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1.
Proc Natl Acad Sci U S A ; 120(43): e2311585120, 2023 Oct 24.
Artigo em Inglês | MEDLINE | ID: mdl-37844255

RESUMO

Single-atom Fenton-like catalysis has attracted significant attention, yet the quest for controllable synthesis of single-atom catalysts (SACs) with modulation of electron configuration is driven by the current disadvantages of poor activity, low selectivity, narrow pH range, and ambiguous structure-performance relationship. Herein, we devised an innovative strategy, the slow-release synthesis, to fabricate superior Cu SACs by facilitating the dynamic equilibrium between metal precursor supply and anchoring site formation. In this strategy, the dynamics of anchoring site formation, metal precursor release, and their binding reaction kinetics were regulated. Bolstered by harmoniously aligned dynamics, the selective and specific monatomic binding reactions were ensured to refine controllable SACs synthesis with well-defined structure-reactivity relationship. A copious quantity of monatomic dispersed metal became deposited on the C3N4/montmorillonite (MMT) interface and surface with accessible exposure due to the convenient mass transfer within ordered MMT. The slow-release effect facilitated the generation of targeted high-quality sites by equilibrating the supply and demand of the metal precursor and anchoring site and improved the utilization ratio of metal precursors. An excellent Fenton-like reactivity for contaminant degradation was achieved by the Cu1/C3N4/MMT with diminished toxic Cu liberation. Also, the selective ·OH-mediated reaction mechanism was elucidated. Our findings provide a strategy for regulating the intractable anchoring events and optimizing the microenvironment of the monatomic metal center to synthesize superior SACs.

2.
J Am Chem Soc ; 145(42): 23292-23299, 2023 Oct 25.
Artigo em Inglês | MEDLINE | ID: mdl-37819908

RESUMO

Fullerenes offer versatile functionalities and are promising materials for a widespread range of applications from biomedicine and energy to electronics. Great efforts have been made to manipulate the symmetries of fullerene and its derivatives for studying material properties and novel effects, such as ferroelectricity with polar symmetry; however, no documentary report has been obtained to realize their ferroelectricity. Here, for the first time, we demonstrated clear ferroelectricity in a fullerene adduct formed by C60 and S8. More is different: the combination of the most symmetric molecule C60 with the highest Ih symmetry and molecule S8 with high D4d symmetry resulted in the polar C60S8 adduct with a low crystallographic symmetry of the C2v (mm2) point group at room temperature. The presented C60S8 undergoes polar-to-polar ferroelectric phase transition with the mm2Fm notation, whose ferroelectricity was confirmed by a ferroelectric hysteresis loop and ferroelectric domain switching. This finding opens up a new functionality for fullerenes and sheds light on the exploration of more ferroelectric fullerenes.

3.
Inorg Chem ; 62(49): 19930-19936, 2023 Dec 11.
Artigo em Inglês | MEDLINE | ID: mdl-37990884

RESUMO

Organic-inorganic hybrid perovskites (OIHPs) have been emerging as a hot research topic due to their potential applications in energy storage, semiconductors, and electronic devices. Herein, we systematically investigated the synthesis and phase transition behaviors of the enantiomeric OIHPs, (R) and (S)-N,N-dimethyl-3-fluoropyrrolidinium cadmium bromide ([DMFP][CdBr3]), and the hybrid trigonal structure [DMFP]3 (CdBr3)(CdBr4). The enantiomers have a mirror-symmetric structure and enhanced solid-state phase transition points of 417 and 443 K, in contrast to the nonfluorinated parent compound, N,N-dimethyl-pyrrolidinium cadmium bromide ([DMP][CdBr3], 385 K). Moreover, racemic H/F substitution on the pyrrolidinium cations leads to the formation of a trigonal compound, showing above-room-temperature structural phase transition and dominant ferroelasticity. This work discovers chiral enantiomeric OIHPs through H/F substitution, demonstrating a useful chemical synthesis strategy for exploring novel phase transition materials.

