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1.
A Molecular Ferroelectric Showing Room‐Temperature Record‐Fast Switching of Spontaneous Polarization 下载免费PDF全文
Prof. Zhihua Sun Xianfeng Yi Kewen Tao Chengmin Ji Xitao Liu Dr. Lina Li Shiguo Han Prof. Anmin Zheng Prof. Maochun Hong Prof. Junhua Luo 《Angewandte Chemie (International ed. in English)》2018,57(31):9833-9837
Fast switching of spontaneous polarization (Ps) is one of the most essential requirements for ferroelectrics used in the field of data storage. However, in contrast to inorganic counterparts, the low operating frequency (<500 Hz) for molecular ferroelectrics severely hinders their large‐scale applications. Herein, for the first time, we achieved the room‐temperature fastest switching of the Ps in a new molecular ferroelectric, N‐methylmorpholinium trinitrophenolate ( 1 ), which displays notable ferroelectricity (Ps=3.2 μc cm?2). Strikingly, electric polarizations of 1 have been switched under a record‐high frequency of 263 kHz, and this performance remains stable without any obvious fatigue after ca. 2×105 switching cycles. To our knowledge, 1 is the first organic ferroelectric to switch polarization at such a high operating frequency, exceeding the majority of organic ferroelectrics, which opens up new possibilities for its potential in the field of non‐volatile memory. 相似文献
2.
Designing Efficient and Ultralong Pure Organic Room‐Temperature Phosphorescent Materials by Structural Isomerism 下载免费PDF全文
Dr. Yu Xiong Dr. Zheng Zhao Dr. Weijun Zhao Dr. Huili Ma Prof. Qian Peng Prof. Zikai He Dr. Xuepeng Zhang Dr. Yuncong Chen Xuewen He Prof. Jacky W. Y. Lam Prof. Ben Zhong Tang 《Angewandte Chemie (International ed. in English)》2018,57(27):7997-8001
Pure organic materials with ultralong room‐temperature phosphorescence (RTP) are attractive alternatives to inorganic phosphors. However, they generally show inefficient intersystem crossing (ISC) owing to weak spin–orbit coupling (SOC). A design principle based on the realization of small energy gap between the lowest singlet and triplet states (ΔEST) and pure ππ* configuration of the lowest triplet state (T1) via structural isomerism was used to obtain efficient and ultralong RTP materials. The meta isomer of carbazole‐substituted methyl benzoate exhibits an ultralong lifetime of 795.0 ms with a quantum yield of 2.1 %. Study of the structure–property relationship shows that the varied steric and conjugation effects imposed by ester substituent at different positions are responsible for the small ΔEST and pure ππ* configuration of T1. 相似文献
3.
An Above‐Room‐Temperature Ferroelectric Organo–Metal Halide Perovskite: (3‐Pyrrolinium)(CdCl3) 下载免费PDF全文
Dr. Heng‐Yun Ye Dr. Yi Zhang Dr. Da‐Wei Fu Prof. Ren‐Gen Xiong 《Angewandte Chemie (International ed. in English)》2014,53(42):11242-11247
Hybrid organo–metal halide perovskite materials, such as CH3NH3PbI3, have been shown to be some of the most competitive candidates for absorber materials in photovoltaic (PV) applications. However, their potential has not been completely developed, because a photovoltaic effect with an anomalously large voltage can be achieved only in a ferroelectric phase, while these materials are probably ferroelectric only at temperatures below 180 K. A new hexagonal stacking perovskite‐type complex (3‐pyrrolinium)(CdCl3) exhibits above‐room‐temperature ferroelectricity with a Curie temperature Tc=316 K and a spontaneous polarization Ps=5.1 μC cm?2. The material also exhibits antiparallel 180° domains which are related to the anomalous photovoltaic effect. The open‐circuit photovoltage for a 1 mm‐thick bulky crystal reaches 32 V. This finding could provide a new approach to develop solar cells based on organo–metal halide perovskites in photovoltaic research. 相似文献
