有机磷缓蚀剂分子结构与缓蚀性能的量子化学研究

通过PM3半经验量子化学计算，从微观的角度研究了4种有机磷缓蚀剂，三苯基膦，四苯基氯化磷，氯甲基－三苯基氯化磷，苄基三苯基氯化磷缓蚀性能和分子结构的关系。结果表明：P原子的净电荷，电荷密度，亲电前线电荷密度与缓蚀性能有良好的相关性，缓蚀剂即能通过π电子供出电子与Fe吸附，又能通过P原子接受Fe原子3d轨道中的电子，其强弱主要由P原子上电荷密度高低决定，在双向作用下，缓蚀剂与Fe的吸附作用增强，缓蚀性能提高。根据Fe和缓蚀剂阳离子的前线轨道作用进一步推测了缓蚀剂在HCl溶液中对Fe的缓蚀机理。     

盐酸体系不锈钢缓蚀剂的开发

采用失重法和扫描电镜法,测定了五种缓蚀剂对浸没于8%盐酸介质中不锈钢的缓蚀作用,确定了在盐酸体系中对不锈钢具有较好缓蚀性的单组分、二元和三元缓蚀剂配方.实验结果表明:咪唑啉,十六烷基三甲基溴化铵具有较好的缓蚀效果;十六烷基三甲基溴化胺在使用浓度为700 mg/L时,缓蚀率为90.0%;十六烷基三甲基溴化铵与三乙醇胺、咪唑啉及硫脲复配后,缓蚀剂各组分浓度为单组分最佳浓度一半的情况下,缓蚀率分别达到为91.8%、90.8%和89.7%,缓蚀剂的成本得以下降;三元复配缓蚀剂中,咪唑啉-硫脲-乌洛托品和咪唑啉-硫脲-三乙醇胺两种缓蚀剂的缓蚀率均高于90%,且使用成本低,是理想的盐酸体系不锈钢缓蚀剂.扫描电镜图像表明,添加了缓蚀剂的金属表面腐蚀轻微,表面光滑,且不存在明显的点蚀倾向,缓蚀剂对金属表面起到很好的保护作用.     

金属缓蚀剂Langmuir—Blodgett膜及缓蚀机理的研究

应用Ｌａｎｇｍｕｉｒ－ｂｌｏｄｇｅｔｔ（ＬＢ）技术研究了硬脂酸和十六烷基三甲基溴化胺等金属缓蚀剂在碳钢电极上的取向，单分子膜覆盖层数及分子结构及其缓蚀作用的影响，在实验技术上实现了对缓蚀剂表面膜在分子规模上的控制，文中讨论了这两种缓蚀剂的缓蚀机理。     

季鏻盐缓蚀作用的研究

用失重法、动电位扫描法和载波扫描法研究了七种季鏻盐化合物对1N盐酸中20~#碳钢的缓蚀作用以及季鏻盐分子结构对缓蚀效率的影响。结果表明,季鏻盐化合物是一种混合型缓蚀剂;含有两个磷原子的双鏻化合物的缓蚀效率高于单鏻化合物。在15～50℃范围内,溴化苄基三苯基鏻和1.4—双(溴化三苯基鏻)丁烷在碳钢/溶液界面的吸附遵循Bockris-Swinkels吸附等温式。计算了季鏻盐分子吸附的热力学数据。     

金属缓蚀剂Langmuir－Blodgett膜及缓蚀机理的研究

应用Ｌａｎｇｍｕｉｒ－Ｂｌｏｄｇｅｔｔ（ＬＢ）技术研究了硬脂酸和十六烷基三甲基溴化胶等金属缓蚀剂在碳钢电极上的取向。单分子膜覆盖层数及分子结构对其缓蚀作用的影响．在实验技术上实现了对缓蚀剂表面膜在分子规模上的控制，文中讨论了这两种缓蚀剂的缓蚀机理．     

用量子化学密度泛函理论研究环状含氮化合物分子结构与缓蚀性能的关系

用量子化学计算泛函密度理论(DFT)中的B3LYP方法，在6-31G基组水平上，对5种环状含氮化合物：3-氨基-1,2，4-三唑、2-氨基-1，3，4-二氢噻唑、5-对甲苯基-1，3，4-三唑、3-氨基-5-甲硫基-1，2，4-三唑和2-氨基苯咪唑的缓蚀性能与分子结构及电子结构的关系进行了研究，用Fukui指效分析了分子中原子的反应性．结果表明文中涉及到的分子均为存在共轭体系的平面分子，缓蚀效率与分子的最高占据轨道的能量EHOMO、最低空轨道与最高占据轨道的能量差△E(ELUMO-EHOMO)有较好的相关性．可以认为缓蚀剂分子在金属表面通过亲核作用与金属作用而形成吸附膜。该类缓蚀剂分子是通过吡啶氮原子提供电子与金属发生作用的．     

