Covalently bonded porphyrin networks studied by x-ray absorption and photoemission

Abstract

Molecular self-assembly may be defined as the spontaneous association of molecules under equilibrium conditions into stable, structurally well defined aggregates joined by non-covalent bonds [1]. The basic idea is to synthesize molecular building blocks with predetermined intermolecular bonding properties. However, since molecular self-assembly is based on non-covalent interactions (e.g. hydrogen bonding, metal ligand bonding or van der Waals interactions), the stabilization energies are usually very low [1, 2]. As a consequence conventional self-assembled structures are often unstable even at moderate temperatures. A strategy to overcome this low stabilization energy relies on inducing covalent reactions between the molecular components, thus forming twodimensional covalently bonded networks. The formation of covalent bonds between complementary molecular components is an appealing approach in the fabrication of nanoscale structures, such as nanomeshes and nanolines, because of their high selectivity, strength and directionality [1, 3]. These nanostructures are attractive for their intrinsic properties; for their potential applications such as novel sensing, energy conversion or catalytic devices; for their ability to `trap? other molecules such as fullerenes, creating even more interesting complexes and for their use as templates to direct the growth of, for example, metal clusters with interesting catalytic or magnetic properties.