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Versatile Room‐Temperature‐Phosphorescent Materials Prepared from N‐Substituted Naphthalimides: Emission Enhancement and Chemical Conjugation 下载免费PDF全文
Xiaofeng Chen Dr. Cheng Xu Tao Wang Cao Zhou Jiajun Du Prof. Zhongping Wang Prof. Hangxun Xu Tongqing Xie Prof. Guoqiang Bi Prof. Jun Jiang Dr. Xuepeng Zhang Prof. James N. Demas Prof. Carl O. Trindle Prof. Yi Luo Prof. Guoqing Zhang 《Angewandte Chemie (International ed. in English)》2016,55(34):9872-9876
Purely organic materials with room‐temperature phosphorescence (RTP) are currently under intense investigation because of their potential applications in sensing, imaging, and displaying. Inspired by certain organometallic systems, where ligand‐localized phosphorescence (3π‐π*) is mediated by ligand‐to‐metal or metal‐to‐ligand charge transfer (CT) states, we now show that donor‐to‐acceptor CT states from the same organic molecule can also mediate π‐localized RTP. In the model system of N‐substituted naphthalimides (NNIs), the relatively large energy gap between the NNI‐localized 1π‐π* and 3π‐π* states of the aromatic ring can be bridged by intramolecular CT states when the NNI is chemically modified with an electron donor. These NNI‐based RTP materials can be easily conjugated to both synthetic and natural macromolecules, which can be used for RTP microscopy. 相似文献
6.
Revealing the Charge‐Transfer Interactions in Self‐Assembled Organic Cocrystals: Two‐Dimensional Photonic Applications 下载免费PDF全文
Weigang Zhu Dr. Renhui Zheng Xiaolong Fu Prof. Hongbing Fu Prof. Qiang Shi Dr. Yonggang Zhen Dr. Huanli Dong Prof. Wenping Hu 《Angewandte Chemie (International ed. in English)》2015,54(23):6785-6789
A new crystal of a charge‐transfer (CT) complex was prepared through supramolecular assembly and it has unique two‐dimensional (2D) morphology. The CT nature of the ground and excited states of this new Bpe‐TCNB cocrystal (BTC) were confirmed by electron spin resonance measurements, spectroscopic studies, and theoretical calculations, thus providing a comprehensive understanding of the CT interactions in organic donor–acceptor systems. And the lowest CT1 excitons are responsible for the efficient photoluminescence (ΦPL=19 %), which can actively propagate in individual 2D BTCs without anisotropy, thus implying that the optical waveguide property of the crystal is not related to the molecular stacking structure. This unique 2D CT cocrystal exhibits potential for use in functional photonic devices in the next‐generation optoelectronic communications. 相似文献
7.
Intermolecular Electronic Coupling of Organic Units for Efficient Persistent Room‐Temperature Phosphorescence 下载免费PDF全文
Dr. Zhiyong Yang Dr. Zhu Mao Dr. Xuepeng Zhang Dr. Depei Ou Dr. Yingxiao Mu Prof. Yi Zhang Prof. Cunyuan Zhao Prof. Siwei Liu Prof. Zhenguo Chi Prof. Jiarui Xu Dr. Yuan‐Chun Wu Dr. Po‐Yen Lu Dr. Alan Lien Prof. Martin R. Bryce 《Angewandte Chemie (International ed. in English)》2016,55(6):2181-2185
Although persistent room‐temperature phosphorescence (RTP) emission has been observed for a few pure crystalline organic molecules, there is no consistent mechanism and no universal design strategy for organic persistent RTP (pRTP) materials. A new mechanism for pRTP is presented, based on combining the advantages of different excited‐state configurations in coupled intermolecular units, which may be applicable to a wide range of organic molecules. By following this mechanism, we have developed a successful design strategy to obtain bright pRTP by utilizing a heavy halogen atom to further increase the intersystem crossing rate of the coupled units. RTP with a remarkably long lifetime of 0.28 s and a very high quantum efficiency of 5 % was thus obtained under ambient conditions. This strategy represents an important step in the understanding of organic pRTP emission. 相似文献
8.
