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An easy-to-handle eosin Y-based heterogeneous photocatalyst was prepared by post-functionalization of a polydopamine-coated open cell polyurethane foam (PDA@PUF) via the silanization of the adhesive layer with 3-(triethoxysilyl)propan-1-amine (APTES) and the subsequent EDC-mediated coupling of the resulting amino-functionalized foam with eosin Y. The obtained macroscopic material, EY-APTES@PDA@PUF, showed good efficiency and excellent reusability, in an easy-to-carry "dip-and-play" mode for at least six runs as photocatalyst for the aerobic oxidation of 2-methyl-5-nitroisoquinolin-2-ium iodide to the corresponding isoquinolone. Subsequent investigation of the catalytic efficiency of EY-APTES@PDA@PUF for the oxidation of sulfides to sulfoxides, however, evidenced non-negligible eosin Y leaching, leading to a progressive deactivation of the catalytic foam in this case. Two alternative synthetic protocols for the preparation of the macroscopic photocatalyst were next explored to avoid eosin Y leaching. In both cases however, cycling tests also highlighted a progressive deactivation of the catalytic foams in sulfide-to-sulfoxide oxidation reactions. [ABSTRACT FROM AUTHOR]

Polydopamine-coated polyurethane open cell foams are used as structured supports for molecular catalysts through the covalent anchoring of alkoxysilyl arms by the catechol groups of the mussel-inspired layer. This strong bonding prevents their leaching. No alteration of the mechanical properties of the flexible support is observed after repeated uses of the catalytic materials. [ABSTRACT FROM AUTHOR]

• Heterogeneous Ru(bpy) 3 -photocatalyst on a macroscopic soft structured support. • Covalent anchoring on mussel-inspired adhesive layer. • Efficient oxidative benzylamine homocouplings and cross dehydrogenative couplings. • Facile and excellent reusability in a "dip-and-play" mode. • Improvement of the catalytic performances over the cycling tests. An easy-to-handle, highly reusable and efficient [Ru(bpy) 3 ]2+-based heterogeneous photocatalyst was obtained by post-functionalization of a polydopamine-coated open cell polyurethane foam (PDA@PUF) via a silanization process of the mussel-inspired adhesive layer with 3-(triethoxysilyl)propan-1-amine (APTES), followed by an EDC-mediated coupling with [2,2′-bipyridine]-4-carboxylic acid and further complexation with [Ru(bpy) 2 Cl 2 ] (bpy = 2,2′-bypyridine). The successful covalent grafting of APTES on the PDA layer of PUF and functionalization all over the foam surface with [Ru(bpy) 3 ]2+ was suggested by 29Si CP-MAS NMR, XPS, ICP-AES and SEM-EDX. The macroscopic photocatalyst proved effective in model benzylic amine homocouplings and cross dehydrogenative couplings under visible-light irradiation and molecular oxygen, showing good functional group tolerance and excellent reusability in an easy-to-carry "dip-and-play" mode for at least six runs. Impressively, an improvement of the catalytic performances was even observed in both reactions, which most likely results from a modification of the uppermost layer of polydopamine throughout the successive cycles that renders the photocatalyst more accessible. [Display omitted] [ABSTRACT FROM AUTHOR]