Covalent organic nanosheets (CONs) have emerged as functional two-dimensional materials for versatile applications. Although π-π stacking between layers, hydrolytic instability, possible restacking prevents their exfoliation on to few thin layered CONs from crystalline porous polymers. We anticipated rational designing of a structure by intrinsic ionic linker could be the solution to produce self-exfoliated CONs without external stimuli. In an attempt to address this issue, we have synthesized three self-exfoliated guanidinium halide based ionic covalent organic nanosheets (iCONs) with antimicrobial property. Self-exfoliation phenomenon has been supported by molecular dynamics (MD) simulation as well. Intrinsic ionic guanidinium unit plays the pivotal role for both self-exfoliation and antibacterial property against both Gram-positive and Gram-negative bacteria. Using such iCONs, we have devised a mixed matrix membrane which could be useful for antimicrobial coatings with plausible medical benefits.

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.

Ionic covalent organic nanosheets (iCONs), a member of the two-dimensional (2D) nanomaterials family, offer a unique functional platform for a wide range of applications. Herein, we explore the potential of an ethidium bromide (EB)-based covalent organic framework (EB-TFP) that self-exfoliates in water resulting in 2D ionic covalent organic nanosheets (EB-TFP-iCONs) for the selective detection of double-stranded DNA (dsDNA). In an aqueous medium, the self-exfoliated EB-TFP-iCONs reassemble in the presence of dsDNA resulting in hybrid EB-TFP-iCONs-DNA crystalline nanosheets with enhanced fluorescence at 600 nm. Detailed steady-state and time-resolved emission studies revealed that the reassembly phenomenon was highly selective for dsDNA when compared to single-stranded DNA (ssDNA), which allowed us to use the EB-TFP-iCONs as a 2D fluorescent platform for the label-free detection of complementary DNA strands.

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.

Ionic covalent organic nanosheets (iCONs), amember of the two-dimensional (2D) nanomaterials family, offer au nique functional platform for aw ide range of applications.H erein, we explore the potential of an ethidium bromide (EB)-based covalent organic framework (EB-TFP) that self-exfoliates in water resulting in 2D ionic covalent organic nanosheets (EB-TFP-iCONs)f or the selective detection of double-stranded DNA( dsDNA). In an aqueous medium, the self-exfoliated EB-TFP-iCONs reassemble in the presence of dsDNAr esulting in hybrid EB-TFP-iCONs-DNA crystalline nanosheets with enhanced fluorescence at 600 nm. Detailed steady-state and time-resolved emission studies revealed that the reassembly phenomenon was highly selective for dsDNAwhen compared to single-stranded DNA (ssDNA), which allowed us to use the EB-TFP-iCONs as a2D fluorescent platform for the label-free detection of complementary DNAstrands.Supportinginformation and the ORCID identification number(s) for the author(s) of this article can be found under: https://doi.

Exfoliation of 2D layered materials to ultrathin nanosheets and their scalable fabrication to homogeneous thin films are gaining extensive attention among the scientific community due to their emerging importance in sensing, separation and catalysis. COFs represent a new class of organic 2D material which posses a predesignable porous and crystalline framework structure. Attempts to exfoliate them as 2D nanosheets and their further fabrication to large scale thin films proved to be difficult. Strong π-π stacking between layers and possible re stacking after exfoliation are two major obstacles to achieve single or a few layered CONs. Meanwhile, insolubility and poor dispersion of COF crystallites in various solvents prevents their fabrication to produce uniform thin films which could have significant impact in separation or in opto-electronic devices. In order to address these shortcomings, we developed scalable, uniform, and durable CON thin films through the Layer by Layer (LbL) assembly at the air-water interface. The synthesis of functionalized CONs were done by [4+2] Diels-Alder cycloaddition reaction between N-hexylmaleimide and anthracene based COF. The successful functionalization of COF layers disturbs the π-π interaction and loss of planarity of the anthracene units. This results in exfoliation of COF to functionalized CONs. The functionalized CONs are highly stable and dispersible in various organic solvents (DMA, DMF, NMP, CHCl3, DCM) which is found to be stable for more than one month. Taking into account these observations, we fabricated scalable CON thin films via LbL assembly at the air-water interface. It is important to note that, the thin film thickness can be controlled by adjusting the CONs concentration, and it is possible to fabricate 1.2 nm to 2.5 µm thickness of CON sheets. We speculate the dispersion interaction between alkyl groups plays the pivotal role for holding the nanometer sized CONs together to form defect free self standing thin films.[1] Khayum, M