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An ultrasensitive photoelectrochemical (PEC) aptasensor was originally designed by using ZnIn2S4/ReS2 as a photoactive material and AgInS2 as a signal amplifier. The signal amplifier AgInS2 was incubated on the terminal of H-DNA (immobilized on the ZnIn2S4/ReS2/FTO surface), leading to an enhanced photocurrent response. Then, due to the introduction of DNA2, the formation of a double-stranded structure caused AgInS2 to keep away from the electrode surface, and the photocurrent was reduced. In the presence of kanamycin, DNA2 was released from the system due to the competition relationship, and a restored photocurrent response was obtained. The combination of ZnIn2S4/ReS2 and AgInS2 accelerated the electron transfer and enhanced the separation efficiency of photogenerated electron–hole pairs, resulting in an improved performance of the PEC aptasensor, which was capable of accurate and sensitive detection of kanamycin in actual samples. [ABSTRACT FROM AUTHOR]

We discovered that [(histamine)(18-crown-6)2][BF4]2 is a high-temperature host–guest inclusion complex that presents decent piezoelectric properties (d33 = 5 pC/N), undergoes a phase transition at 406 K, and also possesses potential ferroelectricity. This work provides a new idea for constructing host–guest inclusion piezoelectrics. [ABSTRACT FROM AUTHOR]

With prosperity, decay, and another spring, molecular ferroelectrics have passed a hundred years since Valasek first discovered ferroelectricity in the molecular compound Rochelle salt. Recently, the proposal of ferroelectrochemistry has injected new vigor into this century-old research field. It should be highlighted that piezoresponse force microscopy (PFM) technique, as a non-destructive imaging and manipulation method for ferroelectric domains at the nanoscale, can significantly speed up the design rate of molecular ferroelectrics as well as enhance the ferroelectric and piezoelectric performances relying on domain engineering. Herein, we provide a brief review of the contribution of the PFM technique toward assisting the design and performance optimization of molecular ferroelectrics. Relying on the relationship between ferroelectric domains and crystallography, together with other physical characteristics such as domain switching and piezoelectricity, we believe that the PFM technique can be effectively applied to assist the design of high-performance molecular ferroelectrics equipped with multifunctionality, and thereby facilitate their practical utilization in optics, electronics, magnetics, thermotics, and mechanics among others. [ABSTRACT FROM AUTHOR]

A host–guest inclusion compound, 18-crown-6 oxonium tetrachloride-gallium(III), was shown to undergo a 4/mmmFmm2-type ferroelectric phase transition with four crystallographically equivalent polarization directions at 337 K. To the best of our knowledge, this is the first host–guest inclusion compound shown to be a high-temperature multiaxial molecular ferroelectric. [ABSTRACT FROM AUTHOR]

Ferroelectric polarization is sensitive to external stimuli, such as temperature or pressure, the variation of which can induce a slight change in crystal structure. Similarly, for ferroelectric crystals in host–guest systems, the inclusion of different guest molecules can affect the crystal packing a small amount; however, it may alter the ferroelectric properties significantly. In this report, we discovered that the supramolecular host–guest system Cu(1,10-phen)2SeO4·(diol) (phen is the abbreviation of phenanthroline) can distinguish cis–trans isomers via physical signal feedback, i.e. dielectric/ferroelectric responses. The supramolecular crystal is nonferroelectric and shows inconspicuous dielectric behavior when trans-1,2-cyclohexanediol is included, while a ferroelectric system is achieved when the host interacts with cis-1,2-cyclohexanediol. Moreover, the ferroelectric–paraelectric phase transition involved in cis-1,2-cyclohexanediol occurs together with an interesting chair-boat conformation change, as well as an order–disorder transition. As far as we know, this is the first discovery showing that dielectric/ferroelectric signal responses can be used to distinguish cis–trans isomers in the field of ferroelectric materials. This finding enriches studies of the molecular ferroelectric family and might provide inspiration for smart device design. [ABSTRACT FROM AUTHOR]

The significant Tc enhancement of 110 K in [N-fluoromethyldabconium] triiodide lead caused by the promising design of H/F substitution is the first and unprecedented, opening up an applicable and universal strategy to effectively regulate the Tc working temperature in phase transition materials. [ABSTRACT FROM AUTHOR]

Molecular bistable dielectric switches represent a class of highly desirable intelligent materials due to their sensitive switchable responses, simple and environmentally friendly processing, light weights, and mechanical flexibility. However, most of these switches can only work at a very low temperature, extremely limiting their potential applications. Herein, three layered organic–inorganic hybrid perovskite-type compounds of the general formula A2BX4, [NH3(CH2)2Cl]2[CdCl3Br] (1), [NH3(CH2)2Cl]2[CdCl4] (2) and [NH3(CH2)2Cl]2[CdBr4] (3), which display sensitive dielectric switching reversibility and remarkable switching anti-fatigue, have been successfully designed. Differential scanning calorimetry and dielectric measurements for 1 confirm its reversible phase transition at around 166 K. Through anion modulation, the phase transition temperatures of 2 and 3 can be greatly improved up to 237 K and 254 K, respectively. Structural analysis discloses that the phase transition temperature's shifts may result from the differences among the inorganic frameworks. Moreover, due to the significant order–disorder transitions of ammonium cations, the permittivities of 1, 2 and 3 change abruptly at around the phase transition points, making them excellent stimuli-responsive electrical switches. Such an anion-modulated method will open up new possibilities of highly efficiently tuning the phase transition temperature of molecular bistable dielectric switches. [ABSTRACT FROM AUTHOR]

