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.

The Crystalline Porous Polymeric materials (CPPs) also well known as Covalent Organic Frameworks (COFs) have concerned substantial research interest because of their extensive applications in molecular storage and separation, catalysis, sensing, opto-electronics etc. [1]. The overall properties and real time employments of such materials not only rely on the compositions but also their nano-scale morphology which plays an incredible role [2]. Therefore, an explicit understanding of the morphology-modulation with respect to their constituents is really demanding. This study accounted a detailed molecular level investigation on morphological evaluation in COFs emanates entirely from its primary building units. Here two new highly crystalline, permanently porous imine linked based COFs named 2,3-DhaTta (Surface area 1700 m2/g) and 2,3-DhaTab (Surface area 413 m2/g) was solvothermally synthesised by faintly varying linker core while retaining all other external factors unchanged. These COFs are found to self template into diverge morphologies including ribbons (2,3-DhaTta) and hollow spheres (2,3-DhaTab). Their mechanisms of formation have been thoroughly and systematically investigated where hollow sphere formation in this case was guided by inside out Ostwald Ripening phenomenon. Moreover, based on DFT (Density Functional Theory) study a significant correlation between stacking energy of two adjacent COF layers with their backbone planarity was established which was believed to be the predominant guiding factor for governing their crystallinity, porosity and morphological diversity evaluation [3].

Noncovalent interactions, in particular the hydrogen bonds and nonspecific long-range electrostatic interactions are fundamental to biomolecular functions. A molecular understanding of the local electrostatic environment, consistently for both specific (hydrogen-bonding) and nonspecific electrostatic (local polarity) interactions, is essential for a detailed understanding of these processes. Vibrational Stark Effect (VSE) has proven to be an extremely useful method to measure the local electric field using infrared spectroscopy of carbonyl and nitrile based probes. The nitrile chemical group would be an ideal choice because of its absorption in an infrared spectral window transparent to biomolecules, ease of site-specific incorporation into proteins, and common occurrence as a substituent in various drug molecules. However, the inability of VSE to describe the dependence of IR frequency on electric field for hydrogen-bonded nitriles to date has severely limited nitrile's utility to probe the noncovalent interactions. In this work, using infrared spectroscopy and atomistic molecular dynamics simulations, we have reported for the first time a linear correlation between nitrile frequencies and electric fields in a wide range of hydrogen-bonding environments that may bridge the existing gap between VSE and H-bonding interactions. We have demonstrated the robustness of this field-frequency correlation for both aromatic nitriles and sulfur-based nitriles in a wide range of molecules of varying size and compactness, including small molecules in complex solvation environments, an amino acid, disordered peptides, and structured proteins. This correlation, when coupled to VSE, can be used to quantify noncovalent interactions, specific or nonspecific, in a consistent manner.

A visible light active porphyrin-based porous organic polymer having high chemical stability and surface area has been synthesized and its ability to influence the photocatalytic activity of large band gap-TiO nanoparticles has been tested. The resultant composite shows improved photocatalytic activity as compared to the parent precursors. This study provides insights into the photosensitizing ability of the polymer in addition to its ability to firmly harbor nanoparticles onto its surface.