Luminescent Two-Dimensional Metal–Organic Framework Nanosheets with Large π-Conjugated System: Design, Synthesis, and Detection of Anti-Inflammatory Drugs and Pesticides

Abstract

Two-dimensional (2D) metal–organic framework (MOF) nanosheets, with largely exposed surface area and highly accessible active sites, have emerged as a novel kind of sensing material. Here, a luminescent 2D MOF nanosheet was designed and synthesized by a facile top-down strategy based on a three-dimensional (3D) layered MOF {[Zn­(H2L)­(H2O)2]·H2O} n (Zn-MOF; H4L = 3,5-bis­(3′,5′-dicarboxyphenyl)-1H-1,2,4-triazole). With a large π-conjugated system and rigid planar structure, ligand H4L was elaborately selected to construct the bulk Zn-MOF, which can be readily exfoliated into 2D nanosheets, owing to the weak interlayer interactions and easy-to-release H2O molecules in the interspaces of 2D layers. Given the great threat posed to the ecological environment by anti-inflammatory drugs and pesticides, the developed luminescent Zn-MOF nanosheets were utilized to determine these organic pollutants, achieving highly selective and sensitive detection of diclofenac sodium (DCF) and tetramethylthiuram disulfide (TMTD). Compared to the detection limits of 3D Zn-MOF (7.72 ppm for DCF, 6.01 ppm for TMTD), the obviously lower detection limits for 2D Zn-MOF nanosheets toward DCF (0.20 ppm) and TMTD (0.18 ppm) further revealed that the largely exposed surface area with rigid planar structure and ultralarge π-conjugated system greatly accelerated electron transfer, which brought about a vast improvement in response sensitivity. The remarkable quenching performance for DCF and TMTD stems from a combined effect of photoinduced electron transfer and competitive energy absorption. The possible sensing mechanism was systematically investigated by the studies of powder X-ray diffraction, UV–vis, luminescence lifetime, and density functional theory calculations.

Metal–Organic Framework-Based Fluorescent Sensors for the Detection of Pharmaceutically Active Compounds

“…Liu et al synthesized a 2D nanosheet of Zn-MOF, which had a LOD of 0.2 ppm and K sv of 4.32 × 10 4 M –1 toward DS sensing. The PL quenching of the 2D-nanosheet of Zn-MOF by DS was ascribed to the electron transfer from the MOF to DS …”

“…The PL quenching of the 2D-nanosheet of Zn-MOF by DS was ascribed to the electron transfer from the MOF to DS. 144 5.14. Antibacterial Drugs.…”

Exfoliation of a Coordination Polymer Based on a Linear π-Conjugated Ligand into an Ultrathin Nanosheet for Glyphosate Sensing

“…Owing to the weak hydrogen-bonding interactions between the 2D Cd-L coordination networks, it is probable that the prepared Cd-1 can be exfoliated into nanosheets induced by solvents through ultrasonication. According to previous studies, the solvents have an important effect on the exfoliation of layered CPs. , Thus, we first surveyed some common solvents, including water, methanol, ethanol, isopropanol, DMF, acetonitrile, acetone, ether, ethyl acetate (EA), tetrahydrofuran (THF), and triethylamine by soaking the pristine crystals of Cd-1 in these solvents under ultrasonication. , The suspension obtained in isopropyl alcohol exhibited a significant Tyndall effect upon irradiation with an incident laser light beam, suggesting the formation of the Cd-1 nanosheet ( Cd-1-NS ). In order to further illustrate the morphology of the prepared Cd-1-NS , scanning electron microscopy (SEM), transmission electron microscopy (TEM), and atomic force microscopy (AFM) measurements were conducted, and the results clearly demonstrated the formation of 2D nanosheets.…”

Fabrication of ultrathin two-dimensional MOF nanosheets with cage-like cavities showing excellent adsorption for lead(ii)

“…[22][23][24][25][26] The 2D MOF nanosheets hold the structural characteristics of both bulky MOFs and 2D materials, such as versatile compositions and functions, exposed surface area, innumerable accessible surface-active sites, and nanoscale thickness, which were facile for the interaction with substrate molecules, affording improved performance in catalysis, sensing, separation, etc. [27][28][29][30][31][32] The significance of the synthesis of 2D MOF nanosheets was greatly highlighted by these attractive properties and applications. [33][34][35] However, few studies on pollutant capture by 2D MOF nanosheets have been reported thus far.…”