Chemically effect of small molecules (X = CF3, COOH, NH2, NO2) functionalized covalent organic framework (X–COF) as sensors for glyphosate: A computational study

Abstract

The intrinsic structural characteristics of covalent organic frameworks (COFs) significantly influence their adsorption capabilities, particularly in the context of glyphosate. In this study, diverse COFs, incorporating distinctive functional groups (-COOH, -NH2, -NO2, and -CF3), were strategically designed to showcase the effectiveness of functionalized COFs in adsorbing glyphosate utilizing density functional theory (DFT) at the M06-2X/Gen/6-311G(d)/LanL2DZ method. The non-covalent nature of interactions seen in the systems was through a visual study, such as QTAIM and NCI analyses. In this study, the adsorption phenomena results in chemisorption, with the GCS@COF–NH2 (CN1) complex possessing the highest negative adsorption energy of –1.313 eV. Also, relatively higher adsorption energy values were observed in GCS@COF–CF3 (CC1) (–1.305 eV), GCS@COF–COOH (CC2) (–1.239 eV), and GCS@COF–NO2 (CN2) (–1.147 eV) complexes. The functionalized surfaces are stabilized due to the increment in Eg values upon adsorption, with CN2 and CN1 complexes possessing the least energy gap values, indicating relatively lower stability and higher electrical conductivity, electron distribution, and sensitivity. Hence, the COF–NH2 surface has the potential to be used as an adsorbent material for glyphosate pollutants, then followed by the COF–NO2 surface.

Keywords

• Glyphosate
• Functionalized
• Covalent organic framework
• Adsorption
• DFT