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论文类型：期刊论文

发表时间：2017-10-19

发表刊物：JOURNAL OF PHYSICAL CHEMISTRY C

收录刊物：Scopus、SCIE

卷号：121

期号：41

页面范围：22665-22679

ISSN号：1932-7447

摘要：To achieve activatable triplettriplet annihilation (TTA) upconversion, we linked a diiodoBodipy triplet photosensitizing unit and perylene triplet energy acceptor/annihilation/emitter using a disulfide bond (dyad BP-1), which can be selectively cleaved by thiols. For comparison, a reference dyad featuring a shorter and more chemically robust 1,2,3-triazole linker between the two components was also prepared (dyad BP-2). The photophysical properties of these compounds have been studied using steady-state and time-resolved transient spectroscopies; forward singlet energy transfer and backward triplet energy transfer (ping-pong energy transfer) were observed. For BP-1, the rate for forward intramolecular Forster resonance energy transfer from perylene to diiodoBodipy is k(FRET) = 1.9 x 10(8) s(-1), while the backward triplettriplet energy-transfer (TTET) process from diiodoBodipy to perylene was slightly slower, with k(TTET) = 3.7 x 10(7) s(-1). For BP-2, faster energy-transfer kinetics were determined (k(FRET) = 3.1 x 10(8) s(-1) and k(TTET) = 8.4 x 10(7) s(-1), respectively). Interestingly, we found the FRET rate constant is more critically dependent on the length of the linker than the corresponding TTET process, which may have important implications for the design of supramolecular TTA architectures. Lastly, upon cleavage of the disulfide bond in BP-1, intramolecular FRET was effectively shut down, and instead intermolecular TTET was observed, allowing for thiol-activatable TTA upconversion with an improvement in upconversion quantum yield from 0.03% to 0.5% in the presence of thiols.