Perylene-Derived Triplet Acceptors with Optimized Excited State Energy Levels for Triplet–Triplet Annihilation Assisted Upconversion

Abstract

A series of perylene derivatives are prepared as triplet energy acceptors for triplet-triplet annihilation (TTA) assisted upconversion. The aim is to optimize the energy levels of the T1 and S1 states of the triplet acceptors, so that the prerequisite for TTA (2E(T1) > E(S1)) can be better satisfied, and eventually to increase the upconversion efficiency. Tuning of the energy levels of the excited states of the triplet acceptors is realized either by attaching aryl groups to perylene (via single or triple carbon-carbon bonds), or by assembling a perylene-BODIPY dyad, in which the components present complementary S1 and T1 state energy levels. The S1 state energy levels of the perylene derivatives are generally decreased compared to perylene. The anti-Stokes shift, TTA, and upconversion efficiencies of the new triplet acceptors are improved with respect to the perylene hallmark. For the perylene-BODIPY dyads, the fluorescence emission was substantially quenched in polar solvents. Moreover, we found that extension of the π-conjugation of BODIPY energy donor significantly reduces the energy level of the S1 state. Low S1 state energy level and high T1 state energy level are beneficial for triplet photosensitizers.

Activation of Electron‐Deficient Quinones through Hydrogen‐Bond‐Donor‐Coupled Electron Transfer

“…In comparison, DDQ, a more powerful oxidant than Q that finds widespread use in organic synthesis, lacks the intrinsic reactivity to perform this ET reaction independently (ΔG ET = +4.4 kcal/mol). 31 The ability of 4 to participate in HBD-coupled ET was examined further with additional electron donors, and it was found to facilitate oxidation of perylene in a yet more unfavorable process (ΔG ET = +19.8 kcal/mol) 32 (Figure S7). …”

“…Zuschriften 552 www.angewandte.de to facilitate oxidation of perylene in ay et more unfavorable process (DG ET =+19.8 kcal mol À1 ; [32] Figure S7). Having identified HBDs capable of promoting ET to electron-deficient quinones,wesought to probe their possible utility as catalysts for synthetic reactions involving ET.A n oxidative lactonization was selected as am odel transformation that would illustrate the catalytic use of HBDs to promote quinone-mediated ET (Scheme 2a).…”

Synthesis of Hexasubstituted Boron‐Dipyrromethenes Having a Different Combination of Substituents

“…Thus, the absorption and fluorescence studies on BODIPYs 1 – 12 indicate that the presence of methyl/aryl substituents on the BODIPY core significantly alter the electronic properties compared with unsubstituted BODIPY46 23 . Furthermore, in comparison with hexa‐alkylated BODIPYs such as 2,6‐diethyl‐1,3,5,7‐tetramethyl‐8‐phenyl‐3a,4a‐diaza‐ s ‐indacene47 ( 24 ), BODIPYs 1 – 12 show significant bathochromic shifts of the absorption and emission bands (Table 1), but have lower fluorescence yields and singlet‐state lifetimes, which indicates that the aryl groups in BODIPYs 1 – 12 undergo free rotation thereby enhancing the non‐radiative decay channels.…”

“…Furthermore, the reduction potentials of BODIPYs 1 – 12 experience a cathodic shift compared with 23 , which indicates their electron‐rich nature. However, compared with alkylated BODIPY47 24 , BODIPYs 1 – 12 are difficult to oxidize and easier to reduce. Thus, the potential shifts of BODIPYs 1 – 12 depend on the electron‐donating and ‐withdrawing nature of the substituents present on the BODIPY core.…”

An N^N Platinum(II) Bis(acetylide) Complex with Naphthalimide and Pyrene Ligands: Synthesis, Photophysical Properties, and Application in Triplet–Triplet Annihilation Upconversion

“…The solutions were degassed by bubbling with N 2 , and the upconverted emission was detected with an RF 5301PC spectrofluorometer (Shimadzu). The upconversion quantum yields ( Φ UC ) were calculated according to the reported method [Equation ] …”