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Ferroelastic semiconductor materials have garnered significant research interest due to their promising applications in the fields of shape memory, superelasticity, templated electronic nanostructures, mechanical switching, and optoelectronic transmission. However, the toxicity of lead-based structures and low phase-transition temperature (Tc) greatly constrain the application scenarios of ferroelastic semiconductors. Here, using an H/OH-substitution-induced homochiral strategy, we synthesize a pair of lead-free ferroelastic semiconductors (R/S-CTA)2SbCl5 (CTA = 3-chloro-2-hydroxypropyltrimethyllammonium) having semiconductor properties with an indirect bandgap of 3.41 eV. They crystallized in the chiral space group P212121 at room temperature, and both undergo 422F222 type ferroelastic phase transitions with Tc up to 410 K, accompanied by a large entropy change of 68.75 and 66.09 J mol−1 K−1, respectively. Owing to the introduction of chirality, they exhibited temperature-dependent nonlinear second-harmonic generation (SHG) properties. Relatively, the achiral TMCP (TMCP = N,N,N-trimethylchloropropylamine) makes the phase transition properties of centrosymmetric TMCP2SbCl5 ordinary compared to chiral R/S-pair. This is precisely the main starting point of homochiral strategies in phase transition and optical structure research, while arousing research interest. This work, which provides a new avenue for the design of high-Tc lead-free ferroelastic semiconductor compounds, is a powerful motivation for the realization of multifunctional materials related to chirality. [ABSTRACT FROM AUTHOR]

Chiral organic–inorganic hybrid materials with multi-channel switchable characteristics play an important role in the fields of sensors, intelligent switches, and information memorizers. The introduction of chiral organic amine into materials with photoluminescent properties is expected to achieve multi-channel switchable characteristics. Here, we report a pair of chiral organic–inorganic hybrids (R-HASD)2MnBr4 and (S-HASD)2MnBr4 (HASD = 2-hydroxy-5-azaspiro[4.5]decan) containing spirocyclic cations and having dielectric/second harmonic generation (SHG)/photoluminescence (PL) triple-channel switchable properties. Both compounds undergo a reversible plastic phase transition around 380 K. Under ultraviolet (UV) irradiation, both of them show intense green emission and their photoluminescence quantum yields (PLQYs) are above 70%. Therefore, multifunctional hybrid compounds with triple-channel dielectric/SHG/PL switches and excellent PL properties have been successfully prepared. This work is of great significance for further exploration of chiral multifunctional switchable materials. [ABSTRACT FROM AUTHOR]

Highly efficient asymmetric hydrogenation of dibenzo[b,f][1,4]oxazepine, dibenzo[b,f][1,4]thiazepine and dibenzo[b,e]azepine derivatives with chiral cationic ruthenium diamine catalysts has been developed, giving diverse chiral seven-membered N-heterocycles with excellent results (up to 99% yield and 99% ee). Moreover, it was found that the catalyst counteranion regulated the enantioselectivity obviously in the hydrogenation of dibenzo[b,f][1,4]thiazepine and dibenzo[b,e]azepine derivatives. [ABSTRACT FROM AUTHOR]

Nowadays, carbon nanomaterials are considered as the most important supercapacitor electrode materials. But it's still a great challenge to design rational structures of carbon materials at both nano and micro scales to endow carbon electrode materials with outstanding electrochemical performance. Herein, a well-designed compressible and elastic N-doped porous carbon nanofiber aerogel (N-PCNFA) with hierarchical cellular structures in both the PAN/ZIF-8-based carbon nanofibers and the 3D carbon monolith was prepared by a simple method. A large specific surface area was obtained for the construction of abundant pore structures and a robust architecture was built by the introduction of mechanically reinforced structures, which would endow the N-PCNFA electrode material with a vast surface area for ion adsorption/desorption, plenty of short channels for electrolyte diffusion and stable frameworks during the charge/discharge process. N heteroatoms were also incorporated into the carbon material as active sites for faradaic redox reactions. Thus, the N-PCNFA electrodes exhibited superior electrochemical performance, with a high specific capacitance of 279 F g−1 at 0.5 A g−1, consisting of pseudocapacitance (∼46%) and electrochemical double-layer capacitance (∼54%), remarkable rate performance of 59% at 20 A g−1 and excellent long-term durability. Moreover, the simple and general strategy for construction of compressible and elastic porous carbon nanofiber aerogels with delicate microstructures is also applicable to other advanced functional materials for a wide range of applications. [ABSTRACT FROM AUTHOR]

Wearable strain sensors are a compelling need for health monitoring while designing facile and flexible strain sensors with both super-high sensitivity and a wide strain range in an environment-friendly and scalable way remains challenging. Besides, the mechanism underlying these sensors is still insufficiently studied. Here, we propose a handy method to fabricate flexible strain sensors based on an electrospun thermoplastic polyurethane (TPU) mat by coupling silver nanowires (AgNWs) and reduced graphene oxide (rGO). The TPU-based strain sensors with AgNWs and rGO alone exhibited high strain sensitivity and a broad working range, respectively, due to the morphological differences between the two types of nanomaterials. In contrast, the rGO/AgNWs/TPU sensor showed a synergistic effect on strain sensitivity and sensing range because of the interaction between the AgNWs and rGO, as well as the coupling effect arising from their assembly. For instance, the sensors with hybrid nanomaterials had ultrahigh sensitivity (gauge factor, GF ≈ 4.4 × 107) and a wider detection range in comparison with the counterpart strain sensors with AgNWs/TPU and rGO/TPU (both GFs in the range of hundreds). Besides, the sensors showed reliable responses to various frequencies and strains, as well as long-term stretching (1000 cycles). These strain sensors were applied to monitor human body motions, such as joint motion and muscle movement, which revealed their potential in healthcare and human-machine interfacing applications. [ABSTRACT FROM AUTHOR]