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Multifunctional response materials showing potential applications in the fields of sensors and optoelectronic devices have attracted widespread attention. However, the synergistic effect of multiple properties in a molecular compound remains a challenge. Herein, we report a multifunctional response material (TPA)2MnBr4 (1), (TPA+ = tetrapropylamine), which undergoes a reversible structural phase transition at 403/370 K. The phase transition further induces a switchable dielectric anomaly and luminescence response. Moreover, the reversible conversion of the χMT value and fluorescence emission was also observed near the phase transition temperature. This work provides a new impetus for the development of Mn(II)-based multifunctional response materials. [ABSTRACT FROM AUTHOR]

All crystals are not ideal, and many of their properties are often determined not by the regular arrangement of atoms, but by the irregular arrangement of crystal defects. Many properties of materials can be controlled effectively by proper use of solid defects. By substitution of NH4+ ion of a hexagonal perovskite structure (H2dabco)(NH4)(NO3)3 (dabco=1,4‐diazabicyclo[2.2.2]octane, 1) with Cd2+ ion, we obtained a new metal‐vacancy compound (H2dabco)2Cd(H2O)2(NO3)6 (2). It exhibits a ferroelectric‐paraelectric phase transition at 261 K. A comparison of the various‐temperature single‐crystal structures indicates that the coordination twist of Cd2+ ion leads to instability of the lattices and excellent ferroelectricity. These findings reveal that the vacancy can be utilized as an element to produce ferroelectricity and may start the chemistry of metal‐vacancy coordination compounds. These findings reveals that the vacancy can be utilized as an effective means to tune the symmetry and produce ferroelectricity. [ABSTRACT FROM AUTHOR]

Copper (I) based halide scintillators have received high attention due to their high light yield. At the same time, researchers are increasingly interested in exploring organic‐inorganic hybrid copper(I) based halides, due to the diversity and tunability of structures. Here, we describe high‐efficiency photoluminescence and X‐ray excited luminescence in (DFPD)3Cu2I5 (1) (DFPD=4,4‐difluoro‐bipiperidinium). 1 is comprised of a unique [Cu2I5]3− cluster, which have typical structure allowing high‐transition‐probability self‐trapped exciton emission (one Cu+ ion adopts the tetrahedral coordination geometry, the other trigonal planar coordination geometry, the Cu−Cu distance (2.574 Å) is short). Accordingly, 1 shows efficient yellow‐green photoluminescence with the maximum at 527 nm, a full‐width at half‐maximum of 99.2 nm, a large Stokes shift of 214 nm (1.6 eV) and a quantum yield of 77.15 %. Polycrystalline 1 can also convert high‐energy X‐ray photons into UV‐visible pulsed fluorescence with the light yield of 5000 photons/MeV. This finding plays a valuable role in the development of organic‐inorganic hybrid copper(I) based scintillators. [ABSTRACT FROM AUTHOR]

Organic–inorganic hybrid molecular ferroelectrics have attracted broad attention in the field of research of ferroelectric materials. Following the surge of stable candidates, hybrid bimetal molecular-based materials have been recently explored to achieve excellent ferroelectricity. However, rare hybrid bimetal molecular ferroelectrics were reported. Inspired by "ferroelectrochemistry", a chiral nitrite-based hybrid bimetal molecular ferroelectric material, [(R)-3-quinuclidinol]2[LiCo(NO2)6] (1), was reported. The ferroelectric-paraelectric phase transition (C2 ↔ P321) behaviour of 1; was found at 343 K (Curie temperature, Tc) with a spontaneous electronic polarization (Ps) of 0.52 μC cm−2 and a coercive field (Ec) of 48 kV cm−1 at 298 K. Various-temperature single crystal structural analysis and dielectric constant measurements reveal that the rapid rotation of the organic cation and slight order–disorder transition of the NO2− anion are the origin of the ferroelectricity. To our knowledge, 1 is the first example of a nitrite-based hybrid bimetal molecular ferroelectric material that is triggered by an external electric field. This finding establishes a clear stimulus–structure–response relationship in advanced hybrid ferroelectric materials. [ABSTRACT FROM AUTHOR]

Zero-dimensional (0D) hybrid metal halides have attracted much attention due to their rich composition, excellent optical stability, large exciton binding energy, etc. Photoelectric switchable multifunctional materials can integrate multiple physical properties (e.g., ferroelectricity, photoluminescence, magnetic, etc.) into one device and are widely used in many fields such as smart switches, sensors, etc. However, multifunctional materials with thermal energy storage, stimulant dielectric response, and light-emitting properties are rarely reported. Here, we synthesized a new organic–inorganic hybrid metal halide single crystal [TEMA]2MnBr4 (1) (TEMA+ = triethylmethylammonium). Compound 1 undergoes a reversible phase transition at a high temperature of 344/316 K, having a large thermal hysteresis of 28 K and exhibits high stability dielectric switching characteristics near the phase transition temperature. The single crystal exhibits green emission at 513 nm under UV excitation, originating from the 4T1g(G) → 6A1g(S) transition of Mn2+ ions. Excitingly, this single crystal's photoluminescence quantum yield (PLQY) is as high as 80.78%. This work provides a strategy for the development of organic-inorganic hybrid optoelectronic multifunctional materials with high-efficient light emission and switchable dielectric properties. [ABSTRACT FROM AUTHOR]

Multifunctional materials with working temperatures near room temperature are crucial for practical applications. Until now, it is still a great challenge to obtain such materials. In this paper, a complex of (C5NH13Cl)2MnBr4 (1) with a structural phase transition near room temperature is reported. The phase transition induces switchable magnetic properties, dielectric anomalies and luminescent response over the same range of temperatures. It is the first time the synergetic effect of magnetism, dielectricity and luminescence near room temperature have been observed in the same molecular complex. [ABSTRACT FROM AUTHOR]