Xin Ai Yingxin Chen Yuting Feng Prof. Dr. Feng Li 《Angewandte Chemie (International ed. in English)》2018,57(11):2869-2873
There is only one family of room‐temperature luminescent radicals, the triphenylmethyl radicals, to date. Herein, we synthesize a new stable room‐temperature luminescent radical, (N‐carbazolyl)bis(2,4,6‐tirchlorophenyl)methyl radical (CzBTM), which has improved properties compared to the triphenylmethyl radicals. X‐ray crystallography, electron paramagnetic resonance spectroscopy, and magnetic susceptibility measurements confirmed the radical structure. CzBTM shows room‐temperature deep‐red to near‐infrared emission in various solutions. Both thermal and photo stability were significantly enhanced by the replacement of trichlorobenzene by the carbazole moiety. The electroluminescence results of CzBTM verify its potential application to circumvent the problem of triplet harvesting in traditional fluorescent OLEDs. A new family of stable luminescent radicals based on CzBTM is anticipated. 相似文献
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《Angewandte Chemie (International ed. in English)》2017,56(46):14743-14748
Multi‐photon absorption (MPA) is among the most prominent nonlinear optical (NLO) effects and has applications, for example in telecommunications, defense, photonics, and bio‐medicines. Established MPA materials include dyes, quantum dots, organometallics and conjugated polymers, most often dispersed in solution. We demonstrate how metal–organic frameworks (MOFs), a novel NLO solid‐state materials class, can be designed for exceptionally strong MPA behavior. MOFs consisting of zirconium‐ and hafnium‐oxo‐clusters and featuring a chromophore linker based on the tetraphenylethene (TPE) molecule exhibit record high two‐photon absorption (2PA) cross‐section values, up to 3600 GM. The unique modular building‐block principle of MOFs allows enhancing and optimizing their MPA properties in a theory‐guided approach by combining tailored charge polarization, conformational strain, three‐dimensional arrangement, and alignment of the chromophore linkers in the crystal. 相似文献
11.
《中国化学》2018,36(9):845-850
The arylthio‐substituted tetrathiafulvalenes (Ar‐S‐TTFs) are electron donors having three reversible states, neutral, cation radical, and dication. The charge‐transfer (CT) between Ar‐S‐TTFs ( TTF1 — TTF3 ) and iodine (I2) is reported herein. TTF1 — TTF3 show the CT with I2 in the CH2Cl2 solution, but they are not completely converted into cation radical state. In CT complexes of TTF1 — TTF3 with I2, the charged states of Ar‐S‐TTFs are distinct from those in solution. TTF1 is at cation radical state, and TTF2 — TTF3 are oxidized to dication. The iodine components in complexes show various structures including 1‐D chain of V‐shaped (I5)–, and 2‐D and 3‐D iodine networks composed of I2 and (I3)–. 相似文献
12.
Wei Xu Yaguo Yu Xiaonan Ji Huarui Zhao Jinming Chen Yanyan Fu Huimin Cao Qingguo He Jiangong Cheng 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(45):16164-16168
The stability of pure organic room‐temperature phosphorescent (RTP) materials in air has been a research hotspot in recent years. Without crystallization or encapsulation, a new strategy was proposed to obtain self‐stabilized organic RTP materials, based on a complete ionization of a photo‐induced charge separation system. The ionization of aromatic phenol 4‐carbazolyl salicylaldehyde (CSA) formed a stable H‐bonding anion–cation radical structure and led to the completely amorphous CSA‐I film. Phosphorescent lifetimes as long as 0.14 s at room temperature and with direct exposure to air were observed. The emission intensity was also increased by 21.5‐fold. Such an amorphous RTP material reconciled the contradiction between phosphorescence stability and vapor permeability and has been successfully utilized for peroxide vapor detection. 相似文献
13.
