Efficacy of the Ionic Liquid 1,4-Bis(carboxymethyl)piperazine-1,4-diium Chloride as a Catalyst for Xanthenes/Acridines Synthesis: Spectral Characterization, X-ray Structure, and Nematicidal Activity

Abstract

In this research paper, a straightforward and efficient approach for synthesizing the 1,4-bis(carboxymethyl)piperazine-1,4-diium chloride [BCMPZ][2Cl] ionic liquid salt (IL) catalyst is introduced. The morphology, thermal stability, and functionality of the synthesized [BCMPZ][2Cl] IL were characterized using spectroscopic, electron microscopy, and thermal analysis. A density functional theory (DFT) study, including infrared spectroscopy (IR), powder X-ray diffraction (PXRD), Thermogravimetric analysis (TGA), and scanning electron microscopy with energy-dispersive X-ray spectroscopy (SEM with EDX), were employed. The well-characterized ionic liquid (IL) assisted as a catalyst in the synthesis reaction involving aldehydes, dimidone, and arylamine to yield 1,8-dioxo-octahydroxanthene and 1,8-dioxo-9-aryl-10-aryl-decahydroacridine derivatives (3a-i and 4a-b) with high yields, getting up to 97%. The structure of the synthesized molecules was confirmed through various physicochemical techniques, including 1H and 13C NMR, IR, elemental analysis, and MS. X-ray single crystal diffraction techniques were also used to elucidate the geometry of one of the synthesized molecules (3f). The heterogeneous catalyst (IL) used in the synthesis of the molecules was successfully recycled and reused without additional treatment of purification. The synthesized xanthines were found to inhibit nematode activity, thus they may act as potential nematicides for crop protection. The present study also identified five different compounds that were effective against Meloidogyne incognita. Compound 3a reduced nematode egg hatching by 65% at a concentration of 2000 ppm, which was the highest efficacy in tested compounds. Compound 3c had a mortality rate of 80% against nematodes. Overall, the developed method has many advantages, including fast reaction time, economic efficiency, and minimal catalyst loading, making it a promising method for future research in the field of heterocycle synthesis and crop protection.