Spectroscopic structure-property relationships of a series of polyaromatic platinum acetylides.

To develop a structure–spectroscopic property relationship in platinum acetylides having poly(aromatic hydrocarbon) ligands, we synthesized a series of chromophores with systematic variation in the number of fused aromatic rings (nFAR) and ligand topology (polyacene (L), polyphenanthrene (Z), or compact(C)). We measured ground-state absorption, fluorescence, and phosphorescence spectra. We also performed nanosecond and femtosecond transient absorption experiments. To extend the range of compounds in the structure–property relationship, we did DFT calculations on an expanded series of chromophores. Both the DFT results and experiments show that the S1 and T1 state energies are a function of both nFAR and the ligand topology. In the L chromophores, the S1 and T1 state energies decrease linearly with nFAR. In contrast, the S1 and T1 state energies of the Z chromophores oscillate around a fixed value with increasing nFAR. The C chromophores have behavior intermediate between the L and Z chromophores. A parall...