Recent advances of NIR dyes of pyrrolopyrrole cyanine and pyrrolopyrrole aza-BODIPY: Synthesis and application

Organic dyes with intense absorption and emission in the near-infrared (NIR) region have received more and more attention due to their wide applications. Two promising NIR chromophores, pyrrolopyrrole cyanine (PPCy) and pyrrolopyrrole aza-BODIPY (PPAB), possess outstanding features such as strong NIR absorption bands with high extinction coefficients, high fluorescence quantum yields in the NIR region, high thermal and photochemical stability. In this review, we outline the latest achievements in the molecular guidelines and photophysical process control for developing efficient PPCy and PPAB dyes. Their design principle, chemical structures and synthesis routes (symmetric and asymmetric dyes, water-soluble dyes, aggregation-induced emission (AIE)active dyes, and dimer) are highlighted. The potential practical applications including organic optoelectronics, fluorescence bioimaging, amine detection, photodynamic therapy (PDT), photothermal therapy (PTT), photo-acoustic imaging (PAI) are reviewed. The outlook, challenges and future opportunities for the development of PPCy and PPAB are also presented. We believe that this review will give a future perspective for PPCy and PPAB-based NIR dyes, allowing facile synthesis, great structural diversity and multi-functional applications.

Automated summary

Organic dyes with strong absorption and emission in the near-infrared region have attracted increasing attention. Promising NIR chromophores, PPCy and PPAB, possess outstanding characteristics such as high extinction coefficients, fluorescence quantum yields, and stability. By molecular design and photophysical control, efficient PPCy and PPAB dyes can be developed for various practical applications.