4.
Proc Natl Acad Sci U S A ; 117(49): 30966-30972, 2020 12 08.
Artigo em Inglês | MEDLINE | ID: mdl-33229548

RESUMO

Organic Fenton-like catalysis has been recently developed for water purification, but redox-active compounds have to be ex situ added as oxidant activators, causing secondary pollution problem. Electrochemical oxidation is widely used for pollutant degradation, but suffers from severe electrode fouling caused by high-resistance polymeric intermediates. Herein, we develop an in situ organic Fenton-like catalysis by using the redox-active polymeric intermediates, e.g., benzoquinone, hydroquinone, and quinhydrone, generated in electrochemical pollutant oxidation as H2O2 activators. By taking phenol as a target pollutant, we demonstrate that the in situ organic Fenton-like catalysis not only improves pollutant degradation, but also refreshes working electrode with a better catalytic stability. Both 1O2 nonradical and ·OH radical are generated in the anodic phenol conversion in the in situ organic Fenton-like catalysis. Our findings might provide a new opportunity to develop a simple, efficient, and cost-effective strategy for electrochemical water purification.


Assuntos
Eletroquímica , Peróxido de Hidrogênio/química , Ferro/química , Compostos Orgânicos/química , Polímeros/química , Purificação da Água , Catálise , Eletrodos , Fluorescência , Radical Hidroxila/análise , Fenóis/química , Superóxidos/análise
5.
J Appl Biomed ; 21(1): 48-57, 2023 04.
Artigo em Inglês | MEDLINE | ID: mdl-37016778

RESUMO

Oleanolic acid (OA) is a pentacyclic triterpenoid with favourable physiological activity. It is widely distributed in more than 200 species of plants. OA has garnered significant interest because of its potential biological activities, such as antioxidant, bacteriostatic, and hair growth-promoting effects. To study the effect of OA on hair growth and related mechanisms, we investigated hair growth in mice with testosterone-induced androgenetic alopecia (AGA) that were treated with three different concentrations of OA. The antioxidant, bacteriostatic, and cytotoxic effects of OA were evaluated. We found that mice with testosterone-induced AGA treated with 1% or 0.5% OA showed significantly enhanced hair growth and increased vascular endothelial growth factor/glyceraldehyde-3-phosphate dehydrogenase ratio and levels of fibroblast growth factor receptor and insulin-like growth factor 1. Using an immunofluorescence staining assay, we demonstrated that ß-catenin, a key Wnt signalling transducer, was highly expressed in the OA-treated groups. These results suggest that OA may promote hair growth by stimulating hair matrix cell proliferation via the Wnt/ß-catenin pathway and lowering the levels of tumour necrosis factor-alpha, and transforming growth factor-beta 1, dihydrotestosterone, and 5α-reductase.


Assuntos
Ácido Oleanólico , beta Catenina , Camundongos , Animais , beta Catenina/metabolismo , Ácido Oleanólico/farmacologia , Citocinas , Fator A de Crescimento do Endotélio Vascular/metabolismo , Antioxidantes , Alopecia/induzido quimicamente , Alopecia/tratamento farmacológico , Alopecia/metabolismo , Folículo Piloso/metabolismo , Folículo Piloso/patologia , Testosterona
6.
J Am Chem Soc ; 144(42): 19559-19566, 2022 Oct 26.
Artigo em Inglês | MEDLINE | ID: mdl-36222219

