How to effectively regulate the electromagnetic parameters of magnetic composites to achieve better microwave absorption (MA) performances is still a serious challenge. Herein, we constructed nanocomposites composed of magnetic constituents and carbon materials to obtain high-efficiency electromagnetic wave absorbers. Self-assembled, multi-interfacial, and porous RGO/MWCNT/Fe3O4 hybrids (GMFs) were synthesized via in situ one-pot solvothermal method. The growth mechanism of the GMFs would be that the defects on reduced graphene oxide (RGO) provide sites for the crystallization of Fe3O4. Also, the RGO and Fe3O4 were further linked by the cross-connection of multiwalled carbon nanotubes (MWCNTs), which acted as a bridge. The MA mechanism of GMFs was studied while considering the synergistic effects between the three components (RGO, MWCNT, and raspberry-shaped Fe3O4) and their multi-interfacial and porous structure. Also, the MA performance of the GMFs was conducted. The GMFs exhibited a maximum reflection loss (RL) value of −61.29 dB at 10.48 GHz with a thickness of 2.6 mm when the contents of RGO and MWCNT were 6.3 and 1.3 wt %, respectively. The RL values (≤−10 dB) were observed to be in the range of 8.96–12.32 GHz, and the effective microwave absorption bandwidth was tunable from 3.52 to 18 GHz by changing the sample thickness. The results revealed that the multi-interfacial and porous structure of the GMFs is beneficial to MA performance by inducing multiscatterings. Since no toxic solvents were used, this method is environmentally friendly and has potential for large-scale production. The prepared GMFs may have a wide range of applications in MA materials against electromagnetic interference pollution.

All of the reagents were purchased from Aldrich-reagent and used without further purifications. 1 H NMR spectra and 13 C NMR spectra were recorded on a Bruker Advance III 500 MHz spectrometer and using DMSO-d 6 (500 MHz for 1 H or 125 MHz for 13 C, respectively) as solvent. Chemical shifts of 1 H and 13 C NMR spectra were expressed in δ values (ppm) downfield from tetramethylsilane. Microanalyses were taken on a VARIOX Elemental Analyzer. Mass spectra were carried out on VARIAN1200. IR spectra were obtained on a TENSOR 27 spectrometer. Melting points were recorded on microscope (SGW X-4) melting point apparatus. The reaction was monitored by TLC. Experimental details and characterizationGeneral procedure for preparation of oxindole derivatives 3a-3p and 5a-5e A mixture of the isatin 1 or acenaphthenequinone 4 (1 mmol), indole 2 (2 mmol), p-TSA (10 mol %), CH 2 Cl 2 (10 mL) was added to 50 mL flask and stirred at room temperature until the the completion of the reaction (Scheme 1, 2). Then the solid was filtered and washed with CH 2 Cl 2 (5 mL) and ethanol (5 mL) in turns, affording the product in excellent yields, which was recrystallized from ethanol to produce pure crystalline products. The products were identified by elemental analysis, MS, 1 H NMR, 13 C NMR, and IR spectra. Scheme 1. Preparation of product 3a-3p Scheme 2. Preparation of product 5a-5e Spectroscopic and characterization data 3,3-di(1H-indol-3-yl)indolin-2-one (3a): Yield: 92%; white solid; m. p. 318-320 (lit. [26]

An efficient mild one-pot synthesis of spiro [indoline-3,4'-pyrano[2,3-c]pyrazole derivatives by a four-component reaction of hydrazine, a β-keto ester, isatin, and malononitrile catalysed by L-proline in water is reported.

An efficient synthesis of spiro [indoline-3,7′-pyrrolo[1,2-c]imidazole] is achieved through a three-component reaction of isatins, malononitrile, and hydantoin/2-thiohydantoin in water catalysed by NaHCO 3 . All the target compounds were screened for the Cell Division Cycle 25 Phosphatase B (CDC25B) inhibitory activities.

Rapid and Efficient Synthesis of 3,3-Di(1H-indol-3-yl)indolin-2-ones and 2,2-Di(1H-indol-3-yl)-2H-acenaphthen-1-onesCatalyzed by p-TSA. -The title compounds (III) and (V) are obtained by reaction of various isatins or acenaphthenequinone, resp., with indoles under mild reaction conditions. -(YU, J.; SHEN, T.; LIN, Y.; ZHOU, Y.; SONG*, Q.; Synth.