Imine Compounds Research Articles

Reprocessable, chemically recyclable, and flame-retardant biobased epoxy vitrimers

Conventional epoxy thermosets exhibit outstanding mechanical performances, excellent thermal and dimensional stabilities, and prominent resistances to chemical/solvent corrosions but are limited because they are dependent on fossil resources, cannot be reprocessed, and are not fire safe. Herein, we reported biobased, flame-retardant, reprocessable, and chemically recyclable epoxy thermosets synthesized with bio-based glycerol triglycidyl ether (GTE) as an epoxy monomer, vanillin derived imine compound as a hardener, and 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO) as a reactive fire-retardant agent. The curing kinetics investigation manifested that the curing reaction was activated with increasing DOPO content. The relationship between structure and properties of the vitrimers were studied in detail. The BEVs showed excellent physical properties with a tensile strength and glass transition temperature higher than 80 MPa and 100 °C, respectively. They possessed outstanding reprocessability and could be chemically recycled easily owning to the presence of the exchangeable imine bonds. The BEV with 6 wt% DOPO showed excellent fire resistance with a UL-94 V-0 rating and a LOI at 26.4% as well as much lower peak heat release rate and total heat release than the control vitrimer without DOPO. The BEVs with combination of excellent mechanical properties, reprocessability, chemical recyclability, and flame retardancy showed a bright future as an alternative to conventional epoxy thermosets for better sustainability and fire-safety.

A water-stable Schiff base fluorophore: AIEE behavior, reversible mechanofluorochromism, detection of water content and viscosity of automobile brake fluid, and cell imaging

Imine compounds (Schiff base) have been reported with aggregation-induced emission (AIE)/aggregation-induced emission enhancement (AIEE) characteristics: they were weakly or non-emissive when dissolved well in organic solvents while the fluorescence emission turned on drastically in the presence of water. However, for some of the Schiff bases, the enhanced emission upon aggregation is derived from their parent aldehydes rather than the Schiff base molecule themselves due to the hydrolysis. The susceptibility to hydrolysis has thus limited the wide application of Schiff bases in aqueous media. In this work, a water-stable Schiff base fluorophore DBSFCN was synthesized in which the triphenylamine (TPA) electron donor and benzonitrile electron acceptor were joined together by the imine structure. The hydrolytic stability of DBSFCN was confirmed by structural and spectral analysis. Meanwhile, DBSFCN displayed significant fluorescence emission enhancement in a water/tetrahydrofuran (THF) mixture with high water content and relatively good fluorescence quantum yield at the solid state (0.48), which exhibited a typical AIEE feature. Based on the water stability and AIEE characteristic of DBSFCN, a quantitative method for the determination of water content and kinematic viscosity of the automobile brake fluid was established. In addition, DBSFCN was available in living cell imaging and reversible mechanofluorochromism.

Oxime-Conjugated Dendrimers as Therapeutics for Organophosphate Poisoning

Organophosphates (OPs) are a class of organophosphorus compounds which have a general structure of O=P(OR)3. Paraoxon (also known as POX) is an organophosphate found in insecticides often used in agriculture in impoverished countries. OPs are also used in nerve gas agents such as Sarin gas, used in warfare.These molecules are extremely toxic and can be lethal at low doses. Organophosphates negatively impact the body’s neurotransmitter enzyme, acetylcholinesterase. Muscle spasms, paralysis, narrowed pupils, glossy eyes, confusion, and the over-secretion of bodily fluids such as sweat, saliva, mucus, and tears, are symptoms of organophosphate poisoning (Fletcher, 2017). To reduce the harmful effects from this organic compound, we have designed and screened dendrimer nanoparticles modified with poly (ethylene glycol) chains and with small reactor molecules. Dendrimers are synthetic macromolecules, which contain chains of repeated, branching molecules that form a tree-like or snowflake-like structure. Dendrimers can be used to enhance permeability in drug delivery. There are many active sites attached to small reactor molecules on the dendrimer branches, allowing for the successful and efficient inactivation of POX before penetrating the skin (Mukherjee, 2015). The second focus of our experiment was to screen for hundreds of oxime molecules that most effectively reactivate acetylcholinesterase. Oxime molecules are an organic imine compound that can be used to detach the toxic OPs from acetylcholinesterase. OP’s bind to Ser200 on the enzyme, leading to inactivation. Oxime molecules bind in a nucleophilic attack to the phosphorus on organophosphate, causing it to diffuse away from the enzyme. This paper highlights the two focuses of our experiment: 1. Perform enzyme assays to screen for the best compounds at reactivating acetylcholinesterase, and 2. Attach oxime molecules at the branching sites of dendrimers to enhance permeability into the subdermal layer of the skin. We have identified some potential oxime molecules and dendrimers to be complexed and used as a treatment for OP poisoning or incorporated into a cream-based drug product to protect those at high risk of exposure to organophosphates.

