Xiang Yu

Oak Ridge National Laboratory, Oak Ridge, Florida, United States

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Publications (37)120.3 Total impact

  • [Show abstract] [Hide abstract]
    ABSTRACT: In continuation of our program aimed at the discovery of new natural-product-based insecticidal agents, twenty-six deoxypodophyllotoxin derivatives modified in the D-ring were synthesized and evaluated as insecticidal agents against the pre-third-instar larvae of oriental armyworm, Mythimna separata (Walker) in vivo at 1mg/mL. The configuration of three compounds 3, 4, and IIIi was unambiguously determined by single-crystal X-ray diffraction. It demonstrated that aminolysis of deoxypodophyllotoxin in the presence of pyrrolidine and piperidine could result in complete inversion of the configuration of the carbonyl group at its C-2 position. Five compounds IIa, IIi-k, and IIIh showed the equal or higher insecticidal activity than toosendanin. Especially IIj displayed the most potent insecticidal activity with the final mortality rate of 65.5%.
    Bioorganic & medicinal chemistry letters. 08/2014;
  • Bioorganic & medicinal chemistry letters 06/2014; 24(12):2621–2624. · 2.65 Impact Factor
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    ABSTRACT: In continuation of our program aimed at the discovery and development of natural-product-based insecticidal agents, a series of novel hydrazone derivatives of podophyllotoxin, which is a naturally occurring aryltetralin lignan and isolated as the main secondary metabolite from the roots and rhizomes of Podophyllum species, were synthesized and evaluated as insecticidal agents against the pre-third-instar larvae of oriental armyworm, Mythimna separata (Walker) in vivo at 1mg/mL. Especially compounds 8i, 8j, 8t, and 8u showed the more potent insecticidal activity with the final mortality rates greater than 60%.
    Bioorganic & medicinal chemistry letters 04/2014; · 2.65 Impact Factor
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    ABSTRACT: As part of our ongoing efforts to discover new natural-product-based insecticidal agents, in the present study, an efficient method for the stereoselective α-chlorination at the C-2 position of 2'(2',6')-(di)halogenopodophyllotoxin derivatives was firstly developed. Subsequently, a series of novel esters of 2α-chloro-2'(2',6')-(di)halogenopicropodophyllotoxin with modified C, D and E rings of podophyllotoxin were smoothly obtained. Finally, all the title compounds were tested against the pre-third-instar larvae of oriental armyworm (Mythimna separate Walker) at 1 mg/mL. It was found that besides their 2'-halogen-substituted E-ring, the stereoselective α-chlorination at the C-2 position of 2'(2',6')-(di)halogenopodophyllotoxins was also related to the chlorination reagents. Especially 2α-chloro-4α-(benzoyl)oxy-2'-chloropicropodophyllotoxin (6e) and 2α-chloro-4α-(2-chlorophenylacyl)oxy-2'-bromopicropodophyllotoxin (8f) showed the most potent insecticidal activity with the final mortality rates greater than 60%. For 4α-(alkylacyl)oxy derivatives of 2α-chloro-2'(2',6')-(di)halogenopicropodophyllotoxin, the effect of the length of their side chain at the C-4 position of podophyllotoxin skeleton on the insecticidal activity was not very obvious; For 4α-(arylacyl)oxy derivatives of 2α-chloro-2'-chloro/bromopicropodophyllotoxin, the electronic effect of the substituents on their phenyl ring at the C-4 position of podophyllotoxin skeleton on the insecticidal activity was observed.
    Journal of Agricultural and Food Chemistry 04/2014; · 3.11 Impact Factor
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    ABSTRACT: To discover the new natural-product-based insecticidal agents, four series of sixty novel 4β-acyloxypodophyllotoxin analogs modified in the C and E rings were prepared, and their insecticidal activity was tested against the pre-third-instar larvae of oriental armyworm, Mythimna separata (Walker) in vivo at the concentration of 1mg/mL. It demonstrated that the position of the dioxo group on the E-ring of 4'-demethylepipodophyllotoxin was regioselectively controlled by the chlorine atom at its C-2' position when 2'-chloro-4'-demethylepipodophyllotoxin was oxidized by sodium periodate. Among all the derivatives, IIIi exhibited the best potent insecticidal activity with the final mortality rate of 63.3%. To alkylacyloxy series, the proper length of the side chain at the C-4 position of Ia-g, IIa-g and IIIa-g was important for their insecticidal activity.
