Construction\nof Crystalline Nitrone-Linked Covalent\nOrganic Frameworks Via Krohnke Oxidation

Abstract

Developing\ndiverse synthetic routes to prepare various crystalline\ncovalent organic frameworks (COFs) and enrich the family of COFs is\nvery important and highly desirable. In this research, we demonstrate\nthat Kröhnke oxidation (originally developed to prepare carbonyl\ncompounds) can be employed as an efficient method to construct two\ncrystalline nitrone-linked COFs (CityU-1 and CityU-2) through the\ningenious design of the polynitroso-containing precursors as well\nas the exquisite control of the polymerization conditions. The formation\nand structure of nitrone-based linkage units have been confirmed through\na mode reaction. The as-obtained crystalline COFs have been characterized\nby Fourier transform infrared and X-ray photoelectron spectroscopy,\npowder X-ray diffraction patterns, and scanning electron microscopy.\nNotably, CityU-1 exhibits a BET specific surface area of 497.9 m²g^–1 with an I₂ capture capacity\nof 3.0 g g^–1 at 75 °C. Our research would provide\nmore chances to prepare various crystalline COFs for diverse applications.