A fluorene based imine compound: Structural characterization, DNA binding properties and fluorescence sensor properties towards metal ions

In the course of this work, a new fluorene-based Schiff base compound (SB) from the condensation reaction 2-aminofluorene and 4-(diethylamino)salicylaldehyde was synthesized and its structure was characterized by FTIR, 1H/13C NMR spectroscopies and elemental analysis. Crystal structure of the synthesized compound (SB) was determined single crystal X-ray diffraction study. Crystal structure of the compound was solved in monoclinic unit cell and P21 space group. The molecule shows phenol-imine intramolecular hydrogen bond and molecules are connected by CH····π interactions. The Schiff base compound was then screened for its DNA binding properties by using UV–vis absorption, fluorescence and viscosity studies. All DNA binding data showed that the compound interacts with FSdsDNA via intercalation. The intrinsic DNA binding constant of the compound from UV–vis spectral data was 3.00×104 M−1 which is significantly lower than ethidium bromide (an intercalating agent). The compound was further investigated for colorimetric sensing of metal ions. Colorimetric sensor properties of the compound towards Fe(III), Pb(II), Zn(II), Cu(II), Al(III), Hg(II), Co(II), Mn(II) and Ni(II) ions were investigated in solution. The compound showed selective sensing properties for Cu(II) under 365 nm light. Jobs variation study indicated that the Cu(II) to receptor ratio was 2:1.

Unravelling the redox behaviour of a carbon nitride polymer-based ternary heterostructure for CO2 photoreduction promoted by amine coupling

Imine compounds are essential commodity chemicals used in synthetic organic chemistry and pharmaceuticals, along with as the sacrificial donor in the photoreduction of CO2 into solar fuels.

Mechanism of photocatalyzed imine conversion: a relay process of sequential energy transfer, single electron transfer and proton transfer

The use of imine compounds to generate alkyl radicals has been a topic of interest among synthetic chemists.

Electrochemical and Theoretical Examination of Some Imine Compounds as Corrosion Inhibitors for Carbon Steel in Oil Wells Formation Water

Electrochemical and Theoretical Examination of Some Imine Compounds as Corrosion Inhibitors for Carbon Steel in Oil Wells Formation Water

The Effect of Temperature and Thermodynamic Parameters on the Ionization Constants of Some Imines Derived from Vanillin with substituted aniline

This work presents a method for the preparation of imine compounds including Schiff bases derived from vanillin with aniline, o-nitroaniline, o-tolidene and o-chloroaniline. Compounds' structures of the prepared compounds were confirmed by physical methods like melting point, infrared spectroscopy (IR), electronic spectroscopy (U.V), and nuclear magnetic resonance spectroscopy (NMR).
 The ionization constants of the imine nitrogen proton Ka1 and the phenol hydroxyl group proton Ka2 were determined using the spectrometric titration method at five temperatures including 293,298,303,308 and 313K in a buffer solution medium. The thermodynamic of ionization for imines confirm that ionization reactions in these imines are accompanied by an increase of parameters ∆Gº and ∆Hº. These mean that ionization reactions in these imines are non-spontaneous and endothermic respectively. ∆Sº values of ionization reactions estimated have a negative and a positive signs.

