Boronic BODIPY-derived

Fluorescence imaging is the most powerful technique currently available for continuous observation of the dynamic intracellular processes of living cells. Fluorescein is widely employed as the core of various fluorescence probes used in imaging important biological effectors. Despite the extensive use of fluorescein derivatives and the importance of the applications, the mechanism that controls the quantum yield of fluorescence has not been fully established. I report herein photoinduced electron transfer (PeT) mechanism that can control the fluorescence quantum yields of fluorescein and boron dipyrromethene (BODIPY) derivatives. 

BODIPY has a rigid structure, which can be formed by boron insertion with BF3 OEt2 into a dipyrromethene unit. Generally, the synthesis of BODIPY derivatives starts from the dipyrromethene precursor. It is relatively easy to construct the precursor using the well-known pyrrole condensation reaction. There are two common synthetic strategies, especially for symmetric and unsymmetric BODIPY cores, respeetively. 

Boron-dipyrromethene (BODIPY) derivatives have attracted attention as fluorescent stable dyes bearing sharp absorption bands with high molar extinction values and emission bands... 

As we will see, the choice of electron donors associated with porphyrins has not evolved much over the years. In previous review articles, electron donors such as carotenes, aryl amines, and ferrocene derivatives have been examined. Concerning the class of energy donors, over the past decade, boron dipyrylmethanes (BODIPY) are probably the most widely used series of compounds. A very detailed study of their association and their excitation energy transfer to porphyrins has been carried out by LindseyIt should be noted that condensed aromatics such as anthracene, and especially perylene derivatives, may be good substitutes for BODIPYs. 

Let us consider an example. Time-resolved methods allow a detailed description of excited state and of their useful properties, e.g., as sensitizers. A popular class of oxygen sensitizers is that of boron dipyrromethene (9, BODIPY) and their derivatives, e.g., the diiodo derivative 10 in Scheme 6.4, in view of applications such as photodynamic therapy [24]. 

Figure 8 View of a Zn(II)-based MOF that combines a tetracarboxylate-derived porphyrin with a bis-pyridyl substituted BODIPY (difluoro-boron-dipyrromethene) ligand. (Reprinted with permission from Ref 41. Copyright (2011) American Chemical Society.)...

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