三维分等级花状Cd0.8Zn0.2S的结构调控及其光催化CO2还原

近年来,光催化CO2还原被视为一种既能解决能源短缺又能减少温室气体,改善人类生存环境的绿色新型技术.然而,由于CO2气体的相对稳定性,构建高催化活性和高选择性的催化体系仍然面临着巨大挑战.锌硫镉固溶体作为一种廉价的固溶类材料,具有吸光范围适宜、化学性质稳定以及能带结构可调控等特点,在光催化还原CO2的方面表现出巨大的潜力.本文发展了一种简单的原位自组装法合成三维分等级花状结构的Cd0.8Zn0.2S,主要包括Cd^2+和Zn^2+离子在含硫氛围下自组装成核状前体,然后以柠檬酸钠作为形貌诱导剂进一步组装生长,同时控制Cd2+/Zn2+摩尔比和反应时间以实现三维分等级花状Cd0.8Zn0.2S的合成.结果表明,三维分等级花状结构的Cd0.8Zn0.2S在光催化还原CO2的过程中表现出优异的催化活性和稳定性.其中,在光照3 h后,CO产量达到41.4μmol g^?1,大约是相同光照条件下Cd0.8Zn0.2S纳米颗粒的三倍(14.7μmol g^?1).此外,三维分等级花状结构的Cd0.8Zn0.2S在光催化过程中展现出对光催化产物CO的较高选择性(89.9%),其中在没有任何牺牲剂或共催化剂作用下的TON为39.6.太赫兹时域光谱(THz-TDS)表明,这种三维分等级花状结构的Cd0.8Zn0.2S相较于Cd0.8Zn0.2S纳米颗粒更有利于对光的吸收,从而提高对光的有效利用率.原位漫反射傅立叶变化红外光谱表征分析揭示了三维分等级花状结构的Cd0.8Zn0.2S在光催化过程中表面吸附物质以及光催化还原中间体的存在及转化.通过实验数据和理论机理预测表明,该种三维分等级花状结构的Cd0.8Zn0.2S具有较高的电流密度和较好的载流子传输能力.基于这种三维的花状结构,使得Cd0.8Zn0.2S具有较大的比表面积和吸附位点,进一步提升体系的CO2吸附性能和光生电子的转移效率,从而有效提高光催化CO2还原的活性.     

Comparison of the Structural Evolution of β Polypropylene during the Sequential and Simultaneous Biaxial Stretching Process

In this work, the lamellar structural evolution and microvoids variations of β polypropylene(β-PP) during the processing of two different stretching methods, sequential biaxial stretching and simultaneous biaxial stretching, were investigated in detail. It was found that different stretching methods led to significantly different lamellae deformation modes, and the microporous membranes obtained from the simultaneous biaxial stretching exhibited better mechanical properties. For the sequential biaxial stretching, abundant coarse fibers originated from the tight accumulation of the lamellae parallel to the longitudinal stretching direction, whereas the lamellae perpendicular to the stretching direction were easily deformed and separated. Those coarse fibers were difficult to be separated to form micropores during the subsequent transverse stretching process, resulting in a poor micropores distribution. However, for the simultaneous biaxial stretching, the β crystal had the same deformation mode, that is, the lamellae distributed in different directions were all destroyed, forming abundant microvoids and little coarse fibers.     

Dynamic Ring-chain Equilibrium of Nucleophilic Thiol-yne “Click” Polyaddition for Recyclable Poly(dithioacetal)s