Mechanically robust, hydrothermal aging resistant, imine-containing epoxy thermoset for recyclable carbon fiber reinforced composites

Imine compounds have been proved to possess great potential in the design and preparation of sustainable epoxy thermosets. However, it is still a great challenge to develop imine-containing hardener with definite structure due to the randomness of condensation reaction between aldehydes and primary amines. Herein, a novel amine hardener containing imine bond is synthesized successfully by selecting 4-imidazole formaldehyde and 3-aminobenzylamine as raw materials. The asymmetric structure of raw material can avoid uncontrollable reaction and ensure that this hardener possesses definite chemical structure. Due to high activity of hardener, the resultant epoxy thermosets with high cross-linked density exhibit excellent thermostability and fine hydrothermal aging resistance. Furthermore, such thermosets show good mechanical properties (tensile strength of ∼76 MPa), which are comparable to that of commercial Diglycidyl Ether of Bisphenol A epoxy resin cured by 4,4-Diaminodiphenyl methane. More interestingly, increasing the equivalent ratio of active hydrogen to epoxy can introduce more dynamic covalent C=N linkage into the cross-linked network, thus the epoxy thermoset further achieves the decomposition within 3 h and the corresponding composite laminates also are recycled efficiently under mild condition. This work demonstrates the feasibility and potential of preparing high-performance degradable epoxy thermoset and corresponding recyclable composites based on well-designed imine-containing hardener.

In silico analysis of koranimine, a cyclic imine compound from Peribacillus frigoritolerans reveals potential nematicidal activity

Pine wilt disease (PWD) is a destructive vector-borne forest disease caused by the nematode Bursaphelenchus xylophilus. To date, several options are available for the management of pine wilt disease; however constant development and search for natural products with potential nematicidal activity are imperative to diversify management options and to cope with the possible future emergence of resistance in parasitic nematodes. Here, a combined metabolomics and genomics approach was employed to investigate the chemical repertoire and biosynthetic potential of the bacterial endophyte Peribacillus frigoritolerans BE93, previously characterized to exhibit nematicidal activity against B. xylophilus. Feature-based molecular networking revealed the presence of diverse secondary metabolites. A cyclic imine heptapeptide, koranimine, was found to be among the most abundant secondary metabolites produced. Genome mining displayed the presence of several putative biosynthetic gene clusters (BGCs), including a dedicated non-ribosomal peptide synthase (NRPS) BGC for koranimine. Given the non-ribosomal peptide nature of koranimine, in silico molecular docking analysis was conducted to investigate its potential nematicidal activity against the target receptor ivermectin-sensitive invertebrate α glutamate-gated chloride channel (GluCl). Results revealed the binding of koranimine at the allosteric site of the channel—the ivermectin binding site. Moreover, the ligand-receptor interactions observed were mostly shared between koranimine and ivermectin when bound to the α GluCl receptor thus, suggesting a possibly shared mechanism of potential nematicidal activity. This study highlights the efficiency of combined metabolomics and genomics approach in the identification of candidate compounds.

Controlling C-steel dissolution in 1 M HCl solution using newly synthesized ρ-substituted imine derivatives: Theoretical (DFT and MCs) and experimental investigations

• ρ- substituted imines as C-steel corrosion inhibitor. • Δ N of SB-OCH 3 is higher than SB-CH 3 . • SB-OCH 3 enhances the R ct of C-steel to 374.9 Ω.cm 2 . • Adsorption type of tested imine compounds was physicosorption. • SB-OCH 3 resisted C-steel corrosion under severe conditions. Corrosion is an inevitable process, but its control is the goal of the researchers using organic inhibitors. So, newly successfully prepared ρ-substituted imine compounds namely;( E )- N,N -dimethyl1-4-((tolylimino)methyl)aniline (SB-CH 3 ) and ( E )-4 (((4methoxyphenyl)imino)methyl)- N,N -dimethylaniline (SB-OCH 3 ) have been fabricated to control the C-steel dissolution in 1M HCl. Hammett concept and theoretical calculated parameters were applied to predict the adsorption affinity of the prepared imine derivatives and the laboratory gravimetric and electrochemical tests accompanied with surface analysis tools were conducted to confirm these predictions. The fabricated imine compounds suppressed the C-steel reaction with efficacy of more than 90 %. The SB-OCH 3 exhibited higher adsorption affinity than SB-CH 3 and they acted as hydride C-steel corrosion inhibitors and followed Langmuir isotherm. The Δ G a d s * values of C-steel reactions in presence of these compounds were around -37 kJmol −1 . The inhibition performance of SB-CH 3 and SB-OCH 3 was function in their concentrations, molecular weight, and solution temperature. SB-CH 3 and SB-OCH 3 suppressed C-steel reaction at high temperature and the SB-OCH 3 showed highest efficiency (76.8%) at 60 °C. The activated thermodynamic parameters of C-steel reaction in existence and nonexistence of 1 × 10 −3 M imine compounds were calculated and discussed. The comparison findings with the previously published compounds confirmed the superiority of the understudied imine derivatives.

