In this work, coumarin derivatives (C) are used to enhance the fluorescence of graphene quantum dots (GQDs) by covalently linking the carboxyl groups on the edge of the GQD sheet. The as-synthesized coumarin-modified graphene quantum dots (C-GQDs) have a uniform particle size with an average diameter of 3.6 nm. Simultaneously, the C-GQDs have strong fluorescence emission, excellent photostability, and high fluorescence quantum yield. C-GQDs and CN– can form a C-GQDs+CN– system due to deprotonation and/or intermolecular interactions. The introduced hydroquinone (HQ) is oxidized to benzoquinone (BQ), and the interaction between BQ and the C-GQDs+CN– system could lead to fluorescence enhancement of C-GQDs. Meanwhile, the redox reaction between BQ and ascorbic acid (AA) can be used for quantitative detection of AA with CN– and HQ being used as substrates. Based on the above mechanism, C-GQDs are developed as a multicomponent detection and sensing platform, and the detection limits for CN–, HQ, and AA were 4.7, 2.2, and 2.2 nM, respectively. More importantly, satisfactory results were obtained when the platform was used to detect CN–, HQ, and AA in living cells and fresh fruits.

Color-tunable and white light-emitting lanthanide-based complex/coordination polymer materials have attracted increasing interest recently due to the exceptional luminescent and chromogenic properties. Recent advances from 2014 to 2018 on white-light-emitting lanthanide-based materials are classifiedly highlighted in light of different aggregate states and lanthanide species in the coordination assemblies. The future advances in this field are also predicted.

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