RESUMO

Chirality exists everywhere from natural amino acids to particle physics. The introduction of point chirality has recently been shown to be an efficient strategy for the construction of molecular ferroelectrics. In contrast to point chirality, however, axial chirality is rarely used to design ferroelectrics so far. Here, based on optically active 1,1'-bi-2-naphthol (BINOL), which has been applied extensively as a versatile chiral reagent in asymmetric catalysis, chiral recognition, and optics, we successfully design a pair of axial-chiral BINOL multiferroics, (R)-BINOL-DIPASi and (S)-BINOL-DIPASi. They experience a 2F1-type full ferroelectric/ferroelastic phase transition at a high temperature of 362 and 363 K, respectively. Piezoelectric force microscopy and polarization-voltage hysteresis loops demonstrate their ferroelectric domains and domain switching, and polarized light microscopy visualizes the evolution of stripe-shaped ferroelastic domains. The axial-chiral BINOL building block promotes the generation of the polar structure and ferroelectricity, and the organosilicon component increases the rotational energy barrier and thus the phase transition temperature. This work presents the first axial-chiral high-temperature multiferroic crystals, offering an efficient path for designing molecular multiferroics through the introduction of axial chirality.

7.
Osteoporos Int ; 33(11): 2347-2355, 2022 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-35833955

RESUMO

The association between socioeconomic status (SES) and bone mineral density (BMD) in men remains controversial. We showed that SES was positively associated with BMD in American men. Confounding factors like race/ethnicity and age could affect the association. INTRODUCTION: Based on the data from the National Health and Nutrition Examination Survey (NHANES), 2011-2020, this article aims to investigate the association of SES (poverty income ratio (PIR) and education level) with the BMD in American men. METHODS: We evaluated the association of SES with BMD in 4446 men aged ≥ 20 years (mean age, 41.0 ± 13.4 years) from the NHANES 2011-2020. BMD was measured by dual-energy X-ray absorptiometry (DXA) at the lumbar spine. We used multivariate linear regression models to examine the relationship between SES and total spine BMD, adjusted for a large range of confounding factors. RESULTS: Compared with other PIR quarters, individuals in the highest quarter of PIR were more likely to be older and white and had fewer smoking or drinking behaviors. After adjusting for race/ethnicity, age, drinking and smoking behavior, body mass index (BMI), total protein, serum calcium, serum uric acid, cholesterol, serum phosphorus, and blood urea nitrogen, PIR was positively correlated with total spine BMD (ß = 0.004 95% CI: 0.001-0.007, P = 0.006). Individuals with the highest degree (college degree or above) had a 0.057 g/cm2 greater BMD than that of the lowest degree (less than 9th grade) (ß = 0.057 95% CI: 0.037-0.077, P < 0.001). CONCLUSIONS: Our study indicates that SES was positively associated with the lumbar BMD among American men. Clinicians, healthcare providers, and policymakers should consider the unequal SES of men when implementing osteoporosis prevention and treatment strategies.


Assuntos
Densidade Óssea , Ácido Úrico , Absorciometria de Fóton , Adulto , Proteínas Sanguíneas , Cálcio , Humanos , Vértebras Lombares , Masculino , Pessoa de Meia-Idade , Inquéritos Nutricionais , Fósforo , Classe Social , Estados Unidos/epidemiologia
8.
Cancer Cell Int ; 22(1): 143, 2022 Apr 02.
Artigo em Inglês | MEDLINE | ID: mdl-35366902

