A Carboxyl‐Functionalized Covalent Organic Framework Synthesized in a Deep Eutectic Solvent for Dye Adsorption

Abstract

Instead of using organic solvents, a deep eutectic solvent (DES) composed of tetrabutylammonium bromide and imidazole (Bu4NBr/Im) was employed as a solvent for the first time to synthesize covalent organic frameworks (COFs). Due to the low vapor pressure of the Bu4NBr/Im‐based DES, a new carboxyl‐functionalized COF (TpPa‐COOH) was synthesized under environmental pressure. The as‐synthesized TpPa‐COOH has open channels, and the DES can be removed completely from the pores. The dye adsorption performance of TpPa‐COOH was examined for three organic dyes with similar molecular sizes: one anionic dye (eosin B, EB) and two cationic dyes (methylene blue, MB and safranine T, ST). TpPa‐COOH showed an excellent selective adsorption effect on MB and ST. The electronegative keto form in TpPa‐COOH might help to form electrostatic and π–π interactions between the π‐stacking frameworks of TpPa‐COOH and the positive plane MB and ST molecules. The adsorption isotherms of MB and ST on TpPa‐COOH were further investigated in detail, and the equilibrium adsorption was well modeled by using a Langmuir isotherm model. Together with hydrogen bonding, TpPa‐COOH showed higher adsorption capacity for ST than for MB (1135 vs. 410 mg g−1). These results could provide a guidance for the green synthesis of adsorbents in removing organic dyes from wastewater.

On-Surface Bottom-Up Construction of COF Nanoshells towards Photocatalytic H 2 Production

“…The former peak located in the low-angle region is assigned to the (100) plane of TPPA, corresponding to the hexagonal pore about 1.8 nm in diameter calculated from the Bragg equation ( d = nλ /2sin θ ), which demonstrates the well-preserved long-range ordered structure [ 24 ]. The latter peak originates from the (001) plane of TPPA, indicating the formation of two-dimensional COF crystalline with the hexagonal topology [ 18 , 25 ]. The corresponding π − π stacking distance is calculated to be about 0.33 nm, which is consistent with the lattice fringe observed in the HRTEM image ( Figure 1(d) ).…”

Organic Dyes versus Adsorption Processing

“…A carboxyl-functionalized covalent organic framework (TpPa-COOH) was synthesized under environmental pressure and the adsorptive properties were investigated using eosin B (anionic dye) as well as the cationic dyes methylene blue and safranine T [ 64 ]. TpPa-COOH showed a selective adsorption effect on the two cationic dyes.…”

Palladium anchored on a covalent organic framework as a heterogeneous catalyst for phosphorylation of aryl bromides

“…The 1 H NMR, 13 C NMR, and 13 P NMR spectra were recorded on Zhongke Niujin AS 400 spectrometer using deuterated solvents as internal standard and chemical shifts are reported in parts per million. The mass spectra were measured on a According to previously reported procedures, [39] a mixture of Bu 4 NBr (9.66 g, 30 mmol) and Im (4.76 g, 70 mmol) were ground with a mortar and pestle, transferred to a round-bottom flask, and heated at 100 C for 1 h. A homogeneous colorless liquid was formed, which was dried under vacuum at 60 C for 6 h.…”