Uncovering Latent Responsiveness of Ni-Organic Framework to Electronic and Optical Stimuli through an Amino Acid-Regulated Defect Engineering

Intentionally incorporating defects into the crystalline network of metal–organic frameworks (MOFs) tailors the structure and electronic levels, boosting the overall activity, thereby enhancing its suitability for the intended application. Here, missing linker vacancies are introduced into a nickel terephthalate framework using a biocompatible and chiral amino acid, l -cysteine. The consequent strains in the first shell distance of Ni–O bonds, as confirmed using the X-ray absorption near-edge spectroscopy and extended X-ray absorption fine structure analysis, generate new electronic states that modify the behavior of the framework. Interestingly, this defect-engineered framework displays superior sensing response toward not one but two stimuli, namely, electrical bias and light. This enhanced sensing potential is tapped to quantify a commonly prescribed antibiotic, nitrofurantoin (NFT), optically and an associated biomarker, l -tyrosine (TYR), electrochemically. The experimental findings of the superior activity are further supported with molecular charge distribution plots and adsorption energy calculations using DFT analysis, which elucidate its ability to preconcentrate and specifically bind with TYR and NFT. Thus, the defective Ni-MOF demonstrates selective detection of NFT and TYR with a detection limit of 130 and 43.8 nM, respectively. Furthermore, the developed material also realizes the detection of TYR and NFT in human blood serum samples, validating its prospects as a reliable material in multimodal devices for human health profiling.