Showing papers in "New Journal of Chemistry in 2021"

A novel electrochemical aflatoxin B1 immunosensor based on gold nanoparticle-decorated porous graphene nanoribbon and Ag nanocube-incorporated MoS2 nanosheets

Abstract: The accurate and precisive monitoring of aflatoxin B1 (AFB1), which is one of the most hazardous mycotoxins, especially in agricultural products, is significant for human and environmental health. AFB1 generally contaminates agricultural products such as corn and feedstuff. In this paper, a novel electrochemical AFB1 immunosensor was constructed based on Ag nanocubes (AgNCs) incorporated trigonal metallic MoS2 nanosheets with 1T phase (AgNCs/1T-MoS2) as signal amplification and gold nanoparticles/porous graphene nanoribbon (AuNPs/PGNR) as an electrochemical sensor platform. First, the chronoamperometry method was implemented to provide electrodeposition of AuNPs on PGNR following chemical reduction of PGNR. Immobilization of the primer AFB1 antibody was performed via amino-gold affinity between primer antibody and AuNPs/PGNR composite. Subsequently, the conjugation of seconder antibody to AgNCs/1T-MoS2 was performed by strong π–π and electrostatic interactions. To describe the surface morphology and elemental composition of the prepared electrochemical AFB1 immunosensor, physicochemical characterization techniques such as scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), and X-ray diffraction (XRD) were used. Furthermore, cyclic voltammetry (CV), differential pulse voltammetry (DPV), and electrochemical impedance spectroscopy (EIS) techniques were used to evaluate the immunosensor's electrochemical performance. The developed electrochemical AFB1 immunosensor offered a good sensitivity with a detection limit (LOD) of 2.00 fg mL−1. Finally, an electrochemical AFB1 immunosensor with satisfactory selectivity, stability and reusability was applied in wheat samples with high recovery.

Potentialities of selenium nanoparticles in biomedical science

Abstract: Nanotechnology is defined as the branch of science dealing with extremely small-sized particles with a size in the range of 1–100 nm, which are termed nanoparticles. Due to the extremely small size of nanoparticles, they display unique electronic and optical properties, which differentiate them from their bulk form. Thus, due to the unique properties of nanoparticles, they play a crucial role in a variety of fields, including the biomedical, environmental, agricultural, and industrial fields. Selenium belongs to Group 16 of the periodic table with an atomic number of 34 and its nanoparticles have been highlighted as a potential material to alleviate several problems due to the formation of biofilms, production of ROS, low redox activity, etc. These nanoparticles can be synthesized through chemical, physical and biological methods. Since existing reviews mainly concentrated on the individual applications of selenium nanoparticles such as in diagnosis and therapeutics, the present review mainly highlights the potential activity of selenium nanoparticles in the biomedical domain, making them a potential theragnostic agent. Specifically, this review will present detailed information on the bioimaging and therapeutic activity, together with the role of selenium nanoparticles in the current scenario of the ongoing pandemic (SARS-CoV-2). It will also focus on procedures for their synthesis and properties that make them potential candidates for applications in various domains. Finally, we provide a detailed future outlook.

Photocatalytic activity of new nanostructures of an Ag(I) metal–organic framework (Ag-MOF) for the efficient degradation of MCPA and 2,4-D herbicides under sunlight irradiation

Abstract: A new Ag(I) metal–organic framework (Ag-MOF) [Ag(p-OH-C6H4COOH)2(NO3)]n [Ag(PHBA)2(NO3)]n, (1) (PHBA: C8H6O4{p-hydroxybenzoic acid}) was synthesized using two different methods; the laying method (single crystal) and sonochemical irradiation (nanostructures). Scanning electron microscopy (SEM), powder XRD, and FT-IR spectroscopy were used to characterize the materials. The impacts of various parameters, including the ultrasonic (US) power, reaction time, reactant concentration, and temperature requirements to reach a controlled synthesis were extensively investigated. Compound 1-5 (obtained via sonochemical irradiation) showed an excellent catalytic activity towards simultaneous photodegradation of 2-methyl-4-chlorophenoxyacetic acid (MCPA) and 2,4-dichlorophenoxyacetic acid (2,4-D) in an aqueous solution under sunlight irradiation. The response surface methodology (RSM) for the modelization and optimization of the photodegradation of the MCPA/2,4-D mixture was utilized. The maximum photodegradation efficiencies for 2,4-D and MCPA (96.0 and 98.0% respectively) were observed under optimal conditions of C0 = 4.5 mg L−1, catalyst dose = 0.4 g L−1, pH = 5.5 and irradiation time = 20 min. The determined quantum yield of Ag-MOF was 3.21 × 10−5 molecules per photon with excellent reusability in terms of the degradation efficiency (e.g., 97% for the first cycle and 86% for the fifth). Ag-MOF is suggested for the efficient treatment of organic pollutants in wastewater systems.

