Covalent Bond Formation Research Articles

Study on corrosion and wear behavior mechanism of Zr-based bulk amorphous

The adsorption behavior of oxygen on Zr41.2Ti13.8Cu12.5Ni10Be22.5 (Vit1) (001) and Zr (110) surfaces is studied by DFT First-principles calculations method. In addition, electrochemical corrosion and wear tests were used to study the corrosion and wear mechanism of Zr41.2Ti13.8Cu12.5Ni10Be22.5 (Vit1) and Zr-1. The results indicate that the absorption energies of O at the top of Ti and Zr atoms are larger that of O at top of Cu and Ni atoms, which indicates that O at Ti and Zr atoms is more stable than that of O at Cu and Ni atoms. The O-Zr covalent bond formed by O adsorption on the Zr(110) surface has a maximum layout (0.24) at the bridge site, and the covalent bond formation is stronger and the adsorption is more stable. The corrosion current density of Vit1 is lower than that of Zr-1. The passivation film formed by ZrO2, TiO2, CuO and other components of Vit1 has higher corrosion resistance in H2SO4 solution, and the corrosion resistance of Vit1 is stronger than that of Zr-1. In addition, the wear performance of Vit1 is better than that of Zr-1. The results will provide an important guide to the corrosion and wear resistance of Zr-based bulk amorphous materials.

Essential Oil of Origanum vulgare as a Green Corrosion Inhibitor for Carbon Steel in Acidic Medium

In this study, Oregano (Origanum vulgare) leaf essential oil was studied as an environmental-friendly anticorrosion agent for carbon steel in aggressive hydrochloric acid. The corrosion inhibition of O. vulgare was characterized by surface morphology, electrochemical, weight loss, theoretical and computational methods. It was found that the highest inhibition performance of O. vulgare was 85.64% at 2 g/l in 1 M HCl. The results of Langmuir isotherm and adsorption thermodynamics investigation demonstrated that the O. vulgare inhibitor adsorbed on the metal surface by the formation of rigid covalent bonds. The adsorption and inhibition centers of the selected inhibitor were studied by the computational methods, resulting in that the hydroxyl functional groups and benzoyl rings are mainly responsible for the high inhibition efficiency.

Colouration and Performance Evaluation of Ethiopian Kusha Fibres

ABSTRACT Bast fiber dyeing process is common practice as the value addition of most bast fibers demanded for various commercial and household applications. In this research work, kusha fiber (extracted previously) was subjected to dyeing using direct, reactive, vat and cationic dyes for the first time. Dyeing process was perfrmed using concentrations 0.5%, 1%, & 3% (W/W) dye to fiber with MLR 1:20. After dyeing process, performance of dyed fiber and tensile tests were conducted. The results revealed that K/S value of all dyed kusha fiber samples increases as the concentration of dyes applied increases. The dyed fibers color fastness to washing was found good both in dry and wet rubbing fastness. Reactive dyed samples have shown good rubbing fatness performance over the others. Regarding light fastness, the result shows there was good performance for all samples according to blue wool light fastness standard that exceeds 6. The tensile strength and elongation of dyed samples showed slight decrement both in vat and direct dyed samples; whereas, considerable decrement was observed both in reactive and basic dyed samples due to formation of covalent bond and acid processing medium.

Development of self-healing vanillin/PEI hydrogels for tissue engineering

Self-healing materials recover mechanical damages to expand the lifetime of the material provided. In this study, self-healing hydrogels have been successfully prepared using a novel and simple technique. Vanillin is a natural monomer, used as a bio-based cross-linker for UV-induced bonding and Schiff-base bonding. Methacrylate-functionalized vanillin (M-VAN) is covalently integrated with the polymer matrix. While M-VAN supports polymer matrix with its vinyl group, its aldehyde functionality helps the formation of dynamic covalent imine bonds via Schiff-base formation. The hydrogel showed excellent self-healing ability overnight under physiological conditions without external addition. In addition, the hydrogel surface was modified by collagen and its cell viability was investigated. The prepared scaffolds showed good cell viability of 124% and 163% compared to the control sample. The developed self-healing material reveals that it has possible uses for future biomedical applications and tissue engineering studies due to the self-healing mechanism taking place under ambient conditions.

