Excellent quantum yield enhancement in luminescent metal-organic layer for sensitive detection of antibiotics in aqueous medium

Luminescent metal-organic layers (LMOLs) that can effectively improve fluorescence quantum yield and sensing performance are rarely reported. Herein, a novel tetracarboxyl-substituted tetraphenylethene (TPE) ligand 1,1,2,2-tetrakis[(3-carboxyphenyl)phenyl]ethylene (H4T3CPPE) with significant aggregation-induced emission (AIE) effect was synthesized. A 2D luminescent cage-based metal-organic framework [Zn2(T3CPPE)(H2O)2] (complex 1) was prepared by the reaction of H4T3CPPE with zinc salt, and then highly luminescent TPE-based LMOL 1 was obtained from complex 1 by ultrasonication-induced exfoliation method, which was used to detect nitrofuran antibiotics (NFT and NFZ) in aqueous solution selectively and sensitively. Compared to bulk luminescent metal-organic framework complex 1, the LMOL 1 delaminated in isopropanol has an fluorescence quantum yield enhancement, reaching 99% in LMOL 1 from 62.9% in complex 1 and exhibits higher fluorescence quenching effect towards nitrofuran antibiotics with lower limit of detections (LODs). Compared with other antibiotics, at a fluorescent titration concentration of 50.5 μM, nitrofuranone and nitrofurantoin can quench the fluorescence of LMOL 1 more effectively with the quenching efficiency of 84.9% and 87.7%, respectively, indicating it can function as an excellent luminescence sensor to detect these antibiotics.