Near-IR BODIPY Dyes à la Carte - Programmed Orthogonal Functionalization of Rationally Designed Building Blocks

Abstract

Herein, we report the synthesis of polyfunctional BODIPY building blocks suitable to be subjected to several reaction sequences with complete chemoselectivity, thereby allowing the preparation of complex BODIPY derivatives in a versatile and programmable manner. The reactions included the Liebeskind-Srogl cross-coupling reaction (LSCC), nucleophilic aromatic substitution (SAr), Suzuki, Sonogashira, and Stille couplings, and a desulfitative reduction of the MeS group. This novel synthetic protocol is a powerful route to design a library of compounds with tailored photophysical properties for advanced applications. In this context, it is noteworthy that it offers a straightforward and cost-effective strategy to shift the BODIPY emission deep into the near-infrared spectral region while retaining high fluorescence quantum yields as well as highly efficient and stable laser action. These new dyes outperform the lasing behaviour of dyes considered as benchmarks over the red spectral region, overcoming the important drawbacks associated with these commercial laser dyes, namely low absorption at the standard pump wavelengths (355 and 532 nm) and/or poor photostability. Versatile functionalization of the BODIPY core: The borondipyrromethene (BODIPY) system has been derivatized in a versatile manner through a strategy based on orthogonal reactivity (see figure). This has allowed access to some red/NIR-emitting dyes with superior properties to current commercial laser dyes.