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

Journal article

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.

Authors: Yang, S; Forsyth, E; Lin, W; Setchfield, K; Crespo-Otero, R

• Publication status: Published
• Peer review status: Peer reviewed
• Publisher: American Chemical Society
• Journal: ACS Omega
• Volume: 11
• Issue: 3
• Pages: 4475-4484
• Publication date: 2026-01-12
• Acceptance date: 2026-01-05
• DOI: 10.1021/acsomega.5c10499
• EISSN: 2470-1343
• ISSN: 2470-1343
• Language: English
• Keywords: Singlet oxygen; Cyanine; Fluorescence; Oxygen; Energy conversion efficiency