【作者】 唐智勇；

【导师】 胡云楚； 赵莹；

【作者基本信息】 中南林业科技大学 ， 应用化学， 2010， 硕士

【摘要】 双氰乙基系列偶氮染料是一类重要的分散染料,其结构特征是偶合环上的氨基连有两个氰乙基,两个芳环之间以-N=N-键连,含有共轭π电子体系。芳香环上取代基不同,共轭体系的电子能级会有一定的差别,进而影响其光谱性质。本文采用氰乙基化反应和重氮偶合反应合成了12个双氰乙基偶氮染料,应用密度泛函理论(DFT)和含时密度泛函理论(TD-DFT)对其电子结构和吸收光谱进行了计算,通过实验结果与理论计算相结合,分析了染料分子的电子结构与最大吸收波长(λmax)之间的关系。首先,以苯胺、间甲苯胺和间氯苯胺为原料,使用无水AICl3为催化剂,分别催化3个芳胺与丙烯腈发生加成反应,合成了3个双氰乙基芳胺偶合组分(N,N-二氰乙基苯胺、N,N-二氰乙基间甲基苯胺和N,N-二氰乙基间氯苯胺)；将3个双氰乙基芳胺偶合组分分别与4个重氮组分(对硝基苯胺、对硝基邻氯苯胺、2,4-二硝基-6-氯苯胺和2,4-二硝基-6-溴苯胺)经过重氮化、偶合反应,合成了12个双氰乙基偶氮染料,探讨了其合成工艺,并采用核磁共振氢谱、红外光谱、质谱、元素分析和紫外可见光谱对其进行了结构表征。然后,采用Gaussian 03程序包对合成的3个双氰乙基芳胺偶合组分和12个双氰乙基偶氮染料进行几何构型全优化和频率分析,得到表征分子特征的量子化学参数,键长、二面角、自然电荷布居、前线轨道能量及组成,并且用TD-DFT/PCM方法计算了分子的吸收光谱。结果表明：1)、对于3个双氰乙基芳胺偶合组分,预测了其进行重氮偶合反应最佳位点在苯环的C(6)位,CH3和Cl的引入使分子的前线轨道能降低,能隙变小；2)、对于12个双氰乙基偶氮染料,随着取代基引入数目的增加,增加了取代基与苯环的共轭,但是,由于取代基之间的空间阻碍效应,分子骨架的平面性降低,进而降低了分子骨架中π电子云共轭,因此,取代基的共轭效应与空间阻碍效应使得分子的电子能级有增有减,可以预测吸收光谱会产生红移或蓝移；3)、12个双氰乙基偶氮染料的前线轨道能量随着吸电子取代基的引入而降低,随着供电子取代基的引入而升高；前线轨道能隙随着重氮环上吸电子取代基的引入而降低,随着偶合环上CH3和Cl的引入而升高,其HOMO电子云主要集中在分子的偶合部分,LUMO电子云主要集中在分子的重氮部分,当分子吸收光谱时,电子云从偶合环向重氮环转移,-N=N-起到了很好的桥梁作用。最后,通过对实验检测结果和理论计算结果的深入分析,总结出了双氰乙基偶氮染料中不同取代基对分子的电子结构和吸收光谱的影响。结果表明：12个双氰乙基偶氮染料的λmax实验值和计算值有着很好的一致性,在重氮环上,随着取代基的增加,染料分子的λmax依次出现红移；在偶合环上,引入CH3和Cl,染料分子的λmax均蓝移。λmax实验值与前线轨道能隙的相关系数R2=0.9177,λmax实验值与λmax气态条件下得到的计算值相关系数R2=0.9531,λmax实验值与λmax丙酮溶液中得到的计算值相关系数R2=0.8187。由此可见,理论计算对染料分子的设计与吸收光谱的预测有很好的指导意义。更多还原

