Cu(II) salen complex grafted onto KCC-1 as a convenient multifunctional heterogeneous catalyst for the preparation of 4H-benzochromenes

A complex of Cu(II) salen was grafted on the surface of KCC-1 nanoparticles using 3-chloropropyltrimethoxysilan as a linker to obtain Cu(II) salen@KCC-1. SEM and TEM images showed the porous, spherical nanosized particles with a 200 nm diameter. EDX and TGA analyses approved the incorporation of Cu(II) salen on the surface of KCC-1, while AAS showed that about 0.68 mmol g⁻¹ of copper content was incorporated on the KCC-1 surface. Since, Cu(II) makes strong complex with salen ligands, they can be acted as useful catalysts. Subsequently, the synthesis of 2-amino-4H-benzochromenes was studied in the presence of Cu(II) salen@KCC-1 at 80 °C. The expected products were formed within very short reaction times in good to high yields. It was understood that Cu(II) salen@KCC-1 is an active heterogeneous recoverable catalyst that can be employed several times with no significant loss in its catalytic activity.