The shortwave infrared (SWIR) spectral region beyond
1200 nm offers
optimal tissue penetration depth and has broad potential in diagnosis,
therapy, and surgery. Here, we devised a novel class of fluorochromic
scaffold, i.e., a tetra-benzannulated xanthenoid (EC7). EC7 absorbs/emits maximally at 1204/1290 nm in CH2Cl2 and exhibits an unparalleled molar absorptivity
of 3.91 × 105 cm–1 M–1 and high transparency to light at 400–900 nm. It also exhibited
high resistance toward both photobleaching and symmetry breaking due
to its unique structural rigidity. It is feasible for in vivo bioimaging
and particularly suitable to couple with the shorter-wavelength analogues
for high-contrast multiplexing. High-contrast dual-channel intraoperative
imaging of the hepatobiliary system and three-channel in vivo imaging
of the intestine, the stomach, and the vasculature were showcased. EC7 is a benchmark fluorochrome for facile biomedical exploitation
of the SWIR region beyond 1200 nm.