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Elucidation of the Intersystem Crossing Mechanism in a Helical BODIPY for Low‐Dose Photodynamic Therapy
Author(s) -
Wang Zhijia,
Huang Ling,
Yan Yuxin,
ElZohry Ahmed M.,
Toffoletti Antonio,
Zhao Jianzhang,
Barbon Antonio,
Dick Bernhard,
Mohammed Omar F.,
Han Gang
Publication year - 2020
Publication title -
angewandte chemie international edition
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 5.831
H-Index - 550
eISSN - 1521-3773
pISSN - 1433-7851
DOI - 10.1002/anie.202005269
Subject(s) - intersystem crossing , bodipy , photochemistry , photosensitizer , helicene , photodynamic therapy , triplet state , chemistry , quantum yield , excited state , molecule , fluorescence , singlet state , physics , atomic physics , organic chemistry , quantum mechanics
Abstract Intersystem crossing (ISC) of triplet photosensitizers is a vital process for fundamental photochemistry and photodynamic therapy (PDT). Herein, we report the co‐existence of efficient ISC and long triplet excited lifetime in a heavy atom‐free bodipy helicene molecule. Via theoretical computation and time‐resolved EPR spectroscopy, we confirmed that the ISC of the bodipy results from its twisted molecular structure and reduced symmetry. The twisted bodipy shows intense long wavelength absorption ( ϵ =1.76×10 5 m −1 cm −1 at 630 nm), satisfactory triplet quantum yield (Φ T =52 %), and long‐lived triplet state ( τ T =492 μs), leading to unprecedented performance as a triplet photosensitizer for PDT. Moreover, nanoparticles constructed with such helical bodipy show efficient PDT‐mediated antitumor immunity amplification with an ultra‐low dose (0.25 μg kg −1 ), which is several hundred times lower than that of the existing PDT reagents.