Rapid, Scalable Construction of Highly Crystalline Acylhydrazone Two-Dimensional Covalent Organic Frameworks via Dipole-Induced Antiparallel Stacking

Abstract

Covalent organic frameworks are an emerging class of porous crystalline organic materials that can be designed and synthesized from the bottom up. Despite progress made in synthesizing COFs of diverse topologies, the synthesis methods are often tedious and unscalable, hampering practical applications. Herein, we demonstrate a scalable, robust method of producing highly crystalline acylhydrazone two-dimensional (2D) COFs with diversified structures (six examples) under open and stirred conditions, with growth typically completed in only 30 min. Our strategy involves selecting molecular building blocks that have bond dipole moments with spatial orientations that favor antiparallel stacking and whose structure allows the restriction of intramolecular bond rotation (RIR) via intra-and interlayer hydrogen bonding. This method is widely applicable for hydrazide linkers containing various side-chain functionalities and topicities. By this strategy, the gram-scale synthesis of two highly crystalline COFs (up to 1.4 g yield) was obtained in a one-pot reaction within 30 min.

Rational Fabrication of Crystalline Smart Materials for Rapid Detection and Efficient Removal of Ozone

“…Smart materials (also referred to intelligent or stimuli‐responsive materials) can undergo reversible changes by external stimuli, such as temperature, light, pH, gases, chemical compounds, or moisture, have attracted intense attention in many fields as diverse as sensors, [15] actuators, [16] artificial muscles, [17] and information storage [18] . Covalent organic frameworks (COFs) [19–21] have emerged as a new class of smart materials and exhibited diverse, intelligent applications such as actuating, [22] drug delivery, [23, 24] and sensing [25] due to their high crystallinity and porosity, [26] defined pore environment, [27] high emission efficiency, [28] and extraordinary chemical stability [29, 30] . Moreover, COFs can be readily predesigned and post‐synthetically modified.…”

2D-Covalent Organic Frameworks with Interlayer Hydrogen Bonding Oriented through Designed Nonplanarity

“…15,16 However, interlayer hydrogen bonding in COFs is much rarer. There are only a few examples of hydrazone 17,18 or urea 12 containing COFs where interlayer hydrogen bonding is observed or predicted, reported in literature. Several COFs have been reported that have interlayer C-H⋯O, and C-H⋯N hydrogen bonding through sidechain interactions, 13,14,19 however, more canonical N-H⋯O hydrogen bonding interactions similar to those found between amide groups found in Nature, or in synthetic polymers such as Kevlar or Nylon, are much rarer.…”

Nanoscale covalent organic frameworks as theranostic platforms for oncotherapy: synthesis, functionalization, and applications

“…To give the readers a better understanding of this promising approach, detailed examples of COF syntheses in an atmospheric solution are summarized in Table 1. [120][121][122][123][124][125][126][127][128][129][130][131][132][133][134]…”