Nickel substituted polyoxometalates in layered double hydroxides as metal-based nanomaterial of POM–LDH for green catalysis effects

Three nickel substituted Keggin-type polyoxometalates, α-[SiW(9)O(37){Ni(H(2)O)}(3)](−10) (denoted as SiW(9)Ni(3)), was intercalated into Zn(3)Al based Layered Double Hydroxide (Zn(3)Al-LDH) by the selective ion-exchange technique. The as-synthesized nanocomposite, SiW(9)Ni(3)@Zn(3)Al, was used as heterogeneous nanoreactor to promote the synthesis of drug-like aminoimidazopyridine small molecule skeletons via the well-known Ugi-type Groebke–Blackburn–Bienaymé reaction (GBB 3-CRs) in the absence of any acid/additive and under mild and solvent-free conditions. A synergistic catalytic effect between SiW(9)Ni(3) polyoxometalate and Zn(3)Al-LDH precursors is evidenced by a higher catalytic property of the SiW(9)Ni(3)@Zn(3)Al composite compared to the individual constituents separately. Lewis/Bronsted acidity of the SiW(9)Ni(3) polyoxometalate and Zn(3)Al-LDH precursors appear to be essential for the catalytic performance of the composite. Furthermore, the catalytic performance of SiW(9)Ni(3)@Zn(3)Al was also tested in GBB 3-CRs synthesis of amino imidazothiazole under mild and solvent-free conditions.