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-[SiW9O37{Ni(H2O)}3]-10 (denoted as SiW9Ni3), was intercalated into Zn3Al based Layered Double Hydroxide (Zn3Al-LDH) by the selective ion-exchange technique. The as-synthesized nanocomposite, SiW9Ni3@Zn3Al, 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 SiW9Ni3 polyoxometalate and Zn3Al-LDH precursors is evidenced by a higher catalytic property of the SiW9Ni3@Zn3Al composite compared to the individual constituents separately. Lewis/Bronsted acidity of the SiW9Ni3 polyoxometalate and Zn3Al-LDH precursors appear to be essential for the catalytic performance of the composite. Furthermore, the catalytic performance of SiW9Ni3@Zn3Al was also tested in GBB 3-CRs synthesis of amino imidazothiazole under mild and solvent-free conditions.

Zirconium based porous coordination polymer (PCP) bearing organocatalytic ligand: A promising dual catalytic center for ultrasonic heterocycle synthesis.

Herein, the efficient role of ultrasonic irradiation both in synthesis of Zr based porous coordination polymer (Zr-PCP) nanoparticles and boosting its catalytic activity, towards the benzimidazoles synthesis is represented. We use an amine based ligand (amino-terephthalate) for PCP and we exhibit that it can have a synergistic catalytic activity. In this work, a unique nano-engineering of cooperative and synergistic catalytic activity of zirconium, as a Lewis acid, and aminophenylene, as an organocatalyst, in the synthesis of heterocycles is presented for the synthesis of benzimidazole from cascade reaction of phenylene diamine with aldehyde at ambient temperature. Zr and amine groups of the Zr-PCP are active catalytic sites which in combination with the ultrasonic irradiation leads to a high selectivity and rapid catalytic production of benzylimidazoles. N2 adsorption-desorption along with BJH analyses confirm the microporosity of the catalyst and recyclability shows that the catalyst is green and sustainable heterogeneous microporous catalyst.