Schiff Base Research Articles

Substituted furan-carboxamide and Schiff base derivatives as potential hypolipidemic compounds: evaluation in Triton WR-1339 hyperlipidemic rat model

Substituted furan-carboxamide and Schiff base derivatives as potential hypolipidemic compounds: evaluation in Triton WR-1339 hyperlipidemic rat model

Experimental and molecular modelling demonstration of effective DNA and protein binding as well as anticancer potential of two mononuclear Cu(II) and Co(II) complexes with isothiocyanate and azide as anionic residues

In the present study, one mononuclear Cu(II) [CuL(SCN)] (1) and one mononuclear Co(II) [CoLN3] (2) complexes, with a Schiff base ligand (HL) formed by condensation of 2-picolylamine and salicylaldehyde, have been successfully developed and structurally characterized. The square planer geometry of both complexes is fulfilled by the coordination of one deprotonated ligand and one ancillary ligand SCN−(1) or N3−(2) to the metal centre. Binding affinities of both complexes with deoxyribonucleic acid (DNA) and human serum albumin (HSA) are investigated using several biophysical and spectroscopic techniques. High values of the macromolecule-complex binding constants and other results confirm the effectiveness of both complexes towards binding with DNA and HSA. The determined values of the thermodynamic parameters support spontaneous interactions of both complexes with HSA, while fluorescence displacement and DNA melting studies establish groove-binding interactions with DNA for both complexes 1 and 2. The molecular modelling study validates the experimental findings. Both complexes are subjected to an MTT test establishing the anticancer property of complex 1 with lower risk to normal cells, confirmed by the IC50 values of the complex for HeLa cancer cells and HEK normal cells. Finally, a nuclear staining analysis reveals that the complexes have caused apoptotic cell death.

Preparation of Schiff base metal catalyst and its catalytic synthesis of propylene carbonate from CO2

In recent years, research on the conversion of CO2 into fine chemical products has emerged as a prominent and dynamic area of study. In this study, four ligands were synthesized using salicylaldehyde, o-phenylenediamine, ethylenediamine, hexanediamine, and 2,6-diaminopyridine as precursors. Subsequently, these ligands were reacted with cobalt nitrate, zinc chloride, and aluminum chloride to synthesize 12 Schiff base metal complexes, which were employed as catalysts for the synthesis of propylene carbonate from CO2 and epichlorohydrin. The findings reveal that the SF-L/Co catalyst demonstrated superior performance, potentially attributed to the robust chelating capability of Co, leading to the provision of more acidic metal centers. Characterization of SF-L/Co was conducted utilizing scanning electron microscopy (SEM), Fourier-transform infrared spectroscopy (FT-IR), energy-dispersive X-ray spectroscopy (EDS), and X-ray diffraction (XRD) techniques. Process conditions were optimized, resulting in the achievement of a 100% yield and selectivity of propylene carbonate under optimal reaction conditions, without the generation of any by-products. Furthermore, the catalyst exhibited remarkable reusability, demonstrating consistent catalytic activity over five successive cycles without a substantial decrease in performance.

Green and Efficient Synthesis, Spectroscopic, Characterization, Antibacterial Activity of Some Selected Transition Metal Complexes of Novel Schiff Base Ligand Derived from 2-amino 5-methyl benzimidazole with 2-bromo Isophthalaldehyde

Green and Efficient Synthesis, Spectroscopic, Characterization, Antibacterial Activity of Some Selected Transition Metal Complexes of Novel Schiff Base Ligand Derived from 2-amino 5-methyl benzimidazole with 2-bromo Isophthalaldehyde

Novel pyrene-based Schiff base ligand as a fluorescent sensor for Al3+ and colorimetric sensor for Ni2+ ions detection: Synthesis, photo-physical and cell imaging studies

