C_6H_2(OH)_3CH_3氧化成羟基苯甲酸反应路径的DFT研究

运用密度泛函(DFT)理论,采用Materials Studio 8.0,用GGA/BP方法研究了C_6H_2(OH)_3CH_3氧化成羟基苯甲酸的反应路径。结果表明,甲基上的氢原子被氧化成羟基以及羟基被氧化为醛基及醛基被氧化成羧基均为放热过程。分子C_6H_2(OH)_3CH_3中甲基氧化成羧基的主路径为三个氢原子氧化反应路径,其路径为C_6H_2(OH)_3CH_3+3O→C6H2(OH)3C(OH)3→C6H2(OH)3COOH+H2O,该路径受限于羟基直接被氧化成羧基过程,需克服130 k J/mol的反应势垒,反应速率常数对数ln(k)为-22.96 s-1;醛基、羟基优先被氧化成羧基的顺序为:-CHO-C(OH)3-HC(OH)2-H2C(OH);提高反应温度、氧气浓度均有利于羟基苯甲酸的生成,适当的催化剂有利于促进整个反应的进行。     

Multi-functional Photoelectric Sensor Based on a Three-fold Interpenetrated Cd(II) Coordination Polymer for Sensitively Detecting Different Ions

Athree-fold interpenetrated cadmium coordination polymer[Cd₃(BTC)₂(H₂O)₉]·2H₂O(CP 1)(H₃BTC=1,3,5-benzenetricar-boxylic acid) was selected and synthesized to investigate its photoelectric properties. CP 1 showed excellent sensitivity for Cr₂O₇^2- and Fe³⁺, low limit of detection(LOD:0.39 µmol/L for Cr₂O₇^2- and 1.72 µmol/L for Fe³⁺) and stability as electrochemical sensor. More importantly, fluorescence sensing studies indicated that CP 1 exhibits sensing activity for Fe³⁺, Fe²⁺, and MnO₄^- with good cyclic stability and selectivity. Low LOD and high-sensitivity capability of CP 1 make it a potential multifunctional photoelectric sensor.     

酸性溶液中Fe2+ /Fe3+相互转换对电极还原行为的影响

采用线性扫描伏安法和循环伏安法研究了含有Cl^-、SO₄^2-的酸性溶液中Fe²⁺/Fe³⁺相互转换对电极反应和Fe³⁺还原过程的影响. 结果表明: [Fe]_T=1 mol·L-1条件下,溶液中Fe³⁺/Fe²⁺的还原析出过程经过两个阶段：(1) E=0.35 V左右Fe³⁺还原成Fe²⁺过程; (2) E=-0.3 V之后H+的还原同时Fe²⁺离子与OH^-相结合生产Fe(OH)₂; Fe³⁺/Fe²⁺的相互转化主要影响Fe³⁺的第一还原阶段的还原峰电流和峰电位. |ipa/ipc|值随c(Fe³⁺ )/c(Fe²⁺ )增大而增大,且扫描速度慢时影响大,扫描速度快时影响小; 0.50 mol·L^-1 Fe²⁺+0.50 mol·L^-1 Fe³⁺时,随扫描速率的变化|ipa/ipc|值变化最小(|i_pa/i_pc|≈1.20). 同时,c(Fe³⁺ )/c(Fe²⁺ )也影响平衡电位,平衡电位随c(Fe³⁺ )/c(Fe²⁺ )增大而正移,电位从E₁=0.501 V升至E₅=0.565 V.     

