Influence of Solvation and Structural Contributions on Fluorescence of Dipyrrine Dyes

«Оn-off» fluorescent sensors for aromatic analytes based on zinc(II) bis(dipyrromethenate)s

This paper presents the results of spectral-luminescence research of binuclear zinc(II) helicates with tetra-, octa-, and decamethylsubstituted 3,3'-bis(dipyrromethene)s ([Zn₂L₂]) in binary mixtures of cyclohexane with aromatic hydrocarbons (benzene, toluene, and m-xylene). Structure effects of zinc(II) helicates, and aromaticity criteria of analytes (HOMA, NICS, δ) on the fluorescence quenching efficiency of [Zn₂L₂] in the presence of aromatic compounds was considered. It was found that decamethylsubstituted 3,3'-bis(dipyrromethenate)s compared to tetra-, and octamethylsubstituted-analogs shows the highest fluorescence sensitivity to the presence of aromatic compounds. High specificity of spectral-luminescence characteristics changing in the presence of particular aromatic analytes provides the possibility of using [Zn₂L₂] helicates as new fluorescent sensors of aromatic compounds trace amount (120ppb to 56ppm) in organic media.