A new three-dimensional zinc-based metal-organic framework as a fluorescent sensor for detection of cadmium ion and nitrobenzene

In this study, a novel three-dimensional zinc-based metal-organic framework (Zn-MOF), i.e., {Zn-2(L)(2)(DMF)(2)H2O}(n) (L = 2,5-bis(phenylamino)-1,4-benzenedicarboxylic acid) was designed and developed under solvothermal condition. As a proof-of-principle, a pi-conjugated framework of carboxylate ligand capable of "bottom up" synthesis was integrated with metal ion to construct a novel MOF for sensing applications. As expected, the synthesized Zn-MOF exhibited fluorescence enhancement for cadmium ion (Cd2+) and sensing of nitrobenzene (NB) through fluorescence quenching. The detection limits were calculated to be 0.12 mu M for Cd2+ and 1.19 mu g mL(-1) for NB based on signal-to-noise ratio of 3:1. Moreover, various techniques and density functional theory investigations verified that the possible sensing mechanisms for Cd2+ and NB included ion exchange and photoinduced electron transfer, respectively. Finally, their practical applications on real samples also demonstrated that the Zn-MOF-based sensor can be effectively utilized for detection and imaging of Cd2+ present in the real water samples and living cells. This study may inspire future research and design of target fluorescent MOFs with specific functions. (C) 2017 Elsevier Inc. All rights reserved.