Two antioxidant 2,5-disubstituted-1,3,4-oxadiazoles ( CoViTris2020 and ChloViD2020 ): successful repurposing against COVID-19 as the first potent multitarget anti-SARS-CoV-2 drugs

Abstract: Repurposing of known drugs and compounds as anticoronavirus disease 2019 (anti-COVID-19) agents through biological reevaluation of their activities, especially the anti-severe acute respiratory syndrome coronavirus 2 (anti-SARS-CoV-2) activities, is a new viable trend in drug discovery for the COVID-19 pandemic in 2020. Comprehensive inhibition of the enzymes and proteins of coronavirus and coronavirus 2 (i.e., multitarget inhibition) can be considered one of the most promising strategies for the development of highly potent remedies for COVID-19. However, almost all the reported inhibitors of the different life cycle stages of SARS-CoV-2 lack extreme potency against the major and fateful SARS-CoV-2 enzymes (e.g., RNA-dependent RNA polymerase “RdRp”, papain-like protease “PLpro”, and main protease “Mpro”). Herein, two antioxidant polyphenolic 1,3,4-oxadiazole compounds previously synthesized by me were repurposed and introduced, 1,2,3-tris[5-(3,4,5-trihydroxyphenyl)-1,3,4-oxadiazol-2-yl]propan-2-ol (named CoViTris2020) and 5-[5-(7-chloro-4-hydroxyquinolin-3-yl)-1,3,4-oxadiazol-2-yl]benzene-1,2,3-triol (named ChloViD2020), as the first multitarget SARS-CoV-2 inhibitors with higher potencies than other drugs reported to date (about 65, 171, and 303.5 times for CoViTris2020 and 20, 52.5, and 93 times for ChloViD2020 compared to those of remdesivir, ivermectin, and favipiravir, respectively). These two unique 2,5-disubstituted-1,3,4-oxadiazole derivatives were computationally studied (through molecular docking in almost all SARS-CoV-2 proteins and one human protein) and biologically evaluated (through one of the most credible in vitro anti-COVID-19 assays) for their anti-COVID-19 activities. The results of the computational docking showed that CoViTris2020 and ChloViD2020 exhibited very high inhibitory binding affinities with most of the docked SARS-CoV-2/human proteins (e.g., they exhibited low binding energies of −12.00 and −9.60 kcal mol−1, respectively, with RdRp-RNA). Interestingly, the results of the biological assay showed that CoViTris2020 and ChloViD2020 exhibited very high and extremely significant anti-COVID-19 activities (anti-SARS-CoV-2 EC50 = 0.31 and 1.01 μM, respectively). Additionally, they may also be very promising lead compounds for the design and synthesis of new anti-COVID-19 agents (through structural modifications and further computational studies). Therefore, further investigations for the development of CoViTris2020 and ChloViD2020 as anti-COVID-19 drugs through in vivo biological evaluations and clinical trials are necessary. In brief, the development of CoViTris2020 and ChloViD2020 as the first two members of the new and promising class of anti-COVID-19 polyphenolic 2,5-disubstituted-1,3,4-oxadiazole derivatives will result in a therapeutic revolution for the treatment of SARS-CoV-2 infection and its accompanying COVID-19.

A van der Waals heterostructure of MoS2/MoSi2N4: a first-principles study

Abstract: Motivated by the successful preparation of MoSi2N4 monolayers in the last year [Y.-L. Hong et al., Science, 2020, 369, 670–674], we investigate the structural, electronic and optical properties of the MoS2/MoSi2N4 heterostructure (HTS). The phonon dispersion and the binding energy calculations refer to the stability of the HTS. The heterostructure has an indirect bandgap of 1.26 (1.84) eV using PBE (HSE06) which is smaller than the corresponding value of MoSi2N4 and MoS2 monolayers. We find that the work function of the MoS2/MoSi2N4 HTS is smaller than the corresponding value of its individual monolayers. The heterostructure structure can enhance the absorption of light spectra not only in the ultraviolet region but also in the visible region as compared to MoSi2N4 and MoS2 monolayers. The refractive index behaviour of the HTS can be described as the cumulative effect which is well described in terms of a combination of the individual effects (the refractive index of MoSi2N4 and MoS2 monolayers).

Bio-mass derived functionalized graphene aerogel: a sustainable approach for the removal of multiple organic dyes and their mixtures

Abstract: Herein, fabrication of a functionalized graphene aerogel (f-GA) from a biomass (pear fruit)-derived graphene aerogel (GA) is described. Functionalization showed a prominent effect that results in the improved adsorption capacity of f-GA compared to GA, and even better (∼more than double) than commercially available activated carbon (AC). f-GA has been studied for the removal of three different model pollutant dyes, namely crystal violet (CV), methylene blue (MB), rhodamine B (RhB) and their mixtures, along with it also being used for dye removal from unknown real industrial samples. Moreover, a detailed comparative analysis showed the adsorption capacity of f-GA towards CV, MB, and RhB has been improved up to ∼6, ∼7, and ∼10 times, respectively, compared to that of control GA. The recyclability of f-GA was also tested: it works for five cycles without losing its apparent performance.

Revisiting lignin: a tour through its structural features, characterization methods and applications

Abstract: Lignin is a complex organic polymer found in the plant cell wall with important biological functions, such as water transport, mechanical support, and resistance to various stresses. It is considered the second most abundant biopolymer on earth and the largest natural source of aromatics. Despite being annually co-produced in massive amounts, during cellulose fragmentation in the pulp industry and ethanol biorefinery, it is clearly undervalued; most of it is discarded or burned as fuel for energy production and, so far, only ca. 1–2% of lignin has been utilized as a high-value product. This underuse makes lignin the future resource of choice to produce green fuels and a wide range of added-value biomaterials and chemicals, which can contribute to the transition to more sustainable industries. However, its great variability between plant families combined with its complex and chemically inert structure is challenging researchers who seek for strategies regarding its valorization. With this scope, several different approaches have emerged regarding the development of better and efficient isolation methods, purification and characterization techniques, and improved methodologies for lignin chemical modification and blending with other compounds. These improvements represent important opportunities for the creation of value-added lignin-based biopolymers and materials and some have already shown potential to be scaled up. All these aspects are pedagogically introduced and discussed in this review.

