Green design, synthesis, and characterization of a novel eight-membered silicon-boron-based cyclo-1,5-di(p-tolyl)-3,3,7,7-tetraphenyl-1,5-dibora-3,7-disiloxane, a Lewis acid, and its use for the adsorption of Fe3+ and Methylene blue from aqueous solution

Abstract

Metal ions such as Fe³⁺ and dye contamination such as methylene blue (MB) have caused environmental and health problems, particularly through industrial wastewater discharge. Some conventional treatment methods of removing these toxins are inefficient and unsustainable. Thus, this study focuses on the synthesis and characterization of cyclo-1,5-di(p-tolyl)-3,3,7,7-tetraphenyl-1,5-dibora-3,7-disiloxane, a Lewis acid, and its application in the adsorption of Fe³⁺ and MB from aqueous solution. The compound was synthesized via a condensation reaction between diphenylsilanediol (4.3 g, 19.97 mmol) and p-tolylboronic acid (2.72 g, 20.03 mmol) at reflux for 12 h. The crude product was recrystallized from petroleum ether yielding 2.89 g of blocky, colorless crystals (90% yield, melting point 260 °C). The compound was characterized using powder X-ray diffraction (PXRD) and fourier transform infrared (FT-IR) spectroscopy. Thereafter, the synthesized compound was used for the adsorption of Fe³⁺ and MB. The adsorption isotherms for both Fe³⁺ and MB follow the Freundlich with R² values of 0.8967 and 0.8769, respectively. These adsorption study results show the potential of the synthesized novel compound, as an adsorbent for the removal of Fe³⁺ and MB in aqueous solution, offering a promising future for application in wastewater treatment and environmental remediation.