Broadband Visible Light-Absorbing [70]Fullerene-BODIPY-Triphenylamine Triad: Synthesis and Application as Heavy Atom-Free Organic Triplet Photosensitizer for Photooxidation

Abstract

A broadband visible light-absorbing [70]fullerene-BODIPY-triphenylamine triad (C70-B-T) has been synthesized and applied as a heavy atom-free organic triplet photosensitizer for photooxidation. By attaching two triphenylmethyl amine units (TPAs) to the π-core of BODIPY via ethynyl linkers, the absorption range of the antenna is extended to 700 nm with a peak at 600 nm. Thus, the absorption spectrum of C70-B-T almost covers the entire UV–visible region (270–700 nm). The photophysical processes are investigated by means of steady-state and transient spectroscopies. Upon photoexcitation at 339 nm, an efficient energy transfer (ET) from TPA to BODIPY occurs both in C70-B-T and B-T, resulting in the appearance of the BODIPY emission at 664 nm. Direct or indirect (via ET) excitation of the BODIPY-part of C70-B-T is followed by photoinduced ET from the antenna to C70, thus the singlet excited state of C70 (1C70*) is populated. Subsequently, the triplet excited state of C70 (3C70*) is produced via the intrinsic intersystem crossing of C70. The photooxidation ability of C70-B-T was studied using 1,5-dihydroxy naphthalene (DHN) as a chemical sensor. The photooxidation efficiency of C70-B-T is higher than that of the individual components of C70-1 and B-T, and even higher than that of methylene blue (MB). The photooxidation rate constant of C70-B-T is 1.47 and 1.51 times as that of C70-1 and MB, respectively. The results indicate that the C70-antenna systems can be used as another structure motif for a heavy atom-free organic triplet photosensitizer.

Efficient Red-to-Blue Triplet–Triplet Annihilation Upconversion Using the C70-Bodipy-Triphenylamine Triad as a Heavy-Atom-Free Triplet Photosensitizer

“…C 70 -BDP-T, BDP-T, and C 70 -1 were synthesized according to the literature. 43 The structures and purities of these compounds were verified using 1 H NMR, 13 C NMR, and mass spectrometry. The precursors all were analytically pure and were purchased from Sigma-Aldrich Co. and used without any purification.…”

“…C 70 -BDP-T , BDP-T , and C 70 -1 were synthesized according to the literature . The structures and purities of these compounds were verified using 1 H NMR, 13 C NMR, and mass spectrometry.…”

“…Recently, we have synthesized a novel heavy-atom-free triad photosensitizer with the C 70 -bodipy-triphenylamine (C 70 -BDP-T) structure. 43 Scheme 1 shows its molecular structure, along with a comparator, bodipy-triphenylamine (BDP-T) dyad. In contrast to bodipy itself, the triphenylamine (TPA) unit of the triad and dyad increases the conjugation of the bodipy unit, thus extending molecular absorption to the NIR-I region with an onset of 670 nm.…”

“…Recently, we have synthesized a novel heavy-atom-free triad photosensitizer with the C 70 -bodipy-triphenylamine ( C 70 -BDP-T ) structure Scheme shows its molecular structure, along with a comparator, bodipy-triphenylamine ( BDP-T ) dyad.…”

Visible Light-Induced Aerobic Oxidative Dehydrogenation of C–N/C–O to C=N/C=O Bonds Using Metal-Free Photocatalysts: Recent Developments

“…Recycling of the methylene blue-dyed polyester fabrics and 99 was not carried out, while 98 was recovered and reused three times, with a slight decrease in its activity at the third catalytic cycle. In addition, two C60-BODIPY photosensitizers (C60-B1/C60-B2, 100a,b) [227], a C70-BODIPY-triphenylamine triad (C70-B-T, 101) [228] and a meso-tetrakis(N-methylpyridinium-4-yl)porphyrin supported on the sodium salt of Amberlyst 15 nanoparticles and complexed with formic acid (nanoAmbSO3@H2TYMPyP(HCO2H)2, 102a) [229] and BF3 (nanoAmbSO3@H2TYMPyP(BF3)2, 102b) [230] were employed in the mentioned transformation, obtaining Juglone (85, R 1 = R 2 = R 5 = H, R 4 = OH) in high yield (only quantum yield was given in the case of using 100 and 101) (Figure 31). The recyclability of 100 and 101 was not tested, while 102a and 102b were recycled but in a different photo-oxidation reaction.…”