Tunable Crystallinity and Charge Transfer in Two‐Dimensional G‐Quadruplex Organic Frameworks 下载免费PDF全文
Prof. Yi‐Lin Wu Dr. N. Scott Bobbitt Jenna L. Logsdon Natalia E. Powers‐Riggs Jordan N. Nelson Xiaolong Liu Timothy C. Wang Prof. Randall Q. Snurr Prof. Joseph T. Hupp Prof. Omar K. Farha Prof. Mark C. Hersam Prof. Michael R. Wasielewski 《Angewandte Chemie (International ed. in English)》2018,57(15):3985-3989
DNA G‐quadruplex structures were recently discovered to provide reliable scaffolding for two‐dimensional organic frameworks due to the strong hydrogen‐bonding ability of guanine. Herein, 2,7‐diaryl pyrene building blocks with high HOMO energies and large optical gaps are incorporated into G‐quadruplex organic frameworks. The adjustable substitution on the aryl groups provides an opportunity to elucidate the framework formation mechanism; molecular non‐planarity is found to be beneficial for restricting interlayer slippage, and the framework crystallinity is highest when intermolecular interaction and non‐planarity strike a fine balance. When guanine‐functionalized pyrenes are co‐crystallized with naphthalene diimide, charge‐transfer (CT) complexes are obtained. The photophysical properties of the pyrene‐only and CT frameworks are characterized by UV/Vis and steady‐state and time‐resolved photoluminescence spectroscopies, and by EPR spectroscopy for the CT complex frameworks. 相似文献
14.
Huapeng Liu Zhuoqun Lu Baolei Tang Cheng Qu Zuolun Zhang Hongyu Zhang 《Angewandte Chemie (International ed. in English)》2020,59(31):12944-12950
Flexible organic single crystals capable of plastic or elastic deformations have a variety of potential applications. Although the integration of plasticity and elasticity in a crystal is theoretically possible and it may cause rich and complex deformations which are highly demanded for potential applications, the integration is hard to realize in practice. Here, we show that through utilizing different modes of external forces for influencing molecular packing in different crystallographic directions, plastic helical twisting and elastic bending can both be achieved for a crystal, and they can even be realized simultaneously. Detailed crystallographic analyses and contrast experiments disclose the mechanisms behind these two kinds of distinct deformations and their mutual compatibility. Based on the plastically twistable nature of the crystal, a new application field of flexible organic single crystals, namely polarization rotators, is successfully opened up. 相似文献
15.
From the viewpoint of para‐meta topological bridging effect on the electronic coupling in organic mixed‐valence (MV) systems, the optically induced and thermally assisted intramolecular charge/spin transfer (ICT/IST) processes have been investigated for three bis(triarylamine) (BTA) radical cations as missing key compounds in very basic BTA MV systems. In contrast to the case of p‐ and m‐dinitrobenzene radical anions, the difference in the strength of electronic coupling (V) was not so large for the present BTA MV radical cations, although they still fall within the paradigm of strong V for para‐linkage and weak V for meta‐linkage. Unexpectedly, it has been found that meta‐phenylenediamine radical cation has an electronic coupling comparable to those in the para‐conjugated BTA‐based MV species, and the ICT/IST rate exceeds the ESR time‐scale. This finding is very encouraging considering that sufficient electronic communication can be ensured even when the redox‐active centers are linked directly by the meta‐phenylene bridge, thus broadening the selection of π‐bridging units for molecule‐based optoelectronics. 相似文献
16.
《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2017,129(48):15536-15540
Organic room‐temperature sodium‐ion battery electrodes with carboxylate and carbonyl groups have been widely studied. Herein, for the first time, we report a family of sodium‐ion battery electrodes obtained by replacing stepwise the oxygen atoms with sulfur atoms in the carboxylate groups of sodium terephthalate which improves electron delocalization, electrical conductivity and sodium uptake capacity. The versatile strategy based on molecular engineering greatly enhances the specific capacity of organic electrodes with the same carbon scaffold. By introducing two sulfur atoms to a single carboxylate scaffold, the molecular solid reaches a reversible capacity of 466 mAh g−1 at a current density of 50 mA g−1. When four sulfur atoms are introduced, the capacity increases to 567 mAh g−1 at a current density of 50 mA g−1, which is the highest capacity value reported for organic sodium‐ion battery anodes until now. 相似文献
17.
