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用2-羟基-1-萘甲醛和含杂环胺合成出7种席夫碱,利用IR和1HNMR对其结构进行了表征。利用UV-Vis和IR研究了光致变色的性能,并且探讨了变色性能与化合物结构的关系。结果表明:虽然这7种席夫碱的亚胺基团的邻位都具有羟基,但只有2-羟基萘甲醛缩2-胺基-3-甲基吡啶和2-羟基萘甲醛缩5-甲基噻唑表现出光致变色的性能。在经历了波长为365 nm的紫外光辐射之后,2-羟基萘甲醛缩2-胺基-3-甲基吡啶的紫外光谱中λ<400 nm的吸收谱带中的吸收峰的强度都不同程度降低了;2-羟基萘甲醛缩5-甲基噻唑在498 nm处出现新的吸收峰,并且随着紫外光照射时间的延长,该新吸收峰和2-羟基萘甲醛缩2-胺基-3-甲基吡啶在592 nm处的吸收峰都逐渐增强,说明光致变色的性能是由于烯醇亚胺-酮胺构型互变异构导致的。红外光谱检测结果显示,2-羟基萘甲醛缩2-胺基-3-甲基吡啶、2-羟基萘甲醛缩5-甲基噻唑在经历了紫外光辐射后,羟基氢的伸缩振动的吸收峰急剧减弱以至消失不见,而两者在1 686、1 730 cm-1处分别出现新的小的羰基伸缩振动吸收峰,此外红外光谱中指纹区的吸收也发生了比较明显的变化,这些都进一步说明烯醇亚胺-酮胺的互变异构。比较这7种席夫碱的结构可知,化合物的吡啶环上亚胺基团的邻位或者噻唑环上连接有供电子基团时,表现出光致变色性能的可能性较大。
Seven kinds of Schiff bases were synthesized from 2-hydroxy-1-naphthaldehyde and heterocyclic amine. Their structures were characterized by IR and 1HNMR. The properties of photochromism were studied by UV-Vis and IR, and the relationship between the color change properties and the structure of the compounds was also discussed. The results showed that: Although the 7 kinds of Schiff base imine groups have hydroxyl groups in the ortho-position, but only 2-hydroxynaphthalene formaldehyde 2-amino-3-methyl pyridine and 2-hydroxynaphthalene formaldehyde 5- Thiazoles exhibit photochromic properties. The intensity of the absorption peak in the absorption band of λ <400 nm in the ultraviolet spectrum of 2-hydroxynaphthalene aldehyde 2-amino-3-methylpyridine is different from that of the absorption band at 365 nm Decreased; the new absorption peak of 2-hydroxynaphthalide 5-methylthiazole appeared at 498 nm, and with the extension of ultraviolet irradiation time, the new absorption peak and 2-hydroxynaphthalene formaldehyde 2-amino- The absorption peak of 3-picoline increased at 592 nm, which indicated that the photochromism was caused by the tautomerism of enol-imine-ketamine. The result of FTIR showed that the absorption peak of hydroxyl-hydrogen stretching vibration after 2-hydroxynaphthalene-formaldehyde 2-amino-3-methylpyridine and 2-hydroxynaphthalene-formaldehyde 5-methylthiazole underwent ultraviolet radiation Abruptly diminished and even disappeared. However, the two new carbonyl stretching vibration peaks appeared at 1 686 and 1 730 cm-1, respectively. In addition, the absorption of finger region in the infrared spectrum also changed obviously, which further The tautomerism of enolase-ketoamine is illustrated. Comparing the structures of these seven Schiff bases shows that there is a high possibility that the compounds exhibit photochromic properties when ortho-positions on the imine groups of the pyridine ring or electron-donating groups are attached to the thiazole ring.