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991.
Xue Liu Wenting Mao Dr. Jingang Jiang Dr. Xinqing Lu Mingming Peng Dr. Hao Xu Prof. Lu Han Prof. Shun-ai Che Prof. Peng Wu 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(17):4520-4529
The conversion of the alkali-treated intergrowth germanosilicate CIT-13 into the single-crystalline high-silica ECNU-21 (named after East China Normal University) zeolite, with a novel topology and a highly crystalline zeolite framework, has been realized through a creative top-down strategy involving a mild alkaline-induced multistep process consisting of structural degradation and reconstruction. Instead of acid treatment, hydrolysis in aqueous ammonia solution not only readily cleaved the chemically weak Ge(Si)−O−Ge bonds located within the interlayer double four ring (D4R) units of CIT-13, but also cleaved the metastable Si−O−Si bonds therein. This led to extensive removal of the D4R units, and also generated silanol groups on adjacent silica-rich layers, which then condensed to form a novel daughter structure upon calcination. Individual oxygen bridges in the reassembled ECNU-21 replaced the germanium-rich D4R units in CIT-13, thereby eliminating the original intergrowth phenomenon along the b axis. With an ordered crystalline structure of 10-ring (R) channels as well as suitable germanium-related Lewis acid sites, ECNU-21 serves as a stable solid Lewis acid catalyst for the shape-selective hydration of ethylene oxide (EO) to ethylene glycol (EG) at greatly reduced H2O/EO ratios and reaction temperature in comparison with the noncatalytic industrial process. 相似文献
992.
Xiao Jun-An Cheng Xiu-Liang Peng Hai Li Jin-Lian Xie Zhen-Zhen Chen Wen-Qiang Liu Zhi-Ping Xiao Qi Su Wei Yang Hua 《中国科学:化学(英文版)》2020,63(6):785-791
A diastereoselectivity-controllable formal [3+2]-cycloaddition of arylvinyl oxirane 2,2-diesters with cyclic N-sulfonyl imines is developed, affording the corresponding tricyclic oxazolidine derivatives in moderate to excellent yields with excellent diastereoselectivities in the presence of palladium(0) or scandium(III) triflate. This protocol allows selective synthesis of diastereomers of tricyclic oxazolidine derivatives under switchable and mild conditions. Further transformations of the obtained products were conducted by removing ester groups and arylvinyl moieties. 相似文献
993.
Hairan Zhang Qiuyue Zhang Ling Zhang Tingting Pei Erni Li Huiting Wang Prof. Qian Zhang Prof. Lixin Xia 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(6):1535-1542
Poly(N-isopropylacrylamide)-modified graphene oxide (PNIPAm-GO), which is a type of thermally responsive GO, was designed and synthesized through a covalent “grafting-from” strategy. The as-prepared modified nanosheets integrated the individual advantages of two components, such as the thermal sensitivity of the PNIPAm terminal as well as the conductivity and the open 2D structure of the GO substrate. PNIPAm-GO was able to perform the reversible regulation of hydrophilicity/hydrophobicity in aqueous solution upon variations in the temperature. Such a unique property might also lead to the utilization of PNIPAm-GO as an intelligent electrode material to achieve a switchable electrochemical response toward a [Fe(CN)6]3−/4− probe. The PNIPAm-GO modified glassy carbon electrode (PNIPAm-GO/GC electrode) was able to exhibit better electrochemical performance in an ON/OFF switching effect than the PNIPAm-modified glassy carbon electrode (PNIPAm/GC electrode) without GO owing to the intrinsic properties and large surface area of the introduced GO. Moreover, it was found that the PNIPAm-GO/GC electrode also displayed excellent thermally responsive electrocatalysis toward the detection of 1,4-dihydro-β-nicotinamide adenine dinucleotide (NADH) and dopamine (DA), which resulted in two different catalytic statuses on the same electrode. This kind of switchable catalytic performance of the PNIPAm-GO/GC electrode might greatly enhance the flexibility of its application, and thus it is expected to have wide potential for applications in the fields of biosensors and biocatalysis. 相似文献
994.
Haolin Lin Shenhe Fu Zhigui Deng Haiqiong Zhou Hao Yin Zhen Li Zhenqiang Chen 《Annalen der Physik》2019,531(11)
Superoscillation is an intriguing wave phenomenon which enables subwavelength features propagating into far field and hence has potential applications in super‐resolution microscopy as well as particle trapping and manipulation. While previous demonstrations mostly concentrate on designing complicated nanostructures for generating uncontrollable superoscillatory functions, here a new technique which allows for creating polynomially shaped superoscillatory functions that contain phase singularity arrays is demonstrated both theoretically and experimentally. Such a technique is implemented in optical experiments for the first time and controllable superoscillatory lobes with feature much below the diffraction limit is achieved. More importantly, a general theoretical framework, which, to our knowledge, has not been reported before, is developed to show how the created superoscillations propagate to a distance of many Rayleigh ranges and eventually disappear when the distance is sufficiently larger. The validity of the model is confirmed by the experiments. The results may trigger further studies in light field shaping and manipulations in subwavelength scale. 相似文献
995.
Wang Xuedong Hua Chaolong Xu Xinwei Wei Dongzhi 《Applied biochemistry and biotechnology》2019,188(1):138-146
Applied Biochemistry and Biotechnology - In order to obtain high 4-androstene-3,17-dione (AD) yield, nucleus degradation needs to be avoided during phytosterol bioconversion process with... 相似文献
996.
997.