RESUMO

BACKGROUND: Pancreatic adenocarcinoma (PAAD) is a severe malignant with a 5-year survival rate of approximately 9%. Oleanolic acid is a well-known natural triterpenoid which exhibits pharmacological activities. We previously synthesized a series of oleanolic acid derivatives and evaluated the tumor-suppressive activity of olean-28,13ß-lactam (B28) in prostate cancer. However, the detailed mechanism remains to be understood. METHODS: The anti-tumor activity of B28 in PAAD was confirmed by RTCA, colony formation assay and flow cytometry. GO and KEGG enrichment analyses were performed to analyze the differentially expressed genes (DEGs) obtained by RNA sequencing. The effects of B28 on cell bioenergetics were evaluated by seahorse analyzer. Lenti-virus packaged plasmids were performed to knockdown or overexpress target genes. Alteration of mitochondrial membrane potential, ROS and GSH/GSSG were measured by corresponding detection kits according to the manufacturer's protocol. RESULTS: We evaluated and confirmed the promising anti-tumor activity of B28 in vitro. RNA-seq profile indicated that multiple metabolic pathways were interrupted in B28 treated PAAD cells. Next, we demonstrated that B28 induces cellular bioenergetics crisis to inhibit PAAD cells growth and induce cell death. We further validated that cell cycle arrest, inhibition of cell growth, cell apoptosis and cell bioenergetics disruption were functionally rescued by ROS scavenger NAC. Mechanistically, we found glutamine metabolism was inhibited due to B28 administration. Moreover, we validated that down-regulation of GLS1 contributes to ROS generation and bioenergetics interruption induced by B28. Furthermore, we elucidated that YTHDF1-GLS1 axis is the potential downstream target of B28 to induce PAAD cell metabolic crisis and cell death. Finally, we also confirmed the anti-tumor activity of B28 in vivo. CONCLUSIONS: Current study demonstrates B28 disrupts YTDFH1-GLS1 axis to induce ROS-dependent cell bioenergetics crisis and cell death which finally suppress PAAD cell growth, indicating that this synthesized olean-28,13ß-lactam maybe a potent agent for PAAD intervention.

9.
Inorg Chem ; 61(15): 5836-5843, 2022 Apr 18.
Artigo em Inglês | MEDLINE | ID: mdl-35388698

RESUMO

Hybrid organic-inorganic perovskites (HOIPs) have emerged as multifunctional materials with remarkable optical and electronic properties. In particular, 2D-layered lead iodide-based HOIPs possess great practical application potential in the photoelectric field. In this work, we report H/F substitution-induced 1D-to-2D increment of lead iodide HOIPs. The enantiomeric HOIPs, S- and R-FPPbI3 (FP = 3-fluoropyrrolidinium), were achieved by monofluoride substitution on the spacer cations of the parent HOIP, PyPbI3 (Py = pyrrolidinium), showing mirror image structural relationship and reversible solid-state phase transition. A 2D-layered HOIP, (DFP)2PbI4 (DFP = 3,3-difluoropyrrolidinium), was achieved with a low band gap of 2.09 eV through difluoride substitution, thanks to the expansion of the Pb-I network from 1D to 2D. This work highlights the exploration of 1D chiral and 2D-layered HOIP materials with reversible phase transitions through H/F substitution strategies.


Assuntos
Iodetos , Cátions , Eletrônica
10.
Environ Sci Technol ; 56(1): 564-574, 2022 01 04.
Artigo em Inglês | MEDLINE | ID: mdl-34918924

RESUMO

Recycling of deactivated palladium (Pd)-based catalysts can not only lower the economic cost of their industrial use but also save the cost for waste disposal. Considering that the sulfur-poisoned Pd (PdxSy) with a strong Pd-S bond is difficult to regenerate, here, we propose a direct reuse of such waste materials as an efficient catalyst for decontamination via Fenton-like processes. Among the PdxSy materials with different poisoning degrees, Pd4S stood out as the most active catalyst for peroxymonosulfate activation, exhibiting pollutant-degradation performance rivaling the Pd and Co2+ benchmarks. Moreover, the incorporated S atom was found to tune the surface electrostatic potentials and charge densities of the Pd active site, triggering a shift in catalytic pathway from surface-bound radicals to predominantly direct electron transfer pathway that favors a highly selective oxidation of phenols. The catalyst stability was also improved due to the formation of strong Pd-S bond that reduces corrosion. Our work paves a new way for upcycling of Pd-based industrial wastes and for guiding the development of advanced oxidation technologies toward higher sustainability.