【Abstract】 Double-cyanoethyl azo dyes are an important class of disperse dyes. Their molecular structures have the characteristic of amino of coupling ring with two cyanoethyls,-N=N- between the two aromatic rings, and having the conjugatedπelectron system. With the difference of substituted groups of aromatic ring, the electronic energy levels of conjugated system will have a certain differences, and then it will affect its spectral properties.In this paper, we have synthesized twelve double-cyanoethyl azo dyes by cyanoethyl reaction and diazo coupling reaction. Furthermore, we have calculated their electronic structures and absorption spectras by density functional theory (DFT) and time-dependent density functional theory (TD-DFT). The relationship between their electronic structures and their maximum absorption wavelength (λmax) was analyzed by combining experimental results and theoretical calculations.First, three double-cyanoethyl aromatic amines were synthesized by the addition reaction of aniline, m-toluidine and m-chloroaniline with acrylonitrile in the present of anhydrous AlCl3, they were N,N-2-cyanoethyl aniline, N,N-bis (2-cyanoe-thyl)-m-toluidine and N,N-bis (2-cyanoethyl)-m-chloroaniline. Subsequently, twelve double- cyanoethyl azo dyes were synthesized by diazo coupling reaction of coupling component with diazo components, which obtained by diazotizing p-nitroaniline, p-nitro-o-chloroaniline,2,4-dinitro-6-chloroaniline and 2,4-dinitro-6- bromoaniline. Their synthetic technology was explored, at the same time their structures were characterized by 1H NMR, IR, MS, elementary analysis and UV-Vis spectrum.Secondly, The geometry of three double-cyanoethyl aromatic amine coupling component and twelve double-cyanoethyl azo dyes were fully optimized by Gaussian 03, meanwhile, their frequencies were analysed. Then we gained the quantum chemical parameters, bond length, dihedral angle, the natural charge population, frontier molecular orbital energy and composition, the molecular absorption spectras were gained by the method of TD-DFT/PCM. The results showed that:1), For three double-cyanoethyl aromatic amine coupling component, C(6) of benzene ring was predicted the best site in diazo coupling reaction. Frontier orbital energy was decreased with the introduction of CH3 and Cl, the energy gap also becomes small.2), For twelve double-cyanoethyl azo dyes, the substituted groups conjugated with the benzene ring were increased with increasing of the number of substituted groups, however, the plane of molecular skeleton were lower because the space baffle effect between substituted groups, furthermore, the conjugated ofπelectron cloud of molecular skeleton were reducing. So, the molecular electronic energy levels have increases and decreases because of the conjugate effect and the space baffle effect of substituted groups. we can predict the absorption spectra red shift or blue shift.3), Frontier orbital energy was decreased with the introduction of electron withdrawing substituted groups, it was increased with the introduction of electron donor substituted groups. Frontier orbital energy gap was decreased with the introduction of electron withdrawing substituted groups on diazo ring, it was increased with the introduction of CH3 and Cl on coupling ring. The HOMO electron cloud of twelve double-cyanoethyl azo dyes was concentrated in the coupling part of the molecule, the LUMO electron cloud was concentrated in the molecular diazo part, the electron cloud moved from the coupling ring to the diazo ring when the molecular was absorbing spectrum.-N=N- played the role of a bridge.Finally, The experimental results and calculation results were deeply analyzed. The impact of different substituted groups of double-cyanoethyl azo dyes on molecular electronic structure and absorption spectras was summarized. The results showed that theλmax of experimental data and calculated data of twelve double-cyanoethyl azo dyes have a good consistency. On the diazo ring, theλmax of dye molecules turn red shift with the increase of substituted groups, on the coupling ring, theλmax of dye molecules turn blue shift with the introduction of CH3 and Cl. The correlation coefficient ofλmax was R2=0.9177 between experimental data and the frontier orbital energy gap, the correlation coefficient ofλmax was R2=0.9531 between experimental data and calculated data under the gaseous condition, the correlation coefficient ofλmax was R2=0.8187 between experimental data and calculated data under acetone. This shows that the theoretical calculation has a good guiding significance for the design of dye molecular and forecast of absorption spectrum.更多还原