Design of Two‐Dimensional Heteropolyacid‐Covalent Organic Frameworks Composite Materials for Acid Catalysis

Abstract

Covalent organic frameworks (COFs) is a rapidly developing field in material chemistry. However, COFs still have very limited applications due to the absence of functional groups. In this work, we demonstrate the efficient way for the synthesis of crystalline composite based on phosphotungstic acid and 2D imine CIN-1 type of COF. Heteropolyacid behaves as structure directing agent and it is stabilized between the layers of COF. The composite material shows a layered-sheet arrangement of large imine network layers with sizes up to 1.5 μm. Owing to the strong interaction of heteropolyacid with COF, the resultant material shows high activity and stability with no leaching during acid-catalyzed esterification reaction.

Enhanced Catalytic Activity for Levulinic Acid Esterification Using Covalent Organic Framework Heterogenized Heteropolyacids

“…The thermal stability of the HPW-LZU1 catalysts was investigated by TGA (Figure S1A), with all HPW-LZU1 TGA curves showing a smooth weight loss below 200 °C due to the desorption of adsorbed moisture and solvent. The catalysts keep thermally stable below 400 °C and start to sharply decompose at 400 °C. , The weight loss assigned to pure HPW below 300 °C is due to the removal of physically adsorbed water and crystal water (Figure S1B), and the gradual weight loss from 500 to 900 °C originates from the decomposition of the Keggin anion . Based on the TGA curves of the catalysts, the HPW/LZU1 mass ratio values were calculated for cross checking (Table ), and they were found to be very close to the values determined by elemental analysis.…”

Covalent organic framework derived synthesis of Ru embedded in carbon nitride for hydrogen and oxygen evolution reactions

“…The tube of a Radleys Carousel reactor was charged with RuCl 3 ·H 2 O (0.03 g), 2-(diphenylphosphino)benzaldehyde (0.03 g), piperazinedicarbaldehyde (0.17 g), melamine (0.100 g) and DMSO (12 mL) according to the procedure of CIN-1 material synthesis. 36 The tube was degassed with dry N 2 and refluxed at 180 °C for 72 h in an inert atmosphere. After cooling to room temperature, the precipitated product was isolated by filtration and washed with dry ethanol, acetone, THF and dichloromethane sequentially.…”

“…2b, the FTIR spectra of pure CIN-1 and Ru@CIN-1 depicted distinct peaks of triazine ring vibrations at 1540, 1490 and 1340 cm −1 . 36,47 The FTIR spectrum of the Ru-DBP complex comprised peaks at 1967 cm −1 assigned to coordinated C]O stretching vibration, and 1630 and 1400 cm −1 due to carbon-carbon stretching vibrations of the aromatic rings. 48 The disappearance of the C]O group vibrations and the appearance of benzene aromatic ring vibrations during the crystallization of Ru@CIN-1 indicated the successful incorporation of the Ru-DBP complex into the CIN-1 structure.…”

Synthesis of stack plate covalent organic framework nanotubes using a self-assembled acid as a soft template

“…Hydrogen-bonding between -COOH (TMA) with -NH 2 (PDA) and -C=O (TFA) results in the condensation of COFs monomers perpendicular to the TMA rod. For example, the use of heteropolyacid in crystallization of COF has been reported earlier 35 . The removal of TMA by washing leads to the generation of the void space inside of the nanotubes (Figure 3d).…”

“…For example, the use of a heteropolyacid in the crystallization of COF has been reported earlier. 35 The removal of TMA by washing leads to the generation of the void space inside of the nanotubes (Fig. 3d).…”