One-pot synthesis of nanoscale carbon dots-embedded metal-organic frameworks at room temperature for enhanced chemical sensing

Metal-organic frameworks (MOFs) with their unique features have attracted considerable attention as promising candidates for diversified applications. The integration of MOFs and other materials not only leads to further enhancement of single-phase MOFs in mechanical and electrical property, but also surprisingly brings out a number of new functionalities; therefore, increasing research interest has been aroused in this area, and a variety of composites, including MOF-porous carbon, MOF-carbon nanotube, MOF-graphite or graphene oxide, and MOF-carbon fiber, have been developed. In this study, we report a highly luminescent carbon dots-embedded metal-organic framework (CDs@MOF) material. The CDs@MOF composite was synthesized via a facile one-pot route by introducing carbon dots (CDs) with a high quantum yield into a zeolitic imidazolate framework-8 (ZIF-8) growth medium, which permitted the incorporation of CDs directly into the framework during the reaction. Herein, ZIF-8 was treated as absorbents to selectively capture and enrich the target analyte, and CDs were employed as a tentacle to selectively and sensitively sense the bonding interactions between ZIF-8 and target molecules and further transduce these chemical events to detectable fluorescence signals. Therefore, the resulting CDs@ZIF-8 exhibited excellent fluorescence selectivity and sensitivity toward quercetin (QCT) derived from the incorporated highly fluorescent CDs and showed enrichment for QCT that originated from the well-defined microporous MOFs component, which further increased the fluorescence sensitivity. Moreover, QCT could be detected in a wide concentration range of 0.01-50.0 mu M with a low LOD of 3.5 nM.