Fluorescence quenching mechanism and the application of green carbon nanodots in the detection of heavy metal ions: a review

Abstract: Fluorescent carbon nanodots (CNDs) are renowned as a new family of zero-dimensional nanomaterials. In the current scenario, CNDs are considered an iconic research field because of their desirable fluorescent behavior, biocompatibility, the ease of functionalization, chemical inertness, and photostability. There are many ways to produce CNDs but natural renewable carbon sources can produce CNDs on a large scale. This can be a significant advantage for researchers to explore their versatile applications. Hitherto, CNDs have been scrutinized as a selective and sensitive fluorescent sensor for different heavy metal ions even at femtomolar ranges. This review overlooks all the previously provided information on the synthesis, properties, and application of CNDs. However, it focuses on the fluorescence-sensing mechanism of heavy metal ions using green-derived CNDs as the detection tool. We give a brief outline of green sources utilized in the CND synthesis, its properties, and the fluorescence mechanism of CNDs. Finally, we comprehensively summarize the quenching mechanism of heavy metal ions to illustrate the related green CND-based sensors. Furthermore, problems and possible solutions to overcome the future path of CNDs in this sensing field are discussed.

Design and synthesis of new 4-(2-nitrophenoxy)benzamide derivatives as potential antiviral agents: molecular modeling and in vitro antiviral screening

Abstract: Regarding the crucial role of deubiquitinase (DUB) enzymes in many viruses, in particular, Adenovirus, HSV-1, coxsackievirus, and SARS-CoV-2, DUB inhibition was reported as an effective new approach to find new effective antiviral agents. In the present study, a new wave of 4-(2-nitrophenoxy)benzamide derivatives was designed and synthesized to fulfill the basic pharmacophoric features of DUB inhibitors. The molecular docking of the designed compounds against deubiquitinase enzymes of the aforementioned viruses was carried out. Significant molecular docking results directed us to conduct in vitro antiviral screening against the aforementioned viruses. The biological data showed very strong to strong antiviral activities with IC50 values ranging from 10.22 to 44.68 μM against Adenovirus, HSV-1, and coxsackievirus. Compounds 8c, 8d, 10b, and 8a were found to be the most potent against Adenovirus, HSV-1, coxsackievirus, and SAR-CoV-2, respectively. Also, the CC50 values of the examined compounds ranged from 72.93 to 120.50 μM. Finally, the in silico ADMET and toxicity studies demonstrated that the tested members have a good profile of drug-like properties. Furthermore, we concluded the structure–activity relationship (SAR) of the newly designed and synthesized compounds regarding their in vitro results, which may help medicinal chemists in further optimization to obtain more potential antiviral candidates in the near future as well.

Superhydrophobic, superamphiphobic and SLIPS materials as anti-corrosion and anti-biofouling barriers

Abstract: Nature-inspired interfacial materials with special wettability have received considerable attention owing to their superior properties and promising multifunctional applications. Owing to the unique interfacial phase contacts and liquid–repellent property, the interfacial materials with special wettability provide a great potential for corrosion inhibition and biofouling suppression. Thus, this brief review and perspective study provides an overview about the characteristics, fabrication and recent advances of three types of interfacial materials with special wettability, namely superhydrophobic, superamphiphobic and slippery liquid-infused porous surface (SLIPS) toward anti-corrosion and anti-biofouling applications. The bottlenecks and future research priorities of the functional interfacial materials with special wettability were pointed out to accelerate the comprehensive understanding and the development of this research field.

Biomedical applications of metal–organic framework (MOF)-based nano-enzymes

Abstract: Natural enzymes are highly specific biocatalysts that can selectively catalyse specific biological reactions. However, the high preparation cost and easy deactivation of natural enzymes limit their practical applications. In the past ten years, nano-enzymes have been developed rapidly because of their excellent physical and chemical properties, low cost, high stability and easy storage, and can be used as a bridge to natural enzymes. These are a class of enzyme-like nanomaterials, which have some similarities with natural enzymes in terms of their total size, shape and surface charge. They themselves can simulate the bionic catalytic function of enzymes through the catalytic activity of inorganic materials. Metal–organic frameworks (MOFs) and their derivatives are expected to be substitutes for conventional enzymes in enzymatic reactions, and nano-enzymes have shown potential in the field of biomedicine, such as in antimicrobial drugs, biological detection and cancer treatment. In this review, the various types of MOF-derived nano-enzymes and the activities of corresponding simulated enzymes are summarized, and the latest applications of MOF-derived nano-enzymes in biosensing, as antibacterial compounds and in cancer treatment are mainly introduced. In addition, the development prospects of nano-enzymes is introduced in order to provide new ideas for the design and applications of nano-enzymes in the future.

