Synthesis and crystal structure of hydroquinone-β-cyclodextrin complex

The title inclusion complex with the formula [(C₄₂H₇₀O₃₅)₂·(C₆O₂H₆)₃·(H₂O)_21.2(CH₃OH)₂] has been crystallized and characterized by single crystal X-ray analysis. The complex crystallizes in the triclinic system, space group P1, with a = 1.5500 (1), b = 1.5536(1), c = 1.8246(1) nm, α = 113.17(2), β = 99.12(2), γ = 103.37(3)o, V = 3.7739 (4) nm³, Z = 1; D_c = 1.343 g/cm³, μ = 0.124 mm^-1, F(000) = 1594, R = 0.0795 and S = 0.9639. Two independent molecules of β -cyclodextrin (β -CD) form a “head-to-head” dimer. The fairly important factor of the position and stability of the guest in the host cavity is the solvation of the polar group of the guest.     

Crystal structure and surface photo-electric property of Mn（Ⅱ） coordination supramolecules

Two Mn（Ⅱ） coordination supramolecules, [Mn2（C8HTO2）4（phen）2（p-H20）] （1） and [Mn2（btec）（phen）2（H2O）6]·2H2O （2） （phen=1,10-phenanthroline, H4btec=1,2,4,5-benzenetetracarboxylic acid）, were synthesized by hydrothermal method. The crystal structures of the complexes were determined by X-ray single crystal diffraction. The result indicates that （1） and （2） are both binuclear Mn（Ⅱ） complexes. The existence of hydrogen bonds makes the binuclear complexes become further connected to coordination supramolecules, which possess 1D and 3D infinite structures respectively. The complexes were identified by IR, UV-Vis, surface photovoltage spectrum （SPS） and field-induced surface photovoltage spectrum （FISPS）. The results of SPS for the complexes indicate that they both exhibit positive surface photovoltage response bands in the range of 300-600 nm. The SPS phase spectrum and FISPS of complexes indicate that they show certain p-type semiconductor characteristic. However, the intensity, position and number of the SPV response bands are different obviously. The difference of the SPV response bands is mainly attributed to the different structures of the complexes and the different coordination environment of Mn（ll） in the two complexes. This paper discusses the action of hydrogen bonds in the construction of the supramolecule and the change on the surface photovoltage of complex in different coordination environment.     

Crystal structure and photoelectricity property of Fe(II/III) coordination supermolecules

Three new mixed-ligand Fe(II/III) complexes [Fe₂(μ₂–btec)(μ₂–H2btec)(phen)₂(H₂O)₂]_n (1), [Fe2(btec) (phen)₂(H₂O)₄] (2), and {[Fe(o-pha)(phen)(H₂O)]•H₂O}_n (3) (phen=1,10-phenanthroline, o-H₂pha=o-phthalic acid, H₄btec=1,2,4,5-benzenetetracarboxylic acid) have been hydrothermally synthesized and detected by single crystal X-ray diffraction, showing that complexes (1) and (2) are both bridged by the betc⁴⁻ ligands to form 1D chain and dinuclear structure and complex (3) is bridged by the o-pha groups to form 1D chain structure. The coordinated modes of the carboxyl groups adopt μ₂-η¹η¹ηη¹η¹ and μ₂-η²η¹ respectively in com-plexes (2) and (3). The betc groups in complex (1) show two different coordinated modes: μ₂-η¹η¹η¹η¹ and μ₂-η¹η¹. In addition, the hydrogen bonds and π…π type interactions make the complex molecule further connect to three-dimensional and two-dimensional networks respectively. These complexes are detected by IR, UV-Vis-NIR and surface photovoltage spectrum (SPS). The SPS of complexes (1)–(3) indicate that there are positive SPV responses in the range of 300–600 nm and show p-type semiconductor characteristic. Because the structure, the valence and the coordinative environment of the Fe ions are all different in the three complexes, the intensity, position and the number of the response bands are different obviously. The results of SPS are corresponding with UV-Vis-NIR spectra.     

