Surface Organization of Polyoxometalate Hybrids Steered by a 2D Supramolecular PTCDI/Melamine Network

A 2D supramolecular honeycomb network built on hydrogen bonding of perylene-3,4,9,10-tetracarboxylic acid diimide (PTCDI) and 1,3,5-triazine-2,4,6-triamine (Melamine) has been self-assembled on Au(111) by a solution processed method. The ability of the porous network to host functional molecular oxides or polyoxometalates (POMs) has been investigated using a functionalized species [PW11O39{p-C6H4-C C-C6H4-NHC(O) (CH2)(4){-CH(CH2)(2)S-S-}}](4-)(K-Ge(w)[S-S]): this inorganic/organic hybrid built on a Keggin-type POM core and an organic tether incorporating a thioctic acid function has been designed to enhance the host guest interaction by the formation of covalent Au-S bonds. XPS analysis confirmed the presence of the POMs that are covalently held onto the surface. Probed by STM operating under ambient conditions, the spatial organization of the POMs display some reminiscence of the organic template, while monitoring the POM deposition at various immersion times by PM-IRRAS showed that the POM raising at the substrate is fostered.