Yang Li

Bio: Yang Li is an academic researcher from Sun Yat-sen University. The author has contributed to research in topics: Catalysis & Smelting. The author has an hindex of 5, co-authored 12 publications receiving 184 citations.

Direct aerobic liquid phase epoxidation of propylene catalyzed by Mn(III) porphyrin under mild conditions: evidence for the existence of both peroxide and Mn(IV)-oxo species from in situ characterizations

Abstract: Generally, gaseous propylene is hard to oxidize directly in liquid phase by dioxygen under mild conditions. Here, the liquid phase epoxidation of propylene to propylene oxide (PO) using molecular oxygen catalyzed by manganese porphyrins (MnTPPCl) in the presence of benzaldehyde was developed. Manganese(III) porphyrin exhibited excellent activity for the selective oxidation of propylene under mild conditions. The conversion of propylene and selectivity towards PO can reach 38% and 80%, respectively. The turnover frequency (TOF) of MnTPPCl catalyst reached 1840 h−1. Experiment evidences that the generation of peroxide and Mn(IV) oxo species during propylene epoxidation occurred, which was confirmed by in situ IR, in situ UV and matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF-MS). On the basis of the experimental results, the mechanism for the epoxidation of propylene in the presence of metalloporphyrins and benzaldehyde with dioxygen was proposed. The mechanism is also supported by density functional theory (DFT) calculations.

Semi-rational screening of the inhibitors and β-lactam antibiotics against the New Delhi metallo-β-lactamase 1 (NDM-1) producing E. coli

Abstract: Bacteria containing blaNDM-1 gene are a growing threat to almost all clinically β-lactam antibiotics Especially, the New Delhi metallo-β-lactamase (NDM-1) has become a potential public survival risk In this study, a novel and efficient strategy for inhibitors and β-lactam antibiotics screening using recombinant New Delhi metallo-beta-lactamase (NDM-1) was developed First, the gene of blaNDM-1 were identified and cloned from multi-drug resistance of Acinetobacter baumannii isolate; by the means of protein expression and purification, recombinant NDM-1 activity was up to 685 U ml−1, and high purity NDM-1 protein with activity of 3474 U mg−1 was obtained Finally, for NDM-1, the inhibitors (aspergillomarasmine A (AMA) and EDTA) with high affinity (HI) and the β-lactam antibiotics (imipenem) with low affinity (LA) were screened out Surprisingly, the inhibition of the NDM-1 was enhanced by the use of inhibitor combinations (AMA–EDTA (1 : 2)), where the IC50 of AMA–EDTA was reduced by 88% and 95%, respectively, comparing to the AMA and EDTA alone More interesting, AMA–EDTA could restore the activity of imipenem when tested against NDM-1 expressing strains (E coli and Acinetobacter baumannii), with a working time of 120 min and 330 min, respectively This method is expected to be used in high-throughput screening, drug redesign (including new inhibitors and drugs) and “old drug new use”

Synthesis of Cyclic Carbonates from Epoxides and Carbon Dioxide by Using Organocatalysts

Abstract: The synthesis of cyclic carbonates through coupling of carbon dioxide with epoxides is 100 % atom economical and is already performed on an industrial scale. Its impact regarding the use of carbon dioxide as a renewable carbon source is expected to grow significantly in the near future, so that the development of efficient catalysts is of high interest in academia and industry. To improve the carbon footprint and sustainability of the cycloaddition reaction, the use of organocatalytic methods is a promising approach. Herein, available metal-free catalysts for the preparation of cyclic carbonates are described and elaborated concerning the overall sustainability of the process. Therefore, the required reaction conditions, as well as the activity of the catalysts and their reusability, are compared and evaluated. In addition to ammonium-, phosphonium-, or imidazolium-based single-component catalysts and their supported analogues, the growing field of research concerning dual catalysts are also discussed in detail.

Recent Developments in the Synthesis of Cyclic Carbonates from Epoxides and CO 2

Abstract: The use of CO2 as a C1 building block will be of essential importance in the future. In this context the synthesis of cyclic carbonates from epoxides and CO2 gained great attention recently. These products are valuable compounds in a variety of chemical fields. The development of new catalysts and catalytic systems for this atom-economic, scalable, and industrially relevant reaction is a highly active research field. Over the past 17 years great advances have been made in this area of research. This chapter covers the survey of the important known classes of homogeneous catalysts for the addition of CO2 to epoxides. Besides pioneering work, recent developments and procedures that allow this transformation under mild reaction conditions (reaction temperatures of ≤100 °C and/or CO2 pressures of 0.1 MPa) are especially emphasized.