Electronic structure and optical properties of germanium-bridged platinum(II)-containing diethynylfluorene monomer and oligomers: A theoretical investigation

We apply quantum-chemical techniques to investigate the structural, electronic, and optical properties of some platinum-containing fluorenyleneethynylenegermylene-derived monomers and oligomers. The aim of our quantum-chemical calculations is to investigate the role of the transition metal centers in the organometallic system in terms of electronic structure and to estimate the influence of metal on the optical properties of the monomer and oligomers. The results indicate that there is a weak electronic interaction between the metal-based fragment and the π-conjugated organic segments, and consequently the photophysical properties are mainly based on the fluorenyleneethynylene (TFT) π-conjugated fragment with little contribution from the metal center. The role of metal center can be described as weak delocalization coupled with strong localization characteristic along the organometallic backbone. The introduction of platinum ions into the π-conjugated structure leads to bathochromic shifts in the absorption features as compared to those for the free ligands.