Multifunctional cobalt metal–organic framework luminescent probe for the efficient sensing of Cr2O72−, MnO4− and nucleobases

Abstract

Metal–organic frameworks have been studied extensively due to their varied functionality and properties in sensing, catalysis, adsorption, etc. Herein, we report the “turn-off” fluorescence detection of oxo-anions as well as nucleobases using a Co-based MOF. The sensing of toxic anions such as Cr₂O₇²⁻ and MnO₄⁻ has become of the utmost importance due to their adverse effect on the environment as well as on human health. In addition, the molecular recognition of purine and pyrimidine nucleobases is related their significance for genetic and epigenetic control. An imbalance/change in the bases will hamper the stability of DNA and RNA along with other biological functions. Therefore, their detection is also of great importance for biological science as well as clinical diagnostics. We report a multi-responsive probe, i.e., Co-MOF, that shows excellent stability in water and can detect MnO₄⁻ and Cr₂O₇²⁻ oxo-anions in aqueous media at concentrations as low as 9.5 × 10⁻⁷ M and 2.6 × 10⁻⁶ M, respectively. For the detection of nucleobases, it can sense and quantify up to 0.0969 μM cytosine, 3.1 μM adenine, 3.5 μM guanine, 3.0 μM thymine and 3.0 μM uracil. The underlying sensing mechanism is also discussed through Stern–Volmer plots, spectral overlap studies and time-resolved fluorescence studies.