水蒸汽浴FeS2高效Fenton降解甲草胺(英文)

由于硫化铁在自然环境中的丰富性,其生成活性氧和降解各种有机污染物的类Fenton活性已被广泛研究。然而,由于表面含铁活性位点的暴露有限,它们的类Fenton活性通常不高。在本研究中,以黄铁矿(FeS₂)为例,基于水蒸汽对FeS₂的热处理,开发了一种提高硫化铁矿物Fenton活性的新策略,研究发现经水蒸汽热处理后的FeS₂ (Heat-FeS₂)对甲草胺(ACL)的非均相Fenton活性比由水热反应制备的母体FeS₂ (Fresh-FeS₂)更高。在初始pH为6.3时,Heat-FeS₂-Fenton体系对ACL的降解速率为0.48 min^-1,约为Fresh-FeS₂-Fentton体系的23倍。电子自旋共振分析和苯甲酸探针实验证实,与Fresh-FeS₂-Fenton体系相比,在Heat-FeS₂-Fenton体系中产生更多的羟基自由基(·OH)...     

溴代酞菁铁配合物的光谱电化学性质研究

本文对μ-氧-四溴酞菁铁配合物([TBPcFe]₂O)的电化学性质及光谱电化学性质进行了研究。结果表明,μ-氧-四溴酞菁铁在所研究的电压区问内经历了三个单电子氧化还原反应,其半波电势为0.06V,—0.75V及—1.33V(相对于甘汞电极),分别对应于Fe³⁺/Fe³⁼、Fe²⁺/Fe⁺及TBPc^2-/TBPc^3-电对的氧化还原反应。光谱电化学性质研究亦观察到相应酞菁配合物的特征光谱。     

UiO-66-NH2/wood的设计构筑及高效去除水中微量重金属离子性能

矿山开采、 金属冶炼、 新型金属材料的发展以及城市供水系统老化所造成的重金属(铅、 镉、 汞、 砷、 铬、 铜及锌等)污染问题已日趋严重. 传统的水处理方法很难有效地去除低浓度的重金属污染物. 本文以天然木材为载体, 采用溶剂热合成法, 在木材三维孔道中原位合成UiO-66-NH₂金属有机框架材料(MOFs)纳米颗粒, 制备了UiO-66-NH₂/wood复合膜材料. 该复合膜材料对去除水中微量重金属离子(Hg²⁺, Cu²⁺)表现出优异的性能. 当处理速率为1.1×10² L?m^-2?h^-1时, 该复合膜材料去除水中微量重金属离子的效率仍可达到90%以上, 且处理后水中重金属离子含量低于国家饮用水标准. 这可归因于木材本身独特的三维孔道结构, 在提高水通量的同时, 还可以增加水溶液中重金属离子与MOFs颗粒的接触机会, 以及孔道内均匀分布的UiO-66-NH₂ MOFs颗粒中的—NH₂可以与重金属离子通过配位作用相结合. 该UiO-66-NH₂/wood复合膜材料还具有良好的重复利用性, 在连续6次循环使用后其去除效率无明显变化, 有望进行实际应用.     

新型磷-钒-氧层状化合物[H2en]2[H3O]6[Co(H2O)2(VO)8(OH)4(PO4)8]的水热合成与晶体结构

金属磷酸盐材料在吸附、离子交换、离子传导和催化剂方面有潜在的应用前景[1～5]. 近年来, 通过水热反应合成了一些A-V-P-O化合物. 在这些化合物中, A一般为碱金属或有机阳离子, 如层状结构的[H2N(C4H8)2NH2][(VO)4(OH)4(PO4)2][6] 和[H2N(C2H4)3NH2][(VO)8(HPO4)3(PO4)4*(OH)2]*2H2O[6], 一维链状结构的 [H2NCH2CH2NH3(VO)(PO4)][7], 手性双螺旋结构的 [(CH3)2NH2]K4[(VO)10(H2O)2(OH)4(PO4)7]*H2O[8]以及具有三维骨架结构的化合物 [H3N(CH2)3NH3K(VO)3(PO4)3][9], [H3N(CH2)3NH3]2[V(H2O)2(VO)6(OH)2(HPO4)3(PO4)5]*3H2O[10]和[H3N(CH2)2NH3][(VO)3(H2O)2(PO4)2(HPO4)4][11].     

