Designing of a novel dual-function cross-linked wrinkled fibrous silica nanocomposite containing bipyridinum dichloride bridges and brønsted acidic unites and its catalytic application in xanthene synthesis

Fibrous silica nanospheres (KCC-1) as important class of mesoporous silica material has a three-dimensional dendritic superstructure. This arrangement provides a high surface area and large pore volume, making it suitable for various applications, including gas storage, separation, and catalysis. Preparation of an acidic fibrous inorganic–organic hybrid nanocomposite and investigation of its application as a powerful catalyst in the one pot multi-components condensation reaction of dimedone, α /β-naphthol and aromatic aldehydes under solvent free conditions is the subject of this work. In the present study, a Brønsted solid acid wrinkled fibrous silica nanocomposite containing internally bivalent organic cationic cross-linkers in its framework was successfully synthesized. For the synthesis of the target organic−inorganic hybrid nanocomposite, KCC-1-Bipy+22Cl−/Pro-SO3H, after preparation of bivalent organosilane bridging agent, Si(OEt)3/Pro-BiPy+22Cl−/Pro-Si(OEt)3 via nucleophilic substitution reaction of (3-chloropropyl) triethoxysilane and bipyridine and its insertion into the pore walls of dendritic fibrous nanostructured silica through a sol−gel process, the surface of the obtained heterogeneous hybrid nanocomposite, KCC-1-Bipy+22Cl− was functionalized with thiol groups through post grafting process by (3- mercaptopropyl) trimethoxysilane and then oxidation of SH groups by H2O2. This method has the advantages of high yields, cleaner reactions, simple methodology, short reaction times, easy workup, and greener conditions. In addition, the nanocatalyst can be easily separated from the reaction mixture and reused several times without significant decrease in activity and promises economic as well as environmental benefits.