Silica-bonded 1,4-diaza-bicyclo[2.2.2]octane-sulfonic acid chloride catalyzed synthesis of spiropyran derivatives

•Introduce of silica-bonded 1,4-diaza-bicyclo[2.2.2]octane-sulfonic acid chloride (SBDBSAC).•Characterization of SBDBSAC by several different techniques.•Application of SBDBSAC as nanostructured catalyst on the synthesis of spiropyrans.•Reusability of SBDBSAC.

In this research, a novel nanostructured heterogeneous catalyst, namely silica-bonded 1,4-diaza-bicyclo[2.2.2]octane-sulfonic acid chloride (SBDBSAC), as an acidic ionic liquid based on 1,4-diaza-bicyclo[2.2.2]octane ring bonded to silica has been prepared and fully characterized by several techniques such as fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), thermogravimetric analysis (TGA), differential thermogravimetric (DTG), scanning electron microscope (SEM), transmission electron microscopy (TEM) and energy dispersive X-ray analysis (EDX). The nanostructured catalyst has been suxessfully used as reusable nanostructured catalyst for green, simple and efficient synthesis of spiropyrans by the one-pot tandem Knoevenagel-Michael-cyclization reaction of isatin derivatives or acenaphthenquinone with barbituric acid derivatives, and 1,3-dicarbonyl compounds under aqueous media.

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