Quantifying and fine adjusting the solid-state fluorescence wavelength of 1-thienyl-2-arylethylene

Abstract

Thirty two 1-thienyl-2-arylethylene derivatives (XAEY) were synthesized and their solid-state fluorescence emission wavelengths Em (nm) were determined. The effects of substituents X and Y on the fluorescence wavelengths were analyzed in detail. The quantitative correlation analysis for the Em was carried out by employing the ground-state polarity parameters and excited-state parameters of the substituents X and Y. A quantitative equation was obtained and its reliability was verified by the leave-one-out (LOO) method. The obtained results show: (1) For the compounds XAEY, when the group Y on the aryl group is fixed, the Em order is 2′-methyl-2-thienyl-AEY > 3-thienyl-AEY > 2-thienyl-AEY; when thienyl (X) is fixed, the Em of XAEY with electron-withdrawing group Y is longer than that of XAEY with electron-donating group Y; (2) The Em of XAEY can be finely adjusted by changing groups X and Y. That is, one can obtain a series of compounds with continuous fluorescence emission wavelength in range of 450–600 nm via selecting different groups X or Y. (3) The 2′-methyl has an additional red shift effect on the Em of 2′- methyl-2-thienyl-AEY. The results of this paper can provide an important reference for studying theoretically solid-state fluorescence emission spectra of organic compounds and designing corresponding fluorescent material molecules.