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

Abstract

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.

Single‐Photon Near‐Infrared‐Responsiveness from the Molecular to the Supramolecular Level via Platination of Pentacenes

“…Meanwhile, the LUMO energy levels were −2.316 eV for 1 and −2.710 eV for 3 (Figure 1 b). [Pt(PBu 3 ) 2 I] + perturbs the HOMOs than the LUMOs, due to higher energy matching between the HOMO of 6,13‐dialkynylpentacene and the 5 d orbital of Pt II centers [9b,c] . The calculated HOMO–LUMO gap decreased from 3 (1.90 eV, 652 nm) to 1 (1.85 eV, 670 nm), consistent with the experimental results.…”

Luminescent Tetranuclear Gold(I) Dibenzo[g,p]chrysene Derivatives: Effect of the Environment on Photophysical Properties

“…Phosphorescence is a distinctive photophysical property of transition-metal complexes, mainly those containing heavy atoms, due to efficient spin-orbit coupling (SOC) that relaxes the spin selection rule, favors triplet state population, and increases the radiative rate for triplet emission. However, ligand-dominated fluorescence is frequently observed in some polyaromatic complexes [13][14][15][16][17]. Hence, it has become clear that the presence of heavy elements does not guarantee a fast intersystem crossing (ISC) rate; the molecular structure and the nature of the ligands, and the relative positions of singlet and triplet states, play a critical role in determining the intersystem crossing (ISC) rate.…”

Investigation of the Amide Linkages on Cooperative Supramolecular Polymerization of Organoplatinum(II) Complexes

“…According to the previous literature, the former band corresponds to π-π* transition of the chiral N-[(1S)-1-phenylethyl] benzamide moieties [ 44 ]. Meanwhile, the latter band is assigned to PEt 3 -based intra-ligand (IL) π-π* transition, together with some admixture of metal d orbitals [ 45 , 46 ]. In the CD spectrum, a very weak Cotton effect below 330 nm was observed at 323 K, which derives from the intrinsic molecular chirality ( Figure 1 a).…”