Chemically Delaminated Free-Standing Ultrathin Covalent Organic Nanosheets

• Published in: Angewandte Chemie International Edition Vol. 55; no. 50; pp. 15604 - 15608
• Main Authors: Khayum, M. Abdul, Kandambeth, Sharath, Mitra, Shouvik, Nair, Sanoop B., Das, Anuja, Nagane, Samadhan S., Mukherjee, Rabibrata, Banerjee, Rahul
• Format: Journal Article
• Language: English
• Published: Germany Blackwell Publishing Ltd 12.12.2016; Wiley Subscription Services, Inc
• Edition: International ed. in English
• Subjects: anthracene; covalent organic frameworks; hydrophobic effects; lamellar structures; porous polymers; Thin films; anthracene; covalent organic frameworks; porous polymers; lamellar structures; hydrophobic effects
• ISSN: 1433-7851; 1521-3773
• DOI: 10.1002/anie.201607812

Covalent organic nanosheets (CONs) are a new class of porous thin two‐dimensional (2D) nanostructures that can be easily designed and functionalized and could be useful for separation applications. Poor dispersion, layer restacking, and difficult postsynthetic modifications are the major hurdles that need to be overcome to fabricate scalable CON thin films. Herein, we present a unique approach for the chemical exfoliation of an anthracene‐based covalent organic framework (COF) to N‐hexylmaleimide‐functionalized CONs, to yield centimeter‐sized free‐standing thin films through layer‐by‐layer CON assembly at the air–water interface. The thin‐layer fabrication technique presented here is simple, scalable, and does not require any surfactants or stabilizing agents. The chemical exfoliation of anthracene‐based covalent organic frameworks (COFs) into covalent organic nanosheets (CONs) was enabled by a [4+2] Diels–Alder cycloaddition reaction with N‐hexylmaleimide. Centimeter‐sized self‐standing CON thin films of tunable thickness were then fabricated by layer by layer (LbL) assembly at an air–water interface.