Data from: Fluorescence and photophysical properties of xylene isomers in water: with experimental and theoretical approaches

A thorough analysis of the photophysical properties involved in electronic transitions in excitation-emission spectra of xylene isomers have been carried out using the TD-DFT (PBEPBE/6-31+G(d,p)) method. For the first time the structural and spectroscopic investigation to distinguish isomers of xylene, a widespread priority pollutant were conducted experimentally and theoretically. The fluorescence properties of xylene isomers (sole and mixture (binary and ternary)) in water were studied. The fluorescence peak intensities of xylenes were linearly correlated to concentration, by order p-xylene>o-xylene>m-xylene at excitation/emission wavelength (ex/em) of 260nm/285nm for o-, m-xylene and ex/em 265nm/290nm for p-xylene at same concentration. The theoretical excitation/emission wavelengths were at ex/em 247nm/267nm, 248nm/269nm and 251nm/307nm for o-, m- and p-xylene respectively. The vertical excitation and emission state energies of p-xylene (ex/em 4.94eV/4.03 eV) were lower and internal conversion energy difference (0.90 eV) was higher than m-xylene (ex/em 5.00eV/4.60eV ) (0.4eV) and o-xylene (ex/em 5.02eV/4.64eV) (0.377eV). The order of theoretical emission and oscillator strength (f) (0.0187>0.0175> 0.0339) p-xylene>o-xylene>m-xylene was observed in agreement with the experimental fluorescence intensities. These findings provide a novel fast method to distinguish isomers based on its photophysical properties.