Effect of meso-substituent and solvent nature on spectral properties, pH-stability and affinity to blood transport proteins of BODIPY dyes

The paper is focused on a comparative analysis of the structural and solvation factors on the spectral properties, pH-stability and lipophilicity of BODIPY biomarkers containing in meso-position methyl group, carboxylic acid residues and their esters. The affinity of meso-BODIPYs to blood transport proteins was studied. Dyes intensely absorb (e -45000-90000) and fluoresce (to u -100 %) in the range of 493- 504 and 508-520 nm, respectively. meso-substitution causes a hypsochromic shift (by -4-11 nm) of the maximum of the intense absorption band and a noticeable increase of the Stokes shift (up to -1.7-2.6 times) of BODIPYs compared to the meso-unsubstituted analog. It has been shown that the introduction of a carboxyl group into the BODIPY meso-position significantly (by a factor of -2) increases the hydrophilicity of the compounds, and the presence of ester groups in the structure leads to an increase of the hydrophobicity of the luminophores by a factor of -1.3 compared to the meso-unsubstituted dye. It has been demonstrated that compounds are stable in a wide pH range and exhibit intense fluores-cence (to u -80 %), while carboxyl BODIPYs can be considered as pH sensors for alkaline media. Introducing carboxylic acid residues and their esters into the meso-position of BODIPY is an excellent way to increase affinity dyes to biostructures, including blood transport proteins.(c) 2022 Elsevier B.V. All rights reserved.