Synthesis of New Methoxy Actived Mono and Bis-indole Compounds

An indole hydrazone has successfully been synthesized employing Schiff base reaction conditions starting from 4,6-dimethoxy-2,3-diphenylindole-7-carbaldehyde with hydrazine hydrate. The reaction of this compound with acetone yielded indole based imine compound. The structure of targeted compound was identified by mass and 1H spectroscopy along with single crystal X-ray diffraction technique. Also, bromination of bis-indole with N-bromo succinimide was produced corresponding bromo bis-indol derivative.

Identification and characterization of mercaptopyrimidine-based small molecules as inhibitors of nonhomologous DNA end joining.

Mercaptopyrimidine derivatives are heterocyclic compounds with potent biological activities including antiproliferative, antibacterial, and anti-inflammatory properties. The present study describes the synthesis and characterization of several mercaptopyrimidine derivatives through condensation of 5,6-diamino-2-mercaptopyrimidin-4-ol with various heterocyclic and aromatic aldehydes. Previous studies have shown that SCR7, synthesized from 5,6-diamino-2-mercaptopyrimidin-4-ol, induced cytotoxicity by targeting cancer cells by primarily inhibiting DNA Ligase IV involved in nonhomologous end joining, one of the major DNA double-strand break repair pathways. Inhibition of DNA repair pathways is considered as an important strategy for cancer therapy. Due to limitations of SCR7 in terms of IC50 in cancer cells, here we have designed, synthesized, and characterized potent derivatives of SCR7 using 5,6-diamino-2-mercaptopyrimidin-4-ol as the starting material. Several synthesized imine compounds exhibited significant improvement in inhibition of end joining and cytotoxicity up to 27-fold lower concentrations than SCR7. Among these, two compounds, SCR116 and SCR132, showed increased cancer cell death in a Ligase IV-dependent manner. Treatment with the compounds also led to reduction in V(D)J recombination efficiency, cell cycle arrest at G2/M phase, accumulation of double-strand breaks inside cells, and improved anti-cancer potential when combined with γ-radiation and radiomimetic drugs. Thus, we describe novel inhibitors of NHEJ with higher efficacy and potential, which can be developed as cancer therapeutics.

Preparation, characterization and biological activity of some new seven-membered heterocyclic compounds

Introduction: The synthesis of Schiff base has huge importance to prepare a lot of heterocyclic compounds, Oxazepines can be prepared by reaction of imine compounds with anhydrides to obtain seven-membered heterocyclic compound. Materials and Methods: A series of 1, 3-oxazepine derivatives were prepared, firstly preparation of the imines (S1-S2) from reaction of 2-chlorobenzaldehyde with each of p-toluidine and 4, 4’-Methylenedianiline and using glacial acetic acid as a catalyst. The second step involves the reaction of prepared Schiff bases (S1-S2) with both 3-nitrophthalic anhydride and Itaconic anhydride in dry benzene to produce 1,3-oxazepine derivatives (OX1-OX4), The antibacterial activity determined by using Agar well diffusion procedure method, against two types of bacteria, which it gram-positive (Staphylococcus aureus) and gram-negative (Escherichia coli). Results and Discussion: Oxazepine compounds are formed through Pericyclic reactions which are concerted processes that pass through a single cyclic transition state structure involving simultaneously breaking and formation of bonds. The compounds were identified by using FT-IR and NMR technology. Conclusions: The possibility of preparing some mono-chelating and bi-chelating Schiff bases derived from the reaction of 2-chlorophenzaldehyde with different aromatic primary amines and preparing some of the new oxazepine compounds through the reaction of the Schiff bases with different anhydrides in benzene, which can be used to extract metal ions from their solutions. The biochemical efficacy of compounds demonstrated that their ability to inhibit Staphylococcus aureus was greater compared with the ability to inhibit Escherichia coli.