SO_4~(2-)功能化处理对Fe_2O_3催化剂上氨选择性催化还原NO_x性能的促进机理研究

采用沉淀法制备了Fe(OH)_3和Fe_2O_3。通过硫酸化处理得到SO_4~(2-)/Fe(OH)_3和SO_4~(2-)/Fe_2O_3两种催化剂,并将其应用于氨选择性催化还原NO_x(NH_3-SCR)反应,研究了SO_4~(2-)功能化处理对Fe_2O_3催化剂上NH_3-SCR脱硝性能的促进机理。结果表明,与纯的Fe_2O_3相比,硫酸化处理得到的催化剂上SCR活性得到显著提升;其中,SO_4~(2-)/Fe(OH)_3表现出更加优异的催化性能,在250-450℃时NO_x转化率高于80%,且具有优异的稳定性和抗H_2O+SO_2性能。XRD、Raman、TG、FT-IR、H_2-TPR、NH_3-TPD和in situ DRIFTS等表征结果显示,硫酸功能化处理能抑制Fe_2O_3的晶粒生长,同时SO_4~(2-)与Fe~(3+)结合形成硫酸盐复合物,提高了催化剂表面酸性位点的数量和酸强度,抑制了Fe_2O_3上的氨氧化反应,从而提高了其脱硝催化性能。     

A multi-responsive luminescent sensor towards Fe_(3+) and acetone based on a Cd-containing metal–organic framework

A Cd-containing metal–organic framework(Cd L), formula as {[Cd_3(L)_2(H_2O)_6] 1.5DMF}, has been synthesized under solvothermal condition by the reaction of 4,40,400-(methylsilanetriyl)tribenzoic acid(H_3L) and Cd~(2+)ion. Single-crystal X-ray diffraction reveals that Cd L displays a three-dimensional framework with 2-fold interpenetration and DMF molecules locate in the void space of the channels. A topological analysis of the framework indicates Cd L is a 3,4-connected pto net. The photoluminescence properties of Cd L are systematically studied in detail. Impressively, Cd L shows excellent detection performance towards Fe~(3+)ion and acetone in the sensing experiments, which undoubtedly demonstrates the great potential of Cd Lasa highly selective multi-responsive luminescent sensor for the detection of organic solvents and metal ions.     

Improved electrochemical properties in the Li3Fe2(PO4)3 by titanium and vanadium doping

Ti⁴⁺ ions were introduced to the VO₄^3- substituted Li₃Fe₂(PO₄)₃ by sol-gel method. Simultaneous substitution of Ti⁴⁺ for Fe³⁺ and VO₄^3- for PO₄^3- in the Li₃Fe₂(PO₄)₃ resulted in a net improvement in the rate capability and cycling performance, as compared with the single Ti⁴⁺ or VO₄^3- substituted compound.     

The dehydroxylation of basic aluminum sulfate: An infrared emission spectroscopic study

The tridecameric aluminum polymer [AlO₄Al₁₂(OH)₂₄(H₂O)₁₂]⁷⁺ was prepared by forced hydrolysis of Al³⁺ up to an OH/Al molar ratio of 2.2. Upon addition of sulfate, the tridecamer crystallized as the monoclinic basic aluminum sulfate Na_0.1[AlO₄Al₁₂(OH)₂₄(H₂O)₁₂](SO₄)_3.55. The dehydroxylation of the basic aluminum sulfate has been studied by Fourier transform in-situ infrared emission spectroscopy over a temperature range of 200° to 750°C at 50°C intervals. The spectrum is characterized by the sulfate ν₁ (1024 cm⁻¹), ν₃ doublet (1117 and 1168 cm⁻¹) and the ν₄ doublet (568 and 611 cm⁻¹) modes. Furthermore, minor bands assigned to nitrate are observed. Upon heating from ≈350° to 400°C major changes are observed, especially in the bandwidth and band intensities. The bands in the hydroxyl stretching region due to the Al₁₃ group disappear, whereas the bands around 1050 cm⁻¹ display various changes in bandwidths, intensities and positions associated with the dehydration and dehydroxylation of the basic sulfate and the changing of the structure into an aluminum oxosulfate. The nitrate bands diminish upon heating.     

