Co3O4 / NiO @ GQDs @ SO3H nanocatalyst has been used as an effective catalyst for the preparation of 2,4-diamino-6-arylpyrimidine-5-carbonitrile derivatives through a three-component reaction of malononitrile, aromatic aldehydes and guanidine hydrochloride under reflux conditions in ethanol. The catalyst has been characterized by FT-IR, XRD, SEM, EDS, BET, TGA, XPS and VSM. Atom economy, reusable catalyst, low catalyst loading, applicability to a wide range of substrates and high yields of products are some of the notable features of this protocol.The best results were gained in EtOH and we found that the reaction gave convincing results in the presence of Co3O4/NiO@GQDs@SO3H nanocomposite (4 mg) under reflux conditions. This green nanocatalyst could be used for other significant organic reactions and transformations. Further explorations of similar protocols are underway in our laboratory. This recoverable catalyst will provide a regular platform for heterogeneous catalysis, green chemistry, and environmentally benign protocols in the near future. Manuscript profile

Crosslinked sulfonated polyacrylamide (Cross- PAA- SO3H) attached to nano - Fe3O4 as an efficient heterogeneous solid acid catalyst has been used for the preparation of spiro[ pyrazoloquinoline - oxindoles] and spiro[ chromenopyrazolo - oxindoles] through a four-component reactions of phenylhydrazine or hydrazine hydrate, isatins, ketoesters and naphthylamine or 2 - naphthol under reflux condition in ethanol.Spirooxindoles have appeared as a series of significant heterocycles due to their presence in a wide spectrum of natural and synthetic organic compounds. These activities make spirooxindoles attractive goals in organic synthesis. The modifying crosslinked polyacrylamides make them attractive objects in chemistry and polymer science. Sulfonated polyacrylamides have unique characteristics such as high strength, hydrophilicity, and proton conductivity. The statistic of results from SEM images clearly demonstrate that the average size of Cross-PAA-SO3H@nano-Fe3O4 is about 7-25 nanometers. The remarkable advantages of this methodology are easy work-up, short reaction times, high to excellent product yields, operational simplicity, low catalyst loading and reusability of the catalyst. Manuscript profile

Functionalized SBA - 15 (Immobilization of Pd on the modified SBA - 15) has been utilized as an efficient catalyst for the preparation of chromenes by multi-component reactions of aromatic aldehydes, malononitrile and 4-hydroxycoumarin under reflux in ethanol. The catalyst has been characterized by X - ray diffraction spectroscopy ( XRD ), Field emission scanning electron microscopy ( FE - SEM ), Transmission electron microscopy (TEM), Energy-dispersive X - ray spectroscopy ( EDX ), X - Ray photoelectron spectroscopy (XPS), Fourier-transform infrared spectroscopy (FT - IR), N2 adsorption analysis, Temperature Programmed Desorption (TPD), and Differential thermal analysis (TGA - DTA). The structures of the products were deduced from their 1 H NMR, 13 C NMR, FT - IR, and elemental analyses. The advantages of this method include the reusability of the catalyst, low catalyst loading, excellent yields in short reaction times and easy separation of products, with no recrystallization required. Manuscript profile

Co3O4/NiO@GQDs@SO3H nanocatalyst has been used as an effective catalystfor the preparation of 2,4-diamino-6-arylpyrimidine-5-carbonitrile derivativesthrough a three-component reaction of malononitrile, aromatic aldehydes andguanidine hydrochloride under reflux conditions in ethanol. The catalyst has beencharacterized by FT-IR, XRD, SEM, EDS, BET, TGA, XPS and VSM. Atom economy,reusable catalyst, low catalyst loading, applicability to a wide range of substratesand high yields of products are some of the notable features of this protocol. Manuscript profile

Cross-linked sulfonated polyacrylamide (Cross-PAA-SO3H) attached to nano-Fe3O4 as an efficientheterogeneous solid acid catalyst has been used for the preparation of spiro[pyrazoloquinoline-oxindoles]and spiro[chromenopyrazolo-oxindoles] through a four-component reactions of phenylhydrazineor hydrazine hydrate, isatins, ketoesters and naphthylamine or 2-naphthol under reflux conditions inethanol. The remarkable advantages of this methodology are easy work-up, short reaction times, highto excellent product yields, operational simplicity, low catalyst loading and reusability of the catalyst. Manuscript profile

An efficient four-component synthesis of benzopyranopyridines is described by one-pot condensation of salicylaldehydes, thiols and 2 equiv of malononitrile with nano-PbWO4 as a robust and reusableheterogeneous catalyst under ultrasonic irradiation. Lead tungstate (PbWO4) nanostructures have been synthesized via a sonochemical method based on the reaction between lead (II) nitrate and sodium tungstate dihydrate in an aqueous solution. Some advantages of this protocol include use of simple and readily available starting materials, rapid assembly of medicinally privileged heterocyclic molecules, reusability of the catalyst, low amount of the catalyst and application of the sonochemical methodology as an efficient technique and innocuous means of activation in synthetic chemistry. Manuscript profile