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Organic–inorganic hybrid perovskites are categorized as multifunctional materials due to their structural designability and functional diversity. Herein, two manganese-based organic–inorganic perovskite type compounds [Me3NNH2]MnCl3 (1) and [(CH3)3NCH2CH2F]2MnCl4 (2) were synthesized by reactions of trimethylhydrazine iodide and (fluoromethyl)trimethylammonium bromide with MnCl2 in concentrated hydrochloric acid aqueous solution. Differential scanning calorimetry (DSC) and dielectric measurements revealed that compounds 1 and 2 undergo reversible phase transitions at about 327 K and 352 K, respectively. Significantly, under the excitation of 365 nm, compounds 1 and 2 emit green and red luminescence, which originate from the octahedral [MnCl6] and tetrahedral [MnCl4] moieties. [ABSTRACT FROM AUTHOR]

Often, the quasi-spherical molecule 1,4-diazabicyclo[2.2.2]octane (2.2.2-dabco) is chosen to prepare switchable materials with a high phase transition temperature. We wished to reduce molecular symmetry but maintain a quasi-spherical shape. Hence, a similar molecule, 1,4-diazabicyclo[3.2.2]nonane (3.2.2-dabcn), was used to react with equimolar amounts of HClO4 or HReO4 in aqueous solution. Two compounds [3.2.2-Hdabcn]X (X = ClO4, 1; ReO4, 2) with high phase-transition points at 418 K for 1 and 394.6 K and 419.2 K for 2, respectively, were isolated, in which one-dimensional cationic chains were connected by different types of hydrogen bonds. Differential scanning calorimetry and dielectric-permittivity measurements revealed that 1 and 2 showed switchable phase transition and dielectric anomalies. Compound 1 also showed a reversible second-harmonic-generation effect. [ABSTRACT FROM AUTHOR]

A one-dimensional organic–inorganic hybrid perovskite material [3.3.0-dabco]PbBr3 (1) was synthesized by the reaction of 1,5-diazabicyclo[3.3.0]octane (3.3.0-dabco) with PbBr2 in concentrated HBr aqueous solution. Differential scanning calorimetry, dielectric measurements, and variable-temperature structural analyses revealed that compound 1 exhibits two successive structural phase transitions from P212121 to Pbcm at 387 K (T1) and then to P6/mmc at 436 K (T2), accompanied by two pairs of dielectric anomalies with a clear one at T1 and an unobvious one at T2. In addition, compound 1 shows a robust second harmonic generation (SHG) effect between SHG-OFF and SHG-ON states during its centrosymmetric to non-centrosymmetric symmetry breaking phase transition at T1. [ABSTRACT FROM AUTHOR]

Organic–inorganic hybrid materials with perovskite structure have recently attracted tremendous interest due to their structural tunability and rich functional properties, such as phase transition and photoelectric properties. Within this context, two discrete tin-based organic–inorganic hybrid compounds [(FMBA)2SnCl6] (1) and [(FMBA)2SnBr6] (2) were prepared by the reaction of 3-fluoro-N-methylbenzylamine (FMBA) with SnX4 (X = Cl, Br) in the corresponding concentrated halogen acids HX. Differential scanning calorimetry (DSC) and dielectric measurements showed that both compounds underwent reversible phase transition and dielectric anomaly at a phase transition point above 400 K. Crystal structure analyses revealed that the phase transition mainly originated from the order and disorder of a fluorine-substituted organic amine structure at low and high temperatures. Meanwhile, both compounds showed a semiconducting property with optical bandgaps of 4.24 eV for 1 and 2.58 eV for 2. This finding of two Sn(IV)-based metal halides with prominent phase transition and semiconducting behaviors will expand an executable pathway for designing multifunctional perovskite-type switchable materials. [ABSTRACT FROM AUTHOR]