A simple fluorescent and colorimetric pyrene-based ((Z)-4-hydroxy-3-((pyren-1-ylmethylene)amino)benzoic acid (HPMB) chemosensor was synthesized through the condensation reaction between pyrene-1-carboxaldehyde and 3-amino-4-hydroxybenzoic acid. The structure of HPMB was elucidated using 1H NMR, MS, and UV–Visible spectroscopic techniques. The receptor HPMB displayed a detectable, colorimetric colour shift in the presence of Ni2+ and the colour of the solution was observed to be light brown. On the other hand, it also exhibited a fluorescent “turn on” response when Al3+ ions were added in DMSO solution (HEPES 0.01 M, pH = 7.4) at room temperature. Job’s plot showed that HPMB binding ratio to Ni2+ and Al3+ ions was in 1:1 ratio. The detection limit for Ni2+ and Al3+ ions was found to be 0.33 × 10-6 M and 0.26 × 10-6 M, respectively. In addition, HPMB was utilised to create a molecular logic gate, and the fluorescence imaging of HeLa cells was investigated because of HPMB’s low cytotoxicity, indicating that it could be used to detect Al3+ and Ni2+ in living cells.

Quaternized oxidized sodium alginate injectable hydrogel with high antimicrobial and hemostatic efficacy promotes diabetic wound healing

In this paper, a hydrogel material with efficient antibacterial, hemostatic, self-healing, and injectable properties was designed for the treatment of diabetic wounds. Firstly, quaternary ammonium salts were grafted with oxidized sodium alginate, and quaternized oxidized sodium alginate (QOSA) was synthesized. Due to the introduction of quaternary ammonium group it has antibacterial and hemostatic effects, at the same time, due to the presence of aldehyde group it can be reacted with carboxymethyl chitosan (CMCS) to form a hydrogel through the Schiff base reaction. Furthermore, deer antler blood polypeptide (DABP) was loaded into the hydrogel (QOSA&CMCS&DABP), showing good swelling ratio and bacteriostatic effect. In vitro and in vivo experiments demonstrated that the hydrogel not only quickly inhibited hepatic hemorrhage in mice and reduced coagulation index and clotting time in vitro, but also significantly enhanced collagen deposition at the wound site, accelerating wound healing. This demonstrates that the multifunctional hydrogel materials (QOSA&CMCS&DABP) have promising applications in the acceleration of skin wound healing and antibacterial promotion.

Stimuli-responsive antioxidant Pickering emulsions stabilized by functionalized cellulose nanocrystals

Stimuli-responsive antioxidant Pickering emulsions play crucial role in many industrial areas. This study demonstrated for the first time oil-in-water Pickering emulsions with outstanding antioxidation and responsive demulsification stabilized by functionalized cellulose nanocrystals (CNCs). Dialdehyde cellulose nanocrystals (DACs) were first prepared through the oxidation of CNCs with periodate, followed by the grafting of p-aminophenols (PAPs) onto their surfaces through Schiff base reaction, affording PAP grafted DACs (DAC-g-PAP) via dynamic covalent linkage. The degree of the oxidation (DO) of DACs had a significant effect on the yield of the targeting DAC-g-PAP nanoparticles. High DO (≥40 %) potentially led to the degradation of DACs during the grafting of PAP. The introduced PAP endowed DACs with excellent radical scavenging capability, thereby providing antioxidant properties while improving the hydrophobicity. DAC-g-PAP nanoparticles were then applied as Pickering emulsifiers to prepare oil-in-water Pickering emulsions. The resultant Pickering emulsions indicated exceptional antioxidant and pH-responsiveness together with good freezing-thaw stability. The structures of DAC-g-PAP nanoparticles were thoroughly characterized in this study.