Assuntos
Poluentes Ambientais , Venenos , Catálise , Oxirredução , Paládio/química , Fenóis , Enxofre
11.
Bioorg Med Chem ; 69: 116890, 2022 09 01.
Artigo em Inglês | MEDLINE | ID: mdl-35777269

RESUMO

Leukemia cells depend on the Wnt/ß-catenin signaling pathway for their growth. Pyrvinium, a known Wnt signaling inhibitor, has demonstrated promising efficacy in the treatment of the aggressive blast phase chronic myeloid leukemia (BP-CML). We previously developed potent inhibitors 1-2 for the Wnt/ß-catenin signaling pathway. However, the further application of these compounds as anti-leukemia agents is limited by their modest anti-leukemia activity in cells and poor aqueous solubility, due to the high molecular planarity of the chemical scaffold. Here, we reported our efforts in the synthesis and in vitro evaluation of 18 new compounds (4a-r) that have been designed to disrupt the molecular planarity of the chemical scaffold. Several compounds of the series showed significantly improved anti-leukemia activity and aqueous solubility. As a highlight, compounds 4c not only maintained excellent inhibitory potency (IC50 = 1.3 nM) for Wnt signaling but also demonstrated good anti-leukemia potency (IC50 = 0.9 µM) in the CML K562 cells. Moreover, compound 4c had an aqueous solubility of 5.9 µg/mL, which is over 50-fold enhanced compared to its parents 1-2.


Assuntos
Leucemia Mielogênica Crônica BCR-ABL Positiva , Via de Sinalização Wnt , Crise Blástica/metabolismo , Linhagem Celular Tumoral , Proliferação de Células , Humanos , Leucemia Mielogênica Crônica BCR-ABL Positiva/tratamento farmacológico , Solubilidade , beta Catenina/metabolismo
12.
Proc Natl Acad Sci U S A ; 116(13): 5878-5885, 2019 03 26.
Artigo em Inglês | MEDLINE | ID: mdl-30850531

RESUMO

For nearly 100 y, homochiral ferroelectrics were basically multicomponent simple organic amine salts and metal coordination compounds. Single-component homochiral organic ferroelectric crystals with high-Curie temperature (Tc) phase transition were very rarely reported, although the first ferroelectric Rochelle salt discovered in 1920 is a homochiral metal coordination compound. Here, we report a pair of single-component organic enantiomorphic ferroelectrics, (R)-3-quinuclidinol and (S)-3-quinuclidinol, as well as the racemic mixture (Rac)-3-quinuclidinol. The homochiral (R)- and (S)-3-quinuclidinol crystallize in the enantiomorphic-polar point group 6 (C6) at room temperature, showing mirror-image relationships in vibrational circular dichroism spectra and crystal structure. Both enantiomers exhibit 622F6-type ferroelectric phase transition with as high as 400 K [above that of BaTiO3 (Tc = 381 K)], showing very similar ferroelectricity and related properties, including sharp step-like dielectric anomaly from 5 to 17, high saturation polarization (7 µC/cm2), low coercive field (15 kV/cm), and identical ferroelectric domains. Their racemic mixture (Rac)-3-quinuclidinol, however, adopts a centrosymmetric point group 2/m (C2h), undergoing a nonferroelectric high-temperature phase transition. This finding reveals the enormous benefits of homochirality in designing high-Tc ferroelectrics, and sheds light on exploring homochiral ferroelectrics with great application.

