Investigating the Structure-property Relationships of Two Cd-based Hybrid Multifunctional Compounds with High Tc, Bright Fluorescence and Wide Band-gap.

Organic-inorganic hybrid multifunctional materials have shown significant application in lighting and sensor fields, owing to their prominent performance and diversity structures. Herein, we synthesized two multifunctional compounds: (propyl-quinuclidone)2 CdBr4 (1) and (F-butyl-quinuclidone)2 CdBr4 (2). By introducing light-emitting organic cation with flexible long chain, 1 and 2 exhibit excellent transition properties and bright blue-white fluorescence. Then, combine fluorescence lifetime and first-principal calculation, providing evidence for the electron transfer emission. Subsequently, investigated the impact of substituent carbon chain length (methyl to butyl), structural rigidity (C-C to C-F) and halide framework (Cl to I) on the fluorescence properties. Results indicate that Cd⋅⋅⋅Cd distance and structural rigidity play an important role in fluorescence. Overall, our research provides valuable insight and example for chemical modifications enhance compound performance.

High-Temperature Phase Transition with Switchable Dielectric Behavior and Significant Photoluminescence Changes in a Zero-Dimensional Hybrid SbBr6 Perovskite.

In the past decade, metal halide materials have been favored by many researchers because of their excellent physical and chemical properties under thermal, electrical, and light stimuli, such as ferroelectricity, dielectric, nonlinearity, fluorescence, and semiconductors, greatly promoting their application in optoelectronic devices. In this study, we successfully constructed an unleaded organic-inorganic hybrid perovskite crystal: [Cl-C6H4-(CH2)2NH3]3SbBr6 (1), which underwent a high-temperature reversible phase transition near Tp = 368 K. The phase transition behavior of 1 was characterized by differential scanning calorimetry, accompanied by a thermal hysteresis of 6 K. In addition, variable-temperature Raman spectroscopy analysis and PXRD further verified the sensitivity of 1 to temperature and the phase transition from low symmetry to high symmetry. Temperature-dependent dielectric testing shows that 1 can be a sensitive switching dielectric constant switching material. Remarkably, 1 exhibits strong photoluminescence emission with a wavelength of 478 nm and a narrow band gap of 2.7 eV in semiconductors. As the temperature increases and decreases, fluorescence undergoes significant changes, especially near Tc, which further confirms the reversible phase transition of 1. All of these findings provide new avenues for designing and assembling new phase change materials with high Tp and photoluminescence properties.

Silver/Antimony-Base Multifunctional Double Perovskite with H/F Substitution Enhance Properties.

Two-dimensional double perovskites have experienced rapid development due to their outstanding optoelectronic properties and diverse structural characteristics. However, the synthesis of high-performance multifunctional compounds and the regulation of their properties still lack relevant examples. Herein, we synthesized two multifunctional compounds, (C6H14N)4AgSbBr8 (1) and (F2-C6H12N)4AgSbBr8 (2), which exhibit high solid-state phase transition temperature, bistable dielectric constant switching, second harmonic generation (SHG), and bright emission. Through H/F substitution, the transition temperature increases and achieves a smaller band gap attributed to reduced interlayer spacing. Furthermore, we investigated the broad emission mechanism of the compounds through first-principles calculation and variable-temperature fluorescence, confirming the presence of the STE1 emission. Our work provides insight into the further development of multifunctional compounds and chemical modification that enhances compound properties.

Targeting inflammatory macrophages rebuilds therapeutic efficacy of DOT1L inhibition in hepatocellular carcinoma.

