In this report, Fe3O4 nanoparticles are modified for the first time with graphene quantum dots (GQD) and used for the stabilization of PdCu bimetallic nanoparticles. The new magnetic compound, PdCu@GQD@Fe3O4, is characterized by different methods such as SEM, high‐resolution (HR)‐TEM, energy‐dispersive X‐ray spectroscopy (EDS) mapping, XRD, and X‐ray photoelectron spectroscopy (XPS). This material is applied as an efficient catalyst for the Sonogashira reaction of aryl iodides, bromides, and chlorides in toluene or N,N‐dimethylacetamide at 60–110 °C in very high yields with 0.3 mol % of Pd loading. According to different tests, such as polyvinylpyridine poisoning, hot filtration, and kinetic studies, this catalyst works under heterogeneous conditions. By magnetic separation of the catalyst, it can be recycled for six consecutive runs with only a small decrease in activity without appreciable structural modification of the reused catalyst, which is characterized by TEM and XPS.

Glycerol and urea were used as green and cheap sources of carbon quantum dots (CQD) for modifying Fe 3 O 4 nanoparticles (NPs). The obtained CQD@Fe 3 O 4 NPs were used for the stabilization of palladium species and the prepared catalyst, Pd@CQD@Fe 3 O 4 , was characterized using various techniques. This magnetic supported palladium was applied as an efficient catalyst for the reduction of aromatic nitro compounds to primary amines at room temperature using very low palladium loading (0.008 mol%) and also for the Suzuki-Miyaura cross-coupling reaction of aryl halides as well as challenging heteroaryl bromides and aryl diazonium salts with arylboronic acids and with potassium phenyltrifluoroborate. This magnetically recyclable catalyst was recovered and reused for seven consecutive runs in the reduction of 4-nitrotoluene to p-toluidine and for ten consecutive runs in the reaction of 4-iodoanisole with phenylboronic acid with small decrease of activity. The catalyst reused in the Suzuki reaction was characterized using transmission electron microscopy, vibrating sample magnetometry and X-ray photoelectron spectroscopy. Using experiments such as hot filtration and poisoning tests, it has been shown that the true catalyst works under homogeneous conditions according to the release-return pathway of active palladium species.

Fe3O4 nanoparticles were modified with pyridyl‐triazole ligand and the new magnetic solid was applied for the stabilization of very small and uniform gold nanoparticles. The resulting magnetic material, Fe3O4@PT@Au, was characterized using various methods. These gold nanoparticles on a magnetic support were applied as an efficient heterogeneous catalyst for the three‐component reaction of amines, aldehydes and alkynes (A3 coupling) in neat water with 0.01 mol% Au loading. Using magnetic separation, this catalyst could be recycled for seven consecutive runs with very small decrease in activity. Characterization of the reused catalyst did not show appreciable structural modification.

A novel heterogeneous catalyst based on palladium nanoparticles supported on 3,3'-bisindolyl(4hydroxyphenyl)methane functionalized magnetite (Fe3O4) nanoparticles was synthesized, characterized and used as catalyst for Sonogashira-Hagihara reaction. The alkynylation of a variety of aryl iodides and aryl bromides with terminal alkynes was carried out at 60 °C under copper and phosphane-free conditions using N,N-dimethyl acetamide as solvent, DABCO as base and low Pd loadings (0.18 mol%) under air. In the case of aryl chlorides, the reaction was carried out at 120 ºC in the presence of tetra-n-butylammonium bromide (TBAB) and 0.36 mol% of Pd catalyst. The heterogeneous palladium catalyst introduced in this study is recoverable by an external magnet and it can be used for seven consecutive runs without a significant loss in catalytic activity.

Dopamine (DA) as a neurotransmitter has a pivotal role in the central nervous system. Because of altered levels of DA in various neuroscience diseases, development of a quick, sensitive, and simple analytical approach to determine DA in biological fluids could be very applicable. In this research, a novel electrochemical sensor based on a carbon paste electrode (CPE) modified with ionic liquid (IL) and carbon quantum dots (CQDs) for measuring DA with uric acid and ascorbic acid was developed. IL and CQDs were synthesized and characterized for their specific properties such as composition, emission, size distribution, and morphology structure.Then, the modified CPE and different DA concentration was determined via cyclic voltammetry. The modified electrode exhibited great electrocatalytic activity for DA oxidation. Under optimal conditions, the calibration diagram for DA was linear within the range of 0.1-50 μM in phosphate buffer (pH = 7.4) and limit of detection was 0.046 μM. The electrode was successfully used in the determination of DA in real samples and generated acceptable outputs. The proposed electrochemical sensor could be an exceptional step forward in DA detection and pave the way for the molecular diagnosis of neurological illnesses.

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The development of new technologies for the efficient degradation of toxic organic pollutants from water resources has received great attention. In this study, we described an effective method for the preparation of Pd nanoparticles (NPs) decorated on nitrogen rich ionic liquid (IL) modified magnetic nanoparticles and its application as the green and recoverable heterogeneous catalyst in the reductive degradation of organic dyes and reduction of nitro compounds. The Fe3O4/SiO2−IL−Pd nanocatalyst was characterized by several techniques namely, FT‐IR, FE‐SEM, EDX‐ elemental mapping, XRD, TEM, XPS, TGA and VSM. The Fe3O4/SiO2‐IL−Pd nanocatalyst was applied for the efficient reduction of structurally different nitroarenes, methyl orange (MO), methylene blue (MB) and methyl red (MR) in aqueous media using NaBH4 as reducing agent at room temperature. Using this catalyst nitroarenes were reduced to corresponding amines very efficiently and organic dyes reduced quantitatively under short reaction times. The catalyst can be recovered and recycled for at least ten runs without a notable decrease in the activity.

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