Two 3d-4f metal-organic frameworks as fluorescent sensor array for the discrimination of phosphates based on different response patterns

Both organic and inorganic phosphates play important roles in biological activities. Considering the conventional methods are not very useful for identifying them from their analogues, the sensor array strategy has emerged in recent years, which is able to distinguish chemical species with similar structure or chemical properties. We propose a fluorescence sensor array based on two 3d-4f metal-organic frameworks (MOFs) by recording their direct one-step fluorescence changes with the addition of various phosphates. With the introduction of d-metal ions in the sensor unit synthesis process, two 3d-4f MOFs display higher sensitivity and noticeable fluorescence differences to five phosphates than the homometallic MOFs. Phosphates show diverse affinities to sensor units, forming the basis of differential sensing. The signals are much easier to collect, enabling the sensor array to simply accomplish the identification. Through statistical analysis, the sensor array is proved to be excellent in discriminating individual phosphate and mixture. Discrimination of five phosphates is successfully performed in serum samples to illustrate the practicability of the sensor array. This work presents an efficient and reliable approach for simultaneous detection of different phosphates, which can be extended to devise other array-based sensing methods.