Soluble and Stable Near-Infrared Dyes Based on Polycyclic Aromatics

Currently, how to obtain near-infrared (NIR) dyes is intriguing and attractive but full of challenges. Although some cyanine dyes have been commercialized, near infrared dyes with intensive NIR absorption and/or emission, good chemical and photo-stability, and high solubility still remain as challenging targets. Certain polycyclic aromatic compounds such as rylenes, porphyrins, and phthalocyanines represent a key class of near-infrared dyes and also give rise to outstanding physical and chemical properties after appropriate chemical modification. This review highlights and updates the principal synthetic strategies used to obtain polycyclic aromatics-based soluble and stable near-infrared dyes. We will also summarize the physical properties of these newly developed NIR dyes, including absorption, emission, quantum yield, solubility and stability.