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71.
A novel graphene oxide (GO) fluorescence switch-based homogenous system has been developed to solve two problems that are commonly encountered in conventional GO-based biosensors. First, with the assistance of toehold-mediated nonenzymatic amplification (TMNA), the sensitivity of this system greatly surpasses that of previously described GO-based biosensors, which are always limited to the nM range due to the lack of efficient signal amplification. Second, without enzymatic participation in amplification, the unreliability of detection resulting from nonspecific desorption of DNA probes on the GO surface by enzymatic protein can be avoided. Moreover, the interaction mechanism of the double-stranded TMNA products contains several single-stranded toeholds at two ends and GO has also been explored with combinations of atomic force microscopy imaging, zeta potential detection, and fluorescence assays. It has been shown that the hybrids can be anchored to the surface of GO through the end with more unpaired bases, and that the other end, which has weaker interaction with GO, can escape GO adsorption due to the robustness of the central dsDNA structures. We verified this GO fluorescence switch-based detection system by detecting microRNA 21, an overexpressed non-encoding gene in a variety of malignant cells. Rational design of the probes allowed the isothermal nonenzymatic reaction to achieve more than 100-fold amplification efficiency. The detection results showed that our strategy has a detection limit of 10 pM and a detection range of four orders of magnitude. 相似文献
72.
Xiangyou Xing Nicholas R. O'Connor Brian M. Stoltz 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2015,127(38):11338-11342
The use of Oxone and a palladium(II) catalyst enables the efficient allylic C H oxidation of sterically hindered α‐quaternary lactams which are unreactive under known conditions for similar transformations. This simple, safe, and effective system for C H activation allows for unusual tunable selectivity between a two‐electron oxidation to the allylic acetates and a four‐electron oxidation to the corresponding enals, with the dominant product depending on the presence or absence of water. The versatile synthetic utility of both the allylic acetate and enal products accessible through this methodology is also demonstrated. 相似文献
73.
Correlation between electron delocalization and structural planarization in small water rings 下载免费PDF全文
Bo Wang Li Wang Xing Dai Yang Gao Wanrun Jiang Jie Han Zhigang Wang Rui‐Qin Zhang 《International journal of quantum chemistry》2015,115(13):817-819
The discovery of the covalent‐like character of the hydrogen bonding (H‐bonding) system [Science 342 , 611(2013)] has promoted a renewal of our understanding of the electronic and geometric structures of water clusters. In this work, based on density functional theory calculations, we show that the preferential formation of a stable quasiplanar structure of (H2O)n(n = 3–6) is closely related to three kinds of delocalized molecular orbitals (MOs; denoted as MO‐I, II, and III) of water rings. These originate from the 2p lone pair electrons of oxygen (O), the 2p bond electrons of O and the 1s electrons of H and the 2s electrons of O and 1s electrons of H, respectively. To maximize the orbital overlaps of the three MOs, geometric planarization is needed. The contribution of the orbital interaction is more than 30% in all the water rings according to our energy decomposition analysis, highlighting the considerable covalent‐like characters of H‐bonds. © 2015 Wiley Periodicals, Inc. 相似文献
74.
Xing‐Ye Mu Chao Li Yu‐Ling Li Yun Liu Xiang‐Shan Wang 《Journal of heterocyclic chemistry》2015,52(2):373-379
A three‐component reaction between an aromatic aldehyde, quinolin‐6‐amine or quinolin‐5‐amine, and tert‐butyl 2,4‐dioxopiperidine‐1‐carboxylate in reflux EtOH gave pyrido phenanthroline derivatives in high yields under catalyst free conditions. The rare C‐H…F hydrogen bond is found in the crystal structure of 6h . 相似文献
75.
Two New Cadmium(II) Compounds based on Distinct Second Building Subunits: Solvothermal Syntheses,Crystal Structures,and Luminescent Properties 下载免费PDF全文
Two cadmium(II) coordination polymers, namely [Cd3(bpt)2(DMA)2]n ( 1 ) and [Cd2(bpt)(btz)(DMF)]n ( 2 ) (H3bpt = biphenyl‐3,4′,5‐tricarboxylic acid, Hbtz = 1H‐benzotriazole, DMA = N,N‐dimethylacetamide; DMF = N,N‐dimethylformamide), were solvothermally synthesized and structurally characterized by single‐crystal X‐ray diffraction. Compound 1 displays a 3D framework based on trinuclear {Cd3(COO)4} subunits and can be simplified into a (4,8)‐connected topological network by viewing bpt3– ligands and trinuclear {Cd3(COO)4} units as 4‐, 8‐connected nodes, respectively. Compound 2 also displays a 3D framework but based on 1D chain subunits controlled by carboxylate groups and btz– ligands. In addition, the thermal stabilities and luminescent properties of compounds 1 and 2 were also investigated. 相似文献
76.
