A Temperatural Semi-Memorized Phase Transition in a 1D Organic-Inorganic Hybrid Material of Sb|||-Based [(CH2)3NH2S]2SbCl5.

The hybrid organic-inorganic materials have received extraordinary attention from the academic community not only because of their natural chemical tunability but also because of their potential in producing exotic physical properties. However, these characteristics are usually caused by the phase transition of materials under changing of external terms, and it is crucial to fully understand their origins. Here, we research an unusual phase transition near room temperature between two ordered phases in a one-dimensional (1D) hybrid organic-inorganic material of Sb|||-based [(CH2)3NH2S]2SbCl5 (1). This phase transition is caused by collective actions, including the primary variation in the bonds of inorganic five-coordinated tetragonal pyramids, displacement and rotation of organic and inorganic components, along with concurrent hydrogen bonds transformation. Afterward, we observe a significant dielectric anomaly at low frequencies between low and high temperatures. This attributed to the fact that two phases coexist with the lessening temperature, which means that a small number of high-temperature features remained but did not occur during the heating process. These findings offer an avenue for inventing a fresh phase transition and dielectric switch hybrid materials, which further open up the prospect for their practical application.

Chiral Switchable Low-Dimensional Perovskite Ferroelectrics.

Low-dimensional hybrid organic-inorganic perovskites (HOIPs) possess more localized electronic states and narrower conduction and valence bands to promote self-trapping of excitons and stronger exciton emission; therefore, they are widely used as building blocks for various applications in the fields of optoelectronics, photovoltaics, light-emitting diodes, luminescence, fluorescence, and so forth. Despite the past decades of intensive study, the discovered low-dimensional chiral HOIPs are rare as of the 1D chiral HOIP single crystals reported in 2003, as well as the low-dimensional chiral HOIP ferroelectrics are particularly scarce since the first chiral two-dimensional (2D) and/or one-dimensional (1D) HOIP ferroelectrics reported. Herein, two new low-dimensional HOIPs with the same conformational formula [R-MPA]2CdCl4 (R-MPA+ = (R)-(-)-1-methyl-3-phenylpropylamine) were successfully synthetized by means of regulating the stoichiometric proportion of R-MPA and CdCl2 in two ways of 1:1 (1) and 2:1 (2). By combining single-crystal X-ray diffraction, circular dichroism (CD) spectroscopy, differential scanning calorimetry, temperature-dependent dielectric constant, temperature-dependent second-harmonic generation (SHG) effect, polarization-dependent SHG response, and P-E hysteresis loop, we reveal that 1 is a 1D nonchiral molecular ferroelectric and 2 is the first zero-dimensional (0D) chiral ferroelectric with distinct CD signals; meanwhile, 2 exhibits increased properties of high-Tc, large dielectric constant, SHG isotropy, and ferroelectricity than that of 1. These results not only shed light on the high tunability of the low-dimensional HOIP ferroelectrics but also open up an avenue to explore multifunctional chiral ferroelectrics.