Synthesis and evaluation of Schiff base as corrosion inhibitor for carbon steel in 1 M HCl solution

Purpose The main purpose of the present study is to introduce new Schiff bases as corrosion inhibitor for carbon steel in 1 M HCl. The inhibitory activity of Schiff base was also assessed. Design/methodology/approach 2,2′-((1Z,1′Z)-((2,2-dimethylpropane-1,3-diyl)bis(azanylylidene))bis(methanylylidene))diphenol was synthesized and it’s performance as an inhibitor was then investigated in 1 M HCl. The inhibition of this compound was studied and evaluated by the chemical methods of electrochemical impedance spectroscopy, electrochemical potential dynamic polarization and Atomic Force microscopy (AFM) method. The thermodynamics parameters were investigated for corrosion of carbon steel in both the absence and presence of Schiff base. Findings The results of the tests showed that this compound has a good performance as an inhibitor and the percentage of inhibition on steel corrosion will increase with increasing concentration and it will reach 70% in the presence of 2 × 10−3 M of this inhibitor. Polarization tests indicated that this compound will act as a mixed inhibitor. Nyquist curves showed that the addition of this substance to the solution increased the charge transfer resistance and decreased the capacity of the double layer. The absorption of the new Schiff base on steel follows Langmuir adsorption isotherm, and the amount of free energy of adsorption indicates the spontaneous adsorption of this inhibitor. Using AFM investigations, the results of electrochemical methods were confirmed. Originality/value Incorporation of a new Schiff base into 1 M HCl is a promising approach for protecting the carbon steel against corrosive solution.

Theory-driven design of graphene schiff base iron nanocomplex as catalyst for composite propellant

New graphene Schiff base iron nanocomplexes (S-792-Fe, S-550-Fe, and S-590-Fe) were designed and fabricated based on investigations of reactions mechanisms of AP pyrolysis, structural analysis of new materials and simulation results of quantum mechanics to deal with the long-standing contradiction between safety and performance for composite propellent combustion catalyst. By taking traditional catalyst Catocene as the benchmark, the S-550-Fe nanocomplexes exhibited competitive catalytic performances, much better anti-migration properties and significantly reduced impact and electrostatic sensitivities. After adding S-550-Fe, the burning rate of propellant enhanced from 13.87 to 19.77 mm s−1 at 15 MPa, and the impact and electrostatic sensitivities are improved to 50.2 cm and 172.12 mJ, respectively. The excellent catalytic performance of S-550-Fe is closely related to its molecular structure, which is manifested by an increase in charge density and a decrease in NH3 oxidation energy barriers. The promotion effects of S-550-Fe on desorption and oxidation of NH3 from the surface of AP is conducive to the rapid and complete pyrolysis of AP, which is reflected in the improvement of combustion rate and temperature gradient. The theory-driven design mode of this work may provide new pathways to tune combustion behaviors of composite propellants from the view of molecular-level insights.

Dispersion of Single-Walled Carbon Nanotubes by Aromatic Cyclic Schiff Bases via Non-Covalent Interactions

One of the challenging issues that hinders the application of single-walled carbon nanotubes (SWCNTs) is the poor solubility and the inevitable formation of bundles. Efforts still need to be made towards solving the problem. Herein, we report a non-covalent strategy to disperse aggregated SWCNTs by aromatic cyclic Schiff bases assisted by ultrasonic techniques. The aromatic cyclic Schiff base (OMM) was synthesized via Schiff base reactions, and the molecular structure was determined by ATR-FT-IR, solid-state 13C-NMR, and HRMS. Although the yielded product showed poor solubility in aqueous solution and organic solvents, it could interact with and disperse the aggregated SWCNTs in dimethyl formamide (DMF) under the condition of ultrasound. UV-vis-NIR, FL, Raman spectra, AFM, and TEM, along with computer simulations, provide evidence for the interactions between OMM molecules and SWCNTs and the dispersion thereof. The semiconductive (7,5), (8,6), (12,1), and (9,7)-SWCNTs expressed a preference for dissolution. The capability of dispersion is contributed by π-π, C-H···π, and lone pair (lp)···π interactions between OMM and SWCNTs based on the simulated results. The present non-covalent strategy could provide inspiration for preparing organic cyclic compounds as dispersants for SWCNTs and then facilitate their further utilization.

