Intramolecular RET Enhanced Visible Light-Absorbing Bodipy Organic Triplet Photosensitizers and Application in Photooxidation and Triplet–Triplet Annihilation Upconversion

Abstract

Resonance energy transfer (RET) was used for the first time to enhance the visible light absorption of triplet photosensitizers. The intramolecular energy donor (boron-dipyrromethene, Bodipy) and acceptor (iodo-Bodipy) show different absorption bands in visible region, thus the visible absorption was enhanced as compared to the monochromophore triplet photosensitizers (e.g., iodo-Bodipy). Fluorescence quenching and excitation spectra indicate that the singlet energy transfer is efficient for the dyad triplet photosensitizers. Nanosecond time-resolved transient absorption spectroscopy has confirmed that the triplet excited states of the dyads are distributed on both the energy donor and acceptor, which is the result of forward singlet energy transfer from the energy donor to the energy acceptor and in turn the backward triplet energy transfer. This 'ping-pong' energy transfer was never reported for organic molecular arrays, and so it is useful to study the energy level of organic chromophores. The triplet photosensitizers were used for singlet oxygen ((1)O2) mediated photooxidation of 1,5-dihydroxylnaphthalene to produce juglone. The visible light absorption of the new visible light-absorbing triplet photosensitizers are higher than the conventional monochromophore based triplet photosensitizers, as a result, the (1)O2 photosensitizing ability is improved with the new triplet photosensitizers. Triplet-triplet annihilation upconversion with these triplet photosensitizers was also studied. Our results are useful to design the triplet photosensitizers showing strong visible light absorbance and for their applications in photocatalysis and photodynamic therapy.

Photochemical upconversion: present status and prospects for its application to solar energy conversion

“…However, efficient TTA-UC is not restricted to these classes of molecules, as others can also satisfy the abovementioned conditions: Transition metal complexes such as Ir(ppy) 3 28 or Ru(dmb) 3 29 also facilitate efficient ISC by incorporating a heavy atom and can act as triplet sensitizers. Borondipyrromethene derivatives (so-called BODIPY dyes) 30 were found to function as rare-metal-free triplet sensitizers at reasonable efficiency, and can also be combined with Ir complexes 31 to increase their absorption strength. Regarding emitter species, most studies have focussed on PAHs, with BODIPY-and conjugated polymer-based emitters being notable exceptions.…”

Efficient Triplet Exciton Fusion in Molecularly Doped Polymer Light‐Emitting Diodes

“…We use simple organic fluorophors including DPA, [15] perylene, [16] and rubrene, [17] which were used in photon upconverters for photovoltaics, and a solution-processable singlet-fission sensitizer, 6,13-bis(triisopropylsilylethynyl) pentacene (TIPS-pentacene), [20,21] as the emissive dopants for FuLEDs. The molecular structures of these emitters are shown in Figure 1b.…”

“…[6][7][8] At the same time, photon upconversion through TTA has been widely considered for next-generation photovoltaic applications. [9][10][11][12][13][14] Effective upconverters have been demonstrated using combinations of a triplet sensitizer such as platinum octaethylporphyrin (PtOEP) [3] and a triplet acceptor/annihilator such as 9,10-diphenylanthracene (DPA), [15] perylene, [16] or rubrene.[17] TTA-upconversion (TTA-UC) quantum yield (ratio of upconverted photons to absorbed photons) of 30% was observed in solution phase. [18] This suggests that the intrinsic efficiency of the TTA-UC reaction (i.e., the This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.…”

Difluoroboranyl derivatives as efficient panchromatic photoinitiators in radical polymerization reactions

“…7, S9). Based on the literature data connected with triplet state absorption spectra of BODIPY derivatives [44][45][46][47][48][49][50] this band may be attributed to the triplet state of currently investigated complexes.…”