Fluorine-Phenanthroimidazole Porous Organic Polymer: Efficient Microwave Synthesis and Photocatalytic Activity

Abstract

A porous polymer containing a fluorophenylphenanthroimidazole core was easily prepared via one-pot Suzuki-Miyaura cross-coupling reactions under microwave heating. These new metal-free polymers have demonstrated heterogeneous photocatalytic activity toward aza-Henry reaction with reasonable recyclability. Their preparation require a minimal workup to build porous networks with control over the apparent surface area and pore volume from suitable molecular building blocks containing 2-(1 H-phenanthro[9,10- d]imidazol-2-yl)-3,5-difluorophenol (PhIm-2F), as rigid and multitopic node, which afforded a conjugated porous polymer (CPP-PhIm-2F). A series of fluorinated ligands have shown their capability in the preparation of soluble and supported cationic Ru(bpy)₂(F-phenanthroimidazole) complexes by reaction with Ru(bpy)₂Cl₂ and demonstrating a beneficial effect of two fluorine atoms on the photocatalytic effect.

Keywords: aza-Henry; conjugated polymer; heterogenized catalyst; phenanthroimidazole; photocatalysis; porous organic polymer; ruthenium photocatalyst.