Antimony Bromide Organic–Inorganic Hybrid Compound with a Long-Chain Diamine Showing Switchable Phase Transition and Second-Harmonic Generation Properties

Organic–inorganic hybrid metal halides have attracted significant attention in recent years due to their excellent optoelectronic properties and potential applications in solar cells. Herein, the organic–inorganic hybrid molecule [N,N-dimethyl-1,3-propanediamine]SbBr5 (1) was synthesized by reacting a long-chain organic diamine N,N-dimethyl-1,3-propanediamine with SbBr3 as a metal halide precursor in HBr aqueous solution. Compound 1 possesses a one-dimensional chainlike structure with the second-harmonic generation switch and two continuous phase transitions above room temperature. The band gap of compound 1 is about 2.62 eV, exhibiting a semiconductive property, which may have important implications for the development of new optoelectronic devices

Organic–Inorganic Hybrid Compound [H₂‑1,5-Diazabicyclo[3.3.0]octane]ZnBr₄ with Reverse Symmetry Breaking Shows a Switchable Dielectric Anomaly and Robust Second Harmonic Generation Effect

An organic–inorganic hybrid molecule [3.3.0-H2dabco]­ZnBr4 (1) with switchable phase transition, dielectric anomaly, and second harmonic generation (SHG) effect was synthesized by reaction of 1,5-diazabicyclo[3.3.0]­octane (3.3.0-dabco) with ZnBr2 in concentrated hydrobromic acid aqueous solution. Differential scanning calorimetry (DSC) and dielectric measurements revealed that 1 exhibits a reversible high-temperature phase transition, accompanied by a distinct step-like dielectric anomaly at 373 K. Exceptionally, the single crystal structure analysis at different temperatures revealed that 1 undergoes reverse symmetry breaking during the phase transition, in which the high-symmetry space group Cc in the low temperature phase (LTP) is transformed to the low-symmetry space group P1̅ in the high temperature phase (HTP). In addition, with the conversion from the non-centrosymmetric (NCS) to the centrosymmetric (CS) space group, the SHG of 1 can switch from SHG-ON to SHG-OFF for at least four cycles without obvious decay

Alkali Metal Organic–Inorganic Hybrid Compounds with Different Crystal Dimensions Show Phase-Transition, Dielectric, and SHG Properties Based on a Quasi-Spherical Amine (1<i>S</i>,4<i>S</i>)‑2,5-Diazabicyclo[2.2.1]heptane

Reactions of a chiral and quasi-spherical molecule [1S,4S-2,5–2.2.1-H2dabch]I2 (1) with alkali metal halide MX (M = Na, K, Cs; X = Cl, Br) at room temperature produced a series of organic–inorganic hybrid (OIH) materials [1S,4S-2,5–2.2.1-H2dabch]NaBr3 (2), [1S,4S-2,5–2.2.1-H2dabch]CsCl3·H2O (3) and [1S,4S-2,5–2.2.1-H2dabch]KBr3·H2O (4). The single-crystal X-ray diffraction analysis revealed that the organic–inorganic framework structures comprised of the templating ligand and alkali metal halides (NaBr, CsCl, KBr) displayed dimensions spanning from one-dimensional (1D) to three-dimensional (3D). Moreover, the results of both differential scanning calorimetry (DSC) and dielectric measurements demonstrated that compounds 1–4 displayed reversible, high-temperature phase transitions and noticeable dielectric anomalies. In addition, the temperature-dependent second harmonic generation (SHG) results revealed crystals 1 and 3 can switch from the SHG-ON to the SHG-OFF state, which was proved by the variable-temperature X-ray diffraction. This research aims to streamline the exploration of multifunctional second harmonic generation (SHG) and dielectric materials that have been synthesized using chiral ligands and alkali metals. This will provide researchers with enhanced opportunities to delve further into this specific research domain

The templating effect of 1,2-cyclohexanediamine configuration on iodoplumbate organic–inorganic hybrid structures

Reactions of R, R-, cis- and trans-1,2-cyclohexanediamine with lead(II) iodide in concentrated HI aqueous solution afforded three organic–inorganic hybrid compounds, [(R, R-1,2-C6H16N2)PbI4] (1), [(cis-1,2-C6H16N2)2Pb2I8]·2H2O (2) and [(trans-1,2-C6H16N2)2PbI6]·2H2O (3), respectively. Single-crystal X-ray diffraction revealed that the inorganic components in 1–3 are constructed with a 2-D monolayer perovskite sheet, a 1-D zigzag chain and only a concrete [PbI6] octahedron which were caused by the different configurations of 1,2-cyclohexanediamine. In addition, 1–3 have been investigated by UV–vis, TG analysis and fluorescence spectra.</p

Three-Dimensional Perovskite Phase Transition Materials with Switchable Second Harmonic Generation Properties Introduced by Homochiral (1<i>S</i>,4<i>S</i>)‑2,5-Diazabicyclo[2.2.1]-heptane

Switchable second harmonic generation (SHG) materials have potential applications in information storage, signal processing, and so on because they can switch between SHG-on and SHG-off states. In this work, we designed and synthesized three organic–inorganic hybrid Rb halide three-dimensional (3D) perovskite materials [1S,4S 2,5-2.2.1-H2dabch]RbX3·0.5H2O (X = Cl, 1; Br, 2; I, 3) based on the chiral 1S,4S-2,5-diazabicyclo[2.2.1]heptane (1S,4S-2,5-2.2.1-dabch). The selection of homochiral organic cations ensures that the compounds 1∼3 crystallize in the noncentrosymmetric and chiral space group P212121, which further leads to reversible SHG responses of the three compounds. Through differential scanning calorimetry (DSC) and dielectric measurements, it revealed that the phase transition point of the compounds 1∼3 increased with RbCl, RbBr, and RbI. This is because the hydrogen interaction H···X between the inorganic framework [RbX3]n and the organic cation [1S,4S-2,5-2.2.1-H2dabch]2+ is increased with the order of I > Br > Cl. This study can provide an effective molecular design strategy for the exploration and construction of temperature-tunable SHG switching materials

