Comparative study of luminescent Cd-MOF and Cd-MOF@HNT nanomaterials for the detection of hydroxyl-functionalized nitroaromatic compounds†

Abstract

Metal–organic frameworks (MOFs) are emerging as a key solution for detecting and adsorbing hazardous nitroaromatic compounds, driven by environmental and security concerns. In this paper, a high pH and water-stable fluorescent MOF (PUC-10) with distorted pentagonal bipyramidal geometry and interesting hcb topology was prepared by a solvothermal method. Furthermore, a PUC-10 NP based composite (PUC-10@HNT) was fabricated and applied for the sensitive detection of hydroxyl group-containing nitroaromatic compounds (NACs). In particular, trinitrophenol (TNP), dinitrophenol (DNP) and para-nitrophenol (4-NP) rapidly quench the fluorescence of PUC-10@HNT, with a detection limit of 0.027 μM, 0.031 μM and 0.036 μM, respectively. The sensing ability of PUC-10 and PUC-10@HNT was compared to signify the composite formation. This method effectively analyzes the respective NACs in natural water and a Whatman-paper-strip sensing element was also developed for efficient visual detection of analytes. Moreover, PUC-10@HNT showed excellent recyclability over four cycles. Based on the DFT calculations, zeta-potential, absorption and photoluminescence spectra of the analytes and probe, the fluorescence quenching mechanism was analyzed and found to be due to a combination of PET, FRET, and competitive light absorption between the analytes and PUC-10@HNT.