Covalent organic framework as fluorescent turn-on/off sensor and an account of operating sensing mechanism

Covalent organic frameworks (COFs) are one of the most sought after field due to their wide range of applications. Application of these highly crystalline materials in fluorescent sensing of diverse analytes is gaining great attention due to selective, sensitive detection, operational simplicity and real time assay. There are some recently published reviews which covered sensing applications of COF having numerous examples like colorimetric, fluorometric, electrochemical sensing. But due to the overwhelming interests of fluorescent sensing of COF-analyte systems, it has become highly wanting to have a compact account of fluorescent COF sensors and the underlying mechanistic interpretation. Some recent reviews were published covering the mentioned issues but no review is there focusing only on the fluorescent COFs and their sensing behavior as well as mechanism. Hence, in this review application of COFs in fluorescent sensors is emphasized along with the discussion of mechanism of action, major challenges limitations with probable strategies for improvement.