13.
Plant Dis ; 2022 Mar 09.
Artigo em Inglês | MEDLINE | ID: mdl-35263152

RESUMO

Tobacco (Nicotiana tabacum) is an important economic crop and widely cultivated in rural areas in south of China. A previously uncharacterized disease was observed on field-grown tobacco during 2020 and 2021 around Tongren city, Guizhou province of China (27°59'25.73" N, 108°7'2.43" E). The disease mainly occurred from fast growing period (about 13-16 leaves) to leaf maturity stage. In severely diseased areas, the incidence rate was between 20%-100%. Symptoms first began as yellow-brown necrotic spots on leaves, then merged into larger irregular necrotic spots surrounded by chlorotic halos. Similar lesions were also found on the stems. Ten symptomatic leaf and stem samples were collected from the different infected plants for pathogen isolation. The small pieces of discolored tissues were surface-disinfected with 2% sodium hypochlorite for 3 min and 75% ethanol for 30 s, rinsed three times with sterile water, and blotted on sterile filter paper, placed on potato dextrose agar thenincubated at 28°C in the dark for 3-4 days. The obtained isolates were purified through single-spore culture. Colonies were initially white and fluffy in appearance, later turning gray. Hyphae were smooth, branched, septa, transparent or light brown. Spores were solitary, oblate or nearly spherical, dark brown to black, smooth, 14.3 to 16.1µm × 11.8 to 15.2 µm in diameter. DNA of fungal isolates were extracted using Fungi Genomic DNA Extraction Kit (Solarbio, Beijing, China), the internal transcribed spacer (ITS) of the ribosomal DNA, ß-tubulin (TUB2) gene and translation elongation factor 1-alpha (TEF1-α) were amplified with primers ITS1/ITS4, ßt2a/ßt2b and EF1-1728F/EF1-986R, respectively. The resulting ITS, TUB2 and TEF1-α sequences were deposited at GenBank, NCBI under accessions MZ882151, MZ927749, MZ927747, respectively. The sequence identity of ITS, TUB2 and TEF1-α with those of Nigrospora oryzae strains HBN (KU254608), HGUP191068 (MZ724102) and LC7307 (KY019409) were 99.64%, 99.29% and 99.65%, respectively. Based on morphological features and phylogenetic analysis, the pathogen was identified as N. oryzae (Wang et al. 2017). Pathogenicity tests were conducted by placing agar plugs-containing fungal mycelia and agar blocks (control) on leaves of tobacco plants grown at 28°C with 60% humidity in greenhouse. Symptoms appeared on the pathogen inoculated leaves seven days after inoculation, whereas the control treatment remained symptomless. The pathogens were reisolated from diseased leaves and identified as N. oryzae based on morphological, molecular and phylogenetic analysis, which were fulfilling Koch's postulates. This pathogen was recently identified from watermelon and kiwifruit in the Guizhou (Far and Rossman, 2021). To our knowledge, this is the first report of leaf spot caused by N. oryzae on Nicotiana tabacum in China.

14.
Zhongguo Zhong Yao Za Zhi ; 47(21): 5797-5805, 2022 Nov.
Artigo em Chinês | MEDLINE | ID: mdl-36471997

RESUMO

Ulcerative colitis(UC) is a continuous inflammatory bowel disease with the main clinical manifestations of abdominal pain, diarrhea, and mucous bloody stools, mainly attacking the colorectal mucosa and submucosa. It is characterized by high recurrence rate, difficult cure, and clustering and regional occurrence. Chinese medicinal prescriptions for the treatment of UC have good therapeutic effect, multi-target regulation, slight toxicity, and no obvious side effects. In particular, the classical prescriptions highlight the characteristics and advantages of traditional Chinese medicine theory and have attracted much attention in recent years. To enable researchers to timely and comprehensively understand the classical prescriptions in the treatment of UC, we reviewed the studies about the pharmacodynamic material basis, quality control, action mechanism, and clinical application of relevant classical prescriptions. We first introduced the latest research progress in the active components such as alkaloids, polysaccharides, saponins, and flavonoids in relevant classical prescriptions. Then, we reviewed the latest research achievements on the quality control of classical prescriptions for the treatment of UC by gas chromatography, liquid chromatography, mass spectrometry, liquid chromatography-mass spectrometry and the like. Further, we summarized the research advances in the mechanisms of relevant prescriptions in the treatment of UC based on network pharmacology, molecular docking, integrated pharmacology platform, and animal experiments. Finally, we generalized the clinical application of the classical prescriptions for clearing heat and removing dampness, mildly regulating cold and heat, soothing liver and regulating spleen, strengthening spleen and invigorating Qi, and tonifying spleen and stomach. By systematic summary of the research progress in relevant classical prescriptions, we hope to promote the application and development of such prescriptions in UC treatment.


