Circularly polarized luminescence (CPL) in simple (small, nonaggregated, nonpolymeric) O-BODIPYs (R)-1 and (S)-1 by irradiation with visible light is first detected as proof of the ability of a new structural design to achieve CPL from inherently achiral monochromophore systems in simple organic molecules. The measured level of CPL (|glum|) in solution falls into the usual range of that obtained from other simple organic molecules (10–5–10–2 range), but the latter having more complex architectures since axially chiral chromophores or multichromophore systems are usually required. The new design is based on chirally perturbing the acting achiral chromophore by orthogonally tethering a single axially chiral 1,1′-binaphtyl moiety to it. The latter does not participate as a chromophore in the light-absorption/emission phenomenon. This simple design opens up new perspectives for the future development of new small-sized CPL organic dyes (e.g., those based on other highly luminescent achiral chromophores and/or chirally perturbing moieties), as well as for the improvement of the CPL properties of the organic molecules spanning their use in photonic applications.
20 February 2020 in Photochemistry and Photobiology
This minireview is devoted to honoring the memory of Dr. Thomas Dougherty, a pioneer of modern photodynamic therapy (PDT). It compiles the most important inputs made by our research group since 2012 in the development of new photosensitizers based on BODIPY chromophore which, thanks to the rich BODIPY chemistry, allows a finely tuned design of the photophysical properties of this family of dyes to serve as efficient photosensitizers for the generation of singlet oxygen. These two factors, photophysical tuning and workable chemistry, have turned BODIPY chromophore as one of the most promising dyes for the development of improved photosensitizers for PDT. In this line, this minireview is mainly related to the establishment of chemical methods and structural designs for enabling efficient singlet oxygen generation in BODIPYs. The approaches include the incorporation of heavy atoms, such as halogens (iodine or bromine) in different number and positions on the BODIPY scaffold, and also transition metal atoms, by their complexation with Ir(III) center, for instance. On the other hand, low‐toxicity approaches, without involving heavy metals, have been developed by preparing several orthogonal BODIPY dimers with different substitution patterns. The advantages and drawbacks of all these diverse molecular designs based on BODIPY structural framework are described.