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Vinylene‐Linked Covalent Organic Frameworks by Base‐Catalyzed Aldol Condensation
Author(s) -
Acharjya Amitava,
Pachfule Pradip,
Roeser Jérôme,
Schmitt FranzJosef,
Thomas Arne
Publication year - 2019
Publication title -
angewandte chemie
Language(s) - English
Resource type - Journals
eISSN - 1521-3757
pISSN - 0044-8249
DOI - 10.1002/ange.201905886
Subject(s) - covalent organic framework , covalent bond , aryl , catalysis , carbanion , aldol condensation , benzene , crystallite , base (topology) , chemistry , condensation , triazine , substituent , aldol reaction , polymer chemistry , materials science , crystallography , organic chemistry , mathematics , physics , mathematical analysis , thermodynamics , alkyl
Two 2D covalent organic frameworks (COFs) linked by vinylene (−CH=CH−) groups (V‐COF‐1 and V‐COF‐2) are synthesized by exploiting the electron deficient nature of the aromatic s ‐triazine unit of C 3 ‐symmetric 2,4,6‐trimethyl‐ s ‐triazine (TMT). The acidic terminal methyl hydrogens of TMT can easily be abstracted by a base, resulting in a stabilized carbanion, which further undergoes aldol condensation with multitopic aryl aldehydes to be reticulated into extended crystalline frameworks (V‐COFs). Both V‐COF‐1 (with terepthalaldehyde (TA)) and V‐COF‐2 (with 1,3,5‐tris( p ‐formylphenyl)benzene (TFPB)) are polycrystalline and exhibit permanent porosity and BET surface areas of 1341 m 2 g −1 and 627 m 2 g −1 , respectively. Owing to the close proximity (3.52 Å) of the pre‐organized vinylene linkages within adjacent 2D layers stacked in eclipsed fashion, [2+2] photo‐cycloadditon in V‐COF‐1 formed covalent crosslinks between the COF layers.