Construction of Two-Dimensional Fluorescent Covalent Organic Framework Nanosheets for the Detection and Removal of Nitrophenols

Abstract

In this work, we synthesized a two-dimensional fluorescent covalent–organic framework (TFPB–TTA COF) nanosheet by selecting and designing reactive monomers to realize the dual-functional processing of nitrophenols. The staggered benzene ring, triazine structure, and imine bond (CN) of the TFPB–TTA COF can capture free nitrophenols through hydrogen bonding and conjugation interaction, and then, the photoinduced electron transfer and fluorescence resonance energy transfer (FRET) between the TFPB–TTA COF and nitrophenols affects the fluorescence emission of the TFPB–TTA COF, realizing the fluorescence sensing of nitrophenols. The large K sv values and the low detection limit suggest that the TFPB–TTA COF can serve as sensitive and selective fluorescence sensors for nitrophenol detection in an aqueous system. At the same time, the strong interaction combined with the porous network structure of the TFPB–TTA COF facilitates the efficient adsorption and removal of nitrophenols. Especially for 2,4,6-trinitrophenol, the maximum adsorption capacity can reach 1045.53 mg/g with good recyclability and high structural stability of the TFPB–TTA COF. This work proposed a simple synthetic method for the construction of a fluorescent COF platform for the sensitive determination and efficient adsorption of nitrophenols.

Porous Organic Frameworks Constructed by the Synergetic Effect of Covalent Bonds and Hydrogen Bonds for the Selective Identification and Detection of Explosives

“…This result is consistent with the PXRD result of CHOF-1 after being soaked in acidic and basic solutions. On the other hand, the linear conjugation polymers (named COP-1) in the crystal structure of CHOF-1 cannot be decomposed due to the chemical stability of Schiff base under the environment of 4-NP, TNP, HCl, and NaOH at low concentrations. , Therefore, the fluorescence spectra of CHOF-1 after its crystal structure were destroyed by NaOH solution (pH = 10) and then respective additions of 4-NP and TNP were measured, as shown in Figure S17. It is found that not only does the fluorescence spectrum of COP-1 match well with that of CHOF-1 but also the fluorescence spectra of COP-1 after the additions of 4-NP and TNP are consistent with those of CHOF-1 upon the addition of 4-NP and TNP.…”

Tale of COF-on-MOF Composites with Structural Regulation and Stepwise Luminescence Enhancement

“…Since the groundbreaking research on covalent organic frameworks (COFs) reported by Yaghi et al, such type of popular crystalline materials have attracted extensive attention. − COFs are constructed from organic ligands through covalent bonds and possess predesigned structures as well as precise customized functions that facilitate the implementation of chemical and structural control. − Despite enormous attractive research on the design and construction of COFs having been conducted for nearly 20 years, there is still great potential for the development of luminescent COF materials. − Notably, the natural π-conjugated structure of COFs is beneficial to study their luminescence performance, while the π–π stacked structure also causes aggregation-induced quenching (ACQ) and hinders the emission of COFs. , Meanwhile, weakening the stacking degree between layers will increase the intramolecular rotation, which is also a dilemma for luminescence. − At present, fluorescent organic linkers with large conjugated structures or with an aggregation-induced luminescence effect are usually selected for the fabrication of luminescent COFs. − Emissive COFs can also be obtained via postmodification or exfoliation. − To improve the luminescence properties of COFs in an effective way, the emergence of luminescent composites based on COFs stands out from single COFs. − As we know, even though luminescent COFs as emerging functional materials have been dramatically studied over the past few years, ,,− research on directly growing COFs on the core substrate with a limited number of layers to improve the luminous efficiency still remains less understood.…”

A Paper-Based Electrochemical Sensor Based on PtNP/COFTFPB−DHzDS@rGO for Sensitive Detection of Furazolidone

“…COFs have stable networks and open channels, which are extraordinarily conducive to the transport of electrolyte ions and have great potential in various applications. It has been reported that some COFs or COF-based sensors have better performance [ 8 , 9 , 10 ]. However, COFs are highly conjugated, and the π–π interaction between layers would lead to a decrease in specific surface area and poor electrical conductivity.…”