Chalcogenides as photocatalysts

Abstract: Chalcogenides are narrow-band gap semiconductors that have been widely used as photocatalysts. These narrow-band gap materials allow more efficient absorption of over 40% of solar energy in the visible light range, which will eventually improve its photocatalytic properties. Under visible light irradiation, these materials generate electron and hole (e−/h+) pairs. Photo-generated e−/h+ pairs have been utilized to split water into hydrogen and oxygen and to remove and degrade industrial, pharmaceutical and agricultural organic/inorganic/biological pollutants that have been accumulated in the environment. In this perspective review, different types of chalcogenides, namely, binary, multinary (ternary and quaternary) and chalcogenide-based heterostructures are presented briefly. This perspective review also highlights the mechanisms involved and remarkable photocatalytic activity enhancement under visible light irradiation that has been widely researched such as the photocatalytic degradation of industrial pollutants and photocatalytic inactivation of bacteria. Lastly, future prospects for the use of chalcogenides as photocatalysts and chalcogenide-based heterostructures were discussed.

The antimicrobial potential and pharmacokinetic profiles of novel quinoline-based scaffolds: synthesis and in silico mechanistic studies as dual DNA gyrase and DHFR inhibitors

Abstract: The resistance of pathogenic microbes to currently available antimicrobial agents has been considered a global alarming concern. Hence, close attention should be paid to the development of novel potent antimicrobials. Herein, we report the synthesis, in vitro antimicrobial evaluation, of two novel sets of quinoline derivatives as potential DNA gyrase and DHFR inhibitors. The design of new compounds depended on modifying the structural aspects of previously reported fluoroquinolones. In both sets, the methyl group replaced the fluorine atom at C-6. In the first set, the diverse heterocyclic fragments of reported antimicrobial potentials, including pyrazole, isoxazole, and pyrimidine, were attached to C-3 of the quinoline scaffold. In the second set, the quinolone ring was replaced with the pyrazolo[3,4-b]quinoline scaffold to examine the effect of this action on the antimicrobial activity and the in silico virtual binding with DNA gyrase and DHFR. The preliminary antimicrobial activity of new compounds was assessed against a panel of pathogenic microbes including Gram-positive bacteria (Streptococcus pneumonia and Bacillus subtilis), Gram-negative bacteria (Pseudomonas aeruginosa and Escherichia coli), and fungal strains (Aspergillus fumigatus, Syncephalastrum racemosum, and Geotriucum candidum). Six derivatives displayed relatively potent antimicrobial activity with a percent activity range of 80–113% relative to ampicillin, gentamicin, and amphotericin B as reference antimicrobial agents. Molecular docking studies were conducted to predict the binding affinities of new compounds toward the active sites of DNA gyrase and DHFR as proposed therapeutic targets.

Magnetization of biochar nanoparticles as a novel support for fabrication of organo nickel as a selective, reusable and magnetic nanocatalyst in organic reactions

Abstract: Catalyst species are an important class of materials in chemistry, industry, medicine and biotechnology. Also, waste recycling is an important process in green chemistry and economic efficiency. Therefore, in order to recycle waste, biochar nanoparticles were prepared from chicken manure. Then, the biochar nanoparticles were magnetized under a green and environmentally friendly method. Finally, the surface of the magnetic biochar nanoparticles was modified and further they were applied as a novel support for fabrication of nickel as a homoselective and reusable catalyst in organic reactions. The structure of this organic–inorganic catalyst has been characterized by N2 adsorption–desorption isotherms, and the SEM, EDS, WDX, XRD, TGA, AAS, FT-IR and VSM techniques. This magnetically recyclable catalyst was used in the homoselective synthesis of tetrazole and pyranopyrazole derivatives. This catalyst can be reused several times without significant loss of its catalytic efficiency. The heterogeneity and stability of this nanocatalyst were studied by hot filtration and the AAS technique. Also, the reused catalyst was characterized by the SEM, EDS, AAS and BET techniques.

Schiff base-functionalized silatrane-based receptor as a potential chemo-sensor for the detection of Al3+ ions

Abstract: Excess Al3+ ions are considered toxic to living organisms Keeping the harmful effects of excess Al3+ metal ions in mind, a new Schiff base = functionalized silatrane as a potential chemo-sensor for the recognition of aluminium metal ions with high selectivity and specificity has been designed and well characterized using various characterization techniques such as IR, 1H NMR, 13C NMR, TGA, and mass spectroscopy The chemo-sensing properties were studied using ultraviolet and fluorescence spectroscopy The absorption spectrum of the synthesized receptor was changed only by the addition of Al3+ ions, while other ions showed negligible changes The 1 : 1 stoichiometric ratio of the chemo-sensor 4b with Al3+ was confirmed by Job's plot and linearity in the B–H plot The limit of detection observed for Al3+ ions was 2273 × 10−7 M and 98 × 10−9 M from ultraviolet and fluorescence spectroscopy, respectively The binding constant from the B–H plot and the Stern–Volmer quenching constant were found to be 02279 × 106 M−1 and 27 × 106 M−1, respectively These results explain the potential chemo-selectivity of the receptor 4b towards Al3+ metal ions, which may be useful for biological and industrial purposes

New quinoxaline-2(1H)-ones as potential VEGFR-2 inhibitors: design, synthesis, molecular docking, ADMET profile and anti-proliferative evaluations