Site-specific encoding of photoactivity and photoreactivity into antibody fragments

Design of biomolecules that perform two or more distinct functions in response to light remains challenging. Here, we have introduced concurrent photoactivity and photoreactivity into an epidermal growth factor receptor (EGFR)-targeting antibody fragment, 7D12. This was achieved by site-specific incorporation of photocaged tyrosine (pcY) for photoactivity and p-benzoyl-ʟ-phenylalanine (Bpa) for photoreactivity into 7D12. We identified a position for installing Bpa in 7D12 that has minimal effect on 7D12–EGFR binding affinity in the absence of light. Upon exposure to 365-nm light, this Bpa-containing 7D12 mutant forms a covalent bond with EGFR in an antigen-specific manner. We then developed a method for site-specific incorporation of pcY and Bpa at two distinct sites in 7D12. Finally, we demonstrated that in the absence of light, this pcY- and Bpa-containing mutant of 7D12 does not bind to EGFR, but irradiation with 365-nm light activates (1) specific binding and (2) covalent bond formation with EGFR.

Improvement of Si3N4/SiO2 etching selectivity through the passivation of SiO2 surface in aromatic carboxylic acid-added H3PO4 solutions for the 3D NAND integration

Selective Si3N4 etching becomes challenging as the number of stacks in three-dimensional Not AND (3D NAND) flash memory devices increases. To suppress changes in the thickness of SiO2 layers in Si3N4/SiO2 multi-stack structures, etching inhibitors should be added to H3PO4 solutions. Notably, carboxylic acids can be adsorbed on OH-terminated substances, such as SiO2, by forming Si-O-C bonds. Therefore, carboxylic acids added to H3PO4 solutions can be adsorbed on SiO2 surfaces, and passivation layers can be formed, suppressing SiO2 etching. When a Si3N4/SiO2 multi-stack structure is dipped in a H3PO4 solution, the Si3N4 layers are removed, and the SiOxNy surfaces on the SiO2 layers are converted into SiOx surfaces with positively charged oxygen vacancies. For aromatic carboxylic acids, C=O bonds in their carboxyl groups can be converted to C-O-, causing electrostatic attraction between the C-O- groups and oxygen vacancies on SiOx surfaces. Consequently, aromatic carboxylic acids can be adsorbed on SiOx surfaces via the electrostatic attraction and Si-O-C covalent bond formation, creating robust passivation layers and suppressing SiO2 etching. However, aliphatic carboxylic acids form only Si-O-C bonds on SiOx surfaces and hence cannot realize the same functions as their aromatic counterparts.

Bonding and Suppression of a Magnetic Phase Transition in EuMn2P2.

Electrons in solids often adopt complex patterns of chemical bonding driven by the competition between energy gains from covalency and delocalization, and energy costs of double occupation to satisfy Pauli exclusion, with multiple intermediate states in the transition between highly localized, and magnetic, and delocalized, and nonmagnetic limits. Herein, we report a chemical pressure-driven transition from a proper Mn magnetic ordering phase transition to a Mn magnetic phase crossover in EuMn2P2 the limiting end member of the EuMn2X2 (X = Sb, As, P) family of layered materials. This loss of a magnetic ordering occurs despite EuMn2P2 remaining an insulator at all temperatures, and with a phase transition to long-range Eu antiferromagnetic order at TN ≈ 17 K. The absence of a Mn magnetic phase transition contrasts with the formation of long-range Mn order at T ≈ 130 K in isoelectronic EuMn2Sb2 and EuMn2As2. Temperature-dependent specific heat and 31P NMR measurements provide evidence for the development of short-range Mn magnetic correlations from T ≈ 250-100 K, interpreted as a precursor to covalent bond formation. Density functional theory calculations demonstrate an unusual sensitivity of the band structure to the details of the imposed Mn and Eu magnetic order, with an antiferromagnetic Mn arrangement required to recapitulate an insulating state. Our results imply a picture in which long-range Mn magnetic order is suppressed by chemical pressure, but that antiferromagnetic correlations persist, narrowing bands and producing an insulating state.

DFT-D3 study of two-dimensional polymerization of C60 crystal under high pressure

The high-pressure behavior of a monomer and 2D polymerized C60 crystals were investigated using DFT-D3 calculations. Although covalent bonds were not observed in monomer upon simple compression, C60 moieties in two-dimensional polymer phases (Immm and phases) exhibited intermolecular electron density, which indicates the formation of covalent bonds between C60 moieties. The C60 crystals were highly compressed under high pressure; however, small compression was observed at the C60 moieties. Both internal energies and PV terms contributed similarly to enthalpy. The deformation of crystals prevented polymerization. These results suggested a different behavior from that of typical inorganic materials.