Epigenetic reprogramming is a promising therapeutic strategy for aggressive cancers, but its limitations in vivo remain unclear. Here, we showed, in detailed studies of data regarding 410 patients with human hepatocellular carcinoma (HCC), that increased histone methyltransferase DOT1L triggered epithelial-mesenchymal transition-mediated metastasis and served as a therapeutic target for human HCC. Unexpectedly, although targeting DOT1L in vitro abrogated the invasive potential of hepatoma cells, abrogation of DOT1L signals hardly affected the metastasis of hepatoma in vivo. Macrophages, which constitute the major cellular component of the stroma, abrogated the anti-metastatic effect of DOT1L targeting. Mechanistically, NF-κB signal elicited by macrophage inflammatory response operated via a non-epigenetic machinery to eliminate the therapeutic efficacy of DOT1L targeting. Importantly, therapeutic strategy combining DOT1L-targeted therapy with macrophage depletion or NF-κB inhibition in vivo effectively and successfully elicited cancer regression. Moreover, we found that the densities of macrophages in HCC determined malignant cell DOT1L-associated clinical outcome of the patients. Our results provide insight into the crosstalk between epigenetic reprogramming and cancer microenvironments and suggest that strategies to influence the functional activities of inflammatory cells may benefit epigenetic reprogramming therapy.

Dielectric Relaxation and Dielectric Switching Behaviors in (N,N-Diisopropylethylamine) Tetrachloroantimonate(III).

Dielectric switches have drawn renewed attention to the study of their many potential applications with the adjustable switch temperatures (Ts ). Herein, a novel antimony-based halide semiconductor, (N,N-diisopropylethylamine) tetrachloroantimonate ((DIPEA)SbCl4 , DIPEA+ =N,N-diisopropylethylamine), with dielectric relaxation behavior and dielectric switches has been successfully synthesized. This compound, consisting of coordinated anion S b C l 4 ∞ - ${{\left[{{\rm S}{\rm b}{\rm C}{\rm l}}_{4}\right]}_{\infty }^{-}}$ chains and isolated DIPEA+ cations, undergoes an isostructural order-disorder phase transition and shows a step-like dielectric anomaly, which can function as a frequency-tuned dielectric switch with highly adjustable switch temperature (Ts ). Variable-temperature single-crystal structure analyses and first-principles molecular dynamics simulations give information about the general mechanisms of molecular dynamics. This work enriches the dielectric switch family and proves that hybrid metal halides are promising candidates for switchable physical or chemical properties.

High-Tc 1D Phase-Transition Semiconductor Photoluminescent Material with Broadband Emission.

One dimensional (1D) organic-inorganic halide hybrid perovskites have the advantages of excellent organic cation modifiability and diversity of inorganic framework structures, which cannot be ignored in the development of multi-functional phase-transition materials in photoelectric and photovoltaic devices. Here, we have successfully modified and synthesized an organic-inorganic hybrid perovskite photoelectric multifunctional phase-transition material: [C7 H13 ONCH2 F]⋅PbBr3 (1). The synergistic effect of the order double disorder transition of organic cations and the change of the degree of distortion of the inorganic framework leads to its high temperature reversible phase-transition point of Tc =374 K/346 K and its ultra-low loss high-quality dielectric switch response. Through in-depth research and calculation, compound 1 also has excellent semiconductor characteristics with a band gap of 3.06 eV and the photoluminescence characteristics of self-trapped exciton (STE) broadband emission. Undoubtedly, this modification strategy provides a new choice for the research field of organic-inorganic hybrid perovskite reversible phase-transition photoelectric multifunctional materials with rich coupling properties.

Zero-Dimensional Sn-Based Enantiomeric Phase-Transition Materials with High-Tc and Dielectric Switching.

The combination of chirality and phase-transition materials has broad application prospects. Therefore, based on the quasi-spherical theory and the thought strategy of introducing chirality, we have successfully synthesized a pair of chiral enantiomeric ligands (R/S)-triethyl-(2-hydroxypropyl)ammonium iodide, which can be combined with a tin hexachloride anion to obtain a pair of new organic-inorganic hybrid enantiomeric high-temperature plastic phase-transition materials: (R/S)-[CH3 CH(OH)CH2 N(CH2 CH3 )3 ]2 SnCl6 (1-R/1-S), which have a high temperature phase transition of Tc =384 K, crystallize in the P21 chiral space group at room temperature, and have obvious CD signals. In addition, compounds 1-R and 1-S have a good low-loss dielectric switch and broadband gap. This work is conducive to the research into chiral high-temperature reversible plastic phase-transition materials, and promotes the development of multi-functional phase-transition materials.

