A ring-shaped 12-Ti-substituted poly(polyoxometalate):synthesis,structure,and catalytic properties

摘要

A new ring-shaped 12-Ti-substituted poly(polyoxometalate)(poly(POM)),K_(10)H_(15)[{K_(2)Na(H_(2)O)_(3)}@{(Ti_(2)O)_(2)(Ti_(4)O_(4))_(2)(A-α-1,3,5-GeW_(9)O_(36))_(2)(A-α-2,3,4-GeW_(9)O_(36))_(2)}]·45H_(2)O(1),has been made under hydrothermal conditions,showing the highest number of Ti centers in Keggin-type poly(POM)family to date.Its obvious feature is that two types of novel chiral trivacant[GeW_(9)O_(36)]^(14-)(A-α-1,3,5-GeW_(9)O_(36)and A-α-2,3,4-GeW_(9)O_(36))segments have been first discovered in POM chemistry,and four[GeW_(9)O_(36)]^(14-)segments are alternately connected by two Ti_(2)O and two Ti_(4)O_(4)cores to form a ring-shaped poly(POM),in which two types of linking modes,Ti_(2)O and Ti_(4)O_(4)bridging cores,are observed for the first time in POMs.The transformation of achiral precursors into chiral POM segments is of great significance for the POM synthetic chemistry.Furthermore,1 as a heterogeneous catalyst can effectively catalyze the oxidation of various thioethers and mustard gas simulant 2-chloroethyl ethyl sulfide(CEES).