Application of SPRA Technology for Delivery of Erythropoietin: Stability Evaluation of Conjugated Erythropoietin with Adamantane and in SPRA Inclusion Complex.

As a widely used therapeutic protein, recombinant human erythropoietin (rhEPO) is currently one of the most effective biopharmaceuticals on the market for the treatment of anemia in patients with chronic renal disease. Increasing in vivo rhEPO half-life and its bioactivity is a significant challenge. It was hypothesized that the application of self-assembly PEGylation retaining activity, named supramolecular (SPRA) technology, could prolong the protein half-life without a significant loss of bioactivity. This study aimed to assess the stability of rhEPO during synthetic reactions, including the conjugation with adamantane and the formation of the SPRA complex. To do this, the secondary structure of the protein was also evaluated. FTIR, ATR-FTIR, Far-UV-CD, and SDS-PAGE methods were employed. Thermal stability studies of SPRA-rhEPO complex and rhEPO were investigated at 37°C for ten days using a nanodrop spectrophotometer. The secondary structure of lyophilized rhEPO, AD-rhEPO, and rhEPO (pH 8) was compared to rhEPO. Results showed that the secondary structure of the protein was unaffected by lyophilization, pH change, and the formation of covalent bonds in conjugation reaction. SPRA-rhEPO complex was also stable for seven days in phosphate buffer (pH 7.4) at 37°C. It was concluded that the stability of rhEPO could increase by complexation using SPRA technology.

Co-folding of soy protein isolates and shellac by structural interplays to induce hydrogels

The feasibility of co-folding of soy protein isolates (SPI) and shellac by pH-shifting method to induce a protein hydrogel was firstly investigated. SPI and shellac at different mass ratios (1.3, 1.5, 1.7, 2.1, and 2.5 w/w) were co-folded by adjusting pH back to 7, 8, and 9, after unfolding at pH 12. The pH-shifting treatments resulted in the conformational change of SPI and the formation of covalent bonds between SPI and shellac, as confirmed by sodium dodecyl sulfate−polyacrylamide gel electrophoresis (SDS-PAGE), Fourier-transform infrared (FTIR) spectroscopy, UV–Vis, fluorescence spectroscopy, and as well as the changes of thermogravimetry. The cold-set hydrogel was prepared from the pH-shifting process by adjust pH to 9 which showed the optimal hardness and rheological properties, accompanied by excellent water-holding capacity (WHC> 90%). Meanwhile, the microscopic observations revealed the formation of uniform microstructure in the gel network. The co-folded hydrogels were proved to have a lower degree of protein hydrolysis (DH) than the same pH-shifted SPI alone during in vitro simulated digestion. Thus, the simple pH manipulation of SPI and shellac may be applied to induce hydrogels, reducing the protein DH during in vitro digestion which provides the potential for delivery of sensitive nutrients.

A detailed experimental performance of 4-quinolone derivatives as corrosion inhibitors for mild steel in acid media combined with first-principles DFT simulations of bond breaking upon adsorption

Four 4-oxo-1,4-dihydroquinoline-3-carboxylate derivatives were synthesized through the Gould-Jacobs method and evaluated as corrosion inhibitors for 1020 mild steel in 1 mol/L hydrochloric acid. Gravimetric experiments showed that those organic molecules present 84–94 % anticorrosive efficiency at 2.00 mmol/L (298 K). At higher temperatures (318 and 338 K), those values go up to 97.3 % for the methoxy-substituted compound. Electrochemical measurements depicted that the charge-transfer mechanism controlled the corrosive and inhibitive processes and that the presence of the four organic substances in the electrolyte enhanced the polarization resistance and significantly diminished the corrosion density current, acting by adsorption on the metal surface. Polarization curves confirmed that they all are mixed-type corrosion inhibitors. Atomic Force Microscopy illustrated the topography of the metallic surface and suggested to the formation of a protective layer. Atomistic simulations by first-principles Density Functional Theory revealed the formation of covalent bonds between quinolone molecules and the iron surface, with MODC and AODC having the stronger negative interaction energy values compared to NODC and CODC compounds. Electronic analysis of the adsorption geometries of molecules at Fe(110) indicated that chemical coordination is a result of strong charge transfer and charge rearrangement upon adsorption.

