酒石酸铅锆的制备、表征及其燃烧催化作用

以酒石酸、硝酸氧锆和硝酸铅为原料,合成出了双金属盐酒石酸铅锆,采用有机元素分析、X射线荧光光谱和FTIR对其进行了表征。在程序升温条件下,利用TG/DTG、DSC、固相原位反应池/FTIR联用技术,研究了酒石酸铅锆的热行为和热分解机理,描述了酒石酸铅锆的热分解过程,分析得出其最终分解产物为ZrO2、PbO和C。利用螺压工艺制备了含酒石酸铅锆的推进剂样品,研究了酒石酸铅锆对双基系推进剂燃烧性能的影响,分析了其燃烧催化作用。结果表明,酒石酸铅锆对双基系推进剂的燃烧具有良好的催化作用,是一种高效的燃烧催化剂;酒石酸铅锆热分解的最终产物PbO是催化燃烧的主要活性物质,推进剂燃烧过程中形成了氧化铅-铅循环催化体系,而锆和碳则起辅助催化的作用。     

壳聚糖的改性及其纳米粒子的制备

通过壳聚糖上的氨基与硬脂酸和硫辛酸的羧基脱水缩合反应,将硬脂酸和硫辛酸接枝在壳聚糖上,引入的疏水性基团使修饰的壳聚糖具有两亲性。对修饰壳聚糖残留的自由氨基进行甲基化,使氨基的pKa值由6.6增加到6.8~7.1。修饰的壳聚糖在水介质中经超声分散即可形成纳米粒子,纳米粒子的Zeta电位为正值,说明修饰壳聚糖中残留的氨基和甲基化的氨基处于纳米粒子的表面。纳米粒子经二硫苏糖醇还原,然后经空气中的氧气氧化,在纳米粒子中形成二硫键交联结构。     

Unusual Structure,Fluxionality, and Reaction Mechanism of Carbonyl Hydrosilylation by Silyl Hydride Complex [(ArN)Mo(H)(SiH2Ph)(PMe3)3]

The reactions of bis(borohydride) complexes [(RN?)Mo(BH₄)₂(PMe₃)₂] ( 4 : R=2,6‐Me₂C₆H₃; 5 : R=2,6‐iPr₂C₆H₃) with hydrosilanes afford new silyl hydride derivatives [(RN?)Mo(H)(SiR′₃)(PMe₃)₃] ( 3 : R=Ar, R′₃=H₂Ph; 8 : R=Ar′, R′₃=H₂Ph; 9 : R=Ar, R′₃=(OEt)₃; 10 : R=Ar, R′₃=HMePh). These compounds can also be conveniently prepared by reacting [(RN?)Mo(H)(Cl)(PMe₃)₃] with one equivalent of LiBH₄ in the presence of a silane. Complex 3 undergoes intramolecular and intermolecular phosphine exchange, as well as exchange between the silyl ligand and the free silane. Kinetic and DFT studies show that the intermolecular phosphine exchange occurs through the predissociation of a PMe₃ group, which, surprisingly, is facilitated by the silane. The intramolecular exchange proceeds through a new non‐Bailar‐twist pathway. The silyl/silane exchange proceeds through an unusual Mo^VI intermediate, [(ArN?)Mo(H)₂(SiH₂Ph)₂(PMe₃)₂] ( 19 ). Complex 3 was found to be the catalyst of a variety of hydrosilylation reactions of carbonyl compounds (aldehydes and ketones) and nitriles, as well as of silane alcoholysis. Stoichiometric mechanistic studies of the hydrosilylation of acetone, supported by DFT calculations, suggest the operation of an unexpected mechanism, in that the silyl ligand of compound 3 plays an unusual role as a spectator ligand. The addition of acetone to compound 3 leads to the formation of [trans‐(ArN)Mo(OiPr)(SiH₂Ph)(PMe₃)₂] ( 18 ). This latter species does not undergo the elimination of a Si? O group (which corresponds to the conventional Ojima′s mechanism of hydrosilylation). Rather, complex 18 undergoes unusual reversible β‐CH activation of the isopropoxy ligand. In the hydrosilylation of benzaldehyde, the reaction proceeds through the formation of a new intermediate bis(benzaldehyde) adduct, [(ArN?)Mo(η²‐PhC(O)H)₂(PMe₃)], which reacts further with hydrosilane through a η¹‐silane complex, as studied by DFT calculations.     