Ferroelectrics are inseparable from symmetry breaking. Accompanying the paraelectric-to-ferroelectric phase transition, the paraelectric phase adopting one of the 32 crystallographic point groups is broken into subgroups belonging to one of the 10 ferroelectric point groups, i.e. C1, C2, C1h, C2v, C4, C4v, C3, C3v, C6 and C6v. The symmetry breaking is captured by the order parameter known as spontaneous polarization, whose switching under an external electric field results in a typical ferroelectric hysteresis loop. In addition, the responses of spontaneous polarization to other external excitations are related to a number of physical effects such as second-harmonic generation, piezoelectricity, pyroelectricity and dielectric properties. Based on these, this review summarizes recent developments in molecular ferroelectrics since 2011 and focuses on the relationship between symmetry breaking and ferroelectricity, offering ideas for exploring high-performance molecular ferroelectrics. [ABSTRACT FROM AUTHOR]

An ultrasensitive photoelectrochemical (PEC) aptasensor was originally designed by using ZnIn 2 S 4 /ReS 2 as a photoactive material and AgInS 2 as a signal amplifier. The signal amplifier AgInS 2 was incubated on the terminal of H-DNA (immobilized on the ZnIn 2 S 4 /ReS 2 /FTO surface), leading to an enhanced photocurrent response. Then, due to the introduction of DNA2, the formation of a double-stranded structure caused AgInS 2 to keep away from the electrode surface, and the photocurrent was reduced. In the presence of kanamycin, DNA2 was released from the system due to the competition relationship, and a restored photocurrent response was obtained. The combination of ZnIn 2 S 4 /ReS 2 and AgInS 2 accelerated the electron transfer and enhanced the separation efficiency of photogenerated electron-hole pairs, resulting in an improved performance of the PEC aptasensor, which was capable of accurate and sensitive detection of kanamycin in actual samples.

We discovered that [(histamine)(18-crown-6) 2 ][BF 4 ] 2 is a high-temperature host-guest inclusion complex that presents decent piezoelectric properties ( d 33 = 5 pC/N), undergoes a phase transition at 406 K, and also possesses potential ferroelectricity. This work provides a new idea for constructing host-guest inclusion piezoelectrics.

Multiferroic materials have attracted great interest because of their underlying new science and promising applications in data storage and mutual control devices. However, they are still very rare and highly imperative to be developed. Here, we report an organic-inorganic hybrid perovskite trimethylchloromethylammonium chromium chloride (TMCM-CrCl 3 ), showing the coexistence of magnetic and electric orderings. It displays a paraelectric-ferroelectric phase transition at 397 K with an Aizu notation of 6/ mFm , and spin-canted antiferromagnetic ordering with a Néel temperature of 4.8 K. The ferroelectricity originates from the orientational ordering of TMCM cations, and the magnetism is from the [CrCl 3 ] - framework. Remarkably, TMCM-CrCl 3 is the first experimentally confirmed divalent Cr 2+ -based multiferroic material as far as we know. A new category of hybrid multiferroic materials is pointed out in this work, and more Cr 2+ -based multiferroic materials will be expectedly developed in the future., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)

The significant Tc enhancement of 110 K in [N-fluoromethyldabconium] triiodide lead caused by the promising design of H/F substitution is the first and unprecedented, opening up an applicable and universal strategy to effectively regulate the Tc working temperature in phase transition materials.

Molecular bistable dielectric switches represent a class of highly desirable intelligent materials due to their sensitive switchable responses, simple and environmentally friendly processing, light weights, and mechanical flexibility. However, most of these switches can only work at a very low temperature, extremely limiting their potential applications. Herein, three layered organic-inorganic hybrid perovskite-type compounds of the general formula A2BX4, [NH3(CH2)2Cl]2[CdCl3Br] (1), [NH3(CH2)2Cl]2[CdCl4] (2) and [NH3(CH2)2Cl]2[CdBr4] (3), which display sensitive dielectric switching reversibility and remarkable switching anti-fatigue, have been successfully designed. Differential scanning calorimetry and dielectric measurements for 1 confirm its reversible phase transition at around 166 K. Through anion modulation, the phase transition temperatures of 2 and 3 can be greatly improved up to 237 K and 254 K, respectively. Structural analysis discloses that the phase transition temperature's shifts may result from the differences among the inorganic frameworks. Moreover, due to the significant order-disorder transitions of ammonium cations, the permittivities of 1, 2 and 3 change abruptly at around the phase transition points, making them excellent stimuli-responsive electrical switches. Such an anion-modulated method will open up new possibilities of highly efficiently tuning the phase transition temperature of molecular bistable dielectric switches.