Novel Green Crosslinked Salecan Hydrogels and Preliminary Investigation of Their Use in 3D Printing

Salecan, a kind of polysaccharide, is produced by the Agrobacterium ZX09 salt tolerant strain. In this study, green crosslinked citric acid-salecan hydrogels are explored as novel materials with a high potential for use in regenerative medicine. The impact of salecan and citric acid on the final crosslinked hydrogels was intensively studied and estimated in terms of the whole physicochemical properties and antimicrobial activity. FTIR spectra demonstrated the successful green crosslinking of salecan through its esterification with citric acid where the formation of strong covalent bonds collaboratively helped to stabilize the entire hydrogel systems in a wet state. Hydrogels presented a microporous morphology, good swelling capacity, pH responsiveness, great mechanical stability under stress conditions and good antibacterial activity, all related to the concentration of the biopolymers used in the synthesis step. Additionally, salecan hydrogels were preliminary investigated as printing inks. Thanks to their excellent rheological behavior, we optimized the citrate-salecan hydrogel inks and printing parameters to render 3D constructs with great printing fidelity and integrity. The novel synthesized salecan green crosslinked hydrogels enriches the family of salecan-derived hydrogels. Moreover, this work not only expands the application of salecan hydrogels in various fields, but also provides a new potential option of designing salecan-based 3D printed scaffolds for customized regenerative medicine.

The versatile utility of cysteine as a target for cancer treatment.

Owing to its unique nucleophilicity, cysteine is an attractive sulfhydryl-containing proteinogenic amino acid. It is also utilized in various metabolic pathways and redox homeostasis, as it is used for the component of major endogenous antioxidant glutathione and the generation of sulfur-containing biomolecules. In addition, cysteine is the most nucleophilic amino acid of proteins and can react with endogenous or exogenous electrophiles which can result in the formation of covalent bonds, which can alter the cellular states and functions. Moreover, post-translational modifications of cysteines trigger redox signaling and affect the three-dimensional protein structure. Protein phosphorylation mediated by kinases and phosphatases play a key role in cellular signaling that regulates many physiological and pathological processes, and consequently, the modification of cysteine regulates its activities. The modification of cysteine residues in proteins is critically important for the design of novel types of pharmacological agents. Therefore, in cancer metabolism and cancer cell survival, cysteine plays an essential role in redox regulation of cellular status and protein function. This review summarizes the diverse regulatory mechanisms of cysteine bound to or free from proteins in cancer. Furthermore, it can enhance the comprehension of the role of cysteine in tumor biology which can help in the development of novel effective cancer therapies.

Recent Advances in Mechanically Transferable III‐Nitride Based on 2D Buffer Strategy

AbstractGroup III‐nitrides have attracted significant attention in recent years for their wide tunable band‐gaps and excellent optoelectronic capabilities, which are advantageous for several applications including light‐emitting diodes, lasers, photodetectors, and large‐size low‐cost power electronic devices. However, conventional epitaxy accompanied by the covalent bond formation renders the transfer of nitride epilayers difficult, thereby limiting the application potential of nitrides in wearable and flexible electronics. Furthermore, interfacial covalent bonds also limit substrate selection and hinder the development of heterogeneous integration between nitrides and other material systems. 2D materials can mitigate these problems significantly. On the one hand, due to the weak van der Waals forces between the layers of 2D materials, influences of lattice mismatch can be avoided to improve crystal quality. On the other hand, delamination and transfer of nitride epilayers can be achieved easily. Therefore, this study focuses on providing comprehensive guidelines regarding the exfoliation of epitaxial layers using 2D materials to provide new design freedoms for nitride devices. Different 2D buffers and release layers have also been discussed. Furthermore, the limitations, promising solutions, future directions, and applicability of this strategy to flexible nitride devices are presented.

Less Is More: Oligomer Extraction and Hydrothermal Annealing Increase PDMS Adhesion Forces for Materials Studies and for Biology-Focused Microfluidic Applications.

