Porous 2D and 3D Covalent Organic Frameworks with Dimensionality‐Dependent Photocatalytic Activity in Promoting Radical Ring‐Opening Polymerization

Abstract

AbstractDimensionality is a fundamental parameter to modulate the properties of solid materials by tuning electronic structures. Covalent organic frameworks (COFs) are a prominent class of porous crystalline materials, but the study of dimensional dependence on their physicochemical properties is still lacking. Herein we illustrate photocatalytic performances of N,N‐diaryl dihydrophenazine (PN)‐based COFs are heavily dependent on the structural dimensionality. Six isostructural imine‐bonded 2D‐PN COFs and one 3D‐PN COF were prepared. All can be heterogeneous photocatalysts to promote radical ring‐opening polymerization of vinylcyclopropanes (VCPs), which typically produces polymers with a combination of linear (l) and cyclic (c) repeat units. The 2D‐PN COFs have much higher catalytic activity than the 3D‐PN COF, allowing the efficient synthesis of poly(VCPs) with controlled molecular weight, low dispersity and high l/c selectivity (up to 97 %). The improved performance can be ascribed to the 2D structure which has a larger internal surface area, more catalytically active sites, higher photosensitizing ability and photoinduced electron transfer efficiency.