Theoretical study on the gas-phase acidity of multiple sites of Cu+-adenine and Cu2+-adenine complexes

The acidities of multiple sites in Cu(+)-adenine and Cu(2+)-adenine complexes have been investigated theoretically. To compare, the acidities of adenine (A) and adenine radical cation (A(*+)) have also been included. The results clearly indicate that the acidities of C-H and N-H groups in Cu(+/2+)-adenine are significantly enhanced relative to the neutral adenine. The acidic order for a given site on adenine and adenine derivatives is as follows: Cu(2+)-adenine > A(*+) > Cu(+)-adenine > A. For Cu(+)-adenine and Cu(2+)-adenine, N3-coordination exhibits N9-H acid, and N1- and N7-coordination exhibits N6-H(a) and N6-H(b) acid, respectively. Additionally, it is found that C2-H group is surprisingly acidic in the coordination complexes. Calculations in aqueous solution reveal that our results can be extrapolated to aqueous solution. Analyses of the electronic properties interpret the highest acidity of Cu(2+)-adenine among the adenine derivatives studied. Also, Electrostatic potential calculations of [A(-H(+))](-) and [A(-H(+))](*) indicate that the removal of H(a) or H(b) from the amino group favors the bidentate coordination, which provides a dative bond from the deprotonated N and the original coordination ligand to copper ion besides the electrostatic interaction between them and thereby stabilizes the [A(-H(+))](-)/[A(-H(+))](*). NBO analysis confirms the electrostatic potential result.     

A new antibody immobilization strategy based on electrodeposition of nanometer-sized hydroxyapatite for label-free capacitive immunosensor

A new antibody immobilization strategy was proposed for the fabrication of a label-free capacitive immunosensor based on electrodeposition of nanometer-sized bioactive hydroxyapatite (HAP). By a procedure of constant current cathodal electrodeposition, a nano-HAP film with bioactivity was formed on a self-assembled β-mercaptoethanol monolayer-modified gold electrode. A suitable amount of chitosan was added into the electrodeposition solution with the aim of obtaining a strong and homogeneous HAP-coating film. After blocking with long-chain alkylthiol and then embedding antibody by coupling with divinylsulphone, the electrode was possessed of a higher initial capacitance value, which was suitable for capacitive transduction. The sensitive layer was characterized by Fourier transform infrared spectrum, scanning electron microscopy and electrochemical method. Human transferrin immunoassay was selected as the testing system. The linear response range of the sensor for transferrin was between 1 and 100 ng/mL with a detection limit of 0.15 ng/mL. After simply rinsing with subacidity solution, the regenerated sensor achieved up to 10 assay cycles without significant loss of sensitivity.     

Chiral organobases: Properties and applications in asymmetric catalysis

Chiral organobases are efficient catalysts used in asymmetric reactions. This review provided a summary of chiral organobases in the aspects of their properties and applications.     

Saqima-like Co<Subscript>3</Subscript>O<Subscript>4</Subscript>/CNTs secondary microstructures with ultrahigh initial Coulombic efficiency as an anode for lithium ion batteries

In this work, Co₃O₄/CNTs composite with Saqima-like secondary microstructure has been synthesized by heat treatment of CoC₂O₄/CNTs precursors being obtained through ultrasonication-assisted precipitation method. Through SEM, in the composites, the microstructures are composed of tightly connected nanoparticles (30–50 nm), and abundant spaces exist among nanoparticles, which can relieve the strain produced by volume effect to ensure the stability of integral structure during cycles; CNTs are dispersed in microstructures and bridge between microstructures, which can form a long-range conductive network in the composite. The electrochemical test indicates that the composite shows ultrahigh initial coulombic efficiency (ICE) of 85%, as well as excellent rate performance and cyclic stability. The high ICE is mainly ascribed to the formation of a stable solid electrolyte interphase (SEI) film only on the outer surface of microstructures. This work offers an available and general way to improve the ICE of transitional metal oxide as an anode material for LIB.     

新工科背景下湖南大学应用化学专业教学改革研究与实践

新工科背景下我国高校强调宽口径、跨学科和复合型的应用化学学科人才培养。结合我校近年来应用化学专业教学改革研究的实际情况,从专业综合改革、实践教学、创新创业及海外课程等几个方面,总结了应用化学专业本科教学的改革成果。     

Nickel(II)‐Catalyzed Asymmetric Propargyl [2,3] Wittig Rearrangement of Oxindole Derivatives: A Chiral Amplification Effect

A highly enantioselective [2,3] Wittig rearrangement of oxindole derivatives was realized by using a chiral N,N′‐dioxide/Ni^II complex as the catalyst under mild reaction conditions. A strong chiral amplification effect was observed, and allowed access to chiral 3‐hydroxy 3‐substituted oxindoles bearing allenyl groups in high yields and enantioselectivities (up to 92 % ee) by using a ligand with only 15 % ee. A reasonable explanation was given based on the experimental investigations and X‐ray crystal structures of enantiomerically pure and racemic catalysts. Moreover, the first catalytic kinetic resolution of racemic oxindole derivatives by a [2,3] Wittig rearrangement was realized with high efficiency and stereoselectivity.     

Introduction to the special column on organocatalysis

正Organocatalysis has become one of the most important frontiers in exploratory organic synthetic research.Because of its connection with reduced energy consumption,greenhouse gas emissions,and waste generation,organocatalysis is increasingly used in pharmaceutical,chemical,food,energy,and agricultural industries.In the     

Fused Isoindigo Ribbons with Absorption Bands Reaching Near‐Infrared

Through fusing isoindigo (IID) units at 6,7;6′,7′‐positions, a series of new near‐infrared (NIR) absorbing and stable ribbon‐like conjugated molecules, namely nIIDs in which n represents the number of IID units, have been synthesized. The optical band gaps of the molecules are lowered from 2.03 eV of 1IID to 1.12 eV of 6IID with the increase of the conjugation length. 3IID, 4IID, and 6IID have strong absorption in the NIR region and exhibit photothermal conversion efficiencies of greater than 50 % under laser irradiation at λ=808 nm.     

专家智能控制器研究

提出增量式专家智能控制器及自学习专家智能控制器的基本结构。应用８０３１、８０９８单片机实现了专家智能控制的数字式闭环控制技术,提高了系统的可靠性及智能度,举出了在调速、控温及恒压供水上的应用实例。