Cues in the micro-environment are key determinants in the emergence of complex cellular morphologies and functions. Primary among these is the presence of neighboring cells that form networks. For high-resolution analysis, it is crucial to develop micro-environments that permit exquisite control of network formation. This is especially true in cell science, tissue engineering, and clinical biology. We introduce a new approach for assembling polydimethylsiloxane (PDMS)-based microfluidic environments that enhances cell network formation and analyses. We report that the combined processes of PDMS solvent-extraction and hydrothermal annealing create unique conditions that produce high-strength bonds between solvent-extracted PDMS (E-PDMS) and glass-properties not associated with conventional PDMS. Extraction followed by hydrothermal annealing removes unbound oligomers, promotes polymer cross-linking, facilitates covalent bond formation with glass, and retains the highest biocompatibility. Herein, our extraction protocol accelerates oligomer removal from 5 to 2 days. Resulting microfluidic platforms are uniquely suited for cell-network studies owing to high adhesion forces, effectively corralling cellular extensions and eliminating harmful oligomers. We demonstrate the simple, simultaneous actuation of multiple microfluidic domains for invoking ATP- and glutamate-induced Ca2+ signaling in glial-cell networks. These E-PDMS modifications and flow manipulations further enable microfluidic technologies for cell-signaling and network studies as well as novel applications.

PH-responsive, salt-resistant, and highly stable foam based on a silicone-containing dynamic imine surfactant

The preparation of a responsive foam, which can be destroyed on-demand and re-formed in a short time upon the imposition of an external environmental stimulus, using a dynamic imine surfactant (DIS) alone, remains a major challenge due to the presence of unreacted oil-soluble precursor. We report herein the design and synthesis of a novel silicone-containing DIS based on commercial 1,3-bis(3-aminopropyl)tetramethyldisiloxane, BAPTS, as an amino-containing precursor, and 3-(4-formylphenoxy)-N,N,N-trimethylpropan-1-aminium, as an aldehyde-containing precursor. 1H NMR spectrometry and FT-IR spectroscopy have been employed to confirm the formation of dynamic covalent bonds and to calculate the conversion of aldehyde to imine. Surface activity and foam properties have been systematically investigated. The results demonstrated that a traditional one-head-one-tail silicone-containing DIS was firstly formed at pH > 7.0 and then transformed into Bola-type DIS at pH > 9.0. Due to the low surface tension resulting from the introduction of silicone group and complete consumption of BAPTS at pH > 9.0, the as-prepared DIS surfactant showed excellent foam performance. Indeed, the foam could be reversibly switched on and off by alternately changing the pH, irrespective of the electrolyte concentration. The foaming performance was only minimally influenced by different electrolytes (NaCl, CaCl2, and MgSO4), but foam stability was sensitive to these electrolytes. Despite the foam becoming highly unstable at low electrolyte concentration (t1/2 < 0.5 min), its stability was significantly enhanced at high electrolyte concentration (t1/2 = 0.5–20 h) due to a microstructure transition from low viscosity spherical micelles to high viscosity rodlike micelles. Such a system may potentially be applied in mineral floatation or foam flood in oil production.

Assessment of the inhibitive performance of a hydrazone derivative for steel rebar in a simulated concrete medium: Establishing the inhibition mechanism at an experimental and theoretical level

In the present work, a low-cost and practical approach based on an eco-friendly corrosion inhibitor is suggested for protecting steel rebar. To this end, a new hydrazone derivative, namely N'-(furan-2-ylmethylene)-2-(5-methoxy-2-methyl-1H-indol-3-yl) acetohydrazide (FMAH) was synthesized and its corrosion inhibition characteristics for steel rebar (STR) in chloride contaminated simulated concrete pore solutions (ClSCPS) were evaluated using experimental and theoretical methods. The electrochemical studies, which were conducted at several periods ranging from 1 h to 30 d indicated that the addition of FMAH to the ClSCPS significantly improved the passive film formation. It considerably increased film and charge transfer resistances at an early immersion stage, then decreased at longer immersion periods. Potentiodynamic polarization curves (PPCs) revealed that the investigated compound could be categorized as a mixed inhibitor with a predominance anodic effect. The gravimetric and potentiodynamic polarization studies confirmed corrosion inhibition efficiencies of 80.9% and 81.1%, respectively, for 1.0 mmol.L-1 FMAH after 30 d of exposure. Surface characterization of corroded and inhibited STR surface by X-ray photoelectron spectroscopy (XPS), SEM coupled with EDS, Raman spectroscopy, atomic force microscopy (AFM) and X-ray diffraction spectroscopy (XRD) revealed that inhibitor molecules chemically adsorbed on the STR forming a highly resistant protective layer against corrosive species. Theoretical modeling of inhibitor’s adsorption on the iron surface by the self-consistent-charge Density-functional tight-binding (SCC-DFTB) indicated the formation of several covalent bonds between carbon and oxygen atoms with the iron atoms. The analysis of FMAH-Fe (110) adsorption systems by projected density of states revealed that FMAH molecules adsorbed on the iron surface through a charge transfer process. The interesting results from the present work would open great opportunities for exploring the anti-corrosion performance of the investigated compound in concrete.