Synthesis of reduced graphene oxide-based hybrid compounds and investigation of their sensing behavior against some nitroaromatic explosives

In the scope of this study, the usability of rGO-based hybrid materials obtained by using different Schiff bases in the detection of some nitroaromatic explosives was investigated. In the first step, synthesis of graphene oxide (GO) containing functional groups (-COOH, –OH etc.) was carried out by the oxidation of graphite via the modified Hummers' method. These functional groups were reduced by the hydrothermal method to obtain the reduced graphene oxide (rGO). In another step, rGO-Cl was obtained from rGO using SOCl2. The purpose of obtaining the rGO-Cl compound is to make the synthesis of hybrid compounds easier from the reaction of rGO-Cl and imine compounds (ER1-ER5). The hybrid materials (FB1-FB5) were successfully synthesized from the reaction of rGO-Cl and imine compounds. FT-IR, UV, FL, SEM, TEM and XRD methods were used to determine the structure of the synthesized materials. The sensing behavior of the synthesized hybrid materials towards some nitroaromatic explosives was investigated. The quenching effect of nitroaromatic explosives on the fluorescence of rGO-based hybrid materials was measured using the fluorimetric titrations. Although GO derivatives are generally sensitive to 2,4-dinitrophenol, it has been determined that the synthesized hybrid compounds are sensitive to different nitroaromatic explosives. The lowest LOD values of the materials were found as (FB1: 8.76 μM; nitrobenzene), (FB2: 16.35 μM; 4-nitrophenol), (FB3: 20.50 μM; picric acid), (FB4: 12.54 μM; 2,4- dinitrophenol) and (FB5: 8.64 μM; 4-nitrophenol), respectively.

Synthesis and Evaluating the Antimicrobial Activities of Various Adducts Prepared from Isatins and Proline

characteristic tissues and cells, exerting their pharmacological aspects and alleviating a lot of diseased processes. Accordingly, this research is about introducing some isatins to be nucleophilically attacked at C3 forming products of azomethine ylide functionality. These iminium compounds were made by allowing certain isatins to be reacted with the secondary amino acid, proline, at acetic acid and methanol medium and then collected after purification to be identified with total Leukocyte count (TLC) and melting point. The structural characterization was performed by fourier-transform infrared spectroscopy (FTIR), proton nuclear magnetic resonance (1H-NMR), and community health nursing (CHN) analysis. The microbiological evaluation was proved with the disc diffusion method on cultured agars of Staphylococcus aureus, some Gram-negative bacilli, and the fungus Candida albicans using more than one concentration of the prepared molecules. It was found that the isatin adduct has no activity, whereas the others, having changed in substituents at position 5, are fluctuated in their action results.

Asymmetric Transfer Hydrogenative Amination of Benzylic Ketones Catalyzed by Cp*Ir(III) Complexes Bearing a Chiral N-(2-Picolyl)sulfonamidato Ligand

A convenient asymmetric reductive amination of benzylic ketones (α-arylated ketones) catalyzed by newly designed Cp*Ir complexes bearing a chiral N-(2-picolyl)sulfonamidato ligand was developed. Using readily available β-amino alcohols as chiral aminating agents, a range of benzo-fused and acyclic ketones were successfully reduced with formic acid in methanol at 40 °C to afford amines with favorable chemo- and diastereoselectivities. The amino alcohol-derived chiral auxiliary was easily removed by mild periodic oxidants, leading to optically active primary β-arylamines without erosion of the optical purity (up to 97% ee). The excellent catalytic performance was retained even upon lowering the amount of catalyst to a substrate/catalyst (S/C) ratio of 20,000, and the amination could be performed on a large scale exceeding 100 g. The precise hydride transfer to iminium species generated from the ketonic substrate and the chiral amine counterpart was suggested by the mechanistic studies on stoichiometric reactions of isolable hydridoiridium complexes and model intermediates such as N,O-acetal, enamine, and iminium compounds.