缓蚀剂构效关系的量子化学研究

用量子化学半经验算法AM1方法,在6-31G基组水平上,对十二种N-芳基-α-氨基苄基膦酸缓蚀性能与分子结构的关系进行了研究,讨论了量子化学计算结果与缓蚀性能的关系。结果表明,这些缓蚀剂的缓蚀效率与分子的最高占据轨道能量EHOMO、氮原子的净电荷、苯环碳原子净电荷之间有很好的相关性,并讨论了缓蚀机理。     

喹啉型双季铵盐酸化缓蚀剂的合成与性能评价

以喹啉和双卤代烃为原料经季铵化反应合成了三种喹啉型双季铵盐酸化缓蚀剂:溴化1,4-二喹啉丁烷(Q-4-Q)、溴化1,6-二喹啉己烷(Q-6-Q)和溴化1,8-二喹啉辛烷(Q-8-Q),采用核磁共振氢谱对其结构进行表征。采用失重法,电化学方法和SEM等方法研究了三种产物在15%HCl溶液中对N80钢的缓蚀性能。结果表明,Q-8-Q的缓蚀性能最佳;双季铵盐Q-8-Q与肉桂醛(CA)最佳复配比为cQ-8-Q∶cCA=1∶1。在15%HCl,90℃条件下,6mmol/L该复配缓蚀剂对N80钢片的缓蚀率达99.79%,缓蚀性能优良;缓蚀剂分子在N80钢片表面形成一层保护膜;该复配缓蚀剂能有效抑制酸液对N80钢表面的腐蚀,是一种以抑制阴极反应为主、属"负催化效应"作用机理的混合型缓蚀剂。     

2-甲基咪唑啉在海水及在海洋大气环境下缓蚀性能的研究

2-甲基咪唑啉具有毒性低的特点，是一种适宜的环保型缓蚀剂。本文的目的在于通过电化学法和挂片法检测2-甲基咪唑啉在海水及海洋大气环境下的缓蚀性能，探讨2-甲基咪唑啉的缓蚀性能与其结构之间的关系。并初步研究了分子内复配对缓蚀性能的影响以及以2-甲基咪唑啉为基础的缓蚀剂的发展方向。     

三苯环咪唑啉季铵盐的合成与缓蚀性能

利用两步法合成了三苯环咪唑啉季铵盐缓蚀剂(简称Q ATI)，并对其结构进行了表征，通过腐蚀失重法、电化学测定等方法对其在HCl、H2SO4 酸洗液中对碳钢的缓蚀效果进行测定.结果表明，三苯环咪唑啉季铵盐缓蚀性能优异.同时探 讨了其缓蚀机理.     

Theoretical investigation of the inhibition of corrosion by some triazole Schiff bases

An examination of quantum chemical and corrosion inhibition studies is carried out to investigate whether any clear links exist between the results of quantum chemical calculations and the experimental inhibition efficiencies. The influence of the investigated triazole Schiff bases, (benzylidine amino) triazole (a), 4‐hydroxy 3‐(benzylidine amino) triazole (b), 2‐hydroxy 3‐(benzylidine amino) triazole (c), and 2‐ hydroxy 3‐(naphthylidine amino) triazole (d) on the inhibition of corrosion of the metal surfaces are studied by density functional theory at the B3LYP/6‐31G level. The calculated quantum chemical parameters correlated to the inhibition efficiency are, the highest occupied molecular orbital (HOMO), the lowest unoccupied molecular orbital (LUMO), the separation energy (ΔE), the dipole moment (µ), the softness (σ), the total negative charge on the whole molecule (TNC), the total charge on the azo‐methine moiety, the molecular volume (V_i), and the total energy (TE). A good correlation between the quantum chemical parameters and the experimental inhibition efficiency is found. High inhibition efficiency for corrosion inhibitors can be achieved by controlling their electronic and structural properties.     