    Bioorganic & medicinal chemistry letters 01/2014; · 2.65 Impact Factor
  • Polymer. 01/2014;
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    ABSTRACT: Herein we prepared a series of novel fraxinellone derivatives modified at the C-1 or C-8 position in its B ring as insecticidal agents against the pre-third-instar larvae of oriental armyworm, Mythimna separata Walker at 1 mg/mL. Five key steric configurations of compounds 2, 3, 8f, 8g, and 8j were further determined by single-crystal X-ray diffraction. It was found that the kinds and the amount of the reduction products of fraxinellone were related to the molar ratio between the reduction agent Red-Al® and the substrate fraxinellone. Among all the derivatives, compounds 2, 8i, 8j and 8o displayed the more promising insecticidal activity than their precursor fraxinellone and toosendanin. The preliminary structure-activity relationships revealed that the lactone (B-ring) of fraxinellone contributed to the observed insecticidal activity; the double bond at the C-2 position of fraxinellone was not necessary for the insecticidal activity; conversion of the oxygen atom of carbonyl group on the lactone of fraxinellone to the sulfur one can not improve the insecticidal activity; introduction of the electron-withdrawing groups on the phenyl ring of 8f, to benzoyloxy series, could result in the more potent compounds.
    Journal of Agricultural and Food Chemistry 11/2013; · 3.11 Impact Factor
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    ABSTRACT: A chemically diverse library of benzimidazole-azo-phenol derivatives was efficiently prepared and screened for their antifungal activities against five phytopathogenic fungi. Some compounds exhibited the potent antifungal activities. As compared with a commercially available agricultural fungicide, hymexazol, especially compound V-5 showed the most promising broad-spectrum antifungal activities against five phytopathogenic fungi. The EC50 values of V-5 against F. graminearum, A. solani, V. mali, B. cinerea, and C. lunata were 0.09, 0.08, 0.06, 0.07, and 0.11 μmol/mL, respectively.
    Combinatorial chemistry & high throughput screening 10/2013; · 2.46 Impact Factor
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    ABSTRACT: Well-defined conjugated polymers in confined geometries are challenging to synthesize and characterize, yet they are potentially useful in a broad range of organic optoelectronic devices such as transistors, light emitting diodes, solar cells, sensors, and nanocircuits. Herein we report a systematic study of optoelectrical properties, grafting density effects, and nanopatterning of a model, end-tethered conjugated polymer system. Specifically, poly(para-phenylene) (PPP) brushes of various grafting density are created in situ by aromatizing well-defined, end-tethered poly(1,3-cyclohexadiene) (PCHD) “precursor brushes”. This novel precursor brush approach provides a convenient way to make and systematically control the grafting density of high molecular weight conjugated polymer brushes that would otherwise be insoluble. This allows us to examine how grafting density impacts the effective conjugation length of the conjugated PPP brushes and to adapt the fabrication method to develop spatially patterned conjugated brush systems, which is important for practical applications of conjugated polymer brushes.
    J. Mater. Chem. A. 10/2013; 1(43).
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    ABSTRACT: In continuation of our program aimed at the discovery and development of natural-product-based insecticidal agents, twenty-six new piperine-based hydrazone derivatives were synthesized from piperine, an alkaloid isolated from Piper nigrum Linn. The single-crystal structures of 6c, 6q and 6w were unambiguously confirmed by X-ray crystallography. Their insecticidal activity was evaluated against the pre-third-instar larvae of Mythimna separata Walker in vivo. Especially compounds 6b, 6i and 6r, the final mortality rates of which, at the concentration of 1mg/mL, were 62.1%, 65.5% and 65.5%, respectively, exhibited more pronounced insecticidal activity compared to toosendanin at 1mg/mL, a commercial botanical insecticide isolated from Melia azedarach. It suggested that introduction of the substituents at the C-2 position on the phenyl ring of the hydrazone derivatives was important for their insecticidal activity.
