Differential Fluorescent Chemosensing of Antibiotics Using a Luminescent Zn(II) Coordination Polymer Based on a 4-Amino-1,8-naphthalimide Tr?ger's Base Fluorophore

The design and development of useful chemosensors for the ultra-trace detection of environmental pollutants and contaminants is a topical area of research. Herein, we report a new nanoscale emissive Zn(II) coordination polymer (TB-Zn-CP) for differential fluorescence sensing of various antibiotics in water. TB-Zn-CP was synthesized using a unique V-shaped green emitting 4-amino-1,8-naphthalimide Troger's base (TBNap) fluorophore. The structural and morphological features of TB-Zn-CP were characterized by various standard spectroscopic and microscopy techniques. The fluorescence titration studies in water demonstrated a remarkable sensitivity and differential fluorescence sensing properties of TB-Zn-CP for the fast detection of different antibiotics. Among different antibiotics, chloramphenicol (CRP), 1,2-dimethyl-5-nitroimidazole (DMZ), and sulfamethazine (SMZ) displayed the highest fluorescence-quenching efficiency and superior sensitivity in their detection. The differential sensing capability of TB-Zn-CP was also indicated by visualizable color changes. The Stern-Volmer quenching constant KSV was determined to be in the order of 103-104 M-1, and the sensitivity was shown to be at a nanomolar (10-9 M) level. All these results confirm that TB-Zn-CP can be a potential and practically useful polymeric sensor for differential fluorescence and visual detection of different antibiotics in water.