Chemically Gradient Hydrogen‐Bonded Organic Framework Crystal Film

• Published in: Angewandte Chemie 2023-07, Vol.135 (29), p.n/a
• Main Authors: Mohammed, Abdul Khayum, Raya, Jésus, Pandikassala, Ajmal, Addicoat, Matthew A., Gaber, Safa, Aslam, Mohamed, Ali, Liaqat, Kurungot, Sreekumar, Shetty, Dinesh
• Format: Article
• Language: English
• Subjects: Chemical bonds; Chemical Gradience; Chemistry; Crystal Films; Crystals; Fabrication; Free-Standing Films; Hydrogen; Hydrogen-Bonded Organic Framework; Interfacial Chemistry; Polymer films; Polymers; Proton Conductivity
• ISSN: 0044-8249; 1521-3757
• DOI: 10.1002/ange.202304313

Hydrogen‐bonded organic frameworks (HOFs) are ordered supramolecular solid structures, however, nothing much explored as centimetre‐scale self‐standing films. The fabrication of such crystals comprising self‐supported films is challenging due to the limited flexibility and interaction of the crystals, and therefore studies on two‐dimensional macrostructures of HOFs are limited to external supports. Herein, we introduce a novel chemical gradient strategy to fabricate a crystal‐deposited HOF film on an in situ‐formed covalent organic polymer film (Tam‐Bdca‐CGHOF). The fabricated film showed versatility in chemical bonding along its thickness from covalent to hydrogen‐bonded network. The kinetic‐controlled Tam‐Bdca‐CGHOF showed enhanced proton conductivity (8.3×10−5 S cm−1) compared to its rapid kinetic analogue, Tam‐Bdca‐COP (2.1×10−5 S cm−1), which signifies the advantage of bonding‐engineering in the same system. We introduce a novel chemical gradient strategy to fabricate a crystal‐deposited HOF on an in situ grown polymer film. The fabricated film showed versatility in chemical bonding along its thickness from covalent to hydrogen‐bonded network and showed improved proton conductivity compared to its polymeric analog.