Targeting the Substrate Binding Site of E. coli Nitrile Reductase QueF by Modeling,Substrate and Enzyme Engineering

Nitrile reductase QueF catalyzes the reduction of 2‐amino‐5‐cyanopyrrolo[2,3‐d]pyrimidin‐4‐one (preQ₀) to 2‐amino‐5‐aminomethylpyrrolo[2,3‐d]pyrimidin‐4‐one (preQ₁) in the biosynthetic pathway of the hypermodified nucleoside queuosine. It is the only enzyme known to catalyze a reduction of a nitrile to its corresponding primary amine and could therefore expand the toolbox of biocatalytic reactions of nitriles. To evaluate this new oxidoreductase for application in biocatalytic reactions, investigation of its substrate scope is prerequisite. We report here an investigation of the active site binding properties and the substrate scope of nitrile reductase QueF from Escherichia coli. Screenings with simple nitrile structures revealed high substrate specificity. Consequently, binding interactions of the substrate to the active site were identified based on a new homology model of E. coli QueF and modeled complex structures of the natural and non‐natural substrates. Various structural analogues of the natural substrate preQ₀ were synthesized and screened with wild‐type QueF from E. coli and several active site mutants. Two amino acid residues Cys190 and Asp197 were shown to play an essential role in the catalytic mechanism. Three non‐natural substrates were identified and compared to the natural substrate regarding their specific activities by using wild‐type and mutant nitrile reductase.     

扫帚状氧化铈制备及其对Pt基阳极催化剂催化性能的影响

采用水热合成法,合成了比表面积为175 m²·g^-1,孔径在2~4nm范围内的扫帚状CeO₂。通过微波辅助乙二醇还原氯铂酸法制备了Pt-CeO₂/RGO催化剂,探究扫帚状CeO₂的添加对Pt基催化剂电催化性能的影响。利用X射线衍射仪（XRD）、扫描电镜（SEM）、N₂吸附-脱附、X射线光电子能谱（XPS）对所制备的CeO₂及催化剂进行表征。利用电化学工作站对催化剂进行电化学性能测试。结果表明,催化剂中CeO₂保持原有扫帚状,Pt纳米粒子均匀分布于石墨烯载体表面;当m_RGO∶m_CeO2=1∶2时,添加了扫帚状CeO₂的Pt-CeO₂/RGO催化剂的电催化性能最优,电化学活性表面积为102.83 m²·g^-1,对乙醇氧化的峰值电流密度为757.17 A·g^-1,1 000 s的稳态电流密度为108.17 A·g^-1,对乙醇催化氧化反应的电荷转移电阻最小,活化能最低。     

一维配位聚合物{[Co(dpa)(H2O)4]·(dpdo)·(H2O)}n(H2dpa=2,2’-联苯二酸,dpdo=N,N’-二氧化-4,4’-联吡啶)的晶体结构和光谱性质

采用水热合成法制备了一个一维配位聚合物{[Co(dpa)(H2O)4].(dpdo).(H2O)}n(1)(H2dpa=2,2′-联苯二酸,dpdo=N,N′-二氧化-4,4′-联吡啶),通过红外光谱、紫外光谱、元素分析、XRPD、TGA和X-射线单晶衍射进行了表征。Co(Ⅱ)原子采取了畸变的八面体构型,6个配位氧原子分别来自于2个dpa2-配体和4个配位水分子。每一个dpa2-配体桥联2个Co髤中心,每一个Co(Ⅱ)原子与2个dpa2-配体配位进而形成了21螺旋链结构。借助溶剂水分子的连接作用,螺旋链之间通过多种O-H…O氢键作用形成了2D网格,通过dpdo和2D网格之间多种类型的氢键作用形成了三维超分子结构。测定了室温下聚合物1的固体荧光光谱。     