Excellent Switchable Properties, Broad-Band Emission, Ferroelectricity, and High Tc in a Two-Dimensional Hybrid Perovskite: (4,4-DCA)2PbBr4 Exploited by H/F Substitution.

Switchable materials have gained significant attention due to their potential applications in data storage, sensors, and switching devices. Two-dimensional (2D) hybrid perovskites have demonstrated promising prospects for designing switchable materials, where the dynamic motion of the organic components coupled with the distortion of the inorganic framework provides the driving force for triggering multifunctional switchable properties. Herein, through the H/F substitution strategy, we report a polar 2D hybrid lead-based perovskite, (4,4-DCA)2PbBr4 (4,4-DCA = 4,4-difluorocyclohexylammonium) (1), which exhibits dual-stable behavior in a dielectric and second harmonic generation (SHG) response during the reversible phase transition process near the high Curie temperature Tc ∼ 409 K. The phase transition temperature is significantly increased by 41 K compared to the corresponding non-fluorinated (CHA)2PbBr4 (CHA = cyclohexylammonium). Remarkably, the material shows rare broad-band yellow emission under UV excitation, attributed to the induction of self-trapped exciton emission by the distortion of the [PbBr6]4- octahedra, as confirmed by the first-principles analysis. 1 also exhibited ferroelectricity with a saturation polarization value and a small coercive field. This study provides a new insight into the modification of multifunctional switchable materials through the H/F substitution strategy.

High-Temperature Ferroelasticity and Photoluminescence in a 2D Monolayer Perovskite Compound: (C5NH8Br)2PbBr4.

Hybrid organic-inorganic perovskites (HOIPs) have attracted much attention due to their excellent properties and easy synthesis. As far as we know, most documented ferroelastics mainly focus on the 3D (three-dimensional) perovskites, the 2D monolayer perovskite ferroelastics are rarely reported before. In this work, we synthesized a 2D lead-based perovskite (C5NH13Br)2PbBr4 (1) (C5NH13Br = 5-bromoamylamine cation) by introducing flexible chain organic cations. The evolution of ferroelastic domains observed by a polarized light microscope confirms that compound 1 undergoes a ferroelastic phase transition at 392/384 K. In addition, its direct band gap is 2.877 eV. Interestingly, the material emits an attractive blue light (quantum yield 5.06%) under UV light. Three structural descriptors are introduced to quantitatively analyze the relationship between structural distortion and the shape of emission peak. This work provides a way to design multifunctional perovskite-type materials.

Large Spontaneous Polarization Ferroelectric Property, Switchable Second-Harmonic Generation Responses, and Magnetism in an Fe-Based Compound.

Since the switchable spontaneous polarization of ferroelectric materials endows it with many useful properties such as a large pyroelectric coefficient, switchable spontaneous polarization, and semiconductor, it has a wide range of application prospects, and the research of high-performance molecular ferroelectric materials has become a hot spot. We obtained a 0D organic-inorganic hybrid ferroelectric [(CH3)3NCH2CH2CH3]2FeCl4 (1) with well-defined ferroelectric domains and excellent domain inversion and exhibited a relatively large spontaneous polarization (Ps = 9 µC/m-2) and a Curie temperature (Tc) of 394 K. Furthermore, compound 1 belongs to the non-centrosymmetrical space group Cmc21 and has a strong second-harmonic generation signal. Interestingly, we also performed magnetic tests on 1, which confirmed that it is a magnetic material. This work provides clues for exploring the application of high-performance molecular ferroelectric materials in future multifunctional smart devices.

Two Manganese(II)-Based Hybrid Multifunctional Phase Transition Materials with Strong Photoluminescence, High Quantum Yield, and Switchable Dielectric Properties: (C6NH16)2MnBr4 and (C7NH18)2MnBr4.

