Covalent organic frameworks embedding single cadmium sites for efficient carboxylative cyclization of CO₂with propargylic amines

Abstract

Converting CO2 into value-added chemicals over efficient and recyclable catalysts has attracted increasing attention. Covalent organic frameworks (COFs) have arisen as elegant heterogeneous catalysts for this subject. Herein, we report...

Metal Variance in Multivariate Metal–Organic Frameworks for Boosting Catalytic Conversion of CO2

“…As shown in Figure S26, a peak at 3280 cm –1 attributed to the N–H in compound 4a gradually decreased as well as new peaks including CO (1785 cm –1 ), CC (1680 cm –1 ), COO (1283, and 1242 cm –1 ), C–O–C (1084 cm –1 ), and N–R (1060 cm –1 ) in oxazolidinones were detected and gradually increased, suggesting the formation of cyclization product 5a with the reaction proceeded. More importantly, a peak at 1388 cm –1 belonging to carbamate stretching vibration (NCOO – ) interacting with the 1 0.1 -2 0.4 -3 0.5 -JNM appeared and subsequently diminished as the reaction proceeded . In addition, when 1 0.1 -2 0.4 -3 0.5 -JNM or DBU was individually added into a CDCl 3 solution of 4a , the intensity of the alkyne proton signal at ∼2.29 ppm remained unchanged.…”

“…More importantly, a peak at 1388 cm −1 belonging to carbamate stretching vibration (NCOO − ) interacting with the 1 0.1 -2 0.4 -3 0.5 -JNM appeared and sub-sequently diminished as the reaction proceeded. 40 In addition, when 1 0.1 -2 0.4 -3 0.5 -JNM or DBU was individually added into a CDCl 3 solution of 4a, the intensity of the alkyne proton signal at ∼2.29 ppm remained unchanged. In sharp contrast, the peak of the alkyne proton almost disappeared after 1 0.1 -2 0.4 -3 0.5 -JNM and DBU were both charged, revealing that the C�C bond can be synergistically activated by 1 0.1 -2 0.4 -3 0.5 -JNM and DBU.…”

Nitrogen-Rich Covalent Organic Polymer for Metal-Free Tandem Catalysis and Postmetalation-Actuated High-Performance Water Oxidation

“…The fabrication of this new two-dimensional (2D) and nitrogen-rich covalent organic polymer (1) involved template-free reaction between 2,2′-bipyridine-5,5′-dicarbonyl dichloride (BpyCOCl) and 2,4,6-tris(4-aminophenyl)triazine (TAPT) following [2 + 3] structural motif (Figure 1). 47 Fourier transform-infrared (FT-IR) spectral data (Figure S3) show the appearance of a new amide C�O stretching band at 1683 cm −1 . Powder X-ray diffraction (PXRD) analysis of the COP (Figure 2a) presented several diffraction peaks (2θ at 7.67°, 17.45°, 20.77°, 24.74°, and 27.75°), revealing crystallinity.…”

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

“…Covalent organic framework (COF) materials are a new type of crystalline porous material which are ingeniously constructed with organic molecules linked by strong covalent bonds (CN, CC, B–O, C–O, etc.). Due to their ultralow density, high crystallinity, high surface area, and ordered accessible porous structures, COF materials have been applied in many fields, such as gas storage/separation, drug delivery, fluorescence sensing, proton conduction, catalysis, and so on. − Two-dimensional (2D) COF materials are a type of COF material which are constructed by π–π stacking of the adjacent COF layers. The extensive π-electron delocalization effect of the 2D COF materials facilitates charge transfer in the materials, which is beneficial for catalytic reactions over the materials.…”