A new periodic mesoporous organosilica containing diimine-phloroglucinol, Pd(ii)-grafting and its excellent catalytic activity and trans-selectivity in C–C coupling reactions

Abstract

A new organosilane precursor has been designed via Vilsmeier–Haack formylation of phloroglucinol followed by its Schiff base condensation with 3-aminopropyl-triethoxysilane (APTES). A novel organic–inorganic hybrid periodic mesoporous organosilica (PMO) LHMS-3 containing the highly coordinating bis(propyliminomethyl)-phloroglucinol moiety inside the pore wall has been synthesized by using this precursor organosilane molecule. Phenolic-OH and imine-N donor sites present in this PMO material have been utilized to anchor Pd(II) species at the surface of the mesopores. Small angle neutron scattering, XRD, HR TEM, SEM, 13C and 29Si solid state MAS NMR, UV-vis and FT IR spectroscopic tools are utilized to characterize the 2D-hexagonal mesophase and the presence of the bis(propyliminomethyl)-phloroglucinol moiety inside the pore wall. This Pd-anchored material Pd-LHMS-3 showed excellent catalytic activity and trans-selectivity in Heck C–C bond formation reactions for the synthesis of a series of value-added aromatic and aliphatic olefins.