We report a dynamic polymerization system based on the reversible nucleophilic Michael polyaddition of activated alkynes and dithiols. Four poly(dithioacetal)s(P1-P4) were prepared via the base-catalyzed thiol-yne "click" polyaddition of two dithiols(1,4-butanedithiol(4 S) and 1,5-pentanedithiol(5 S)) and two alkynones(3-butyn-2-one(Y1) and 1-phenyl-2-propyn-1-one(Y2)) at high concentrations. We systematically investigated the base-catalyzed polymerization of 4 S and Y1(for polymer P1) under different conditions, and found that this polymerization was a highly concentration-dependent dynamic system: polymer P1 was formed at high concentration, while seven-membered dithioacetal, 1-(1,3-dithiepan-2-yl) propan-2-one(C1), was obtained at low concentration. The polymerization of 4 S and Y2(for polymer P4)displayed similar polymerization behavior, generating 2-(1,3-dithiepan-2-yl)-1-phenylethanone(C4) at low concentration. On the contrary,polymer P2(from Y1 and 5 S) was exclusively obtained with no formation of eight-membered dithioacetal. The polymerizations of Y1 with 1,2-ethanedithiol(2 S) and 1,3-dimercaptopropane(3 S) only afforded corresponding five-and six-membered dithioacetals, 1-(1,3-dithiolan-2-yl)propan-2-one(C2) and 1-(1,3-dithian-2-yl) propan-2-one(C3). This dynamic behavior of P1 and P4 was attributed to the concentrationdependent retro-Michael addition reaction between a thiol and a β-sulfido-α,β-unsaturated carbonyl compound catalyzed by bases.Furthermore, polymers P1 and P4 could be depolymerized into C1 and C4 in yields of 58% and 95%, respectively. The ring-opening polymerization of C1 at high concentration could successfully regenerate polymer P1. Thus, a new type of closed-loop recyclable poly(dithioacetal)s was developed.     

A novel thin-layer chromatography-based method for Brazilin quantification

JPC – Journal of Planar Chromatography – Modern TLC - Brazilin, a constituent of the Chinese medicine heartwood, exhibits pronounced anti-tumor effects. To date, brazilin quantification...     

类姜黄素-芳基钌配合物的合成、结构和光照激活抗癌活性

合成了3种含姜黄素衍生物(L¹~L³)和1,3,5-三氮杂-7-磷金刚烷(PTA)配体的芳基钌配合物[(η⁶-p-cymene)Ru(L)(PTA)]PF6(1~3,L=L¹~L³),通过X射线单晶衍射、核磁共振波谱、高分辨质谱、元素分析等方法表征了这些配合物的结构,并用MTT法研究了它们在λ>400 nm的光照辅助下对Hep G2人肝癌细胞的增殖抑制活性。结果表明,这3个配合物均为半三明治型结构;光辅助下,配合物抗癌活性明显提高,其中配合物3对HepG2细胞的IC50值从(60.3±1.1)μmol·L^-1降低至(45.0±6.1)μmol·L^-1。说明光照可以有效提高此类配合物的抗肿瘤活性。     

基于类salen配体的二苯基锡配合物的合成、抗肿瘤活性及其与DNA相互作用

利用类salen配体二苯乙二酮苯甲酰腙或二苯乙二酮水杨酰腙与二苯基二氯化锡反应,合成了2个二苯基锡配合物[(C_6H_5(O)C=N—N=C(Ph)—(Ph)C=N—N=C(O)—C_6H_5)_2SnPh_2(CH_3OH)]·3CH_3OH (1)和 [(o-OH—C_6H_4(O)C=N—N=C(Ph)—(Ph)C=N—N=C(O)—(o-OH—C_6H_4))_2SnPh_2(CH_3OH)]·CH_3OH (2),通过IR、~1H NMR、~(13)C NMR、~(119)Sn NMR、元素分析、HRMS 以及X射线单晶衍射等表征了配合物结构。测试了配合物1、2的热稳定性及其对癌细胞的体外抑制活性,发现配合物2对癌细胞NCIH460、HepG2、MCF7表现出略优的抑制活性。利用紫外可见吸收光谱、荧光猝灭光谱研究了配合物2与ct-DNA之间的相互作用,结果表明配合物以嵌入模式与DNA结合。     