Li3Fe2(PO4)3/C正极材料的电化学性能及其反应机理研究

采用溶胶凝胶及高能球磨制得Li₃Fe₂(PO₄)₃/C材料,利用多种物理及其电化学技术观察材料形貌,表征材料结构及电化学性能,用电化学原位XAFS等初步研究Li₃Fe₂(PO₄)₃/C超理论容量电化学反应机理. 结果显示,Li₃Fe₂(PO₄)₃/C的结构为单斜晶系,空间群P21/n. 2.0 ~ 4.0 V电位区间,10 mAh·g^-1电流密度,Li₃Fe₂(PO₄)₃/C电极的首周期放电比容量为129 mAh·g^-1,达到其理论容量. 若电位区间拓宽至2.0 ~ 4.95 V,其首周期放电比容量高达165 mAh·g^-1,超出理论的“额外”容量30%. 电化学原位XAFS测试未观察到明显的Fe³⁺/Fe⁴⁺氧化还原对参与电化学反应,初步推测“额外”容量可能来自于该复合材料的高浓度表面缺陷.     

Rational Design of Ratiometric Fe3+ Fluorescent Probes Based on FRET Mechanism

As the most abundant transition metal element in mammals, iron(Fe) plays a vital role in life activities. It is of great significance to study the variation of Fe³⁺ level in living organisms. In virtue of the advantages of high sensitivity, good selectivity and low damage to living systems, the fluorescence detection of Fe³⁺ has attracted much attention. Compared with the intensity-based fluorescent probe, the ratiometric fluorescent probe has less interference of environmental and can realize quantitative detection. In this study, four ratiometric Fe³⁺ fluorescent probes, R1, R2, R3 and R4_, were designed and synthesized using fluorescence resonance energy transfer(FRET) mechanism to achieve quantitative detection of Fe³⁺. In the FRET systems, 1,8-naphthalimide fluorophore derivatives were adopted as donors while rhodamine B derivatives were selected as receptors. The connection sites of the donor and acceptor in R3 and R4 are different from those in R1 and R2. All the four probes showed good response and selectivity to Fe³⁺. The energy transfer efficiencies of R3 and R4 were obviously higher than those of R1 and R2. This work provided a promising strategy for the development of fluorescent ratiometic Fe³⁺sensors.     

Fe掺杂g-C_3N_4的制备及其可见光催化性能

以硝酸铁和三聚氰胺为原料制备不同含铁量的Fe掺杂石墨氮化碳(g-C3N4).采用X射线衍射光谱(XRD)、紫外-可见(UV-Vis)光谱、傅里叶变换红外(FT-IR)光谱、电感耦合等离子体-原子发射光谱(ICP-AES)、荧光(PL)光谱、X光电子能谱(XPS)等分析手段对制备的催化剂进行了表征.结果表明,铁以离子形式镶嵌在gC3N4的结构单元中,影响了g-C3N4的能带结构,增加了g-C3N4对可见光的吸收,降低了光生电子-空穴对的复合几率.以染料罗丹明B的降解为探针反应系统研究了不同含铁量对g-C3N4在可见光下催化性能的影响.结果表明,m(Fe)/m(g-C3N4)=0.14%时,制备的Fe掺杂g-C3N4表现出最佳的光催化性能,120 min内罗丹明B的降解率高达99.7%,速率常数达到0.026 min-1,是纯g-C3N4的3.2倍.以叔丁醇、对苯醌、乙二胺四乙酸二钠为自由基(·OH)、自由基(O2-·)和空穴(h+VB)的捕获剂,研究了光催化反应机理.     