Abstract: Eleven new quinoxaline derivatives were designed and synthesized as modified VEGFR-2 inhibitors of our previous work. The synthesized compounds were tested against three human cancer cell lines (HepG-2, MCF-7 and HCT-116). Compounds 11g, 11e and 11c were the most potent members against the tested cells. Compound 11g (IC50 = 4.50, 2.40, and 5.90 μM) was the most potent member compared to doxorubicin (IC50 = 8.29, 9.65, and 7.68 μM) and sorafenib (IC50 = 7.33, 9.41, and 7.23 μM) against HepG-2 and HCT-116, and MCF-7 cell lines, respectively. Compound 11e showed better anti-proliferative activities than doxorubicin and sorafenib with IC50 values of 5.34, 4.19, and 6.06 μM, against HepG-2 and HCT-116 and MCF-7 cell lines, respectively. In addition, the most active anti-proliferative derivatives 11c, 11e, 11f, and 11g were selected to evaluate their inhibitory activities against VEGFR-2. The tested compounds displayed good inhibitory activity with IC50 values ranging from 0.75 to 1.36 μM. Among them, compound 11g was the most active member with an IC50 value of 0.75 μM, compared to the reference drug; sorafenib (IC50 = 1.29 μM). Moreover, docking studies revealed that the synthesized compounds have good binding patterns against the prospective molecular target; VEGFR-2. In addition, in silico, ADMET and toxicity studies showed a high level of drug likeness for the synthesized compounds.

The latest strategies in the fight against the COVID-19 pandemic: the role of metal and metal oxide nanoparticles

Abstract: The outbreak of the COVID-19 epidemic, which appeared at the end of 2019, has had a tremendous impact on the entire world, both in terms of health, economics and the environment. So far, extensive strategies have been implemented for the fast diagnosis, prevention, control and treatment of the SARS-CoV-2 virus. Advances in technologies based on metals and metal oxides nanoparticles such as Ag, Au, Cu2O, TiO2, Fe3O4, have opened up new perspectives in this regard. These materials have been extensively used for the management of COVID-19 due to their unique features. These materials have been applied for the preparation of antiviral face masks, coatings, different immunosensors, etc. In this review, we summarize and highlight the latest technologies, implementations and achievements based on metal and metal oxide nanoparticles in order to fight the emerging coronavirus. We present the preventive and diagnostic strategies to control this epidemic with the help of metals and metal oxide nanoparticles.

Novel 1,3,5-triazine-based pyrazole derivatives as potential antitumor agents and EFGR kinase inhibitors: synthesis, cytotoxicity, DNA binding, molecular docking and DFT studies

Abstract: We herein report the design and synthesis of new 1,3,5-triazine-based pyrazole derivatives (5a–i) with anticancer activity targeting the epidermal growth factor (EGFR) tyrosine kinase. The newly synthesized compounds were characterized using spectroscopic techniques such as 1H NMR, 13C NMR, mass spectrometry and elemental analysis. All the compounds exhibited moderate to good anticancer activity against MCF-7 (human breast), HepG2 (human liver), HCT116 (human colorectal), PC-3 (human prostate), LoVo (human colon) and LoVo/DX (doxorubicin-resistant) cancer cell lines except compound 5i, which exhibited poor activity. Compounds 5f, 5g and 5h possessed more promising anticancer activity and the results were expressed as IC50 values in nM. These compounds also displayed potent inhibitory activity against EGFR-tyrosine kinase with IC50 values of 395.1, 286.9 and 229.4 nM, respectively in comparison with the standard drug, erlotinib. The docking studies revealed that the compounds showed a good affinity towards the target EGFR kinase (PDB ID: 6V6O) by forming multiple H-bonds with amino acids. The binding interaction of the more active compounds (5f, 5g and 5h) with Ct-DNA was explored using spectroscopic, viscometric, electrochemical and docking techniques. Both the experimental and theoretical findings of DNA binding showed consistent results and confirmed the groove mode of interaction of these compounds with DNA. The in vitro ADME properties were also evaluated, thus allowing the identification of optimized compounds as promising anticancer agents. Finally, density functional theory (DFT) geometry optimization and the relevant quantum parameters were calculated for the active compounds using the B3LYP level.

The synthesis, spectroscopic characterization, DFT/TD-DFT/PCM calculations of the molecular structure and NBO of the novel charge-transfer complexes of pyrazine Schiff base derivatives with aromatic nitro compounds