New crystal structure of molecular complex 1-piperidine carboxylate-piperidinium-H<Subscript>2</Subscript>O studied by X-ray single crystal diffraction

Piperidine absorbs CO2 and H2O in air to form a molecular complex： piperidium-l-piperidinecarboxylate-H2O. The structure of the complex was characterized by X-ray single crystal diffraction. The crystal structure was determined to be triclinic, space group P1^-with a=0.648 6（8） nm, b=0.809 200） nm, c= 1.357 1（16） nm, a=96.96706）°, β =102.506（15）°,γ=104.202 05）°, Z=2. The complex is stabilized via five hydrogen bonds between the three components, N-O electrostatic interaction and O-O interaction （electron transfer） betweenl-piperidinecarboxylate and H2O. Due to electron transference of carbamate ion, the oxygen atom in water molecule is strongly negatively charged and the O-H bond is considerably shorter than that of the free molecule of water. The formation of the molecular complex is a reversible process and will decompose upon heating. The mechanism of formation and stabilization is further investigated herein.     

Synthesis and electrochemical properties of LiNi0.8Al0.2−xTixO2 cathode materials by an ultrasonic-assisted co-precipitation method

A new co-precipitation route was proposed to synthesize LiNi_0.8Al_0.2−xTi_xO₂ (x=0.0-0.20) cathode materials for lithium ion batteries, with Ni(NO₃)₂, Al(NO₃)₃, LiOH·H₂O, and TiO₂ as the starting materials. Ultrasonic vibration was used during preparing the precursors, and the precursors were protected by absolute ethanol before calcination in the air. The influences of doped-Ti content, calcination temperature and time, additional Li content, and ultrasonic vibration on the structure and properties of LiNi_0.8Al_0.2−xTi_xO₂ were investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM), and charge-discharge tests, respectively. The results show that the optimal molar fraction of Ti, calcination temperature and time, and additional molar fraction of Li for LiNi_0.8Al_0.2−xTi_xO₂ cathode materials are 0.1, 700°C, 20 h, and 0.05, respectively. Ti doping facilitates the formation of the α-NaFeO₂ layered structure, and ultrasonic vibration improves the electrochemical performance of LiNi_0.8Al_0.2−xTi_xO₂.     

Synthesis and structure of 3D heterometallic （3d-4f） coordination polymers： {[Ln2Cu（pydc）4（H2O）6]·2H2O}n

Two new 3D heterometallic （3d-4f） coordination polymers {[Ln2Cu（pydc）4（H2O）6]·2H2O}n [Ln = Eu （1） and Gd （2）] have been synthesized by hydrothermal reactions and characterized by elemental analysis, X-ray single-crystal analyses, and IR spectroscopy. X-ray crystal structure analyses show that 1 and 2 possess 3D networks and strong intramolecular hydrogen bonding interactions which was confirmed by thermogravimetric （TG） analysis.     

NMR and FT-IR analysis of new molecular complex 1-piperidine-carboxylate-piperidinium-H2O

Piperidine absorbs CO2 and H2O contents in air to form a molecular complex： piperidium-1-piperidinecarboxylate-H2O. The structure of the complex was characterized by FT-IR and NMR. The complex is stabilized via five hydrogen bonds between the three components, N…O electrostatic interaction and O…O interaction （electron transfer） betweenl-piperidinecarboxylate and H2O. Through electron transfer from the carbamate ion, the oxygen atom in water molecule is strongly negatively charged and the O-H bond is considerably shorter than that of free water molecule. The formation of the molecular complex is a reversible process and will decompose upon heating. The mechanism of formation and stabilization is further investigated herein.     

