Mesoporous KIT-۶ as a support for the immobilization of a palladiumorganometallic nanocatalyst and its application in C–C coupling reactions

Many Pd complexes have been used as homogeneous catalysts in cross-coupling reactions [۱].Although some of the Pd complexes have potential for recycling [۲,۳], most of them have problemssuch as deactivation and difficult separation from the solution. Thus, it is necessary to developheterogeneous catalysts which can easily be recovered from the reaction system and reused [۴, ۵].Recently, Ryoo and co-workers reported a new cubic mesoporous silica material named KIT-۶,which was prepared using triblock copolymer (P۱۲۳) as the mesopore directing agent. KIT-۶possesses large readily tunable pores with thick pore walls, high thermal stability, high specificsurface area and large pore volume. Therefore, mesoporous KIT-۶ can be used as a support for thesynthesis heterogeneous catalysts. In this work, a new Schiff base complex of Pd(II) was fabricatedon the surface of KIT-۶. For this purpose Schiff-base ligand was synthesized from condensationof diethylenetriamine (DETA) and salicylic aldehyde (SA). In the next step, Schiff-base ligandwas reacted with (۳-iodopropyl)trimethoxy silane (IPTMS). Then, Schiff base complex ofpalladium was synthesized using a complexation reaction of Pd(OAc)۲. Finally, the obtainedpalladium complex was fixed on KIT-۶ (Pd@SA-Schiff base@KIT-۶) as a new reusable andpractical catalyst in Suzuki reaction. This catalyst was characterized using IR, BET, EDS, SEM,and TGA methods.

Keywords:

Mesoporous silica materials , Nanocatalyst , Suzuki reaction , KIT-۶ , Schiff base complex , Palladium.