Abstract: The novel charge-transfer (CT) solid complexes of pyrazine Schiff bases, derived from 2-aminopyrazine and substituted benzaldehydes (N-benzylidenepyrazin-2-amine, (NBPA)) and N-(((4-dimethylamino)benzylidene)pyrazin-2-amine) (NDMABPA) with some aromatic nitro compounds have been synthesized and characterized experimentally using ultraviolet-visible (UV-Vis) absorption, infrared spectra and proton nuclear magnetic resonance (1HNMR) spectroscopy. Complexes were formed in a molar ratio of 1 : 1 with good indications for the existence of charge-transfer in its molecular structure. Theoretical studies were done on donors and acceptors, elucidating their structures and active sites where the charge-transfer occurs. The experimental work was done in ethanol. Solution characterizations included the determination of the molecular structure of formed CT complexes, verifying the 1 : 1 (donor:acceptor) ratio in ethanol. The quantum mechanical calculations of geometries and energies were attained using the density functional theory with Becke's three parameter exchange functional method. The Lee–Yang–Parr correlation functional approach (B3LYP/DFT) combined with the 6-31G(d,p) basis set has been consecutively carried out in solution using ethanol as a solvent to compliment measured results, and to justify CT within donors and acceptors. The optimized energy, complexation energy, geometrical parameters, natural atomic charges, as well as the 3D-plots of the molecular electrostatic potential maps (MEP) were computed and elucidated. They agreed with the experimental results, wherein complex stabilities are attributed to the occurence of charge-transfer. The electronic spectra were computed and executed using time dependent-density functional theory (TD-DFT) via the addition of polarizable continuum solvation method PCM, PCM-TD-DFT. The allowed singlet transitions are positioned, and their highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) involvement is represented. The descriptions of frontier HOMO and LUMO molecular orbitals attributed to the first four singlet transitions, are shown. For all formed solid complexes, the main relationship between donor and acceptor molecules is through the π–π* interaction. A secondary n–π* transition was noticed in some complexes. The vibrational wavenumbers were also determined using B3LYP/6-31G(d,p), and the results match with the experiment. The small energy gap between HOMO and LUMO energies indicate that CT occurs within donors and acceptors. The hyperconjugative interactions, molecular stability, bond strength and intramolecular CT have been investigated applying natural bond orbital (NBO) analysis. The mean polarizability, total static dipole moment, anisotropy of polarizability, and mean first-order hyperpolarizability have also been attained. The obtained values show that CT complexes are accomplished candidates to non-linear optical (NLO) materials.

ZnCl2 regulated flax-based porous carbon fibers for supercapacitors with good cycling stability

Abstract: Flax fibers, with abundant resources and a low cost, are an excellent precursor of carbon fibers for supercapacitors. At present, they are very attractive for designing electrodes with high electrochemical performance via a simple and green way. Hence, we systemically control the specific surface area and pore structure of flax-based carbon fibers by impregnating them with zinc chloride (ZnCl2) solution. The results show that the dehydration and expansion effects of ZnCl2 affect the microstructure, which is directly related to the specific capacitance. After activation, the optimized electrode exhibited the highest specific capacitance of 105 F g−1 at a current density of 1 A g−1, which has been improved by more than 10 times compared to that of pure-flax based carbon fibers. Moreover, they also show an excellent cycling stability of 98.7% after 10 000 cycles, even at a high current density of 10 A g−1. These results further demonstrate that flax-based electrodes have potential to be applied to some relevant energy storage applications in the future.

Pyrene based materials as fluorescent probes in chemical and biological fields

Abstract: Molecules that experience a change in their fluorescence emission due to the effect of fluorescence enhancement upon binding events, like chemical reactions or a change in their immediate environment, are regarded as fluorescent probes, because of their high selectivity and advantages in the fields of chemical, biological, and medical chemistry. Fluorescent probes have become a predominant aid for the detection of target materials like metal cations, anions, and neutral molecules in the bio-imaging field and also have great importance in the detection of reactive oxygen species (ROS) and reactive carbonyl species (RCS) in living cells, air, soil, and food. Pyrene and its derivatives are important polycyclic aromatic hydrocarbons that act as fluorophores and are widely used as a fluorescent probe on account of their strong emission of fluorescence in live cells, very low cytotoxicity, high fluorescence quantum yield, easy modification, and outstanding cell permeability. In this review, the methods of design and synthesis of versatile pyrene fluorophores for the selective and sensitive quantification of their activity will inspire further reaction development in this interesting area.

Fabrication of high-performance symmetrical coin cell supercapacitors by using one step and green synthesis sulfur doped graphene powders

Abstract: In this work, symmetrical supercapacitors in the form of coin cell types were produced by using S-doped graphene powders. Sulfur doped graphene powders were prepared by cyclic voltammetry in different potential ranges for selective modification of powders by functional groups. S-Doped graphene powders were also characterized by spectroscopic, microscopic, and electrochemical methods. The formation of graphene layers was supported by scanning electron microscopic and Raman spectroscopic analyses. Functional groups formed on the graphene surface were identified by X-ray photoelectron spectroscopy. The electrodes formed with compositions consisting of binding material at 5%, conductive material at 5% and S-doped graphene powder at 90% were used in cyclic charge–discharge tests of the supercapacitors to determine the specific capacitance of them. The highest specific capacitance of the supercapacitors was determined as 176 F/g−1, with a capacity loss of 5% at the end of 1000 cycles in A-SG3M.

