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 23 (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. A series of rapid photochromic DL-serine covalently modified multinuclear lanthanide (Ln 3+ ) 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, in which the polyoxoanion is constituted of two {As 2 W 19 O 59 (OH) 8 (H 2 O)} 6– subunits, joined together by a [W 6 O 23 (OH) 2 (DL-Ser) 2 ] 14‒ fragment and two embedded [Ln 2 (H 2 O) 5 (DL-Ser)] 5+ groups.