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 360/435 nm) of the Si-CQDs. Simultaneously, intense green fluorescence (with a emission peak at 513 nm) appears, probably due to the formation of n-π 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 0.077 μM detection limit. The analytical range extends from 1 to 40 μM. Graphical abstract Schematic of a silicon-doped carbon quantum dot-based ratiometric fluorescence probe with blue and green emission for the visual and fluorometric determination of hydroquinone.