Tri-tert-butyl(N-alkyl)phosphonium ionic liquids: Structure, properties and application as hybrid catalyst nanomaterials

Abstract

A series of sterically hindered tri-tert-butyl(n-alkyl)phosphonium salts (n-CnH2n+1 with n = 1, 3, 5, 7, 9, 11, 13, 15, 17) was synthesized and systematically studied by1H,13C,31 P NMR spectros-copy, ESI-MS, single-crystal X-ray diffraction analysis and melting point measurement. Formation and stabilization palladium nanoparticles (PdNPs) were used to characterize the phosphonium ionic liquid (PIL) nanoscale interaction ability. The colloidal Pd in the PIL systems was described with TEM and DLS analyses and applied in the Suzuki cross-coupling reaction. The PILs were proven to be suitable stabilizers of PdNPs possessing high catalytic activity. The tri-tert-butyl(n-alkyl)phosphonium salts showed a complex nonlinear correlation of the structure–property rela-tionship. The synthesized family of PILs has a broad variety of structural features, including hydro-phobic and hydrophilic structures that are entirely expressed in the diversity of their properties.