Pillar[5]arene-based thiazole NHC/Pd(II) supramolecular coordinated polymer: synthesis, structure and catalytic activity in Suzuki–Miyaura reaction

Abstract

As a booming research theme, heterogeneous catalysts have demonstrated significant advantages over homogeneous catalysts in terms of stability, recyclability, and separability from the reactant mixture. In this study, a supramolecular coordinated polymer (P[5]-SCP) was synthesized by complexing thiazole-derived pillar[5]arene (P[5]) with Pd(II), which was obtained by nucleophilic substitution between 1,4-bis(2-Bromoethoxy) pillar[5]arene and 4-methyl-5-(β-hydroxyethyl) thiazole. The chemical component and structure of the P[5]-SCP were confirmed by NMR, EA, FI-IR, XPS, XRD, SEM, TEM, HR MS. In the Suzuki–Miyaura coupling reaction, the catalytic activity, stability, and recyclability were thoroughly evaluated. The P[5]-SCP had excellent catalytic activity in mild reaction conditions (up to 81% yield) and exhibited little loss of activity after at least five recycles. Furthermore, catalyst P[5]-SCP was easily synthesized from simple raw materials and low-cost, thereby a novel pillar[5]arene based-NHC catalyst was developed in green heterogeneous catalysis.

Graphical abstract