Discovery of Novel and Selective Schiff Base Inhibitors as a Key for Drug Synthesis, Molecular Docking, and Pharmacological Evaluation

Discovery of Novel and Selective Schiff Base Inhibitors as a Key for Drug Synthesis, Molecular Docking, and Pharmacological Evaluation

Synthesis, Spectroscopic Characterization and Study of Antibacterial Potency, Antioxidant Scavenging and in-vitro Anti-inflammatory Properties of Pyrimidine-based Schiff Bases

Synthesis, Spectroscopic Characterization and Study of Antibacterial Potency, Antioxidant Scavenging and in-vitro Anti-inflammatory Properties of Pyrimidine-based Schiff Bases

Application of Cations, Acids, and Antioxidants on Mitigating Acrylamide Formation in Food with a Special Focus on Potato and Cereal Based Foods - A Review

Acrylamide is a toxic substance that formsin food during high-temperature processing methods such as deep-frying, baking, and roasting, through the Maillard reaction or the acrolein pathway. Since acrylamide has been identified for its carcinogenicity, genotoxicity, and neurotoxicity, global food authorities have established benchmark levels for different food categories. Consequently, researchers have proposed various mitigation strategies, focusing on agronomical, chemical, physical, and microbial approaches. However, most of these approaches are associated with high cost, technology, extended time, and poor sensory and nutritional quality. In this context, application of various additives such as metal cations, organic and inorganic acids, and antioxidants in optimum amounts have been effective in reducing acrylamide formation. Additives contribute to reducing acrylamide either by interacting with its precursors and/or intermediate products or by breaking down acrylamide into other non-toxic substances. Since cations can form thermostable asparagine/matrix intermediates through chelation reaction between asparagine and metal cations, asparagine will be unavailable to react with carbonyl compounds to form the Schiff base. Lower pH conditions inhibit the acrylamide formation by blocking the protonation of the α-amino group of asparagine and reducing any possibility for nucleophilic addition reactions with carbonyl groups. Toxicity associated with Maillard products can be reduced by using antioxidants in the frying oil or the food. Polyphenols are capable of reducing the acrylamide formation by directly trapping acrylamide at elevated temperature. It is essential to identify the most appropriate additive, its concentration and the optimum process conditions when applying additives to get an optimal acrylamide inhibition. This review article highlights the effect of various additive applications, their effectiveness and possible future advances in food to control acrylamide formation within the accepted level.Keywords: Acrylamide, Antioxidant, Carcinogenicity, Deep-frying, Maillard reaction

Enhancing Spatial Resolution in Tandem Mass Spectrometry Ion/Ion Reaction Imaging Experiments through Image Fusion.

We have recently developed a charge inversion ion/ion reaction to selectively derivatize phosphatidylserine lipids via gas-phase Schiff base formation. This tandem mass spectrometry (MS/MS) workflow enables the separation and detection of isobaric lipids in imaging mass spectrometry, but the images acquired using this workflow are limited to relatively poor spatial resolutions due to the current time and limit of detection requirements for these ion/ion reaction imaging mass spectrometry experiments. This trade-off between chemical specificity and spatial resolution can be overcome by using computational image fusion, which combines complementary information from multiple images. Herein, we demonstrate a proof-of-concept workflow that fuses a low spatial resolution (i.e., 125 μm) ion/ion reaction product ion image with higher spatial resolution (i.e., 25 μm) ion images from a full scan experiment performed using the same tissue section, which results in a predicted ion/ion reaction product ion image with a 5-fold improvement in spatial resolution. Linear regression, random forest regression, and two-dimensional convolutional neural network (2-D CNN) predictive models were tested for this workflow. Linear regression and 2D CNN models proved optimal for predicted ion/ion images of PS 40:6 and SHexCer d38:1, respectively.

Enhancing bacterial control and daylight-driven water remediation with chitosan-impregnated MoC nanosheets.

