Bis-Metal Complexes of Doubly N‑Confused Dioxohexaphyrins as Potential Near-Infrared-II Photoacoustic Dyes
We investigated the detailed photophysical properties of a series of bis-metal (Zn and Cu) dioxohexaphyrin complexes as potential second near-infrared (NIR-II)-light responsive dyes. A cisoid-configured 28π-electron-conjugated dioxohexaphyrin analogue ( c -3a) containing two peculiar “confused pyrro...
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Published in | Journal of the American Chemical Society Vol. 142; no. 9; pp. 4429 - 4437 |
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Main Authors | , , , , , , , , , , , |
Format | Journal Article |
Language | English |
Published |
WASHINGTON
American Chemical Society
04.03.2020
Amer Chemical Soc |
Subjects | |
Online Access | Get full text |
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Summary: | We investigated the detailed photophysical properties of a series of bis-metal (Zn and Cu) dioxohexaphyrin complexes as potential second near-infrared (NIR-II)-light responsive dyes. A cisoid-configured 28π-electron-conjugated dioxohexaphyrin analogue ( c -3a) containing two peculiar “confused pyrrole” moieties in the framework is identified as a reduced isomer derivative of a transoid 26π-dioxohexaphyrin ( t -2a). The symmetry-altered structure of c -3a affords a heteroleptic inner environment within the NNNN/NNOO donor core, which imparts its highly flexible electronic features and nonplanar geometry. The macrocycle c -3a can be transformed into the corresponding 26π-electron congener ( c -2a) having a coplanar rectangular structure by unique solvent-mediated redox reactivity. Furthermore, upon metal complexation, saddle-distorted bis-metal complexes ( c- M 2 -2a) were formed as the 26π-conjugated structural isomer of the trans-dioxohexaphyrin species (i.e., t -M 2 -2a). These isoelectronic dioxohexaphyrins demonstrate precise geometry-dependent photophysical properties. Broad tailing NIR-II absorption, weak emissive character, and rapid-decay of the S1 state are observed for c -Zn 2 -2a. In contrast, the coplanar t -M 2 -2a exhibits efficient photoacoustic response upon laser excitation with NIR-II light (λ > 1000 nm). To the best of our knowledge, this is the first example of an expanded porphyrin-based photoacoustic contrast agent responsive to NIR-II light. |
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Bibliography: | ObjectType-Article-1 SourceType-Scholarly Journals-1 ObjectType-Feature-2 content type line 23 |
ISSN: | 0002-7863 1520-5126 |
DOI: | 10.1021/jacs.9b13475 |