Controlling Structure from the Bottom-Up: Structural and Optical Properties of Layer-by-Layer Assembled Palladium Coordination-Based Multilayers

Layer-by-layer assembly of two palladium coordination-based multilayers on silicon and glass substrates is presented. The new assemblies consist of rigid-rod chromophores connected by terminal pyridine moieties to palladium centers. Both colloidal palladium and PdCl2(PhCN)2 were used in order to determine the effect of the metal complex precursor on multilayer structure and optical properties. The multilayers were formed by an iterative wet-chemical deposition process at room temperature in air on a siloxane-based template layer. Twelve consecutive deposition steps have been demostrated resulting in structurally regular assemblies with an equal amount of chromophore and palladium added in each molecular bilayer. The optical intensity characteristics of the metal−organic films are clearly a function of the palladium precursor employed. The colloid-based system has a UV−vis absorption maximum an order of magnitude stronger than that of the PdCl2-based multilayer. The absorption maximum of the PdCl2-based fi...