Isocyanurate-Based periodic mesoporous organosilica (PMO-ICS): a highly efficient nanocatalyst for the one-pot multicomponent reactions

The use of heterogeneous catalysts has become highly desirable in recent years, because they incorporate many green chemistry principles.¹ in 1999, mesoporous organosilica hybrids were prepared from bridged organosilane precursors ((ŔO)₃Si–R–Si(OŔ)₃; R: organic bridging group, Ŕ: methyl or ethyl). Such mesoporous hybrids prepared from bridged organosilane precursors have been classified as periodic mesoporous organosilica (PMO).² PMOs are very attractive as support for heterogeneous solid catalysts in fine chemicals synthesis. Isocyanurate bridging periodic mesoporous organosilicate channels (PMO-ICS) was synthesized by hydrolysis co-condensation of tris [3-(trimethoxysilyl) propyl] isocyanurate (ICS) and tetraethoxysilane (TEOS) in the presence of pluronic P123 under acidic condition. ^[3-6]

The obtained PMO-ICS was characterized using X-ray diffraction (XRD) pattern, transmission and scanning electron microscopic (TEM and SEM) images, and Fourier transform infrared (FTIR) spectroscopy. Isocyanurate bridging periodic mesoporous organosilica (PMO-ICS) was shown to be a highly active and efficient recyclable catalyst for three-component synthesis of imidazole derivatives, synthesis of bis (indolyl) methanes under mild reaction conditions in short reaction times and good to excellent yields. The catalyst can be recovered and reused in four subsequent runs without significant decreasing in its activity and selectivity.

Advantages of this work are: Low catalyst loading, environmentally friendly and easy synthesis of catalyst, short reaction times, high to excellent conversions, heterogeneous conditions, easily work up procedure and excellent selectivity and reusability of the catalyst.