    Bioorganic & medicinal chemistry letters 08/2013; · 2.65 Impact Factor
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    ABSTRACT: Unexpected sequential E-ring dihalogenation of podophyllotoxin analogues is reported. It demonstrated that a chlorine/bromine atom was prior introduced at the C2' position of podophyllotoxin, and the corresponding free rotation of E-ring around the C1-C1' bond of 2'-chloro or 2'-bromopodophyllotoxin was restricted. When 2'-chloro or 2'-bromopodophyllotoxin reacted with N-chlorosuccinimide (NCS), the chlorine atom was regioselectively introduced at their C6' position on the E-ring. Whereas 2'-chloro or 2'-bromopodophyllotoxin reacted with NBS, the bromine atom was regioselectively introduced at their C5 position on the B-ring. When 2'-chloropodophyllotoxin reacted with different carboxylic acids in the presence of BF3·Et2O, the steric effect of its E-ring for stereoselective synthesis of 4β-acyloxy-2'-chloropodophyllotoxin derivatives was observed. The insecticidal activity of 2'(2',6')-(di)halogen-substituted podophyllotoxin derivatives were evaluated with Mythimna separata Walker.
    Bioorganic & medicinal chemistry letters 08/2013; · 2.65 Impact Factor
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    ABSTRACT: In continuation of our program aimed at the discovery and development of natural -product-based insecticidal agents, we have prepared three series of novel 4α-acyloxy-2'(2',6')-(di)halogenopodophyllotoxin derivatives modified in the C and E rings of podophyllotoxin, which is a naturally occurring aryltetralin lignan isolated from the roots and rhizomes of Podophyllum hexandrum. Their structures were well characterized by 1H NMR, HRMS, ESI-MS, optical rotation and mp. The stereochemical configurations of compounds 5s, 6b, 6d, and 7q were unambiguously confirmed by single-crystal X-ray diffraction. Their insecticidal activity was evaluated against the pre-third-instar larvae of oriental armyworm, Mythimna separata (Walker) in vivo at a concentration of 1 mg/mL. Among all the derivatives, especially compounds 5a, 5n, 7f, 7n and 7w exhibited the most potent insecticidal activity with the final mortality rates of 70% or so. It suggested that a chlorine or bromine atom introduced at the C2' or C2' and C6' position on the E-ring of podophyllotoxin was necessary for obtaining the potent compounds. It will pave the way for further design, structural modification and development of podophyllotoxin derivatives as insecticidal agents.
    Journal of Agricultural and Food Chemistry 08/2013; · 3.11 Impact Factor
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    ABSTRACT: In continuation of our program aimed at the discovery and development of natural-product-based insecticidal agents, four series of novel cholesterol-based hydrazone derivatives were synthesized, and their insecticidal activity was tested against the pre-third-instar larvae of oriental armyworm, Mythimna separata (Walker) in vivo at 1mg/mL. All the derivatives showed the better insecticidal activity than their precursor cholesterol. Quantitative structure-activity relationship (QSAR) model demonstrated that six descriptors such as RDF085v, Mor06u, Mor11u, Dv, HATS0v and H-046, are likely to influence the insecticidal activity of these compounds. Among them, two important ones are the Mor06u and RDF085v.
