NIR-to-NIR two-photon bio-imaging using very bright tailored amino-heptamethines dyes

Amino-heptamethines are highly conjugated cationic dyes featuring electronic absorption in the red region and strong near-infrared (NIR) fluorescence. Unlike their parent chloro-heptamethine cyanines, substitution of central position polymethine skeleton with an amine confers them a high Stokes shift. This work reports synthesis amino-heptamethines investigation optical properties, including two-photon NIR short-wave infrared (SWIR) ranges, which has been overlooked for such chromophores so far. Their structures were tailored, introducing selected substitutuents on indolenine moieties to modulate hydrophobic/hydrophilic balance investigate potential as NIR-to-NIR probes bio-imaging living cells.