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利用反射红外光谱研究了金表面一系列具有不同碳链长度的偶氮苯巯基衍生物的自组装单分子膜.通过对比各向同性样品的透射谱和单分子膜的反射谱中各个吸收峰强度,定量地研究了分子中各部分的取向与分子结构的关系.我们分别提出了烷基链和偶氮基团取向计算的方法,利用该方法成功地求得了分子中各部分在膜中的倾角.结果显示,当分子中烷基链长度增大时,碳链和偶氮苯基团相对于法线的倾斜逐渐加剧.这种倾角的变化归因于分子中碳链间范德华引力增大时,引起分子逐渐倾斜以达到最佳的范德华接触.同时研究发现,烷基链和偶氮基团受碳链长度变化的影响并不相同.当分子中亚甲基数目增多时,烷基链的倾角迅速增大而偶氮苯倾角的增大则相对缓慢,这反映了它们在空间需求和本身刚性上的不同.
A series of self-assembled monolayers of azobenzene mercapto derivatives with different carbon chain lengths on gold surface were studied by reflection infrared spectroscopy. By comparing the intensity of each absorption peak in the transmission spectra of the isotropic samples and the reflection spectra of the monolayers, , Quantitatively studied the relationship between the orientation and the molecular structure of each part of the molecule.We have separately proposed a method for calculating the orientation of the alkyl chain and the azo group and successfully obtained the inclination of each part in the film The results show that when the length of the alkyl chain in the molecule increases, the tilt of the carbon chain and the azobenzene group relative to the normal gradually increases, which is attributed to the increase of van der Waals attraction between carbon chains in the molecule , Causing the molecules to gradually tilt in order to achieve the best Van der Waals contact.At the same time, it was found that the alkyl chain and the azo group were not affected by the change of carbon chain length.When the number of methylene in the molecule increased, The dip angle increases rapidly and azobenzene dip angle increases relatively slowly, reflecting their differences in space requirements and their own rigidity.