N-heterocyclic carbene bearing thermoresponsive poly(NIPAM) supported palladium (II) complex: Synthetic strategy and application

In this article, we have reported the synthesis of thermoresponsive poly(N-isopropylacrylamide) (PNI-PAM) bearing N-heterocyclic carbene (NHC) based palladium complex through carbene formation. The complex was synthesized from the polymer, which was obtained by SET-LRP (Single Electron Transfer-Living Radical Polymerization) technique using suitable N-heterocyclic carbene (NHC) based initiator. The single-crystal X-ray diffraction (XRD) confirms the structure of the initiator. Furthermore, NMR, FTIR and XPS studies confirmed the formation of the NHC-Pd (II) complex. Our complex possessed unique thermoresponsive characteristics in water i.e, water-soluble at below lower critical solution temperature (LCST) and water-insoluble at LCST. Hence, it can be used as a smart catalyst for Suzuki coupling reactions of various aryl halides in water medium at ambient temperature (30 degrees C). Due to its thermoresponsive behavior, it can be easily recovered from the reaction medium simply by the elevation of temperature and reused for several cycles. (C) 2020 Elsevier B.V. All rights reserved.