Multifunctional materials have always been an attractive research area, but how to combine multiple excellent properties in one compound remains a considerable challenge. Organic-inorganic hybrid compounds are widely used in the design of such materials due to their rich properties and flexible assembly. Herein, two new manganese(II)-based organic-inorganic hybrid compounds, (C6NH16)2MnBr4 (1) and (C7NH18)2MnBr4 (2), are prepared by the solution method. Compounds 1 and 2 both emit extremely strong green light under UV excitation, with high quantum yields of 45.93 and 50.98%, respectively. In addition, reversible solid-state phase transitions and obvious switchable dielectric properties are shown at 378/366 and 361/352 K, respectively. The coexistence of the dual stimulus-response characteristics of temperature and light in compounds 1 and 2 opens a new path for exploring more multifunctional phase transition materials.

A Narrow Bandgap of 2D Ruddlesden-Popper Bilayer Perovskite with Giant Entropy Change and Photoluminescence.

The multifunctional two-dimensional (2D) organic-inorganic hybrid perovskites have potential applications in many fields, such as, semiconductor, energy storage and fluorescent device etc. Here, a 2D Ruddlesden-Popper (RP) perovskite (IPA)2 (FA)Pb2 I7 (1, IPA+ =C3 H9 NI+ , FA+ =CN2 H5 + ) is determined for its photophysical properties. Strikingly, 1 reveals a solid reversible phase transition with Tc of 382 K accompanied by giant entropy change of 40 J mol-1 K-1 . Further optical investigations indicate that 1 reveals a narrow direct bandgap (2.024 eV) attributed to the slight bending of I-Pb-I edge and inorganic [Pb2 I7 ]n layer and a superior photoluminescence (PL) emission with super long lifetime of 0.1607 ms. It is believed that this work will pave an avenue to further design multifunctional semiconductors that combines energy storage and photoelectric materials.

High-Temperature and Large-Polarization Ferroelectric with Second Harmonic Generation Response in a Novel Crown Ether Clathrate.

Molecular ferroelectrics of high-temperature reversible phase transitions are very rare and have attracted increasing attention in recent years. In this paper is described the successful synthesis of a novel high-temperature host-guest inclusion ferroelectric: [(C6 H5 NF3 )(18-crown-6)][BF4 ] (1) that shows a pair of reversible peaks at 348 K (heating) and 331 K (cooling) with a heat hysteresis about 17 K by differential scanning calorimetry measurements, thus indicating that 1 undergoes a reversible structural phase transition. Variable-temperature PXRD and temperature-dependent dielectric measurements further prove the phase-transition behavior of 1. The second harmonic response demonstrates that 1 belongs to a non-centrosymmetric space group at room temperature and is a good nonlinear optical material. In its semiconducting properties, 1 shows a wide optical band gap of about 4.43 eV that comes chiefly from the C, H and O atoms of the crystals. In particular, the ferroelectric measurements of 1 exhibit a typical polarization-electric hysteresis loop with a large spontaneous polarization (Ps ) of about 4.06 µC/cm2 . This finding offers an alternative pathway for designing new ferroelectric-dielectric and nonlinear optical materials and related physical properties in organic-inorganic and other hybrid crystals.

Coupling Narrow Band Gap and Switchable SHG Responses in a New Molecule Ferroelectric: Imidazolyl Propylamine Pentabromo Stibium(III).

Due to the existence of some cross properties such as SHG (second-harmonic generation), ferroelectricity, piezoelectricity, and thermoelectricity, molecular ferroelectrics have been widely used as a composite multipurpose material. Particularly, organic-inorganic molecular ferroelectrics have received much interest recently because of their unique flexible structures, friendly environment, ease of synthesis, etc. Also, these hybrids show great flexibility in band-gap engineering. Here we report a new molecular halide, [C6H13N3SbBr5]n (1; C6H13N3 = 1-(3-aminopropyl)imidazole), which experiences a unique ferroelectric to paraelectric phase transition at around 230 K from space group P21 to P21/c. Significantly, compound 1 exhibits a narrow band gap with a value of 2.52 eV, large pronounced SHG-active, perfect rectangle hysteresis loops with a large spontaneous polarization of 6.86 µC/cm2. DSC (differential scanning calorimetry) and dielectric dependence on temperature tests and the volume change before and after the phase transition show that compound 1 is characterized by a second-order phase transition. These findings will contribute to the multifunctional materials field of organic-inorganic hybrids.

