This paper presents the results of spectral-luminescence research of binuclear zinc(II) helicates with deca-, octa-, and tetramethylsubstituted 3,3'-bis(dipyrromethene)s ([Zn2L2]) in binary mixtures of cyclohexane with m-, o- and p-xylene. Structure effects of [Zn2L2], and aromaticity criteria of analyzes (HOMA, NICS, mu) on the fluorescence quenching efficiency of [Zn2L2] in the presence of xylenes was considered. It was found that decamethyl substituted 3,3'-bis(dipyrromethenate)s compared to octa-, and tetramethylsubstituted-analogs shows the highest fluorescence sensitivity to the presence of aromatic compounds. Quantum-chemical modeling showed that [Zn2L2] fluorescence quenching in the xylenes presence is caused by the formation of [Zn(2)L(2)A(n)] (n = 1 or 2) supramolecular structures. High specificity of spectral-luminescent characteristics changing in the presence of xylenes provides the possibility of using [Zn2L2] helicates as new fluorescent sensors for trace amounts (6.5-99 ppm) detection of methylbenzenes in organic media.