异恶唑衍生物缓蚀剂缓蚀性能的理论评价

采用量子化学计算和分子动力学模拟相结合的方法,对盐酸溶液中2-甲基-5-己基异恶唑、2-甲基-5-十二烷基异恶唑、2-异丙基-5-十二烷基异恶唑和2-叔丁基-5-十二烷基异恶唑4种异恶唑衍生物缓蚀剂抑制低碳钢腐蚀的缓蚀性能进行理论评价,并对其缓蚀机理进行分析。量子化学计算表明,4种缓蚀剂分子的前线轨道主要离域在分子头部的异恶唑环和侧链上,亲电反应活性中心为分子中的N、O原子。分子动力学模拟结果表明,液相条件下,异恶唑衍生物缓蚀剂的极性头部优先吸附于金属表面,而烷基长链在溶剂水的作用下背离金属表面,分子在表面的吸附强度随着头基侧链中甲基个数的增加而增强。理论评价结论与实验结果完全一致。     

DFT theoretical studies of antipyrine Schiff bases as corrosion inhibitors

The anti‐corrosive properties of some antipyrine Schiff bases (benzylidine amino)antipyrine (a), 4‐hydroxy 3‐(benzylidine amino)antipyrine (b), 2‐hydroxy 3‐(benzylidine amino)antipyrine (c), and 2‐hydroxy 3‐(naphthylidine amino)antipyrine (d) are studied using density functional theory at the B3LYP/6‐31G level. The computational calculations are performed to find a relation between their electronic and structural properties and the inhibition efficiency. The calculated quantum chemical parameters correlated to the inhibition efficiency are, the highest occupied molecular orbital (HOMO), the lowest unoccupied molecular orbital (LUMO), the separation energy (ΔE), the dipole moment (µ), the softness (σ), the total negative charge on the whole molecule (TNC), the total charge on the azomethine moiety, the molecular volume (V_i), and the total energy (TE). A good correlation between the quantum chemical parameters and the experimental inhibition efficiency is found.     

Experimental and theoretical study on the inhibition performance of triazole compounds for mild steel corrosion

A relationship between quantum chemical parameters for three triazole compounds and their inhibition ability was studied using electrochemical measurements (potentiodynamic polarization and EIS), molecular dynamic method and quantum chemical calculations. Electrochemical measurements results revealed that the inhibition efficiencies increased with the concentration of inhibitors. The molecular dynamic method results showed that the higher interaction potential between the inhibitor and metal surface, the higher the inhibition efficiency. The quantum chemical calculation results showed that the triazole ring is the active site in these inhibitors and they can absorb on Fe surface by donating electrons to Fe d-orbital.     

Schiff-base derivatives as corrosion inhibitors for carbon steel materials in acid media: quantum chemical calculations

Quantum chemical calculations based on Hartree–Fock, AM1 and B3LYP functions were performed on the three Schiff-base compounds used as corrosion inhibitors for carbon steels in acid media. The quantum chemical calculations were conducted to determine the relationship between inhibition efficiency (IE) and the molecular structure of inhibitors. Several quantum chemical parameters, such as charge distribution, energy and distribution of the highest occupied molecular orbital (E_HOMO) and lowest unoccupied molecular orbital (E_LUMO), absolute electronegativity (χ) and the fraction of electrons (ΔN) transferred from inhibitors to the steel surface, were calculated and correlated with inhibition efficiencies. The results showed that the IE of Schiff-base compounds enhanced with increasing E_HOMO or decreasing E_LUMO; meanwhile, N atoms on Schiff-base molecules were the most probable sites for adsorption of inhibitor molecules on the metal surface. The inhibition mechanisms of three Schiff-base compounds were obtained from different calculation methods, and the results from each method are consistent.     

Diphenolic Schiff bases as corrosion inhibitors for aluminium in 0.1 M HCl: Potentiodynamic polarisation and EQCM investigations

The effects of novel synthesised two Schiff bases on the corrosion of aluminium in 0.1 M HCl were investigated using potentiodynamic polarisation and electrochemical quartz crystal microbalance measurements. Results show that inhibition efficiencies increase with increase in inhibitor concentration. This reveals that the inhibition occurs through adsorption of the inhibitor molecules on the metal surface. Adsorption of these inhibitors follows Temkin adsorption isotherm. The correlation between the inhibitor performances and their molecular structures has been investigated using quantum chemical parameters obtained by MNDO (modified neglect of diatomic overlap) semi-empirical method. Calculated quantum chemical parameters indicate that Schiff bases adsorbed on aluminium surface by chemical mechanism.     

