Premium
Rational Design of Cyclometalated Iridium(III) Complexes for Three‐Photon Phosphorescence Bioimaging
Author(s) -
Jin Chengzhi,
Liang Fengyin,
Wang Jinquan,
Wang Lili,
Liu Jiangping,
Liao Xinxing,
Rees Thomas W.,
Yuan Bo,
Wang Hui,
Shen Yong,
Pei Zhong,
Ji Liangnian,
Chao Hui
Publication year - 2020
Publication title -
angewandte chemie
Language(s) - English
Resource type - Journals
eISSN - 1521-3757
pISSN - 0044-8249
DOI - 10.1002/ange.202006964
Subject(s) - phosphorescence , iridium , fluorescence , microscopy , two photon excitation microscopy , fluorescence lifetime imaging microscopy , penetration depth , materials science , photon , fluorescence microscope , confocal microscopy , rational design , absorption (acoustics) , excitation , biophysics , chemistry , photochemistry , optics , nanotechnology , physics , catalysis , biochemistry , quantum mechanics , composite material , biology
Compared to 2PE (two‐photon excitation) microscopy, 3PE microscopy has superior spatial resolution, deeper tissue penetration, and less defocused interference. The design of suitable agents with a large Stokes shift, good three‐photon absorption (3PA), subcellular targeting, and fluorescence lifetime imaging (FLIM) properties, is challenging. Now, two Ir III complexes (3PAIr1 and 3PAIr2) were developed as efficient three‐photon phosphorescence (3PP) agents. Calculations reveal that the introduction of a new group to the molecular scaffold confers a quadruple promotion in three‐photon transition probability. Confocal and lifetime imaging of mitochondria using Ir III complexes as 3PP agents is shown. The complexes exhibit low working concentration (50 n m ), fast uptake (5 min), and low threshold for three‐photon excitation power (0.5 mW at 980 nm). The impressive tissue penetration depth (ca. 450 μm) allowed the 3D imaging and reconstruction of brain vasculature from a living specimen.