Assuntos
Colite Ulcerativa , Medicamentos de Ervas Chinesas , Animais , Colite Ulcerativa/tratamento farmacológico , Medicamentos de Ervas Chinesas/farmacologia , Simulação de Acoplamento Molecular , Cromatografia Gasosa-Espectrometria de Massas , Medicina Tradicional Chinesa , Prescrições de Medicamentos
15.
Angew Chem Int Ed Engl ; 61(33): e202206034, 2022 Aug 15.
Artigo em Inglês | MEDLINE | ID: mdl-35604204

RESUMO

Organic-inorganic hybrid perovskites (OIHPs) have gained tremendous interest for their rich functional properties. However, the coexistence of more than one of ferroelectricity, ferromagnetism and ferroelasticity has been rarely found in OIHPs. Herein, we report a two-dimensional Cr2+ -based OIHP, [3,3-difluorocyclobutylammonium]2 CrCl4 ([DFCBA]2 CrCl4 ), which shows both ferroelectricity and ferromagnetism. It undergoes a 4/mmmFm type ferroelectric phase transition at a temperature as high as 387 K and shows multiaxial ferroelectricity with a saturate polarization of 2.1 µC cm-2 . It acts as a soft ferromagnet with a Curie temperature of 32.6 K. This work throws light on the exploration of OIHPs with the coexistence of ferroelectricity and ferromagnetism for applications in future multifunctional smart devices.

16.
Chemphyschem ; 22(8): 752-756, 2021 Apr 19.
Artigo em Inglês | MEDLINE | ID: mdl-33590646

RESUMO

Crystalline materials have received extensive attention due to their extraordinary physical and chemical properties. Among them, phase transition materials have attracted great attention in the fields of photovoltaic, switchable dielectric devices, and ferroelectric memories, etc. However, many of them suffer from low phase transition temperatures, which limits their practical application. In this work, we systematically designed crystalline materials, (TMXM)2 PtCl6 (X=F, Cl, Br, I) through halogen substitution on the cations, aiming to improving phase transition temperature. The resulting phase transition of (TMXM)2 PtCl6 (X=F, Cl, Br, I) get a significant enhancement, compared to the parent compound [(CH3 )4 N]2 PtCl6 ((TM)2 PtCl6 ). Such phase transition temperature enhancement can be attributed to the introduction of halogen atoms that increase the potential energy barrier of the cation rotation. In addition, (TMBM)2 PtCl6 and (TMIM)2 PtCl6 have a low symmetry and crystallize in the space group C2 /c and P21 21 21 , respectively. This work highlights the halogen substitution in designing crystal materials with high phase transition temperature.

17.
J Am Chem Soc ; 142(32): 13989-13995, 2020 Aug 12.
Artigo em Inglês | MEDLINE | ID: mdl-32678596

RESUMO

Topological defects such as vortices in ferroelectric materials are attracting tremendous interest because of their splendid possibilities for unique physical phenomena and potential applications in nanoelectronic devices. However, reports of the vortex structure have been scarce in organic ferroelectrics, which are highly desirable for their mechanical flexibility, easy and environment-friendly processing, and low acoustical impedance. Here, we successfully observed the robust triangular domains in a single-component organic ferroelectric, 2-(hydroxymethyl)-2-nitro-1,3-propanediol (1), six of which can form a 6-fold vertex domain structure. To our knowledge, it is the first time that such an intriguing topological vortex gets experimentally confirmed in ferroelectrics. Moreover, the symmetry change of 1 with an Aizu notation of m3mF1 leads to the most 48 crystallographically equivalent polarization directions among all ferroelectrics. With those benefits and excellent piezoelectric properties, compound 1 shows great potential as a reconfigurable electronic element or a mechanical sensor for soft robotics, flexible and wearable devices, and biomachines.