The functionalization of nanoparticles with 2D nanosheets is an effective approach to enhance their functional properties for pollutant removal. This research outlines the synthesis of a 2D-delaminated molybdenum carbide (MXene) chitosan nanocomposite (2D-d-Mo2CTx-Cs NC) with bacterial control and photocatalytic properties for dye adsorption. The nanocomposite includes Tx-surface terminating groups O, OH, and F. In this investigation, the composite was synthesized using the etching method and its formation was confirmed through UV spectra at 288nm. It was characterized through FTIR, XRD, Particle size, Zetapotential, FESEM, HRTEM, EDAX, and XPS analyses. FTIR spectral analysis of NC suggests that amines are formed through a Schiff base reaction between glutaraldehyde and Cs, or through the interaction of terminal aldehydes and carbonyl groups. The XRD analysis confirmed the crystalline structure of the composite. FESEM images revealed irregularly structured nanosheets (NSs) material in the prepared 2D-d-Mo2CTx-Cs NC samples. HRTEM images revealed 2D-d-Mo2CTx NSs impregnated onto Cs with an average size of 50nm, as confirmed by a particle size analyzer, with a zeta potential value of -15mV. Additionally, Mo, C, N, and O are the most significant elements present in the NC, as confirmed by EDAX and XPS analyses. Further, biocompatibility testing of 2D-d-Mo2CTx-Cs NC yielded positive results. Moreover, under sunlight, the composites effectively adsorbed methylene blue with a 90% adsorption capacity, as confirmed by kinetic studies. Furthermore, the synergistic effect of Cs and d-Mo2CTx NSs resulted in significant antibacterial (50-200µl of 1mg/ml) and antibiofilm activity (100µl of 1mg/ml) against pathogenic bacteria. Furthermore, this study represents the first report on the use of 2D-d-Mo2CTx-Cs NC for daylight-influenced photocatalytic applications with a bacteria-controlling effect.

Novel Antipyrine Substituted 4-Thiazolidinones: Synthesis, DNA Binding and Topoisomerase Inhibition Activities, and in-silico Studies

In this study, we report the synthesis and characterization of novel 4-thiazolidinones containing antipyrine (3a-e) derived from the starting compounds of Schiff bases (2a-e). The Schiff bases were synthesized using aldehydes of natural origin, such as citronellal, cuminaldehyde, 2-thiazolecarboxaldehyde, 5-methylfurfural, and syringaldehyde. Their FTIR spectra revealed the enol- tautomeric solid-state structures of compounds 3b and 3d. The pUC18 plasmid DNA binding specificity and capacity of the compounds to catalytically generate topoisomerase I activity were also examined using agarose gel electrophoresis. The compounds induced changes in DNA mobility and showed a topoisomerase I inhibitory effect at all doses. 4-Thiazolidinones had a higher affinity in DNA and topoisomerase I than the Schiff bases. DNA binding and topoisomerase I activities were most effective at low concentration (6 μM) for the compounds of Schiff bases 2a, d, and 4-thiazolidinones 3a, d. Furthermore, this study presents computational methods for addressing the molecules’ drug-like properties. 2a, d, and 3a, d Compounds were used as representative of the most bioactive among the newly synthesized molecules in in-silico studies. The web tools of ADMETlab, SwissADME, OSIRIS, and the BOILED-Egg method were used to conduct in-silico biological studies involving ADME prediction, BBB penetration, gastrointestinal absorption, and toxicity studies. The ADME profile of the query compounds gets within the range of applicability and is at an appropriate level. in-silico Studies revealed that compounds 2a, d, and 3a, d are neither hERG blockers nor AMES toxic. However, compounds 2a and 3a have hepatotoxicity.

Preparation, characterization, single-crystal analysis, and cytotoxic assessment of complexes formed by Schiff base and 8-hydroxyquinoline co-ligand with Co(II), Ni(II), and Mn(II) metal ions