UV/H2O2作用下冰中苯酚的光转化及其与羟基自由基的关系

在UV和H₂O₂作用下考察pH值、 光强、 H₂O₂初始浓度和无机离子等对冰中苯酚光解的影响, 并利用二甲基亚砜（DMSO）捕获体系中生成的
羟基自由基（·OH）研究·OH对冰中苯酚光解的影响. 实验结果表明: H₂O₂可显著促进冰中产生·OH及苯酚光解; 改变光强、 pH值和H₂O₂的初始浓度, 苯酚的光解率随体系中·OH浓度的增加而增大; 加入NO^-₂和NO^-₃可抑制体系中产生·OH及苯酚光解; 加入SO^2-₄不影响体系中·OH的产生及苯酚光解; 加入CO^2-₃和HCO^-₃可抑制体系中产生·OH, 但对苯酚光解影响较小, 这是由于体系中产生了其他自由基所致.     

Synthesis, crystal structure and thermal behavior of Rb(NTO) · H2O

The Rb(NTO)·H₂O crystal has been synthesized by reaction of 3-nitro-1,2,4-triazole-5-one (NTO) with Rb₂CO₃ in aqueous solution. Its crystal structure has been determined. The crystal belongs to monoclinic system. Crystal structure data: space group P2₁ / n; a = 0.633 0(1), b = 0.824 1(2), c =1.296 4(3) nm; β= 97.90(1)°; V = 0.669 9 (2) nm³ , Z = 4, D_c = 2.306 g/cm³, μ= 7.365 nm^-1, F (000) = 448. An eight coordinated compound is formed between Rb⁺ with oxygen atoms and nitrogen atoms. A layer structure is formed by coordination bonds and hydrogen bonds. The thermal decomposition mechanism of this coordination compound is discussed .     

喹啉酮荧光探针的合成及性能研究

通过乙酰乙酸乙酯与间苯二胺反应制得4-甲基-7-氨基-2-喹啉酮(3),进一步与氨三乙酸反应制得新的喹啉酮酰胺衍生物5,其结构经红外、核磁氢谱、质谱等表征。5与La(NO3)3配位得到新的配合物6。元素分析、红外、质谱、热重-差热分析和摩尔电导等确定配合物6的分子式为[La(C16H15N3O6)NO3]·4H2O。荧光测试表明,化合物5与稀土金属La配位后,荧光发光强度明显增加,荧光区间变窄。此外,化合物5与不同浓度鲱鱼精DNA作用的荧光变化情况表明:化合物5与鲱鱼精DNA有较强的相互作用,荧光光谱变化明显;鲱鱼精DNA对化合物5有荧光增强作用,DNA浓度为4.02×10-6mol/L时,增幅最大可达40%。实验结果表明,化合物5在DNA检测或疾病防治等方面有潜在的应用价值。     

化学强化剂提高生物膜填料塔烟气同时脱硫脱氮性能的实验研究

对采用外加化学强化剂提高生物膜填料塔烟气同时脱硫脱氮的性能进行实验研究.结果表明,当按最优化学强化剂添加量添加硝酸镧0.25+硝酸铈0.25 mg/L、硫酸镁0.5 g/L、乙酸钠0.3 g/L时,生物膜填料塔的NOx净化效率可达61.78%,脱硫率为100%.进一步的长时间连续运行实验结果表明,在对SO2的净化效率达到100%的同时,按添加最优化学强化剂条件实验操作的生物膜填料塔的NOx净化效率明显高于对比空白实验的NOx净化效率,其NOx净化效率的平均值提高了14.78%.实验为研究形成提高生物法烟气同时脱硫脱氮性能(尤其对提高烟气脱氮效率)的新型化学强化技术方法奠定了基础.     

