Silicon-doped carbon quantum dots with blue and green emission are a viable ratiometric fluorescent probe for hydroquinone

Silicon-doped carbon quantum dots (Si-CQDs) were employed to fabricate a ratiometric fluorometric probe that shows high selectivity for hydroquinone (HQ). The Si-CQDs were prepared through hydrothermal treatment of N-[3-(trimethoxysilyl)propyl]-ethylenediamine. If HQ is oxidized in a solution of the Si-CQDs, 1,4-benzoquinone will be formed which quenches the blue fluorescence (with excitation/emission peaks at 360/435nm) of the Si-CQDs. Simultaneously, intense green fluorescence (with a emission peak at 513nm) appears, probably due to the formation of n- clathrates or of a quinone imine between 1,4-benzoquinone and amino groups on the surface of the Si-CQDs. The ratio of the green and blue fluorescence can be applied to the determination of HQ with a 0.077M detection limit. The analytical range extends from 1 to 40M.