This study focuses on the preparation of mixed ligand complexes of Ni(II), Co(II), and Mn(II) by combining the co-ligands 2-(((4-fluorophenyl)imino)methyl)-4-methoxy-6-nitrophenol (L1) and 8-hydroxyquinoline (L2). The chemical structures of the all compounds were examined using various techniques, including 1H and 13C NMR, FT-IR, UV–Vis, TGA, molar conductivity, LC-MS/MS, elemental analysis and magnetic susceptibility. The crystal structure of the ligand L1 was determined using single crystal X-ray analysis revealing that the ligand favors the phenol-imine tautomeric form in the solid state. All complexes are suggested to have an octahedral structure. Finally, the MTT assay was used to determine the toxicity level of the mixed ligand complexes in human non-small cell lung cancer (A549) and normal bronchial epithelial cell lines (BEAS-2B). The results showed that the [Ni(L1)(L2).(H2O)2] complex (IC50: 5.97 µM) exhibited high cytotoxic activity at a lower dose than cisplatin compared to the other compounds. In contrast, the [Ni(L1)(L2).(H2O)2] complex was shown to exhibit significantly lower cytotoxic activity (IC50 > 100 s µM) in the BEAS-2B (normal bronchial epithelial cell) cell line. The other compounds [Co(L1)(L2).(H2O)2] and [Mn(L1)(L2).(H2O)2] were shown to have no significant anticancer activity in A549 cells due to their cytotoxic activity at higher doses than cisplatin (IC50 > 100 s µM).

Sustainable Domino C‐N/C‐C Bond Formation with Outstanding E Factors and High Volume Productivity

One of the primary concerns in the development of new chemical reactions pertains to the choice of solvents, many of which can have harmful ecological impacts. Additionally, a major portion of waste generated in the chemical and pharmaceutical industries comes from the solvents employed. The elimination of solvent usage is highly desirable for creation of environmentally friendly chemical processes as it leads to a substantial reduction in waste production. Accordingly, a novel neat reaction was developed for the synthesis of (β‐amino)nitriles as a prominent moiety through a domino process. It involved the use of silylphenyl triflates, Schiff bases, and acetonitrile (CH₃CN) in a 1:1:1 ratio, with CH₃CN served as a starting material rather than a solvent. This reaction was initiated by caesium fluoride (CsF) to form an aryne through 1,2‐elimination followed by sequential 1,2‐addition, proton transfer, and a second 1,2‐addition. Complete conversion was carried out at 25 °C for 1.0 h to give (β‐amino)nitriles in 76–88% yields. This solvent‐free reaction minimized waste production and reduced costs associated with extra reagents, solvents, and labour. It possesses a compelling E factor and impressive volume productivity. This reaction sets a new benchmark for solvent‐free aryne domino processes in green chemistry advancements.

A porous thiosemicarbazide functionalized covalent organic framework served as sensitive fluorescent sensor for Hg2+

The detection of heavy metal pollution in food and environment is of great significance for environmental pollution control and human health. 1,3,5-Tris(p-formylphenyl)benzene (TFPB) and thiosemicarbazide (TS) were used as building blocks to construct a thiosemicarbazide functionalized covalent organic framework (COF) through Schiff base condensation reaction. Hg2+ ions can significantly enhance the fluorescence of the prepared COF-TFPB-TS, and thus COF-TFPB-TS can be utilized for highly selective and sensitive detection of Hg2+ ions. Moreover, COF-TFPB-TS showed high performance for detecting Hg2+ in fresh fruit juice, mineral water and tap water, which demonstrated its ability to be applied in real sample testing.

Synthesis of the polyethylene polyamine-based flexible covalent organic frameworks and their application for capturing and fluorescence sensing iodine

Effective uptake of radioactive steam waste in the fission process is of great vital for the safe use of nuclear energy. Nitrogen-rich polyethylenepolyamine provides effective adsorption sites for the capture of iodine, but triethylenediamine (TEDA)-impregnated activated carbon has the disadvantages of easy sublimation, poor safety, and poor regeneration capacity. Herein, we report five polyethylene polyamine-based (PEPA-based) flexible COFs for the first time which were synthesized by Schiff base polymerization reactions with the flexible knot [2,4,6-tris(4-formylphenoxy)-1,3,5-triazine (TPT–3–CHO)] and flexible linkers (PEPA). The PEPA-based flexible COFs possess large surface areas and strong iodine adsorption capacity, which can be reused. With the increase of the linker lengths, their BET-surface areas decreases, but their adsorption of iodine increase. When dispersed in polar organic solvents, the PEPA-based flexible COFs can fluorescently sense iodine through the electron transfer mechanism and the energy transfer mechanism.