Three new zinc（Ⅱ） coordination polymers： Modulation of extended structures driven by assistant ligands

Three new complexes, [Zn（dtb）（4,4′-bipy）]·5H2O （1）, [Zn（dtb）（bpp）]·H2O （2） and [Zn（dtb）（phen）2]·CH3- CH2OH·H2O （3） （dtb = 5,5′-dithiobis（2-nitrobenzoic acid）, 4,4′-bipy = 4,4′-bipyridine, bpp = 1,3-bi（4-pyridyl） propane, phen = 1,10-phenanthroline）, have been constructed by dtb ligand and zinc salt in the presence of different assistant N-containing ligands under hydrothermal conditions. The structures of the complexes were established by single-crystal X-ray diffraction analysis. Although compounds 1 and 2 are both 2D networks, the cavities＇ forms and pitch of helix are different. The structure of compound 3 shows a 1D helical chain, and is extended by the supermolecule interactions into a 2D framework. These neutral polymeric complexes exhibit structural and dimensional diversity due to the different coordination modes of the flexible dtb ligand and the effect of assistant ligands.     

Experimental and kinetic study on ignition delay times of methane/hydrogen/oxygen/nitrogen mixtures by shock tube

Ignition delay times of methane/hydrogen/oxygen/nitrogen mixtures with hydrogen amount-of-substance fractions ranging from 0–20% were measured in a shock tube facility.The ambient temperature varied from 1422 to 1877 K and the pressure was maintained at 0.4 MPa behind the reflected shock wave.The experiments were conducted at an equivalence ratio of 2.0.The fuel mixtures were diluted with nitrogen gas so that the nitrogen amount-of-substance fraction was 95%.The experimental ignition delay time of the CH4/H2 mixture decreased as the hydrogen amount-of-substance fraction increased.The enhancement of ignition by hydrogen addition was weak when the ambient temperature was >1750 K,and strong when the temperature was <1725 K.The ignition delay time of 20% H2/80% CH4 was only one-third that of 100% CH4 at 1500 K.A modified model based on GRI-Mech 3.0 was proposed and used to calculate the ignition delay times of test mixtures.The calculated results agreed with the experimental ignition delay times.Normalized sensitivity analysis showed that HO·+H2 →H·+H2O was the main reaction for the formation of the H· at 1400 K.As the hydrogen amount-of-substance fraction increased,chain branching was enhanced through the reaction H·+O2→O·+HO·,and this reduced the ignition delay time.At 1800 K,the methyl radical (H3C·) became the key species that influenced the ignition of the CH4/H2/O2/N2 mixtures,and sensitivity coefficients of the chain termination reaction 2H3C·(+M)→C2H6(+M),and chain propagation reaction HO2+H3C·→HO·+CH3O decreased,which reduced the influence of hydrogen addition on the ignition of the CH4/H2 mixtures.     

Kinetics of C2(a3Πu) radical reactions with NO, N2O, O2, H2 and NH3

Pulsed laser photolysis/laser-induced fluorescence (LP-LIF) is utilized to measure rate constants for C₂(a³Π_u) reactions with NO, N₂O, O₂, H₂ and NH₃. Multiphoton dissociation of C₂Cl₄ at 266 nm is employed for the generation of C₂(a³Π_u) radicals. The C₂(a³Π_u) concentration is monitored by the fluorescence of the (0, 0) band of the (d³Π_g&#8596;a³Π_u) transition at 516.5 nm. C₂(a³Π_u) removal rate constants for the reactions are determined as k_NO = (5.46 ± 0.10) × 10^-11 cm³ molecule^-1 s^-1 , k_N2O = (1.63 ± 0.20) × 10^-13 cm³ molecule^-1 s^-1 , k_N2O = (1.58 ± 0.16) × 10^-11 cm³ molecule^-1 s^-1, k_O2 = (5.92 ± 1.00) × 10^-14 cm³ molecule^-1 s^-1, k_H2< 1.0× 10^-14 cm³ molecule^-1 s^-1. Based on the data analysis and theoretical calculation, we suggest that the C₂(a³Π_u) reactions with H₂ and NH₃ proceed via the hydrogen abstraction mechanism, barriers exist at the entrance channel of the reactions of C₂(a³Π_u) with H₂ and NH₃.     

