近赤外シアニン色素の構造-特性相関：高蛍光効率を持つカルコゲン駆動一重項酸素生成

We report the design, synthesis, and optical characterisations of eight novel near-infrared (NIR) cyanine dyes incorporating different chalcogens (O, S, and Se). These dyes exhibited excellent deep-NIR absorption (λ_max = 767-833 nm) and emission (λ_max = 784-859 nm) profiles. TDDFT calculations matched well the experimental trends and data. All compounds exhibited high extinction coefficients (178,000-267,000 cm^-1 M^-1) and good fluorescence quantum yields, resulting in high overall brightnesses. Remarkably, the selenium-containing dyes featuring terminal indole and benzoindole-type units exhibited impressive singlet oxygen quantum yields of around 13%, a standout performance in the deep-NIR region. These values are particularly promising and highlights the potential of these dyes for deep-NIR imaging and photodynamic applications.