High-Temperature Phase Transition Containing Switchable Dielectric Behavior, Long Fluorescence Lifetime, and Distinct Photoluminescence Changes in a 2D Hybrid CuBr4 Perovskite.

A novel organic-inorganic hybrid perovskite crystal, [ClC6H4(CH2)2NH3]2CuBr4 (1), having experienced an invertible high-temperature phase transition near Tc (the Curie temperature Tc = 355 K), has been successfully synthesized. The phase-transition characteristics for compound 1 are thoroughly revealed by specific heat capacity (Cp), differential thermal analysis, and differential scanning calorimetry tests, possessing 16 K broad thermal hysteresis. Multiple-temperature powder X-ray diffraction analysis further proves the phase-transition behavior of compound 1. Moreover, compound 1 exhibits a significant steplike dielectric response near Tc, revealing that it can be deemed to be a promising dielectric switching material. The variable-temperature fluorescence experiments show distinct photoluminescence (PL) changes of compound 1. Further investigation and calculation disclose that the fluorescence lifetime of compound 1 can reach as long as 55.46 µs, indicating that it can be a potential PL material. All of these researches contribute a substitutable avenue in the design and construction of neoteric phase-transition compounds combining high Curie temperature and PL properties.

Two Rare-Earth Molecular Ferroelectrics with High Curie Temperatures, Large Spontaneous Polarization, Switchable Second Harmonic Generation Effects, and Strong Photoluminescence.

Smart multifunctional molecular ferroelectrics bearing high Curie temperatures and diverse excellent physical properties, such as second harmonic generation (SHG) responses, luminescence, and semiconductivity, among others, have significant applications but have seldom been documented. Herein, the rare-earth metals Nd and Pr are introduced into a simple molecular system (nBu4 N)3 [M(NO3 )x (SCN)y ] (nBu4 N= tetrabutyl ammonium, M=rare-earth metal, nBu=CH3 CH2 CH2 CH2 ), and two new multifunctional molecular ferroelectrics are obtained: (nBu4 N)3 [Nd(NO3 )4 (SCN)2 ] (1) and (nBu4 N)3 [Pr(NO3 )4 (SCN)2 ] (2). Their distinct heat and dielectric anomaly dependence on temperature verifies that compounds 1 and 2 experience high-temperature para-ferroelectric phase transitions at 408 and 413 K, respectively. Strikingly, both molecular ferroelectrics possess large spontaneous polarization with Ps values of 9.05 and 8.50 µC cm-2 , respectively, and are further characterized by the appearance of multiple intersecting non-180° domains and polarization switching behavior. In particular, compounds 1 and 2 show good stability with only a small decrease in SHG intensity after switching cycles, suggesting that they have great potential for application in nonlinear optical (NLO) switches. Simultaneously, the rare-earth compounds 1 and 2 present bright yellow-red and bright green fluorescence, respectively, at room temperature.

Reversible Phase Transition with Ultralarge Dielectric Relaxation Behaviors in Succinimide Lithium(I) Hybrids.

Dielectric relaxations have widely applied on high permittivity capacitors, dielectric switches, ferroelectrics, pyroelectrics, and electrical insulating materials. However, few investigations of large dielectric relaxation behaviors on organic-inorganic hybrid materials have been documented before. Here we present a novel two-dimensional succinimide lithium(I) hybrid compound, [Li(PDD)2ClO4]n, 1, (PDD = 2,5-pyrrolidinedione = succinimide) which shows reversible phase transition behavior in the vicinity of 228 K accompanied by an unusual symmetry breaking from I41/amd to C2/c. X-ray single crystal diffractions analysis indicates the twist motion of pyrrolidine heterocycles, and order-disorder motion of ClO4- anions triggered the reversible phase transition. By means of an intuitive crystallographic model (rattling ion model), we further illustrated the mechanism of the interesting reversible phase transition. Particularly, 1 shows ultralarge dielectric relaxation behavior in the vicinity of the phase transition by its dielectric constant dependence on temperatures and frequencies as well as its Cole-Cole relation.

