Micelle-Enabled In Situ Surface Modification of Porous Organic Polymers: Formation of Heterogeneous Microcolony for Efficient Suzuki–Miyaura Coupling in Water

Synthesis of water-stable and dispersible heterogeneous catalysts having high catalytic efficiency is more challenging compared with homogeneous catalysts due to their low dispersity, activity, and spatial confinement of active centers in bulk water. Herein, we are describing systematic studies for the development of heterogeneous microconfinement with the participation of the aqueous micelles via temporal surface modification of porous organic polymer derived from phosphine ligands. Detailed investigations using various techniques such as transmission electron microscopy (TEM), scanning electron microscopy (SEM), tensiometry, confocal laser scanning microscopy (CLSM), and fluorescence lifetime imaging microscopy (FLIM) have been used to understand the role of micelles, reagents, and materials for the generation of microcolonies in water. Two-color fluorescence crossover experiments have also been performed to understand the exchange of reagents from micelles to materials or vice versa, micelles to micelles, and materials to materials. The surfactant-modified microcolonies have been used for the ligation and stabilization of palladium, which was evidenced by high-resolution transmission electron microscopy (HR-TEM), high-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM), and X-ray photoelectron spectroscopy (XPS) analysis. The microcolonies act as the heterogeneous confined space for catalysis in water which is showcasing the Suzuki-Miyaura cross-coupling reaction in water with a ppm level of Pd loading under mild conditions. The catalyst was found to be recyclable for five cycles; easy scale-up of materials and C-C couplings are the additional features. Moreover, these data provide an opportunity for revising reaction models of porous materials in aqueous micellar systems that underpin the development of sustainable heterogeneous catalysis in water.