1-4丁炔二醇和乙二胺对离子液体电沉积Cu的影响

研究了1-4丁炔二醇和乙二胺作为添加剂对在离子液体1-甲基-3-甲基咪唑三氟甲磺酸盐中电沉积Cu的影响。紫外可见光吸收光谱结果表明,当采用1-4丁炔二醇作为添加剂时,1-4丁炔二醇吸附在工作电极表面且未与溶液中的Cu²⁺形成配合物。扫描电镜测试结果表明由于1-4丁炔二醇与离子液体的正离子的竞争吸附使得Cu的沉积电势发生正移并使镀层表面更加均匀平整。当采用乙二胺作为添加剂时,紫外可见光吸收光谱和循环伏安测试结果表明乙二胺与溶液中的Cu²⁺离子形成带有正电荷的络合离子使得Cu的沉积电势发生正移,扫描电镜和原子力显微镜测试结果表明得到了更加均匀的镀层。当同时加入1-4丁炔二醇和乙二胺时,Cu的沉积电势仍然发生正移并得到具有纳米粒径的镀层。     

基于氮氧自由基配体的锰和钴双核配合物的分子结构和磁性

合成了2个基于氮氧自由基配体且结构类似的双核配位化合物,其分子式分别为[Mn₂(hfac)₄(NIT-mo-pmy)₂](1)和[CO₂(hfac)₄(NIT-mo-pmy)₂](2),其中hfac=六氟乙酰丙酮,NIT-mo-pmy=2-(2-甲氧基-5′-嘧啶基)-4,4,5,5-四甲基咪唑啉基-3-氧-1-氧自由基。2个配合物均属于三斜晶系P1空间群,其双核配位单元进一步构筑为中心对称的平行四边形分子阵列。变温磁化率的测试表明,在2个配合物中,中心离子和氮氧自由基单元之间存在反铁磁交换作用。借助构效关系研究,分析了磁作用强度的差异。通过适当近似的磁化学模型,对Mn(Ⅱ)配合物的磁性行为进行了定量拟合,并与相关化合物磁作用强度进行了比对、分析。     

促进学生化学学科核心素养发展的“铁盐和亚铁盐”的单元教学

设计了“铁盐和亚铁盐”的单元教学,以“探究硫酸亚铁的性质”和“线路板腐蚀液的研究”为核心任务,把铁盐与亚铁盐的性质、Fe²⁺和Fe³⁺的相互转化等核心知识贯穿其中,建立从物质类别、元素价态视角研究物质性质及转化的思路方法,促进多维度化学学科核心素养的融合发展。经过多轮次教学改进,结合教学实践过程及其教学效果抽提出“注重应用无机物的认识模型,重点把握研究物质性质的角度和思路”“抓住典型活动,培养学生的关键能力”“设计开放性任务,通过有效的师生对话进行诊断,外显问题解决思路”等教学策略。     

柠檬酸配合法制备CuMnCeOx催化剂及常温催化氧化性能研究

摘要：常温催化氧化是消除室内HCHO污染最可行的方法之一,其中以过渡金属氧化物为代表的催化剂因性能优异、成本低廉而备受广泛关注。采用柠檬酸络合法和水热法制备了一系列CuMnCeOx催化剂,研究考察制备方法及载体对催化剂氧化性能的影响,并利用XRD、SEM、BET、H2-TPR、XPS和IR等对催化剂进行微观表征与分析。研究发现,制备方法及载体类型对催化剂的表面结构形貌、氧化性能产生显著影响,其中采用柠檬酸络合法所制的CuMnCeOx-C催化剂性能最佳,48h的HCHO去除率达98.6%,完全满足GB50325-2001标准要求,其介孔结构,晶体粒径及所形成的铈基铜锰固溶体均利于形成大量氧空位及催化氧化反应,且展示出良好的抗水蒸气和稳定性能,其在常温催化氧化VOCs方面具有重要应用前景。