Boron and nitrogen codoped carbon dots as fluorescence sensor for Fe with improved selectivity.

Carbon dots (CDs) are popular as fluorescence sensors, and metal ions are typical analytes. However, CDs used as fluorescent sensors for Fe have some interferences coming from co-existed ions. In this study, we suspect that sp boron atom in phenylboronic acid group will be more compatible with Fe to form coordination bonds, thereby increasing the selectivity to Fe. Hence, we designed and synthesized boron and nitrogen codoped carbon dots (BN-CDs) for detection of Fe via a hydrothermal method using o-phenylenediamine (OPA) and 4-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)benzylchloroformate as precursors. From the results, we found that BN-CDs had superior selectivity to Fe in the presence of the other common interfering metal ions like Cu, Fe and Pb. Besides, the obtained BN-CDs exhibited good water solubility, favorable photostability, excellent pH stability between pH 2-11, and strong fluorescence intensity with quantum yield up to 31.5 %. These excellent properties of carbon dots validate that our idea is feasible, and can be used for design CDs for Fe detection. Quenching mechanism study showed the fluorescence intensity of BN-CDs could be dramatically quenched by Fe through dynamic and static synergy process. Finally, the as prepared BN-CDs were successfully applied to the determination of Fe in fetal bovine serum and lake water.