Tianrong Yu Yang Gao Bo Wang Xing Dai Wanrun Jiang Ruixia Song Prof. Zhanwen Zhang Prof. Mingxing Jin Prof. Yongjian Tang Prof. Zhigang Wang 《Chemphyschem》2015,16(15):3308-3312
The mechanism of depolymerization is one of the most essential issues in chemical engineering and materials science. In this work, we investigate the depolymerization reactions of three typical free‐radical poly(alpha‐methylstyrene) tetramers by using first‐principles density functional theory. The calculated results show that these reactions all need to overcome the energy barriers in the range of 0.58 to 0.77 eV, and that breaking the C?C bond at the chain end leads to the dissociation of alpha‐methylstyrene monomers from the polymers. Electronic‐structure analysis indicates that the reactions occur easily at the CR3 unsaturated end, and that the frontier molecular orbitals that participate in the reactions are mainly localized at the unsaturated ends. Meanwhile, spin population analysis presents the unique net spin‐transfer process in free‐radical depolymerization reactions. We hope the current findings can contribute to understanding the free‐radical depolymerization mechanism and help guide future experiments. 相似文献
77.
Preparation of novel curcumin‐imprinted polymers based on magnetic multi‐walled carbon nanotubes for the rapid extraction of curcumin from ginger powder and kiwi fruit root 下载免费PDF全文
Zhaohui Zhang Xing Chen Wei Rao Fang Long Liang Yan Yuli Yin 《Journal of separation science》2015,38(1):108-114
A novel molecularly imprinted polymer based on magnetic phenyl‐modified multi‐walled carbon nanotubes was synthesized using curcumin as the template molecule, methacrylic acid as the functional monomer and ethylene glycol dimethacrylate as the cross‐linker. The phenyl groups contained in the magnetic imprinted polymers acted as the assisting functional monomer. The magnetic imprinted polymers were characterized by scanning electron microscopy, Fourier‐transform infrared spectroscopy and vibrating sample magnetometry. Adsorption studies demonstrated that the magnetic imprinted polymers possessed excellent selectivity toward curcumin with a maximum capacity of 16.80 mg/g. Combining magnetic extraction and high‐performance liquid chromatography technology, the magnetic imprinted polymer based on magnetic phenyl‐modified multi‐walled carbon nanotubes was applied for the rapid separation and enrichment of curcumin from ginger powder and kiwi fruit root successfully. 相似文献
78.
Xinchen Kang Wenting Shang Qinggong Zhu Jianling Zhang Tao Jiang Buxing Han Zhonghua Wu Zhihong Li Xueqing Xing 《Chemical science》2015,6(3):1668-1675
We proposed a strategy to synthesize mesoporous inorganic salt particles using the special properties of ionic liquid (IL) mixtures, and hollow mesoporous LaF3, NdF3, and YF3 particles were synthesized and characterized using different techniques. The size of the mesopores in the salt particles was about 4 nm, and the materials were full of crystal defects. The LaF3, NdF3 and YF3 particles were used as the catalysts for the cyanosilylation reaction of benzaldehyde using trimethylsilyl cyanide, and Ru/LaF3 and Ru/NdF3, in which Ru nanocatalysts were supported on the LaF3 and NdF3 particles with mesopores, were used to catalyze hydrogenations of benzene to cyclohexane and levulinic acid (LA) to γ-valerolactone (GVL). It was discovered that the activities of these catalysts were unprecedentedly high for these reactions. Detailed study showed that both the crystal defects and the mesopores in the salt particles played crucial roles for the extremely high catalytic activity. 相似文献
79.
Rong Guo Yilv Guo Yehui Zhang Xiaoshu Gong Tingbo Zhang Xing Yu Shijun Yuan Jinlan Wang 《Frontiers of Physics》2023,18(4):43304
As a two-dimensional material with a hollow hexatomic ring structure, Néel-type anti-ferromagnetic (AFM) GdI3 can be used as a theoretical model to study the effect of electron doping. Based on first-principles calculations, we find that the Fermi surface nesting occurs when more than 1/3 electron per Gd is doped, resulting in the failure to obtain a stable ferromagnetic (FM) state. More interestingly, GdI3 with appropriate Mg/Ca doping (1/6 Mg/Ca per Gd) turns to be half-metallic FM state. This AFM−FM transition results from the transfer of doped electrons to the spatially expanded Gd-5d orbital, which leads to the FM coupling of local half-full Gd-4f electrons through 5d−4f hybridization. Moreover, the shortened Gd−Gd length is the key to the formation of the stable ferromagnetic coupling. Our method provides new insights into obtaining stable FM materials from AFM materials. 相似文献
80.