    Bioorganic & medicinal chemistry letters 07/2013; · 2.65 Impact Factor
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    ABSTRACT: In continuation of our program aimed at the discovery and development of natural-product-based insecticidal agents, a series of new deoxypodophyllotoxin-based phenazine analogs modified in its E-ring were prepared, and their structures were well characterized by 1H NMR, HRMS, ESI-MS, IR, optical rotation and mp. The absolute steric configuration of one key isomer was unambiguously confirmed by X-ray crystallography. Their insecticidal activity was examined against the pre-third-instar larvae of Mythimna separate Walker in vivo at the concentration of 1 mg/mL. All derivatives showed delayed insecticidal activity. Especially compound 9i, containing p-methoxybenzoylamnio at the C-9' position of deoxypodophyllotoxin-based phenazine fragment, exhibited the most promising insecticidal activity with the final mortality rate of 72.4%. According to the symptoms of the tested M. separate, the derivatives likely displayed the anti-molting hormone effect. In addition, preliminary structure-activity relationships were observed. It suggested that the proper length of the side chain of alkylacylamino might be important for their insecticidal activity, and introduction of the acylamino groups at the C-9' position of deoxypodophyllotoxin-based phenazine fragment usually afforded the more potent compounds than those containing the same ones at the C-10' position. It will pave the way for further design, structural modification and development of deoxypodophyllotoxin-based derivatives as insecticidal agents.
    Journal of Agricultural and Food Chemistry 06/2013; · 3.11 Impact Factor
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    ABSTRACT: In continuation of our program aimed at the discovery and development of natural-product-based pesticidal agents, 54 novel N-arylsulfonyl-3-acylindole arylcarbonyl hydrazone derivatives were prepared, and their structures were well characterized by (1)H NMR, (13)C NMR, HRMS, ESI-MS, and mp. Their nematicidal activity was evaluated against that of the pine wood nematode, Bursaphelenchus xylophilus in vivo. Among all of the derivatives, especially V-12 and V-39 displayed the best promising nematicidal activity with LC50 values of 1.0969 and 1.2632 mg/L, respectively. This suggested that introduction of R(1) and R(2) together as the electron-withdrawing substituents, R(3) as the methyl group, and R(4) as the phenyl with the electron-donating substituents could be taken into account for further preparation of these kinds of compounds as nematicidal agents. Six selected descriptors are a WHIM descriptor (E1m), two GETAWAY descriptors (R1m+ and R3m+), a Burden eigenvalues descriptor (BEHm8), and two edge-adjacency index descriptors (EEig05x and EEig13d). Quantitative structure-activity relationship (QSAR) studies demonstrated that the structural factors, such as molecular mass (a negative correlation with the bioactivity) and molecular polarity (a positive correlation with bioactivity), are likely to govern the nematicidal activities of these compounds. For this model, the correlation coefficient (R(2)training set), the leave-one-out cross-validation correlation coefficient (Q(2)LOO), and the 7-fold cross-validation correlation coefficient (Q(2)7-fold) were 0.791, 0.701, and 0.715, respectively. The external cross-validation correlation coefficient (Q(2)ext) and the root-mean-square error for the test set (RMSEtest set) were 0.774 and 3.412, respectively. This study will pave the way for future design, structural modification, and development of indole derivatives as nematicidal agents.
    Journal of Agricultural and Food Chemistry 06/2013; · 3.11 Impact Factor
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    ABSTRACT: Lithium-ion conducting solid electrolytes hold the promise for enabling high-energy battery chemistries and circumventing safety issues of conventional lithium batteries. Achieving the combination of high ionic conductivity and broad electrochemical window in solid electrolytes is a grand challenge for the synthesis of battery materials. Herein we show an enhancement of room-temperature lithium-ion conductivity of 3 orders of magnitude by creating nanostructured Li3PS4. This material has a wide (5 V) electrochemical window and superior chemical stability against lithium metal. The nanoporous structure of Li3PS4 reconciles two vital effects that enhance ionic conductivity: (1) The reduced dimension to nanometer-sized framework stabilizes the high conduction beta phase that occurs at elevated temperatures; and (2) The high surface-to-bulk ratio of nanoporous β-Li3PS4 promotes surface conduction. Manipulating the ionic conductivity of solid electrolytes has far-reaching implications for materials design and synthesis in a broad range of applications such as batteries, fuel-cells, sensors, photovoltaic systems, and so forth.
