One-Pot Cascade Construction of Nonsubstituted Quinoline-Bridged Covalent Organic Frameworks

Abstract

Irreversible locking of imine linkage into stable linkages represents a promising strategy to improve the robustness and functionality of covalent organic frameworks (COFs). We report, for the first time, a multi-component one-pot reaction (OPR) for imine annulation to construct highly stable nonsubstituted quinoline-bridged COFs (NQ-COFs), and equilibrium regulation of reversible/irreversible cascade reactions by addition of desiccant MgSO4 is crucial to achieve high conversion efficiency and crystallinity. The higher long-range order and surface area of NQ-COFs synthesized by OPR than the reported two-step post-synthetic modification (PSM) facilitate charge carriers’ transfer and photogenerated ability of superoxide radical (O2•−), which makes these NQ-COFs be more efficient photocatalysts for O2•− mediated synthesis of 2-benzimidazole derivatives. The general applicability of this synthetic strategy is demonstrated by fabricating 12 other crystalline NQ-COFs with a diversity of topologies and functional groups.