Unusual High-Temperature Reversible Phase-Transition Behavior, Structures, and Dielectric-Ferroelectric Properties of Two New Crown Ether Clathrates.

Molecular ferroelectrics with high-temperature reversible phase-transition behaviors are very rare and have currently become one of the hotspots in the field of ferroelectric materials. Herein we display two new crown ether clathrates possessing unusual high-temperature ferroelectric phase-transition behaviors, cyclohexyl ammonium 18-crown-6 tetrafluoroborate (or perchlorate), [Hcha-(18-crown-6)](+) [BF4](-) (1) and [Hcha-(18-crown-6)](+)[ClO4](-) (2) (Hcha = protonated cyclohexyl ammonium). We have proven their reversible structural phase transitions by variable-temperature PXRD measurements and temperature evolutions of Raman bands. Both clathrates exhibit clear ferroelectric phase transitions at about 397 and 390 K, respectively, revealed by the thermal anomalies of differential scanning calorimetry (DSC) measurements, together with abrupt dielectric anomalies in the heating and cooling processes. The measurements on ferroelectric properties using the single crystals showed optimized spontaneous polarization (Ps) of ca. 3.27 µC cm(-2) for 1 and 3.78 µC cm(-2) for 2.

Spontaneous resolution, asymmetric catalysis, and fluorescence properties of δ- and λ-[cu(tzmp)]N enantiomers from in situ [2 + 3] cycloaddition synthesis.

Although a number of acentric or chiral tetrazole complexes were synthesized from Sharpless reaction, there are no spontaneous resolution Cu(I)-tetrazole compounds from in situ [2 + 3] cycloaddition synthesis that have been reported before. The first enantiomers Δ- and Λ- of metal tetrazole compound [Cu(Tzmp)]n (1) (HTzmp = 3-tetrazolemethylpyridine) were obtained and isolated from in situ [2 + 3] cycloaddition reactions of a flexible organic nitrile (3-cyanomethylpyridine) with sodium azide in the presence of CuCl2 as the Lewis acid. Δ-1 and Λ-1 feature a homochiral helical coordination polymeric system and {4(4).6(2)} two-dimensional framework. The photoluminescence study suggests 1 exhibits strong green fluorescence in solid state with maximal emission peaks around 535 nm. Remarkably, the Δ- and Λ- of [Cu(Tzmp)]n (1) catalyzes the enantioselective Henry reaction with high yield (more than 96%) and certain enantioselectivity (up to 69%).

In situ synthesis and ferroelectric, SHG response, and luminescent properties of a novel 3D acentric zinc coordination polymer.

The 3D acentric metal-organic framework (MOF) of [Zn(Mitz)Cl](n) [1; Mitz = 3-tetrazolyl-6-methyl-5-(4-pyridyl)-2-pyridone] was obtained from in situ [2 + 3] cycloaddition reactions of milrinone [=3-cyano-6-methyl-5-(4-pyridyl)-2-pyridone] with sodium azide in the presence of ZnCl(2) as the Lewis acid. The compound is a typical ferroelectric material with an electric hysteresis loop showing a remnant polarization (P(r)) of ca. 0.21 µC/cm(2) and a coercive field (E(c)) of 2600 V/cm. Powdered samples of 1 display strong second-harmonic-generation responses of ∼2 times larger than that of KH(2)PO(4). Photoluminescent study show that complex 1 and the milrinone ligand exhibit maximal emission peaks at around 409 and 401 nm, respectively, in the solid state at room temperature.