Hybrid materials of the metal–organic framework (MOF), chromium(III) terephthalate (MIL-101), and phosphotungstic acid (PTA) were synthesized in aqueous media in the absence of hydrofluoric acid XRD analysis of the MIL101/PTA composites indicates the presence of ordered PTA assemblies residing in both the large cages and small pores of MIL-101, which suggests the formation of previously undocumented structures The MIL101/PTA structure enables a PTA payload 15–2 times higher than previously achieved The catalytic performance of the MIL101/PTA composites was assessed in the Baeyer condensation of benzaldehyde and 2-naphthol, in the three-component condensation of benzaldehyde, 2-naphthol, and acetamide, and in the epoxidation of caryophyllene by hydrogen peroxide The catalytic efficiency was demonstrated by the high (over 80–90%) conversion of the reactants under microwave-assisted heating In four consecutive reaction cycles, the catalyst recovery was in excess of 75%, whereas the product yields were 

Chromium(III) Terephthalate Metal Organic Framework (MIL-101): HF-Free Synthesis, Structure, Polyoxometalate Composites, and Catalytic Properties

HPWA/MCM-41 mesoporous molecular sieves of appropriate ratios were prepared by loading HPWA on siliceous MCM-41 by the wet impregnation method. The prepared HPWA/MCM-41 materials were characterized by X-ray diffraction analysis (XRD) and BET surface area and FT-IR measurements. The morphology of mesoporous materials was studied by TEM observation. The catalytic activity of the above materials was tested for the condensation of dimedone (active methylene carbonyl compound) and various aromatic aldehyes under liquid phase conditions at 90 °C. The products were confirmed by FT-IR, 1H NMR and 13C NMR studies. HPWA supported MCM-41 catalysts catalyses efficiently the condensation of dimedone and aromatic aldehydes in ethanol and other solvents under liquid phase conditions to afford the corresponding xanthenedione derivatives. Activities of the catalysts follow the order: HPWA/MCM-41(20 wt.%) > HPWA/MCM-41(30 wt.%) > H3PW12O40·nH2O > HPWA/MCM-41(10 wt.%) > HPWA/SiO2 (20 wt.%) > HM (12) > Hβ (8) > Al-MCM-41 (50). Various advantages associated with these protocols include simple workup procedure, short reaction times, high product yields and easy recovery and reusability of the catalyst.

Heteropolyacid (H3PW12O40) supported MCM-41: An efficient solid acid catalyst for the green synthesis of xanthenedione derivatives

Heteropolyacids, their salts and polyoxometalates have been used as catalysts in wide range of organic reactions such as multi components, oxidation, reductions, electrochemical and photochemical reactions. There have been tremendous and continued efforts to modify the catalytic performance of heteropoly acids such as supporting them on MCM, silica gel, etc. In this review, we have attempted to bring some of new applications of heteropolyacids in organic reactions and recent approaches on modifying them, into focus.

Recent developments in use of heteropolyacids, their salts and polyoxometalates in organic synthesis

The Suzuki–Miyaura and Sonogashira coupling were performed using a new, efficient, reusable and recyclable polymer-supported palladium catalyst. Poly(styrene-co-maleic anhydride) as polymer-support is modified with 2-aminothiazole. PdCl 2 was immobilized on this prepared support and its appearance was confirmed by scanning electron microscopy (SEM), energy dispersive spectroscopy analysis of X-rays (EDAX), inductively coupled plasma (ICP) analysis, and FT-IR techniques. In addition, a quantitative description for metal–ligand interactions in the aforementioned polymer-supported palladium complex is investigated by performing theoretical calculations using density functional theory techniques.

PdCl2 on modified poly(styrene-co-maleic anhydride): A highly active and recyclable catalyst for the Suzuki–Miyaura and Sonogashira reactions

A facile approach for the synthesis of 14-aryl- or alkyl-14H-dibenzo[a,j]xanthenes under solvent-free condition

An efficient and facile synthesis of biologically active 14-substituted-14-H-dibenzo[a,j] xanthene derivatives were reported via three-component condensation reaction of β-naphthol and aldehydes in the presence of a catalytic amount of Preyssler type heteropoly acid, under solvent-free conditions. This method is very easy, rapid and high yielding reaction for the synthesis of dibenzo xanthene derivatives.

Zohreh Daroоgheha

Papers

Facile heteropolyacid-promoted synthesis of 14-substituted-14-H-dibenzo[a,j] xanthene derivatives under solvent-free conditions