Exploring the functionalization of Ti-6Al-4V alloy with the novel antimicrobial peptide JIChis-2 via plasma polymerization

This study aimed to characterize the immobilization of the novel JIChis-2 peptide on the Ti-6Al-4V alloy, widely used in the biomedical sector. The antimicrobial activity of JIChis-2 was evaluated in the Gram-negative bacterium E. coli. Its immobilization occurred by inducing the formation of covalent bonds between the N-terminus of the peptides and the surface previously submitted to acrylic acid polymerization via the PECVD technique. Coated and uncoated surfaces were characterized by FTIR, AFM, SEM and EDX. Studies of global and localized corrosion were carried out, seeking to explore the effects triggered by surface treatment in an aggressive environment. Additionally, the ability of the functionalized material to prevent E. coli biofilm formation evidenced that the strategy to immobilize JIChis-2 in the Ti-6Al-4V alloy via PECVD of acrylic acid resulted in the development of a functional material with antibiofilm properties.

Fabrication and properties of Sn(iv) porphyrin-linked porous organic polymer for environmental applications.

A robust porous organic polymer cross-linked by Sn(iv) porphyrin (SnPOP) was fabricated by reacting trans-dihydroxo-[5,15,10,20-tetrakis(phenyl)porphyrinato]tin(iv) (SnP) with fluorinated polyimide (FPI) via sol-gel formation, followed by supercritical CO2 drying. The structural and porous properties of SnPOP were characterized using FT-IR, UV-vis, and fluorescence spectroscopies, along with field-emission scanning electron microscopy and gas sorption experiments. The reaction between the SnP's oxophilic Sn(iv) center and FPI's carboxylic acid moiety resulted in a controllable cross-linked porous texture. This material features the desirable physical properties of porphyrin and exhibits mesoporous structures with a relatively high surface area. SnPOP is thermally stable at temperatures up to 600 °C and highly resistant to boiling water, strong acids, and bases, owing to its assembly via formation of covalent bonds instead of typically weaker hydrogen bonds. The modified chemical and morphological structures of SnPOP showed an impressive CO2 uptake capacity of 58.48 mg g-1 at 273 K, with a preference for CO2 over N2. SnPOP showed significant efficiency in removing pollutant dyes, such as methylene blue and methyl orange, from dye-contaminated water. Additionally, SnPOP was a photocatalyst for fabricating silver nanoparticles of regular shape and size. All these properties make SnPOP a potential candidate for environmental applications like pollutant removal, gas storage, and separation.

Post-synthetic modifications of covalent organic frameworks (COFs) for diverse applications.

Covalent organic frameworks (COFs) are porous and crystalline organic polymers, which have found usage in various fields. These frameworks are tailorable through the introduction of diverse functionalities into the platform. Indeed, functionality plays a key role in their different applications. However, sometimes functional groups are not compatible with reaction conditions or can compete and interfere with other groups of monomers in the direct synthetic method. Also, pre-synthesis of bulky moieties in COFs can negatively affect crystal formation. To avoid these problems a post-synthetic modification (PSM) approach is a helpful tactic. Also, with the assistance of this strategy porous size can be tunable and stability can be improved without considerable effect on the crystallite. In addition, conductivity, hydrophobicity/ hydrophilicity, and chirality are among the features that can be reformed with this method. In this review, different types of PSM strategies based on recent articles have been divided into four categories: (i) post-functionalization, (ii) post-metalation, (iii) chemical locking, and (iv) host-guest post-modifications. Post-functionalization and chemical locking methods are based on covalent bond formation while in post-metalation and host-guest post-modifications, non-covalent bonds are formed. Also, the potential of these post-modified COFs in energy storage and conversion (lithium-sulfur batteries, hydrogen storage, proton-exchange membrane fuel cells, and water splitting), heterogeneous catalysts, food safety evaluation, gas separation, environmental domains (greenhouse gas capture, radioactive element uptake, and water remediation), and biological applications (drug delivery, biosensors, biomarker capture, chiral column chromatography, and solid-state smart nanochannels) have been discussed.