A controllable and reversible broad-band reflector can be obtained by virtue of the response of one-dimensional (1-D) nanomaterials in chiral nematic liquid crystalline media to an external electric field.The colour switching originated from the electro-responsive 1-D nanomaterials and the responsive mechanism was discussed based on the relationship between the pitch distribution and the alignment of nanomaterials.

Single-molecule conductance of a B−N substituted phenanthrene derivative and its isoelectronic CC counterpart was investigated by the scanning tunneling microscopy break junction (STM-BJ) technique. The incorporation of the B−N motif results in a better single-molecule conductivity than the CC analogue. Furthermore, the Lewis acid−base reaction between F − and the B atom of the B−N motif leads to a decrease of the conductance of the BN derivative, which can be understood due to the shifting of the energy positions of the LUMO, as revealed by quantum transport calculations, even though the HOMO−LUMO gap decreases in the B−F Lewis acid−base. These findings provide insights for modulating electron transport properties by isoelectronic structure design. The B−N isoelectronic substituted structure could be a feasible way to design single-molecule devices such as switches and chemical sensors.

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We have demonstrated a facile and low-cost approach for the fabrication of binary "island" shaped arrays (BISA) with high-density hot spots as reproducible surface-enhanced Raman scattering (SERS) substrates by depositing a self-assembled monolayer Au nanoparticle (AuNP) film with small gaps onto a two-dimensional (2D) silica microsphere opal structure. By varying the size of silica spheres, the SERS performance of the BISA substrate with an enhancement factor (EF) of 3.74 × 10 magnitude and the corresponding signal intensity deviation of below 8% using 770 nm silica sphere arrays were achieved. Compared with the assembled monolayer AuNP film on a planar substrate, the BISA enabled the installation of more AuNPs as a source of hot spots due to the undulation of morphology on the nanoscale within the designated laser-illumination area. In addition, a finite-difference time-domain (FDTD) simulation suggested that the BISA structure provided geometric conditions for increasing the intensity of the formed hot spots, and the strong periodic electric fields on the BISA are located not only in the gap between adjacent AuNPs, but also along the boundary of the neighboring island of silica spheres. Surface plasmon-decayed hot carriers (hot electrons and hot holes) from AuNPs can be applied in the field of energy conversion (i.e., photocatalysis), integrated with the SERS as a sensitive optical indicator to accurately monitor the catalytic reaction process. Furthermore, we examined the catalytic reaction process of the dimerization of 4-ATP into DMAB and found that photocatalytic activity could be tuned by changing the size of silica spheres. This study provides a new design route for the fabrication of the SERS platform with high sensitivity and reproducibility to detect molecules or improve catalyst efficiency.

We present two D-π-A organic cationic core structures leading to highly efficient nonlinear optical (NLO) salts (E)-2-(4-(dimethylamino)­styryl)-1,1,3-trimethyl-1H-benzo­[e]­indol-3-ium iodide (P–BI) and (E)-2-(2-(5-(dimethylamino)­thiophen-2-yl) vinyl)-1,1,3 -trimethyl-1H-benzo­[e]­indol-3-ium iodide (S–BI). Single crystals of the above two materials were successfully obtained by the slow evaporation method. Two different polymorphic crystals of both P–BI and S–BI were obtained from different polar solvents. Kurtz powder tests revealed that the maximum second harmonic generation (SHG) efficiency of P–BI with monoclinic space group P21 is 1.14 times the benchmark DAST­(4-N,N-dimethylamino-4,-N,-methylstilbazolium tosylate). Bulk single crystals of P–BI were obtained with size of up to 17.0 × 6.0 × 2.0 mm3 without using seed crystals. This demonstrates that this material exhibits great crystal growth ability along with a high second-order optical nonlinearity, making it a very attractive candidate for NLO applications such as electro-optics and THz-wave generation.

In molecules with both AIE and photochromic properties, light exchange between absorption and fluorescence is reversible under alternating UV/visible treatment.

In this study, we demonstrate a novel method for fabricating polymer stabilized cholesteric liquid crystal (PSCLC) films with non-uniform pitch distribution by utilizing two kinds of photo-induced processes. Based on the large HTP temperature dependence of a chiral dopant, polymer networks were formed at two distant temperature points in sequence. The influence of the polymerization conditions on the reflectance properties of PSCLCs before and after polymerization was investigated. The results strongly suggest that the location and bandwidth of the reflection band can be controlled preferably by adjusting the ultraviolet light intensity and irradiation time of UV-light. In addition, the morphology of the polymer network in the composites was studied using scanning electron microscopy (SEM). A general correlation between polymerization conditions, the network morphology, and the reflective region will be outlined.