However, to reconfigure plasmonic chirality, the strategy of constructing chiral plasmonic systems with a tunable morphology is cumbersome and complicated to apply for integrated devices. Here, we present a simple and effective method that can also manipulate chirality and control chiral light–matter interactions only via strong coupling between chiral plasmonic nanoparticles and excitons. This paper presents a chiral plexcitonic system consisting of L-shaped nanorod dimers and achiral molecule excitons. The circular dichroism (CD) spectra in our strong-coupling system can be calculated by finite element method simulations. We found that the formation of the chiral plexcitons can significantly modulate the CD spectra, including the appearance of new hybridized peaks, double Rabi splitting, and bisignate anti-crossing behaviors. This phenomenon can be explained by our extended coupled-mode theory. Moreover, we explored the applications of this method in enantiomer ratio sensing by using the properties of the CD spectra. We found a strong linear dependence of the CD spectra on the enantiomer ratio. Our work provides a facile and efficient method to modulate the chirality of nanosystems, deepens our understanding of chiral plexcitons in nanosystems, and facilitates the development of chiral devices and chiral sensing. [ABSTRACT FROM AUTHOR]

Perylene diimide-tethered pillar[5]arene derivatives showed significantly varied circular dichroism (CD) spectral responses towards different amino acid derivatives in both the dispersed and aggregated forms. The wide variety of patterns and intensity combinations of CD signals at different wavelengths allowed for the differentiation of not only the configuration but also types of amino acid derivatives with only one chiroptical sensor. [ABSTRACT FROM AUTHOR]

Chiral metamaterials exhibit significant circular dichroism (CD) and chiral signal enhancement, which have the potential to be used in novel nano-optical devices. This work describes a bilayer resonant planar chiral metamaterial (PCM) composed of positive and negative Z-shaped gold nanoparticles. It is found that in the near-infrared region, the structure has obvious optical active and chiral near-field enhancement. To explore the origin of chirality, linear superposition method is applied to analyze chiral response intuitively and concisely. What's more, the dependence of the CD spectra on the PCM parameters was thoroughly explored, showing that the CD properties of the proposed PCM arrays strongly depend on the geometric parameters and material type. The bilayer PCM array proposed in this paper not only has a strong chiral signal but also is easy to prepare. More importantly, the spectrum of PCM can be adjusted by simply adjusting the particle rotation angle and changing the material of the dielectric layer, which has broad potential application prospects in the fields of chiral molecular biosensing and asymmetric information transmission. [ABSTRACT FROM AUTHOR]

Highly symmetrical and aesthetically pleasing molecules have attracted the attention of organic chemists. We synthesized new highly symmetric stereogenic π-conjugated macrocycles with planar or axial chirality. Macrocyclic oligomers synthesized by Yamamoto coupling or Suzuki–Miyaura cross-coupling from the π-unit containing chirality. These cyclization reactions gave multiple oligomers in relatively high yields. We then elucidated their structures and investigated their chiroptical properties, including circular dichroism (CD) and circularly polarized luminescence (CPL). Because of the selection rule for rigid and symmetric structures, these macrocycles exhibit a high dissymmetry factor (gabs or glum) for circularly polarized light in CD or CPL. Several rigid cyclic compounds retain a highly symmetric structure in the excited state and exhibit higher glum values than common chiral organic compounds. This Account provides a brief background regarding chiroptical properties, followed by a summary of the various macrocycles synthesized in this study. We are glad if this Account will be a source of ideas not only for chemists working with π-conjugated compounds, but also for synthetic chemists working with chiral compounds, especially those engaged in asymmetric synthesis. 1 Introduction 2 Brief Description of Chiroptical Properties 3 Stereogenic Macrocycle Based on [2.2]Paracyclophane 3.1 Stereogenic Double-decker Oligothiophene 3.2 Stereogenic Biselenophene Macrocycle 3.3 Helical Oligophenylene Linked with [2.2]Paracyclophane 4 Stereogenic Macrocycle Based on Binaphthyl 4.1 Cyclic Oligomer of Chiral Binaphthyl 4.2 Doubly Twisted Binaphthyl Dimer 4.3 Cyclic Oligomer of Binaphthyl Extended with Paraphenylene 4.4 Curved Helical Paraphenylene Anchoring Chiral Binaphthyl 4.5 Binaphthyl-Hinged [5]-Helicene 5 Summary [ABSTRACT FROM AUTHOR]

Topological invariants are crucial quantities for classifying materials with topological phases. Hence, their connections with experimentally measurable quantities are extremely important. In this context, circular dichroism (CD) provides a protocol to detect the Chern number 0 of the lowest energy Bloch band (LBB) of a semimetal. This hinges on the unequal depletion rates of the Bloch electrons from a filled LBB, under the action of a time-periodic circular drive, depending on the chirality of the polarization. According to the dimensionality of the system (i.e., whether it is two- or three-dimensional), the integrated differential rate for depletion has to be formulated a bit differently in order to relate it to 0 . Our aim is to capture the nature of the CD response for semimetals with anisotropic band dispersions. We show that while the quantization of the CD response for the three-dimensional cases is strongly sensitive to anisotropy, the two-dimensional counterparts show a perfectly quantized response. [ABSTRACT FROM AUTHOR]

Controlling chromophore chirality in three‐dimensional space is crucial for understanding the structure–chiroptical relationship. Such control enables the prediction of ideal materials for use in chiral photonic applications. In this study, optically active multipyrene systems are synthesized on peptoids. Pyrene‐based chiral submonomers, (S)‐ and (R)‐1‐pyrenylethylamine (s1pye and r1pye), are successfully incorporated into peptoids as the respective (S)‐ and (R)‐N‐(1‐pyrenylethyl)glycine (Ns1pye and Nr1pye) units. NMR spectroscopy revealed length‐ and N‐acetylation‐dependent conformational homogeneity enhancement in solution, stabilizing cis‐amides in Ns1pye‐containing peptoids. The X‐ray crystal structure of Ns1pye tetramer displayed a polyproline type‐I (PPI)‐like helix. All of the pyrene‐related absorptions are circular dichroism (CD) active, and the CD signal related to the long‐axis‐polarized transition increased with helical stabilization. Intramolecular excimer generation yielded significant circularly polarized luminescence (CPL) in the excimer emission region. Early‐stage peptoids emitted left‐handed CPL, but upon acquiring a PPI‐like helix character, CPL handedness became inverted. The CPL dissymmetry factor (glum) was comparable or superior (10−2) to that of chiral organic dyes (10−5–10−2). This new class of helical pyrene‐containing peptoids provides a CPL‐active intramolecular excimer, modulating optical activity through peptoid secondary structure homogeneity. [ABSTRACT FROM AUTHOR]

[Display omitted] • The optical properties of carbon nanobelts with zigzag and armchair edges, as well as interlocked carbon nanobelts for chirality. • TPA and ECD techniques can effectively differentiate carbon nanoribbons with different boundaries, revealing their relationship and distinguishing features. • The better comprehension of carbon nanoribbons, mechanically interlocked molecules, and chirality. This paper presents a theoretical study on the optical properties of carbon nanobelts with zigzag and armchair edges, as well as interlocked carbon nanobelts for chirality. The results demonstrate that two photon absorption (TPA) and electronic circular dichroism (ECD) techniques can effectively differentiate carbon nanoribbons with different boundaries, revealing their relationship and distinguishing features. The findings from this research contribute to a better comprehension of carbon nanoribbons, mechanically interlocked molecules, and chirality. [ABSTRACT FROM AUTHOR]