Zn(II) complexes of pyridoxal–α-amino acid Schiff bases showed photochromic behavior in methanol. Spectral studies revealed that intramolecular nucleophilic attack of 5′-hydroxyl group on imine linkage forms cyclic α-amino ether intermediates which thermally return to the original complexes. The photochromism was characteristic of complexes having a 1:1 ligand–metal ratio. Analogous photochromism was also observed with the Cd(II) complex of N-pyridoxylidenevaline having a fully occupied d-orbital like the Zn(II) complexes, whereas no photochromism was observed with other transition metal complexes such as Ni(II), Cu(II), Mn(II), and Co(II) complexes.
吡哆醛-
α-氨基酸席夫碱的 Zn(II) 复合物在
甲醇中显示出光色行为。光谱研究表明,
亚胺连接上的 5′-羟基分子内亲核攻击形成了环状 α-
氨基醚中间体,这些中间体在热作用下会返回到原始配合物。光致变色是
配体与
金属比例为 1:1 的配合物的特征。与 Zn(II) 复合物一样,N-
吡哆基亚缬
氨酸的 Cd(II) 复合物也具有完全占据的 d-轨道,因此也观察到了类似的光致变色现象,而其他过渡
金属复合物,如 Ni(II)、Cu(II)、Mn(II) 和 Co(II) 复合物则没有观察到光致变色现象。