Lithium bond structures of HnY （n=2, 3; Y=O,S, N）…LiNH2 and the abnormal blue shift of N-Li bond

The optimized geometries of the complexes between HnY （n=2, 3; Y=O, S, N） and LiNH2 have been calculated at the B3LYP/6-311＋＋G^＊＊ and MP2/6-311＋＋G^＊＊ levels. Three stable complexes were obtained. Frequency analysis showed that the enlarged 2N-4Li presents the abnormal blue shift in three complexes. The calculated binding energy with basis set super-position error （BSSE） and zero-point vibrational energy （ZPE） corrections of complex Ⅰ-Ⅲ is -58.65, -31.66 and -69.59 kJ·mol^-1 （MP2）, respectively. Natural bond orbital theory （NBO） analysis has been performed, and the results revealed that the H2O…LiNH2 （complex I） and H3N…LiNH2 （complex Ⅲ） are formed with coexisting σ-s and n-s type lithium bond interactions, complex Ⅱ is formed with ττ-s type lithium bond interaction between HnY （n=2,3; Y=O, N） and LiNH2, and H2S…LiNH2 （complex Ⅱ） is formed with n-s type lithium bond interaction between H2S and LiNH2. Natural resonance theory （NRT） and atom in molecule （AIM） theory have also been studied to investigate the bond order and topological properties of the lithium bond structures.     

Supramolecular self-assembly of nickel (Ⅱ)-substituted α-Keggin-type polyoxometalate and polyaniline coated Fe2O3 hollow nanospindle for microwave absorption application

A general strategy has been developed here to supramolecular self-assembly of nickel (Ⅱ)-substituted α-Keggin-type polyoxometalate and polyaniline coated Fe₂O₃ hollow nanospindle (Fe₂O₃ hollow nanospindle@PANI/α-SiW₁₁Ni composites) via electrostatic attraction and hydrothermal method. Fe³⁺ was first hydrolyzed and polymerized into Fe₂O₃, then dissolved into [Fe(H₂PO₄)_x]^3?x, resulting in hollow structure. The polyoxometalate existed in polyaniline as a proton-doped counter-ion form, rather than as a separate crystalline state. The protons and anions entered the PANI main chain and combined with N atoms of amines and imines on the PANI chain ((-NH^?+ ?= ?)/α-[SiW₁₁Ni(H₂O)O₃₉]^6-) to form poles and bipolar delocalization into π bonds of the whole polyaniline molecular chain, which leaded to conductance and polarization. The Fe₂O₃ hollow nanospindle@PANI/α-SiW₁₁Ni composites were proven to be excellent microwave absorber in terms of reflection loss (R_L) and bandwidth. The maximum R_L value was up to ?53.6 ?dB at 3.5 ?mm and 6.9 ?GHz. The broadest absorption bandwidth exceeding ?10 dB was 6.3 ?GHz at a thickness of only 1.9 ?mm. Moreover, the ternary composites presented obvious multi-band absorption with the matching thickness range of 1.5–5 ?mm. The absorption peaks bandwidth reached as wide as 14.3 ?GHz, which included all C-Ku bands. The hollow and core-shell structures could provide non-uniform interface for the induced polarization loss and space for the reflecting and scattering of microwave. The carrier, pair-ion carrier and hydrogen bond network could lead to conduction loss. The magnetic losses were caused by eddy current effect and natural resonance. This work can lay a theoretical foundation for the design and performance regulation of new absorbing materials.     