Recent Progress on Organic Electrode Materials for Multivalent (Zn, Al, Mg, Ca) Secondary Batteries

AbstractMultivalent secondary batteries (MSBs) have attracted great attention in view of their rich resources, low cost, and high safety. However, its development and application are still plagued by electrode materials. With their renewable and highly adjustable structures, organic electrode materials (OEMs) have several advantages over traditional inorganic electrode materials (IEMs), which has become the current research hotspot of electrode materials for MSBs. In this review, we present the recent developments in OEMs used for secondary batteries, including carbonyl compounds, imine compounds, conductive polymers, covalent organic frameworks, organic cyanides, organosulfur polymers and so on. An overview of the structural characteristics, energy storage mechanism, and electrochemical performance of OEMs in MSBs is given. Furthermore, to reveal the reasons for the high performance of the preponderant organic electrode materials, the relationships between material structures, electrolyte system, and battery properties are discussed in detail. Finally, we hope that this review could provide a fundamental guide to developing and designing high‐performance MSBs in the future.

Anchored Palladium Complex-Generated Clusters on Zirconia: Efficiency in Reductive N-Alkylation of Amines with Carbonyl Compounds under Hydrogen Atmosphere.

Carbon-nitrogen bond formation is an important method on both laboratory and industrial scales because it realizes the production of valuable pharmaceuticals, agrochemicals, and fine chemicals. Direct reductive N-alkylation of amines with carbonyl compounds via intermediary imine compounds, especially under catalytic hydrogenation conditions, is one of the most convenient, economical, and environmentally friendly methods for this process. Here we report a novel palladium species on zirconia having specific activity towards hydrogenation of imines but other carbonyl groups remaining intact. The present catalytic property offers a practical synthetic method of functionalized secondary amines by reductive N-alkylation under mild conditions with high atom-efficiency. Mechanistic studies revealed that the catalytically active species is the palladium cluster, which is generated in situ from molecular palladium complexes on the support by exposure to atmospheric hydrogen. These fundamental findings are expected to progress in developing novel cluster catalysts for chemical processes directed towards a sustainable society.

Shedding Light on the Synthesis, Crystal Structure, Characterization, and Computational Study of Optoelectronic Properties and Bioactivity of Imine derivatives.

Two imine compounds named as (E)-2-(((3,4-dichlorophenyl)imino)methyl)phenol (DC2H) and (E)-4-(((2,4-dimethylphenyl)imino)methyl)phenol (DM4H) are synthesized, and their crystal structures are verified using the single-crystal X-ray diffraction (XRD) technique. The crystal structures of the compounds are compared with the closely related crystal structures using the Cambridge Structural Database (CSD). The crystal packing in terms of intermolecular interactions is fully explored by Hirshfeld surface analysis. Void analysis is carried out for both compounds to check the strength of the crystal packing. Furthermore, a state-of-the-art dual computational technique consisting of quantum chemical and molecular docking methods is used to shed light on the molecular structure, optoelectronic properties, and bioactivity of indigenously synthesized compounds. The optimized molecular geometries are compared with their counterpart experimental values. Based on previous reports of biofunctions of the indigenously synthesized imine derivatives, they are explored for their potential inhibition properties against two very crucial proteins (main protease (Mpro) and nonstructural protein 9 (NSP9)) of SARS-CoV-2. The calculated interaction energy values of DC2H and DM4H with Mpro are found to be −6.3 and −6.6 kcal/mol, respectively, and for NSP9, the calculated interaction energy value is found to be −6.5 kcal/mol. We believe that the current combined study through experiments and computational techniques will not only pique the interest of the broad scientific community but also evoke interest in their further in vitro and in vivo investigations.