Abstracts

The development of new fluorescent compounds has been attracting the attention of researchers due to various possibilities of application including cellular biomarkers, fluorescent sensors for analytes of environmental or biological interest, or even in the construction of OLEDs. In this context, BODIPY appears as a class of compounds that, in general, presents excellent properties such as large extinction coefficients, high fluorescence quantum yield, and narrow emission and absorption bands. The insertion of chalcogenated groups into a chromophoric core causes a quenching on the compound's fluorescence, being a strategy that allows these compounds to be used as fluorescence sensors in a turn-on fluorescence process.In this work, we present a combination of our latest results on the synthesis and application of new Se-BODIPYs as fluorescent sensors showing the versatility of the new obtained compounds. The general synthetic route to obtain the new BODIPYs is composed by 3 formal steps, consisting of an alkylation of the hydroxyl group of 4-hydroxibenzaldehyde, followed by reaction with pyrrole, and then the N-assisted complexation with boron, introducing the BF₂ fragment. The selenium post-functionalization of the fluorescent core was conducted in two ways. The first strategy consisted of a bromination step, giving rise to a tetrabrominated compound followed by a selenilation step, using PhSeH, generated in situ, from Ph₂Se₂ and NaBH₄. This method allowed to obtain BODIPYs containing 2 “Br” and 2 “SePh” groups directly connected to the chromophoric core in the final structure. The second strategy was conducted through the selenylation reaction of the BODIPY core, without previous halogenation, using Ph₂Se₂, benzoyl peroxide, and p-toluenesulfonic acid. This method allowed to obtain BODIPYs containing four “SePh” groups in the final structure. A screening with different analytes, including amino acids, biothiols, anions, reactive sulfur species, and some oxidants was conducted by absorption and emission spectra. Four main different applications for the new chalcogenated compounds as fluorescent probes were studied. 1) Se-BODIPY as a fluorescent sensor for selective detection, quantification, and distinction of biothiols (including cysteine (Cys) and glutathione (GSH)), resulting in low detection limits, fast response time, and high fluorescence quantum yield for the products. Cell bioimaging using HeLa cells was also conducted. 2) Se-BODIPY as fluorescent sensor to distinguish Cys/Hcy from GSH using different excitation wavelengths. Kinetic study was conducted allowing to differentiate Cys from Hcy. The sensor was also applied to the quantification of these analytes in urine samples, obtaining good recovery values. Tests using discs of paper were also carried-out, making possible visualization of color variation, without organic solvent. 3) Se-BODIPY as a fluorescent sensor for selective detection of CN^-, OH^- and F^- by fluorescence. 4) BODIPY-doped polymer films and particles were obtained, using PMMA and TPU, for fluorometric detection of NH₄OH and thermometric applications.