Corrosion behavior and mechanism of the automotive hot-dip galvanized steel with alkaline mud adhesion

The corrosion behavior and mechanism of hot-dip galvanized steel and interstitial-free (IF) substrate with alkaline mud adhesion were investigated by scanning electron microscopy (SEM), X-ray diffraction (XRD), electrochemical impedance spectroscopy (EIS), and linear polarization. The results show that non-uniform corrosion occurs on the galvanized steel and IF substrate during 250 h with the mud adhesion. The corrosion products on the galvanized steel are very loose and porous, which are mainly ZnO, Zn₅(OH)₈C₁₂·H₂O and Zn(OH)₂, and Fe-Zn alloy layer with a lower corrosion rate is exposed on the galvanized steel surface; however, the corrosion products on IF substrate are considerably harder and denser, whose compositions of rust are mainly FeOOH and Fe₃O₄, and several pits appear on their surface. The results of continuous EIS and linear polarization measurements exhibit a corrosion mechanism, that is, under activation control, the charge transfer resistances present different tendencies between the galvanized steel and IF substrate; in addition, the evolution of linear polarization resistances is similar to that of charge transfer resistances. The higher contents of dissolved oxygen and Cl- ions in the mud play an important role in accelerating the corrosion.     

Experimental and theoretical studies of the reaction between cationic vanadium oxide clusters and acetylene

The time of flight mass spectrometer coupled with a laser ablation/supersonic expansion cluster source and a fast flow reactor was adopted to study the reactivity of cationic vanadium oxide clusters （VinOS,） toward acetylene （C2H2） molecules under gas phase （P, - 1.14 kPa）, under near room temperature （T, - 350 K） conditions. Association products, VmOnC2H2^＋ （m,n = 2,4; 2,6; 3,7-8; 4,9-11; 5,12-13; 6,13-16, and 7,17）, are observed. The oxidation of C2H2 by （V2Os）n^＋ （n = 1 -3） is experimentally identified. The reactivity of （V2O5）n^＋ decreases as n increases. Density functional theory （DFT） calculations were carried out to interpret the reaction mechanisms. The DFT results indicate that a terminal oxygen atom from V2O5^＋ can transfer overall barrierlessly to C2H2 at room temperature, which is in agreement with the experimental observation. Other experimental results such as the observation of V206C2H2^＋ and nonobservation of V2O7,8C2H2^＋ in the experiments are also well interpreted based on the DFT calculations. The reactivity of vanadium oxide clusters toward acetylene and other hydrocarbons may be considered in identifying molecular level mechanisms for related heterogeneous catalysis.     

Crystal structure and magnetism of the binuclear Gd(III) complex Gd2(C12H8N2)2(C6H5COO)6

In the medium of H₂O, C₂H₅OH and HAC, the reaction of Gd(NO₃)₃·6H₂O with C₆H₅COONa and C₁₂H₈N₂ produced a novel binuclear Gd(III) complex in formula [Gd₂(C₁₂H₈N₂)₂ (C₆H₅COO)₆]. Crystallographic data: crystal system, triclinic; space group, P1; unit cell dimensions, a=1.191 9(2) nm,b =1.244 2(2) nm,c = 1.080 4(2) nm, α = 93.57(3)°, β= 113.33(3)°, γ= 105.06(3)°, Z=l. The finalR =0.037 6. The magnetic measurement of the crystal powder in the temperature region of 1.5–300 K shows that this complex possesses antiferromagnetic property with fitting magnetic parametersJ = −0.471 andg =1.975.     

Hydrogen bonded foldamer-bridged biscoumarins: A UV-Vis absorption and fluorescent study of the solvent effect

Three arylamide-bridged biscoumarin derivatives 1–3 have been designed and prepared. Compounds 1 and 2 are induced by the intramolecular N—H…O and N—H…F hydrogen bonding to possess a helical conformation, and 3 is induced to have an extended conformation. A comparison of their absorption and fluorescent spectra in a variety of solvents of a wide range of polarity with those of control compound 4 reveals that, for foldamers 1 and 2, the intramolecular hydrogen bonding and the helical conformations exist in most solvents, but do not exist or are very weak in DMF and DMSO.