阳极氧化铝膜的表面接枝改性及润湿行为

目的通过对阳极氧化铝膜(AAO)表面化学接枝甲基丙烯酸甲酯,改变其表面的粗糙度和分子结构,从而实现AAO膜表面润湿行为的可控。方法采用二步阳极氧化法制备六方柱形的多孔AAO膜,结构高度有序,并对AAO膜表面进行硅烷化(KH-570)处理,采用活性聚合的方法在其表面接枝上甲基丙烯酸甲酯。采用原子力显微镜(AFM)、X射线衍射仪(XRD)和接触角测定仪对AAO膜及改性后的AAO膜进行了结构表征和润湿行为研究。探讨了阳极氧化的工艺条件及接枝甲基丙烯酸甲酯对AAO膜的形貌和润湿性能的影响。结果 AAO膜孔径在100 nm左右,六边形孔洞分布均匀,并且六边形孔洞垂直于AAO膜表面,孔洞与孔洞平行,通过对其表面接枝甲基丙烯酸甲酯,使得AAO膜的表面水接触角先增大后减小。结论 AAO膜表面的润湿行为,可以通过AAO膜表面化学改性和表面粗糙度共同作用而得以调控。     

Quantum chemical and electrochemical studies on the corrosion inhibition of aluminium in 1 N HNO3 using 1,2,4‐triazine

The present study describes the inhibition of aluminium in 1 N HNO₃ with different concentrations of 1, 2, 4‐triazine precursors 4‐amino‐6‐methyl‐3‐thioxo‐3,4‐dihydro‐1,2,4‐triazin‐5(2H)‐one (AMTDT) and 4‐amino‐6‐benzyl‐3‐thioxo‐3,4‐dihydro‐1,2,4‐triazin‐5(2H)‐one (ABTDT) using electrochemical impedance spectroscopy adsorption studies and quantum chemical calculations at 298 K. As the electron density around the inhibitor molecule increases due to substitution, the inhibition efficiency also increases correspondingly. Quantum chemical approach was used to calculate some electronic properties of the molecule to ascertain the correlation between inhibitive effect and molecular structure of the inhibitor. The corrosion inhibition efficiencies of these molecules and the global chemical reactivity relate to some parameters, such as E_HOMO, E_LUMO, gap energy (ΔE), electronegativity (χ), global hardness (η), and the fraction of electrons transferred from the inhibitor molecule to the metallic atom (ΔN). In addition, the local reactivity has been analyzed through the Fukui function and condensed softness indices.     

Theoretical study of inelastic X-ray scattering spectra for organic materials: Molecular excitation coupled with molecular exciton descriptions

Inelastic X-ray scattering (IXS) spectrum provides a powerful tool to investigate the electronic structure of organic materials, in complimentary to the conventional optical spectra. Starting from a single molecule, then a dimer, and finally a cluster of molecular aggregate, we developed a Frenkel exciton model to describe the IXS process based on the quantum chemical calculations for the molecular excitations in the organic crystal of open-ring photomerocyanine form of spirooxazine (Py-SO). It is shown that the quantum chemical calculation combined with Frenkel exciton model can well describe the experimental measurements in terms of (i) the overall features of the IXS spectra from 2 to 10 eV, (ii) the dispersion behavior of the lowest exciton band, and (iii) the momentum-transfer dependence of the peak intensity. The roles of molecular excited state and the intermolecular interactions have been discussed for the IXS spectra.     

Synthesis and characterization of triphenylamine–benzothiazole-based donor and acceptor materials

A series of π-conjugated compounds were successfully synthesized by varying ratios of triphenylamine as donor (D) and benzothiazole as acceptor (A). The structure–property relationship about photoluminescence based on these synthesized compounds was systematically discussed in detail. Quantum chemical calculations were used to obtain optimized ground-state geometry by hybrid density functional theory (B3LYP) with 6-31G* basis set, spatial distributions of the highest occupied molecular orbital (HOMO), the lowest unoccupied molecular orbital (LUMO) levels of the compounds. As expected, these compounds exhibit high extinction coefficients, high quantum yields, and excellent thermal stability properties. The optical properties clearly indicate that the fluorescent emission properties of these compounds rely largely on the molecular structure.