碳量子点/纳米金@碳纳米管修饰电极同时检测鸟嘌呤和腺嘌呤

制备了一种碳量子点(CQDs)/金纳米颗粒(AuNPs)@羟基化多壁碳纳米管(MWCNT-OHs)复合膜修饰电极用于鸟嘌呤(GA)和腺嘌呤(AE)的同时检测.与裸电极和其它修饰电极相比,复合膜修饰电极能显著提高GA和AE的氧化峰电流及峰电位差,能够对GA和AE同时高灵敏检测.研究了GA和AE在复合膜修饰电极上的电化学行为,结果表明,在0.2 mol/L PBS(pH 7.0)中,GA和AE的氧化峰电流与浓度分别在1～200 μmol/L和2～80μmol/L范围内呈良好的线性关系,检测限分别为0.9和1.8 μmol/L.将该修饰电极用于人体血清样品中GA和AE的同时电化学检测,加标回收率在90.4％～107.4％之间,证明了该修饰电极在生物样品分析领域的应用潜力.     

Recent advances in bismuth vanadate-based photocatalysts for photoelectrochemical water splitting

Photoelectrochemical(PEC) technology is considered to be a promising approach for solar-driven hydrogen production with zero emissions. Bismuth vanadate(BiVO_4) is a kind of photocatalytic material with strong photoactivity in the visible light region and appropriate band gap for PEC water splitting.However, the solar-to-hydrogen efficiency(STH) of BiVO_4 is far away from the 10% target needed for practical application due to its poor charge separation ability. Therefore, this review attempts to summarize the strategies for improving the photocurrent density and especially hydrogen production of BiVO_4 materials through PEC techniques in the last three years, such as doping nonmetal and metal elements, depositing noble metals, constructing heterojunctions, coupling with carbon and metalorganic framework(MOF) materials to further enhance the PEC performance of BiVO_4 photoanode. This review aims to serve as a general guideline to fabricate highly efficient BiVO_4-based materials for PEC water splitting.     

ZIF-derived mesoporous carbon materials prepared by activation via Na2SiO3 for supercapacitor

Metal organic frameworks (MOFs) derived carbonaceous materials have a wide range of applications in the fields of energy storage, catalysis, adsorption and separation, etc. Especially, zeolitic imidazolate framework-8 (ZIF-8) is an excellent candidate to synthesize porous carbon due to the large surface area and high nitrogen content. However, the dominated microporous structure of ZIF-8-derived carbon significantly hinders ionic mass transfer, limiting the improvement of performance. Herein, MOF-derived mesoporous carbon was prepared using ZIF-8 as carbon precursor and cheap sodium silicate (Na₂SiO₃) as activator. The introduction of Na₂SiO₃ created rich mesoporous structure and increased specific surface area, as well as the effects of pyrolysis temperature and Na₂SiO₃ dosage on performance was also investigated. The obtained ZIF-derived porous carbon exhibits good electrochemical performance with specific capacitance of 263 F/g at 1 A/g and excellent cycle life (96.07% after 10,000 GCD cycles) in supercapacitor. The use of cheap Na₂SiO₃ activator provides a new orientation for the preparation of MOF-derived carbons with rich pores, high surface area, and facilitates the large-scale application of MOF-derived carbons.     

Visible light induced tandem reactions: An efficient one pot strategy for constructing quinazolinones using in-situ formed aldehydes under photocatalyst-free and room-temperature conditions

A facile tandem route has been developed for constructing quinazolinones from various aminobenzamides and in-situ generated aldehydes. Visible light was found to play a dual role: first oxidizes the alcohol to the aldehyde and then facilitates its cyclization with o-substituted aniline. Furthermore, alcohols are perfect alternatives to aldehydes because they are greener, more available, more economical, more stable, and less toxic than aldehydes. The first reaction step continuously provides material for the second step, which effectively reduces loss through volatilization, oxidation, and polymerization of the aldehyde, while avoiding its toxicity. A variety of quinazolinones can be prepared in the presence of visible light without any additional photocatalyst. The developed synthesis protocol proceeds with the merits of mild conditions, broad substrate scope, operational simplicity, and high atom efficiency, with an eco-energy source under metal-free, photocatalyst-free, and ambient conditions.