18.
J Am Chem Soc ; 142(13): 6236-6243, 2020 Apr 01.
Artigo em Inglês | MEDLINE | ID: mdl-32159954

RESUMO

Organic-inorganic ABX3 (A, B = cations, X = anion) hybrids with perovskite structure have recently attracted tremendous interest due to their structural tunability and rich functional properties, such as ferroelectricity. However, ABX3 hybrid ferroelectrics with other structures have rarely been reported. Here, we successfully designed an ABX3 hybrid ferroelectric [(CH3)3NCH2F]ZnCl3 with a spontaneous polarization of 4.8 µC/cm2 by the molecular modification of [(CH3)4N]ZnCl3 through hydrogen/halogen substitution. It is the first zinc halide ABX3 ferroelectric, which contains one-dimensional [ZnCl3]-n chains of corner-sharing ZnCl4 tetrahedra, distinct from the anionic framework of corner-sharing or face-sharing BX6 octahedra in the ABX3 perovskites. From zero dimension to one dimension, the high symmetry of ZnCl4 tetrahedra is broken, and all of them align along one direction to form a polar [ZnCl3]-n chain, beneficial to the generation of ferroelectricity. This finding provides an efficient polar anionic framework for enriching the family of hybrid ferroelectrics by assembling with various cations and should inspire further exploration of new classes of organic-inorganic ABX3 ferroelectrics.

19.
J Am Chem Soc ; 142(52): 21932-21937, 2020 Dec 30.
Artigo em Inglês | MEDLINE | ID: mdl-33326208

RESUMO

Organic ferroelectrics are attracting tremendous interest because of their mechanical flexibility, ease of fabrication, and low acoustical impedance. Although great advances have been made in recent years, topological defects such as vortices remain relatively unexplored in the organic ferroelectric system. Here, from [quinuclidinium]ReO4 ([Q]ReO4), we applied the molecular design strategy of H/F substitution to successfully synthesize the organic ferroelectric [4-fluoroquinuclidinium]ReO4 ([4-F-Q]ReO4). Through H/F substitution, the Curie temperature and spontaneous polarization are respectively increased from 367 K and 5.83 µC/cm2 in [Q]ReO4 to 466 K and 11.37 µC/cm2 in [4-F-Q]ReO4. Moreover, under mechanical stress fields, three kinds of stripelike domains with various polarization directions emerge to form a windmill-like domain pattern in the thin film of [4-F-Q]ReO4, in which intriguing vortex-antivortex topological configurations can exist stably. This work provides an efficient strategy for optimizing the properties of organic ferroelectrics and exploring emergent phenomena.

20.
J Am Chem Soc ; 142(28): 12486-12492, 2020 07 15.
Artigo em Inglês | MEDLINE | ID: mdl-32571017

RESUMO

For a century ferroelectricity has attracted widespread interest from science and industry. Inorganic ferroelectric ceramics have dominated multibillion dollar industries of electronic ceramics, ranging from nonvolatile memories to piezoelectric sonar or ultrasonic transducers, whose polarization can be reoriented in multiple directions so that they can be used in the ceramic and thin-film forms. However, the realization of macroscopic ferroelectricity in the polycrystalline form is challenging for molecular ferroelectrics. In pursuit of low-cost, biocompatible, and mechanically flexible alternatives, the development of multiaxial molecular ferroelectrics is imminent. Here, from quinuclidinium perrhenate, we applied fluorine substitution to successfully design a multiaxial molecular ferroelectric, 3-fluoroquinuclidinium perrhenate ([3-F-Q]ReO4), whose macroscopic ferroelectricity can be realized in both powder compaction and thin-film forms. The fluorination effect not only increases the intrinsic polarization but also reduces the coercive field strength. More importantly, it is also, as far as we know, the softest of all known molecular ferroelectrics, whose low Vickers hardness of 10.5 HV is comparable with that in poly(vinylidene difluoride) (PVDF) but almost 2 orders of magnitude lower than that in BaTiO3. These attributes make it an ideal candidate for flexible and wearable devices and biomechanical applications.

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