High performance cobalt nanoparticle catalysts supported by carbon for ozone decomposition: the effects of the cobalt particle size and hydrophobic carbon support

Abstract: Catalytic gaseous ozone decomposition under high humidity is not only an urgent need but also a significant challenge because of the low stability over the available catalysts. By the pyrolysis of ZIF-67 materials, a series of cobalt nanoparticle catalysts with tunable size and supported by hydrophobic nitrogen-doped carbon are developed for the catalytic ozone decomposition under high humidity (RH = 90%). Among them, the ZIF-67-800 catalyst exhibits the highest ozone conversion (ca. 99%) after 6 h. Interestingly, it is found that metallic cobalt nanoparticles are generated during the carbonizing process. Furthermore, the size of the nanoparticle gradually increased from 38 nm to 93 nm with an increase in the carbonizing temperature from 500 °C to 900 °C. The effect of the size of cobalt nanoparticles on the catalytic activity and stability is discussed, and the results imply that only an appropriate size of metallic cobalt particles (ca. 62 nm) may be beneficial for high catalytic activity and robust stability. The surficial oxidized cobalt species and the hydrophobic carbon support (water contact angle = 129°) also play important roles in the improvement of the stability of the decomposition of gaseous ozone under high humidity. The as-prepared ZIF-67-800 catalyst also exhibits a clear advantage over the extensively investigated materials, such as OMS-2 and active carbon. Importantly, the catalytic role of cobalt nanoparticles can be confirmed by the performance comparison of ZIF-67-800 and ZIF-8-800 catalysts, which are derived from ZIF-8 without any cobalt species.

[1,2,4]Triazolo[4,3-a]quinoxaline and [1,2,4]triazolo[4,3-a]quinoxaline-1-thiol-derived DNA intercalators: design, synthesis, molecular docking, in silico ADMET profiles and anti-proliferative evaluations

Abstract: In view of their DNA intercalation activities as anticancer agents, 17 novel [1,2,4]triazolo[4,3-a]quinoxaline derivatives have been designed, synthesized and evaluated against HepG2, HCT-116 and MCF-7 cells. Molecular docking studies were performed to investigate the binding modes of the proposed compounds with the DNA active site. The data obtained from biological testing highly correlated with those obtained from the molecular modeling studies. MCF-7 was found to be the most sensitive cell line to the influence of the new derivatives. In particular, compound 12d was found to be the most potent derivative of all the tested compounds against the three HepG2, HCT116 and MCF-7 cancer cell lines, with IC50 = 22.08 ± 2.1, 27.13 ± 2.2 and 17.12 ± 1.5 μM, respectively. Although this compound displayed nearly one third of the activity of doxorubicin (IC50 = 7.94 ± 0.6, 8.07 ± 0.8 and 6.75 ± 0.4 μM, respectively), it may be useful as a template for future design, optimization, and investigation to produce more potent anticancer analogs. Compounds 12a, 10c and 10d displayed very good anticancer activities against the three HepG2, HCT116 and MCF-7 cancer cell lines, with IC50 = 31.40 ± 2.8, 28.81 ± 2.4 and 19.72 ± 1.5 μM for 12a, 33.41 ± 2.9, 29.96 ± 2.5 and 24.78 ± 1.9 μM for 10c, and 37.55 ± 3.3, 30.22 ± 2.6 and 25.53 ± 2.0 μM for 10d. The most active derivatives, 10c, 10d, 10h, 12a, 12b and 12d, were evaluated for their DNA binding activities. Compound 12d displayed the highest binding affinity. This compound potently intercalates DNA at a decreased IC50 value (35.33 ± 1.8 μM), which is nearly equipotent to that of doxorubicin (31.27 ± 1.8 μM). Compounds 12a and 10c exhibited good DNA-binding affinities, with IC50 values of 39.35 ± 3.9 and 42.35 ± 3.9 μM, respectively. Finally, compounds 10d, 10h and 12b showed moderate DNA-binding affinities, with IC50 values of 50.35 ± 3.9, 57.08 ± 3.3 and 59.35 ± 3.2 μM, respectively.

Chromo-fluorogenic sensing using vitamin B6 cofactors and their derivatives: a review

Abstract: Chromo-fluorogenic chemosensors designed by using a signaling unit (chromophore/fluorophore) and a recognition unit are extensively developed for the sensing of various bioactive and toxic analytes owing to their low-cost, simplicity, and high selectivity and sensitivity. Recently, vitamin B6 cofactors like pyridoxal and pyridoxal 5′-phosphate (PLP) have been employed as a recognition unit for the design of chromo-fluorogenic chemosensors using various organic dyads and functionalized nanomaterials. This review summarizes the chromo-fluorogenic chemosensors developed using the cofactors pyridoxal and PLP. The design of sensors, sensing mechanisms and practical applications of the developed sensors are also discussed. The main aim of this review is to provide future scope for developing chemosensors using the bioactive cofactors as the recognition unit by presenting the results from our research group and the contributions from other groups.

Recent developments in the synthesis of polysubstituted pyridines via multicomponent reactions using nanocatalysts

Abstract: The synthesis of heterocyclic compounds containing a bioactive core including the pyridine molecular framework with diverse pharmaceutical and biological activities is noteworthy. Recently chemists have created novel active pharmacophores via MCRs in the presence of nanocatalysts. The application of various types of nanoparticles as catalysts has been studied in the formation of polyfunctionalized pyridines via multicomponent reactions, and is the subject of this review, which concentrates on their application for the synthesis of pyridine derivatives by multicomponent reactions in the last decade (2010–2020).

