Zinc-tetraphenylporphyrin grafted on functionalised mesoporous SBA-15: synthesis and utilisation for nitroaldol condensation

Functional free-tetraphenylporphyrin (TPP) molecule was prepared by simple one-step method and subsequently zinc ion was introduced in the cavities of TPP (Zn-TPP). The prepared functional free Zn-TPP was grafted by covalent bonding of zinc with amine functionality present on the internal surface of organo-functionalised mesoporous SBA-15 molecular sieves through axial position. The resultant material was completely characterised using various analytical and spectroscopic techniques including Fourier-transform infrared spectroscopy (FT-IR), ultraviolet-visible spectroscopy, proton nuclear magnetic resonance, X-ray powder diffraction, thermo-gravimetry-differential thermal analysis, C-13 magic-angle spinning nuclear magnetic resonance (MAS-NMR), N-2 physisorption studies, scanning electron microscopy (SEM) and transmission electron microscopy (TEM) techniques. The presence of organo-functionality and Zn-TPP on the surface was confirmed by conducting C-13 MAS-NMR and FT-IR studies. Often, zinc containing functional porphyrin derivatives have shown as potential biological, luminescent properties, whereas in the present studies the functional free Zn-TPP and heterogenised functional-free Zn-TPP materials (SBA-15-AM-Zn-TPP) explored for the first time as catalytic materials for nitroaldol condensation under varying reaction conditions. The present functional free Zn-TPP has an advantage of ease on preparation and strong interaction on the surface linker through axial position, which made it a potential catalyst for aldol condensation and exhibit promising catalytic activity.