3D Perovskite (1,5-3.2.2‑H₂dabcn)CsBr₃ with Reverse Symmetry Breaking

Even though hybrid organic–inorganic perovskites (HOIPs) have been studied by many scholars in recent years, there are not many reports on three-dimensional (3D) alkali metal cesium halide perovskites. Here, we report an unprecedented 3D HOIP molecule (1,5-3.2.2-H2dabcn)CsBr3 (1), in which the 3D anionic framework is constructed by corner-sharing CsBr6 octahedra and organic cations [1,5-3.2.2-H2dabcn]2+ are located in the cavities formed by the octahedra. Organic cations interact with an inorganic metal frame via two N–H···Br hydrogen bonds. Compound 1 undergoes a reversible order–disorder phase transition and exhibits switchable dielectric and second-harmonic generation (SHG) properties. Interestingly, product 1 crystallizes in a non-centrosymmetric space group Pmn21 at the low-temperature phase (LTP) and transforms into a centrosymmetric space group P2/m at the high-temperature phase (HTP). The space group Pmn21 in the LTP has a higher symmetry than P2/m in the HTP. This inverted symmetry breaking is very unusual

The Role of Fluorine-Substituted Positions on the Phase Transition in Organic–Inorganic Hybrid Perovskite Compounds

Although research on organic–inorganic hybrid perovskites (OIHPs) has grown exponentially in the past two decades, the high phase transition temperature of OIHP materials is still one of the insurmountable difficulties. Herein, a series of A2BX4 type OIHP materials [(2,n-DFBA)2PbCl4] (n = 3, for 1; n = 4, for 2; n = 5, for 3; n = 6, for 4) have been prepared by reactions of double-substituted difluorobenzylamine (difluorobenzylamine = DFBA) with lead chloride in concentrated HCl aqueous solution. It was found the OIHP compounds 1–3 proceed a switchable phase transition with phase transition temperatures (Tc) at 449 K (1), 462 K (2) and 500 K (3), higher than that of the parent compound [(BA)2PbCl4] (BA = benzylammonium) at 438 K, but compound 4 exhibits no phase transition. A crystal structure analysis elucidated that the organic template ligands DFBA lead in the inorganic part in compounds 1–3 to a two-dimensional (2D) perovskite structure, while that in compound 4 leads to a one-dimensional (1D) chain structure. The different double-substituted positions of fluorine atoms on benzylamine have important influences on the phase transition in compounds 1–4

Discovery of an Antiperovskite Ferroelectric in [(CH₃)₃NH]₃(MnBr₃)(MnBr₄)

It is known that perovskites with the general chemical formula of ABX3 (A, B = cations, X = anion) have been intensively studied over the last half century because of their diverse functional properties, such as ferroelectricity in BaTiO3, piezoelectricity in PZT (lead zirconate titanate), and recently developed photovoltaic properties in CH3NH3PbI3. However, rather less attention has been paid to their “inverse” analogs, antiperovskites, which have a chemical formula X3BA, where A and B are anions and X is a cation. Although most of important ferroelectrics are perovskites, no antiperovskite ferroelectrics have been found since the discovery of antiperovskites in 1930. Here, for the first time, we report a X3BA antiperovskite ferroelectric [(CH3)3NH]3(MnBr3)­(MnBr4) (where (CH3)3NH is X, MnBr3 is B, and MnBr4 is A), which shows outstanding ferroelectricity with a significantly high phase transition temperature of 458 K as well as fascinating photoluminescence properties with two intense emissions. This finding opens a new avenue to explore the golden area of antiperovskites for high-performance functional materials

<i>N</i>‑Allylation of Azoles with Hydrogen Evolution Enabled by Visible-Light Photocatalysis

Direct N-allylation of azoles with hydrogen evolution has been achieved through the synergistic combination of organic photocatalysis and cobalt catalysis. The protocol bypasses stoichiometric oxidants and prefunctionalization of alkenes and produces hydrogen (H2) as the byproduct. This transformation highlights high step- and atom-economy, high efficiency, and broad functional group tolerance for further derivatization, which opens a door for C–N bond formation that is valuable in heterocyclic chemistry

Discovery of an Antiperovskite Ferroelectric in [(CH₃)₃NH]₃(MnBr₃)(MnBr₄)

It is known that perovskites with the general chemical formula of ABX₃ (A, B = cations, X = anion) have been intensively studied over the last half century because of their diverse functional properties, such as ferroelectricity in BaTiO₃, piezoelectricity in PZT (lead zirconate titanate), and recently developed photovoltaic properties in CH₃NH₃PbI₃. However, rather less attention has been paid to their “inverse” analogs, antiperovskites, which have a chemical formula X₃BA, where A and B are anions and X is a cation. Although most of important ferroelectrics are perovskites, no antiperovskite ferroelectrics have been found since the discovery of antiperovskites in 1930. Here, for the first time, we report a X₃BA antiperovskite ferroelectric [(CH₃)₃NH]₃(MnBr₃)­(MnBr₄) (where (CH₃)₃NH is X, MnBr₃ is B, and MnBr₄ is A), which shows outstanding ferroelectricity with a significantly high phase transition temperature of 458 K as well as fascinating photoluminescence properties with two intense emissions. This finding opens a new avenue to explore the golden area of antiperovskites for high-performance functional materials