A novel sulfate-bridged binuclear copper(II) complex: structure, optical, ADMET and in vivo approach in a murine model of bone metastasis

Abstract: The novel sulfate-bridged binuclear copper(II) complex namely [Cu2(μ3-SO4)2(C4H6N2)4] (1) was obtained from the hydrothermal reaction of 2-methylimidazole (hereafter abbreviated as 2-MeIm) with copper(II) sulfate pentahydrate in methanol. Single-crystal X-ray diffraction analysis of 1 (space group P; cell parameters: a = 8.5712(6) A, b = 8.7884(10) A, c = 9.8797(6) A, α = 115.22(1)°, β = 97.26(1)°, γ = 108.82(1)° and V = 606.26(12) A3) revealed the formation of a centrosymmetric dimeric species. Therein, two [Cu(C4H6N2)2] moieties are connected via two sulfate anions in a μ-1κ2O1,O2,2κO3 fashion and resulting in a tricyclo[5.1.13,5] structure. The Cu atom adopts a distorted square pyramidal coordination geometry (τ = 19). Hydrogen bonds between the imidazole amino groups and non-coordinating sulfato oxygen atoms result in a two-dimensional network parallel to (010). To accumulate a greater knowledge on how molecular components engage with their local environment, a Hirshfeld surface (HS) analysis employing 3D molecular surface contours and 2D fingerprint plots have been undertaken. Heating of 1 above 89 °C initiates gradual decomposition stages, which lead to the metal oxide as a final product at 720 °C, as proven by TGA/DSC analysis. UV-visible spectroscopy was exploited to determine bandgap energy and the nature of the electron transition. In vivo, the synthesized complex showed significant ameliorative effects on tumor osteolytic lesions in malignant Walker 256/B breast cancer-induced bone metastases.

Nitric oxide as a therapeutic option for COVID-19 treatment: a concise perspective

Abstract: In the prevailing coronavirus disease-2019 (COVID-19) times, scientists are eager to develop vaccines against COVID-19, and careful measures are being taken to develop an effective drug. Meanwhile, several antiviral compounds have been repurposed for COVID-19 treatment, and drug repurposing has yielded satisfactory results. In the meantime, nitric oxide (NO) is also under clinical trials to find its potentiality as anticoronavirus. This work aims to describe the therapeutic potential of NO for the treatment of deadly COVID-19. The significance of NO in mitigating COVID-19-associated symptomatic complications has also been addressed. NO being a molecule of significant biological interest is naturally synthesized in mammals and is the first member of the “gasotransmitters”. Biosynthesis and biological target studies reveal that this molecule bears the potential to stabilize oxidation stress and on the other hand oxidation stress has been the major cause of co-morbidity deaths of COVID-19. NO has already been reported to be an effective anticorona (first strains of corona virus). Within the past two months there has been an increased focus on the potential of NO for treatment of coronavirus and COVID-19 infection. R-107 and COViNOX are the two famous forms of NO-based prodrugs under clinical investigation against COVID-19. Therefore, it is worth presenting a literature survey based on the view to find utility of this simple molecule in treating COVID-19, a possible mechanism of action against coronavirus and future perspectives entailed with the research. It also becomes fruitful to introduce the use of NO boosters and clinically approved NO-releasing compounds purposeful in supplying NO if its bioavailability is found to be less than the optimal level. So, the profound antiviral effects of NO against coronavirus, and also the role it plays in relieving symptomatic severity of COVID-19 are supportive of the fact to declare NO as a therapeutic option for this disease.

Multi-stimuli-responsive hydrogels and their medical applications

Abstract: The functionality of multi-stimuli-responsive hydrogels in physiological states is the reason for the increased attention of hydrogels nowadays. Multi-stimuli-responsive hydrogels exhibit tunable changes in swelling or mechanical properties in response to predetermined combinations of stimuli such as pH, temperature, ionic strength, electric field, magnetic field, light, chemical triggers, enzyme concentration, redox species, reactive oxygen species (ROS), and glucose levels. This review summarizes the recent advances in multi-stimuli-responsive hydrogels used in medical approaches. The first part of the review highlights the medical applications of polymer-based and supramolecular hydrogels and emphasizes the priority of multi-stimuli hydrogels over single-stimuli hydrogels. Also, recent studies in medical applications of multi-stimuli-responsive hydrogels are collected with a focus on self-healing hydrogels, anti-bacterial materials, and drug-delivery systems.

Small molecule drug conjugates (SMDCs): an emerging strategy for anticancer drug design and discovery

Abstract: Traditional chemotherapy mostly relies on the use of cytotoxic agents, which are typically unable to preferentially localize at the tumor microenvironment resulting in off-target toxicity and dose escalation to therapeutically active regimens. In oncology, selectivity improvement is always challenging for researchers, to decrease off-target toxicity in conventional cancer chemotherapy because of the close similarity between cancer cells and normal cells. Small molecule drug conjugates (SMDCs), a promising approach for targeted therapy, allow small molecules as the targeted ligand to release a potent cytotoxic agent selectively in the tumor microenvironment to enhance the therapeutic potential of anticancer drugs. The SMDCs were designed using a similar concept to that of antibody drug conjugates (ADCs) but their non-immunogenic nature, lower molecular weight and manageable synthesis make them highly effective for tumor cell penetration and they are found to be advantageous over ADCs. A SMDC product 177Lu-DOTATATE is already in the clinic and several others are in clinical trials. In this perspective, we have extensively focused on the different aspects of SMDC design, i.e., targeting ligand, linker, spacer, cleavable bridge and therapeutic payloads. In addition, the types of SMDCs, their possible mechanism of action, application in the clinic and a few other SMDCs under clinical development against different cancers are highlighted.