    Journal of the American Chemical Society 01/2013; 135(3):975. · 10.68 Impact Factor
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    ABSTRACT: A novel selective and sensitive fluorescence ‘on-off-on’ probe based on tetraphenylethylene (TPE) motif for sequential recognition of Fe3+ and Hg2+ in water has been developed. Especially the complex 6-Fe3+ could behave as a ‘turn on’ fluorescent sensor over a wide-range pH value for detection of Hg2+. The selectivity of this complex for Hg2+ over other heavy and transition metal ions is excellent, and its sensitivity for Hg2+ is at 2 ppb in water.
    Bioorganic & medicinal chemistry 01/2013; 21(2):508–513. · 2.82 Impact Factor
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    ABSTRACT: In continuation of our program aimed at the discovery and development of natural-product-based insecticidal agents, we have synthesized eighteen alkyl/alkenylacyloxy derivatives at the C-28 position adopting exo-configuration of toosendanin (3a-r) by the reaction of toosendanin with fatty acids in the presence of N,N'-diisopropylcarbodiimide and 4-dimethylaminopyridine. Their activity was preliminarily evaluated against the pre-third-instar larvae of Mythimna separata Walker in vivo. Especially compounds 3e and 3o displayed the more promising insecticidal activity than their natural precursor, toosendanin. It suggested that for the n-alkyloyloxy series derivatives, the proper length of the side chain R at the C-28 position of toosendanin was very important for their insecticidal activity.
    Combinatorial chemistry & high throughput screening 01/2013; · 2.46 Impact Factor
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    ABSTRACT: The impact of various polymeric compatibilizers, including end-functionalized P3HTs and diblock copolymers containing P3HT, on the structure and function of poly(3-hexylthiophene) (P3HT):[6,6]-phenyl-C61-butyric acid methyl ester (PCBM) bulk heterojunctions is presented. Careful analyses of small angle neutron scattering curves provide a measure of the miscibility of PCBM in P3HT, the average PCBM domain size, and the interfacial area between PCBM and the P3HT-rich phase in the uncompatibilized and compatibilized systems. Differential scanning calorimetry (DSC) also provides information regarding the changes in the crystallinity of P3HT due to the presence of the compatibilizer. Results show that most compatibilizers cause the domain sizes to decrease and the P3HT crystallinity to increase; however, some cause an increase in domain size, suggesting that they are not effective interfacial modifiers. The correlation of morphology with photovoltaic activity shows that the decreased domain size, increased crystallinity and increased interfacial area do not always result in improved power conversion efficiency (PCE). It appears that the introduction of an insulating molecule at the PCBM:P3HT interface as a compatibilizer results in a decrease in PCE. Thus, the presence of the compatibilizer at this interface dominates the photovoltaic activity, rather than the morphological control.
    Journal of Materials Chemistry A: Materials for Energy and Sustainability 01/2013; 1(2).
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    ABSTRACT: A library of new 2-alkyl-2-(N-arylsulfonylindol-3-yl)-3-N-acyl-5-aryl-1,3,4-oxadiazolines was efficiently synthesized from hydrazones and anhydrides under microwave irradiation and solvent-free conditions. Compared with the traditional procedure (100 equiv. of anhydride and 1.5-4 h of reaction time), the present methodology has the advantages of short reaction time (10-20 min), and avoiding excess of anhydride (only 1.5 equiv.). Moreover, two compounds exhibited the promising anti-HIV-1 activity when evaluated for their inhibitory activity against HIV-1 replication in acutely infected C8166 cells.
    Combinatorial chemistry & high throughput screening 11/2012; · 2.46 Impact Factor

Publication Stats

35 Citations
120.30 Total Impact Points

Institutions

  • 2011–2014
    • Oak Ridge National Laboratory
      • • Chemical Sciences Division
      • • Center for Nanophase Materials Sciences
      Oak Ridge, Florida, United States
    • University of Alabama
      • Department of Electrical and Computer Engineering
      Tuscaloosa, AL, United States
  • 2013
    • Henan University of Science and Technology
      Honanfu, Henan Sheng, China
    • Northwest A & F University
      • College of Science
      Yangling, Shaanxi Sheng, China