Construction of Charge Transfer Complexes for Highly Selective Detection and Ultraefficient Separation of Uranium.

Selective detection and efficient separation of uranium from lanthanides (Ln) is very important but currently remains a great challenge considering the chemical similarities between uranium and Ln. Herein, a charge transfer complex (CTC) (TPP-TCNQ CTC) was constructed by introducing triphenylphosphine (TPP) as the donor and 7,7,8,8-tetracyanoquinodimethane (TCNQ) as the receptor. The optical properties of TPP-TCNQ CTC, including absorption, fluorescence, and light scattering (LS), simultaneously exhibit distinct evolution upon the specific interaction with UO, facilitating its sensitive and selective detection with the limit of detection (LOD) down to 6.7 nM for the LS method. More importantly, TPP-TCNQ CTC can coordinate with UO to form coprecipitation in a wide pH range (1.0-9.0) with fast kinetics (1 min) and high specificity (, 3.48 × 10 mL g), achieving the efficient precipitation separation of UO (>90%) without complex procedures. The specific coprecipitation of UO over other Ln favors highly selective detection and ultraefficient separation of UO and endows the TPP-TCNQ CTC with great potential in rare earth tailings treatment. This work offers a new strategy for charge transfer complex (CTC) construction and a promising platform for the detection and separation of radioactive nuclides.