Intramolecular triplet–triplet energy transfer enhanced triplet–triplet annihilation upconversion with a short-lived triplet state platinum(ii) terpyridyl acetylide photosensitizer

Abstract

A model of dendritic compound (Pt-DPA) with two Pt-complex photosensitizer chromophores and two 9,10diphenylanthracene (DPA) acceptor groups covalently attached to the periphery and the core of the poly(aryl ether) dendrimer of generation 1 was prepared. A triplet-triplet annihilation upconversion (TTA-UC) system (Pt-DPA/DPA-OH) was constructed in deaerated DMF by combining Pt-DPA with a dissociative acceptor (DPA-OH). Although the lifetime of the triplet state of Pt-complex is only 52 ns, the upconversion fluorescence from DPA (400 ~ 460 nm) in the Pt-DPA/DPA-OH system was observed with quantum yield of 0.22% upon selective excitation of the Pt-complex with a 473 nm laser, which is due to the efficient intramolecular triplet-triplet energy transfer (Φ TTET > 0.81) from the Pt-complex photosensitizer to the DPA acceptor within Pt-DPA. The acceptor covalently linked with the photosensitizer acts as an energy-relay to transfer the harvested energy to the dissociative acceptor which further undergoes the TTA process. The efficient intramolecular triplet-triplet energy transfer process between the photosensitizer and the acceptor plays an important role for the TTA-UC system building with a short-lived triplet state photosensitizer, which facilitates the production of the triplet state of the acceptor, thus advancing the TTA-UC process. This work presents a new strategy for construction of efficient TTA-UC systems utilizing short-lived triplet state photosensitizers.

Fluorination‐controlled Aggregation and Intermolecular Interactions in Pt(II) Complexes with Tetradentate Luminophores

“…In “breathing” aggregates, Pt−Pt interactions can be used to sense diverse analytes . However, a deeper understanding and a defined control of intermolecular interactions are still required, as stacking most frequently causes lowered solubility, undesired triplet−triplet annihilation and lowered quantum yields ,. We have recently reported on the use of bidentate and tridentate luminophores in Pt(II) complexes that are able to emit as blue or green monomeric species, due to the presence of bulky ancillary ligands preventing intermetallic interactions.…”

Pd–Porphyrin Oligomers Sensitized for Green‐to‐Blue Photon Upconversion: The More the Better?

“…In the TTA‐UC systems, 3 DPA* undergoes decay through two pathways: one is a first‐order decay process, including a combination of the intrinsic phosphorescence and the intersystem crossing to the singlet ground state; the other is the triplet–triplet annihilation decay process. The time dependence of the transient absorption of 3 DPA* (Δ A ( 3 DPA*) t ) and the fraction ( f TT ) of 3 DPA* decaying through the triplet–triplet annihilation pathway can be described by equations (1) and (2): …”

“…In the TTA-UC systems, 3 DPA* undergoes decay through two pathways:o ne is af irst-order decay process, including ac ombinationo ft he intrinsic phosphorescence and the intersystem crossingt ot he singlet ground state;t he other is the triplet-triplet annihilation decay process. The time (1) and (2) [39][40][41] :…”

Dye functionalized-ROMP based terpolymers for the use as a light up-converting material via triplet–triplet annihilation

“…There are a few examples of a direct covalent coupling of both dyes. [37][38][39][40] Only very recent studies investigated the covalent binding of one of the dyes to a polymeric matrix [41][42][43] or even both dyes 2,44 considering the fact that the sensitizer and emitter need to be in close proximity in order to efficiently undergo short-range interactions such as TTET and TTA ( Fig. 1).…”