# Structure–Property Relationships of Near-Infrared Cyanine Dyes: Chalcogen-Driven Singlet Oxygen Generation with High Fluorescence Efficiency

## TL;DR

Scientists designed new near-infrared dyes with high light absorption and efficient singlet oxygen generation, useful for imaging and therapy.

## Contribution

Novel cyanine dyes with chalcogens show high singlet oxygen generation and fluorescence in the deep-NIR range.

## Key findings

- Dyes showed deep-NIR absorption and emission with high extinction coefficients.
- Selenium-based dyes achieved 13% singlet oxygen quantum yield in the deep-NIR region.
- TDDFT calculations aligned with experimental data, confirming structural trends.

## Abstract

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 (λmax = 767–833 nm) and emission
(λmax = 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.