Yan‐Ping Zhang Yue Li Guan‐Cheng Xu Jin‐Yu Li Hua‐Ying Luo Jin‐Yao Li Li Zhang Dian‐Zeng Jia 《应用有机金属化学》2019,33(3)
Two new complexes, namely [Cu6L6] ( 1 ) and [Zn(HL)2] ( 2 ) (H2L = N‐(1‐phenyl‐3‐methyl‐4‐propenylidene‐5‐pyrazolone)‐2‐furancarboxylic acid hydrazide), have been synthesized and characterized. Single crystal X‐ray analysis indicates that complex 1 has a hexanuclear structure and complex 2 exhibits a mononuclear structure. The DNA/bovine serum albumin (BSA) binding properties of complexes 1 and 2 were investigated by absorption spectroscopy and fluorescence quenching. Both complexes could effectively intercalate to DNA with calculated quenching constants of 2.6 × 105 and 1.25 × 105 M?1, respectively. The quenching mechanism of the intrinsic fluorescence of BSA by the complexes was found to be a static one. The cytotoxicities of 1 and 2 were investigated in two human tumor cell lines, human esophageal cancer cells (Eca‐109) and cervical cancer cells (HeLa). Complex 1 exhibits higher antitumor activity than 2 . Furthermore, 1 can inhibit HeLa cells by inducing apoptosis and G0/G1 phase cell cycle arrest. All results demonstrate that 1 and 2 both have DNA/BSA binding capacity and antitumor activity. 相似文献
998.
Dr. Liangqi Gui Xiaoyun Miao Chengjun Lei Kailin Wang Dr. Wei Zhou Dr. Beibei He Prof. Qing Wang Dr. Ling Zhao 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(47):11007-11014
Implementing sustainable energy conversion and storage technologies is highly reliant on crucial oxygen electrocatalysis, such as the oxygen evolution reaction (OER) and oxygen reduction reaction (ORR). However, the pursuit of low cost, energetic efficient and robust bifunctional catalysts for OER and ORR remains a great challenge. Herein, the novel Na-ion-deficient Na2−xCoP2O7 catalysts are proposed to efficiently electrocatalyze OER and ORR in alkaline solution. The engineering of Na-ion deficiency can tune the electronic structure of Co, and thus tailor the intrinsically electrocatalytic performance. Among the sodium cobalt phosphate catalysts, the Na1.95CoP2O7 (NCPO5) catalyst exhibits the lowest ΔE (EJ10,OER−EJ−1,ORR) of only 0.86 V, which favorably outperforms most of the reported non-noble metal catalysts. Moreover, the Na-ion deficiency can stabilize the phase structure and morphology of NCPO5 during the OER and ORR processes. This study highlights the Na-ion deficient Na2−xCoP2O7 as a promising class of low-cost, highly active and robust bifunctional catalysts for OER and ORR. 相似文献
999.
Hao Zhang Dr. Xu Liu Ting-Ting Lu Peng Lv Prof. Wen-Yong Lai 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(15):3909-3917
A series of monodisperse six-armed conjugated starbursts ( Tr1F , Tr2F , and Tr3F ) containing a truxene core and multibranched oligofluorene bridges capped with diphenylamine (DPA) units has been designed, synthesized, and investigated as robust gain media for organic semiconductor lasers (OSLs). The influence of electron-rich DPA end groups on their optoelectronic characteristics has been discussed at length. DPA cappers effectively raise HOMO levels of the starbursts, thus enhancing the hole injection and transport ability. Solution-processed electroluminescence devices based on the resulting six-armed starbursts exhibited efficient deep-blue electroluminescence with clear reduced turn-on voltages (3.2–3.5 V). Moreover, the resulting six-armed molecules showed stabilized electroluminescence and amplified spontaneous emission with low thresholds (27.4–63.9 nJ pulse−1), high net gain coefficients (80.1–101.3 cm−1), and small optical loss (2.6–4.4 cm−1). Distributed feedback OSLs made from Tr3F exhibited a low lasing threshold of 0.31 kW cm−2 (at 465 nm). The results suggest that the construction of truxene-centered six-armed conjugated starbursts with the incorporation of DPA units can effectively enhance EL properties by precisely regulating the HOMO energy levels, and further optimizing their optical gain properties. 相似文献
1000.
Xuan Hao Dr. Hongsen Zhang Dr. Qi Liu Dr. Jingyuan Liu Dr. Rongrong Chen Dr. Jing Yu Prof. Milin Zhang Peili Liu Prof. Jun Wang 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(2):590-597
Enrichment of UVI is an urgent project for nuclear energy development. Herein, magnetic graphitic carbon nitride nanosheets were successfully prepared by in situ anchoring of pyrrhotite (Fe7S8) on the graphitic carbon nitride nanosheet (CNNS), which were used for capturing UVI. The structural characterizations of Fe7S8/CNNS-1 indicated that the CNNS could prevent the aggregation of Fe7S8 and the saturation magnetization was 4.69 emu g−1, which meant that it was easy to separate the adsorbent from the solution. Adsorption experiments were performed to investigate the sorption properties. The results disclosed that the sorption data conformed to the Langmuir isotherm model with the maximum adsorption capacity of 572.78 mg g−1 at 298 K. The results of X-ray photoelectron spectroscopy (XPS) demonstrated that the main adsorption mechanism are as follows: UVI is adsorbed on the surface of Fe7S8/CNNS-1 through surface complexation initially, then it was reduced to insoluble UIV. Thereby, this work provided an efficient and easy to handle sorbent material for extraction of UVI. 相似文献