An ultra-stable Cd coordination polymer based on double-chelated ligand for efficient dual-response of TNP and MnO4-

Abstract

Exploiting an efficient method to detect nitro-aromatic compounds and anion contaminants remains pressing. Coordination polymers (CPs) are great potential luminescence materials for sensing applications, where π-π interaction is useful for improving sensing performance. A bright luminescent Cd-CP {[Cd2(μ2-OAc)2(L)(bdc)]·L·2H2O}n (1) was prepared by utilizing large planar double-chelated ligand tetrapyrido[3,2-a:2′,3′-c:3″,2″-h:2‴,3‴-j]phenazine (L). Its structure contains [Cd2(μ2-OAc)2] units and two double chelated linkers, and presents a 2D 4-connected sql net. These 2D sql networks are accumulated into a unique 3D supramolecular framework through strong intralayer and interlayer π-π interactions. 1 features excellent water, thermal and pH stabilities. The ultra-stable framework exhibits highly selective and sensitive detection of TNP in DMF with fast response time (15 s), high quenching efficiency Ksv (1.16×105 M−1) and low LOD (0.091 ppm). More importantly, the dosage of 1 in detecting TNP is only 0.02 mg/mL, which represents the lowest dosage in TNP sensors. Meanwhile, 1 can rapidly and sensitively recognize TNP and MnO4- in aqueous system with low LOD (0.046 ppm for TNP, 0.028 ppm for MnO4-). Moreover, this dual-response luminescence sensor exhibits good recyclability. The quenching mechanisms have been discussed in detail. This work will contribute to develop economical and efficient luminescence sensors.