Tailoring Intermolecular Interactions for Efficient Room‐Temperature Phosphorescence from Purely Organic Materials in Amorphous Polymer Matrices 下载免费PDF全文
Sungbaek Seo Jaehun Jung Prof. Dr. Jinsang Kim 《Angewandte Chemie (International ed. in English)》2014,53(42):11177-11181
Herein we report a rational design strategy for tailoring intermolecular interactions to enhance room‐temperature phosphorescence from purely organic materials in amorphous matrices at ambient conditions. The built‐in strong halogen and hydrogen bonding between the newly developed phosphor G1 and the poly(vinyl alcohol) (PVA) matrix efficiently suppresses vibrational dissipation and thus enables bright room‐temperature phosphorescence (RTP) with quantum yields reaching 24 %. Furthermore, we found that modulation of the strength of halogen and hydrogen bonding in the G1–PVA system by water molecules produced unique reversible phosphorescence‐to‐fluorescence switching behavior. This unique system can be utilized as a ratiometric water sensor. 相似文献
18.
Hai Zhang Chaoran Luan Dong Gao Meng Zhang Nelson Rowell Maureen Willis Meng Chen Jianrong Zeng Hongsong Fan Wen Huang Xiaoqin Chen Kui Yu 《Angewandte Chemie (International ed. in English)》2020,59(39):16943-16952
Little is known about the pathway of room‐temperature formation of ternary CdTeSe magic‐size clusters (MSCs) obtained by mixing binary CdTe and CdSe induction period samples containing binary precursor compounds (PCs) of MSCs, monomers (Ms), and fragments (Fs). Also, unestablished are dispersion effects that occur when as‐mixed samples (without incubation) are placed in toluene (Tol) and octylamine (OTA) mixtures. The resulting ternary MSCs, exhibiting a sharp optical absorption peak at 399 nm, are labelled CdTeSe MSC‐399, and their PCs are referred to as CdTeSe PC‐399. When the amount of OTA is relatively small, single‐ensemble MSC‐399 evolved without either binary CdTe or CdSe MSCs. When the OTA amount is relatively large, CdTe MSC‐371 appeared initially and then disappeared, while single‐ensemble MSC‐399 developed more deliberately. The larger the OTA amount, the more slowly these changes proceeded. The substitution reaction of CdTe PC + CdSe M/F?CdTeSe PC‐399 + CdTe M/F is proposed to be rate‐determining for the MSC‐399 formation in a Tol and OTA mixture. This study provides further understanding of the transformation pathway between MSCs. 相似文献
19.
Adjusting the Proportion of Electron‐Withdrawing Groups in a Graft Functional Polymer for Multilevel Memory Performance 下载免费PDF全文
Linxin Wu Peng Wang Chunyu Zhang Dr. Jinghui He Dr. Dongyun Chen Jiang Jun Prof. Qingfeng Xu Prof. Jianmei Lu 《化学:亚洲杂志》2016,11(1):102-111
A polymer containing aldehyde active groups (PVB) was synthesized by atom transfer radical polymerization (ATRP), acting as a polymer precursor to graft a functional moiety via nucleophilic addition reaction. DHI (2‐(1,5‐dimethyl‐hexyl)‐6‐hydrazino‐benzo[de]isoquinoline‐1,3‐dione) and NPH (nitrophenyl hydrazine) groups, which contain naphthalimides that act as narrow traps and nitro groups that act as deep traps, were anchored onto the PVB at different ratios. A series of graft polymers were obtained and named PVB‐DHI, PVB‐DHI4‐NPH, PVB‐DHI‐NPH4, and PVB‐NPH. The chemical composition of the polymers was analyzed by 1H‐NMR spectroscopy and X‐ray photoelectron spectroscopy (XPS). Memory devices were prepared from the polymers, and I–V characteristics were measured to determine the performance. By adjusting the ratio of different electron acceptors (DHI and NPH) to 4:1, ternary memory behavior was achieved. The relationship between memory behavior of PVB‐DHIxNPHy and acceptor groups as well as their conduction mechanism were studied in detail. 相似文献