Ligand Perturbations on Fluorescence of Dinuclear Platinum Complexes of 5,12-Diethynyltetracene: A Spectroscopic and Computational Study

To
understand how the PtII ion perturbs the electronic
structures of tetracene, 10 dinuclear [X­(Et3P)2PtII]2-5,12-diethynyltetracene complexes with
different auxiliary ligands were synthesized. Interactions between
the PtII ion and 5,12-diethynyltetracene were probed spectroscopically
and computationally. The dinuclear [X­(Et3P)2PtII]2-5,12-diethynyltetracene complexes exhibit
red-shifted absorption and fluorescence in comparison with those of
5,12-bis­(triisopropylsilylethynyl)­tetracene, with the neutral complexes
with π-donating auxiliary ligands showing a larger red shift
than the cationic complexes with π-accepting ligands. Electronic
structures of the complexes and effects of the metal ions and the
ligands on the electronic transitions of the complexes were investigated
by TD-DFT calculations, the results of which showed that the electronic
structure of the 5,12-diethynyltetracene core is perturbed by π
interactions with the Pt fragments, the extent of which depends on
the energies of the dπ orbitals of the Pt fragments.