Four Coordination Polymers Assembled with a New Biscarboxyl-functionalized Schiff Base Ligand

Based on a new biscarboxyl-functionalized Schiff base ligand 1,2-cyclohexanediamino-N,N'-bis[3-methoxyl-5-(p-carboxyl-phenylazo)] salicylidene(H₄L), four polymers,[(CH₃)₂NH₂]₂·[Mn₃(L)₂(H₂O)₄]·2DMF(CP1),[Fe₂(L)(H₂O)(DMF)](CP2),[(CH₃)₂NH₂]·[Cu(HL)]·H₂O(CP3) and[Ni₂(L)(teta)]·2DMF·H₂O(CP4), have been synthesized(teta=5,5,7,12,12,14-hexamethyl-1,4,8,11-tetraazacyclotetradecane). In CP1, both of the internal[N₂O₂] pocket and the external carboxylate groups of L^4- anion are ligated by Mn²⁺ ions, and the structure displays a layer. In CP2, the Fe²⁺ cations are linked by L^4- anions to form a binuclear double chain. CP3 displays a[Cu₂(HL)₂] dimer. In CP4, the Ni²⁺ ions are connected by L^4- anions to form a chain. The structures are further linked by hydrogen bonds to form 2D or 3D supramolecular architectures, respectively. CP1 exhibits adsorption ability to three organic dyes.     

铁离子催化十二钨酸络钴酸钾氧化羟胺反应的动力学和机理 Ⅱ.在HCIO4-NaClO4介质中的反应

羟胺是典型的显影剂和防氧化剂,研究它的氧化反应机理是很有意义的。前文在HAc-NaAc(pH-3.9-5.0)介质中的研究发现,当Σ[Fe³⁺]<3×10^-6mol·L^-1时,铁离子催化十二钨酸络钴酸钾K₅[CoW₁₂O₄₀](简记为Co³+W)。     

Quadruple-stranded Eu-helicate Assembled from Bis-β-diketonate: Its Stability Towards Metal Ions

Herein, we reported the synthesis and investigation of highly luminescent quadruple-stranded helicate (C₆H₁₆N)₄[Eu₂(MBDA)₄]₂^.3C₄H₁₀O·4C₂H₃N(1-Eu)[H₂MBDA=N-methyl-4,4'-bis(4,4,4-trifluoro-1,3-dioxobutyl)di- phenylamine] for its stability toward metal ions in the solution. The material was characterized via X-ray crystallographic technique, Fourier transform infrared(FTIR) spectroscopy and electrospray ionization quadrupole time-of- flight(ESI-TOF) mass spectrometry. The results on the luminescence quantum yields clearly demonstrate that the ligand can effectively sensitize the luminescence of the Eu³⁺ ions(Φ_overall=15%). Upon the addition of different metal ions(i. e., Ag⁺, Cd²⁺, Zn²⁺, Fe³⁺, Al³⁺ and Ni²⁺) to the CH₃CN solution of compound 1-Eu, the emission intensities of Eu³⁺ ions at 612 nm were affected to some extent, which could be attributed to the presence of ion exchanges between Eu³⁺ ions and the metals ions, and the result was confirmed by ESI-TOF mass spectrometry.     

Exchange constants of Al(III) and Fe(III) on Dowex 50W-X8

The exchange constants tor Al³⁺ and Fe³⁺ ions on the cation-exchange resin Dowex 50W-X8 (H⁺-form) are reported. A batch method of equilibrium at room temperature was used to determine these constants, which are Al³⁺ + 3HR AIR₃ + 3H⁺, K = 1·66 Fe³⁺ + 3HR FeR₃ + 3H⁺, K = 2·19 R denoting the resin.     

Two alkynyl functionalized Co(II)-MOFs as fluorescent sensors exhibiting selectivity and sensitivity for Fe3+ and nitroaromatic compounds

Two alkynyl functionalized 3D frameworks with different structures were successfully synthesized for selective and sensitive detection of Fe³⁺ ions and nitroaromatic compounds through fluorescence quenching.     

Synthetic [FeFe]-H2ase models bearing phosphino thioether chelating ligands

Through the oxidation-reduction combination procedure, the neutral tri-substituted {2Fe3S} complex 2 was synthesized by replacing the CO ligand in 1 with phosphine. This substitution leads to the Fe-Fe bonds in 1 and 2 with large Lewis basicity difference, i.e. △pK_a^MeCN~10.