Intramolecular Down- and Up-Conversion in Dimeric Tetracene Complexes Centered via Platinum(II) and Palladium(II)
Bo Y, Hou Y, Matabuena M, Tykwinski RR, Guldi DM (2025)
Publication Type: Journal article
Publication year: 2025
Journal
DOI: 10.1002/adfm.202426055
Abstract
Two dimeric tetracene complexes, Pt(Ltc)2Cl2 and Pd(Ltc)2Cl2, have been synthesized by coordination of a pyridyl substituted acene- to a Pt(II) and Pd(II) metal center. The photophysical properties of the two dimers are characterized and compared with the free tetracene ligand Ltc, as well as the corresponding monomeric complexes (Pt(Ltc)(Lref)Cl2 and Pd(Ltc)(Lref)Cl2) to shed light on the processes of intramolecular up- and down-conversion, namely triplet-triplet annihilation and singlet fission, respectively. Both the free ligand Ltc and Pt(Ltc)(Lref)Cl2 show high fluorescence quantum yields, while emission is heavily reduced in the Pt(Ltc)2Cl2 and Pd(II) complexes. Dimer Pt(Ltc)2Cl2 exhibits efficient singlet fission within 1.6 ns to form a correlated triplet pair (T1T1), confirming that coupling is mediated through Pt(II) over remarkably long inter-chromophore distances. Subsequently, (T1T1) dissociates into free triplets (T1 + T1) with yields of ca. 50%. Moreover, due to the isoenergetic level of the singlet excited state and (T1T1) for tetracene dimers, some (T1T1) in Pt(Ltc)2Cl2 is observed to undergo intramolecular up-conversion and return to the singlet excited state, followed by upconverted fluorescence. On the other hand, photoexcitation of Pd(Ltc)2Cl2 gives a kinetic behavior that is similar to the monomer Pd(Ltc)(Lref)Cl2, namely no singlet fission but fast intersystem crossing within hundreds of picoseconds. It is noted that triplet formation in the Pd(II) monomer and dimer complexes is low, and that non-radiative decay of the singlet excitons to the ground state dominates in both cases. The singlet excited state of all metal–organic complexes exhibits subtle intrachromophore charge-transfer characteristics in polar solvents and kinetic schemes that are similar to that observed in apolar solvents.
Authors with CRIS profile
Involved external institutions
How to cite
APA:
Bo, Y., Hou, Y., Matabuena, M., Tykwinski, R.R., & Guldi, D.M. (2025). Intramolecular Down- and Up-Conversion in Dimeric Tetracene Complexes Centered via Platinum(II) and Palladium(II). Advanced Functional Materials. https://doi.org/10.1002/adfm.202426055
MLA:
Bo, Yifan, et al. "Intramolecular Down- and Up-Conversion in Dimeric Tetracene Complexes Centered via Platinum(II) and Palladium(II)." Advanced Functional Materials (2025).
BibTeX: Download
Canada (CA)