DL-Serine covalently modified multinuclear lanthanide-implanted arsenotungstates with fast photochromism

A series of DL-serine covalently modified multinuclear lanthanide implanted arsenotungstates K_(2)[{Ln(H_(2)O)_(7)}_(2){As_(4)W_(44)O_(137)(OH)_(18)(H_(2)O)_(2)(DL-Ser)_(2)}{Ln_(2)(H_(2)O)_(5)(DL-Ser)}_(2)]·65H_(2)O(DL-Ser=DL-serine,Ln=La(1),Ce(2),Pr(3))are obtained.Crystal structure analysis shows that these compounds are isomorphic and contain the basic[{As_(4)W_(44)O_(137)(OH)_(18)(H_(2)O)_(2)(DL-Ser)_(2)}{Ln_(2)(H_(2)O)_(5)(DL-Ser)}_(2)]^(8–)polyoxoanion constituted by two{As_(2)W_(19)O_(59)(OH)_(8)(H_(2)O)}^(6–)subunits,a[W_(6)O_(2)_(3)(OH)_(2)(DL-Ser)_(2)]_(14)–fragment,and two embedded[Ln_(2)(H_(2)O)_(5)(DL-Ser)]^(5+)groups,which further build into one dimensional linear chainlike structure via two peripheral Ln^(3+)ions.Most remarkably,these compounds exhibit rapid photochromic behaviors,which changed color quickly from white(1),yellow(2),green(3)to blue(1),brown(2)and glaucous(3)in ten minutes under UV irradiation,and that the colors gradually recovered in the dark for approximately 22 h.