title: Chemically stable multilayered covalent organic nanosheets from covalent organic frameworks via mechanical delamination.
abstract: A series of five thermally and chemically stable functionalized covalent organic frameworks (COFs), namely, TpPa-NO2, TpPa-F4, TpBD-(NO2)2, TpBD-Me2, and TpBD-(OMe)2 were synthesized by employing the solvothermal aldehyde-amine Schiff base condensation reaction. In order to complete the series, previously reported TpPa-1, TpPa-2, and TpBD have also been synthesized, and altogether, eight COFs were fully characterized through powder X-ray diffraction (PXRD), Fourier transform IR (FT-IR) spectroscopy, (13)C solid-state NMR spectroscopy, and thermogravimetric analysis. These COFs are crystalline, permanently porous, and stable in boiling water, acid (9 N HCl), and base (3 N NaOH). The synthesized COFs (all eight) were successfully delaminated using a simple, safe, and environmentally friendly mechanical grinding route to transform into covalent organic nanosheets (CONs) and were well characterized via transmission electron microscopy and atomic force microscopy. Further PXRD and FT-IR analyses confirm that these CONs retain their structural integrity throughout the delamination process and also remain stable in aqueous, acidic, and basic media like the parent COFs. These exfoliated CONs have graphene-like layered morphology (delaminated layers), unlike the COFs from which they were synthesized.
authors.affiliation: Physical/Materials Chemistry Division, CSIR-National Chemical Laboratory , Dr. Homi Bhabha Road, Pune 411 008, India.
authors.forename: Suman
authors.initials: S
authors.lastname: Chandra
authors.forename: Sharath
authors.initials: S
authors.lastname: Kandambeth
authors.forename: Bishnu P
authors.initials: BP
authors.lastname: Biswal
authors.forename: Binit
authors.initials: B
authors.lastname: Lukose
authors.forename: Shrikant M
authors.initials: SM
authors.lastname: Kunjir
authors.forename: Minakshi
authors.initials: M
authors.lastname: Chaudhary
authors.forename: Ravichandar
authors.initials: R
authors.lastname: Babarao
authors.forename: Thomas
authors.initials: T
authors.lastname: Heine
authors.forename: Rahul
authors.initials: R
authors.lastname: Banerjee