Chemistry, Volume 5, Issue 4 (December 2023) – 39 articles

The first total synthesis of the proposed structure of unprecedented indolyl derivative bearing 1,2-propanediol moiety is described. Isomerization of 3-alkoxyindolines through indolenium intermediates was the key step in the total synthesis. ¹H, ¹³C-NMR, IR, and HRMS spectra of the synthetic compound drastically differed to those of the originally reported structure, which suggests the natural product requires revision. Full article

Brown algae possess a diverse array of acidic polysaccharides, including fucoidan. The present research intends to investigate the extraction and characterization of algal polysaccharides to explore their antiviral activity. A light brown sulfated polysaccharide was extracted (with a yield of 18% of dry weight) from Sargassum asperifolium algal powder. The results of fractionation of sulfated polysaccharide revealed the occurrence of two primary fractions: low-sulfated polysaccharides (SPF1) and high-sulfated polysaccharides (SPF2). The bioassays conducted on SPF2 demonstrated a greater level of antioxidant activity compared to SPF1, with respective IC₅₀ values of 17 ± 1.3 µg/mL and 31 ± 1.1 μg/mL after a duration of 120 min. The cytotoxicity of SPF2 on Vero cells was determined, and the calculated half-maximal cytotoxic concentration (CC₅₀) was found to be 178 ± 1.05 µg/mL. Based on these results, an antiviral activity assay was conducted on SPF2. The results demonstrated that SPF2 had greater efficacy against Hepatitis A Virus (HAV) compared to Herpes Simplex Virus Type 1 (HSV-1), with corresponding half-maximal inhibitory concentrations (IC₅₀) of 48 ± 1.8 µg/mL and 123 ± 2.6 µg/mL, respectively. The active SPF2 was characterized by FT-IR, ¹H, and ¹³C NMR spectroscopy. The extracted fucoidan can be used as a natural therapeutic agent in combating various viral infections. Full article

In recent years, transition metal-catalyzed C–H activation and site-selective functionalization have been considered to be valuable synthetic tactics to functionalize organic compounds containing multiple C–H bonds. Pyrene is one of the privileged and notorious polycyclic aromatic hydrocarbons. Pyrene and its derivatives have found applications in various branches of chemical sciences, including organic chemistry, chemical biology, supramolecular sciences, and material sciences. Given the importance of pyrene derivatives, several classical methods, including the C–H functionalization method, have been developed for synthesizing modified pyrene scaffolds. This review attempts to cover the recent developments in the area pertaining to the modification of the pyrene motif through the C–H activation process and the functionalization of C–H bonds present in the pyrene motif, leading to functionalized pyrenes. Full article

Chiral hydroxamic acid (HA) and bis-hydroxamic acid (BHA) ligands have made significant contributions to the field of asymmetric synthesis, particularly in the synthesis of natural products. These ligands possess unique molecular structures that allow for exceptional stereochemical control, leading to their widespread use in catalytic systems. This review highlights the advancements made in asymmetric synthesis using chiral hydroxamic acid and bis-hydroxamic acid ligands and their impact on the synthesis of complex natural products. This discussion encompasses their role in enantioselective C–C bond formation, the functionalization of C–H bonds, the asymmetric transformations involving heteroatoms, and their application in the total synthesis of natural products. The versatility and efficiency of chiral hydroxamic acid ligands and bis-hydroxamic acid ligands make them invaluable tools for synthetic chemists working towards the efficient and selective synthesis of natural products. This review provides a comprehensive overview of their contributions, showcasing their potential to expand the boundaries of chemical synthesis and access the diverse array of natural product scaffolds. Full article

The iron-promoted 1,5-substitution reaction of endocyclic oxiranes with MeMgBr yields exocyclic 2,4,5-trienols with high diastereomeric ratios of up to 100:0. However, for the method’s success, the oxirane ring must have a trans-configuration. The reactions exhibit strong stereoselectivity concerning the methylation mode and the configuration of the resulting exocyclic double bond. Enantiomerically pure enyne oxiranes can be synthesized through Sharpless asymmetric dihydroxylation and subsequent manipulations. With these reagents, it has been possible to produce exocyclic 2,4,5-trienols in enantiopure forms. Importantly, this process maintains chirality without degradation during the center-to-axis transfer of chirality. Full article

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A series of 2,4-disubstituted pyrrolo[2,1-f][1,2,4]triazines containing both aryl and thienyl substituents were synthesized by exploiting the 1,3-cycloaddition reaction of N(1)-ethyl-1,2,4-triazinium tetrafluoroborates with dimethyl acetylenedicarboxylate. The antiviral activity of the synthesized compounds against influenza virus strain A/Puerto Rico/8/34 (H1N1) was studied in experiments on Madin-Darby canine kidney (MDCK) cell culture. Among the pyrrolo[2,1-f][1,2,4]triazine derivatives, compounds with low toxicity and high antiviral activity were identified. Dimethyl 4-(4-methoxyphenyl)-7-methyl-2-p-tolylpyrrolo[2,1-f][1,2,4]triazine-5,6-dicarboxylate was found to demonstrate the best antiviral activity (IC₅₀ 4 µg/mL and selectivity index 188). Based on the results of in vitro tests and molecular docking studies performed, a plausible mechanism of action for these compounds was suggested to involve inhibition of neuraminidase. Full article

The dⁿ number or configuration is a very useful parameter in transition metal chemistry because it conveys information about the expected properties of a d-block metal complex, including its shape, magnetism, thermodynamic stability, kinetic lability, and spectroscopic properties. The dⁿ number can be determined from either the oxidation state (OS) or valence number (VN) of the metal centre, and since, in most cases, these are numerically equal, the derived dⁿ value is the same. However, examples are discussed where the OS and VN are not equal, which results in unavoidable ambiguities in dⁿ values. Following a discussion of these examples, a revised definition of dⁿ is proposed based on the occupation of the frontier molecular orbitals of the complex. Full article

Finding an effective anticancer drug to combat cancer cell resistance remains a challenge. Herein, we synthesized a new series of imidazolone derivatives 4a–4i and assessed their anticancer activities against liver cancer cells (Hep3B), Hela cells, and normal LX2 cells. The imidazolne derivatives were synthesized by the condensation cyclization reaction using the natural product vanillin as a starting material. Among the synthesized imidazolones are those with an alkyl sulfate moiety that are water-soluble and showed enhanced anticancer activity against the tested cancer cells. The anticancer testing results showed that compound 4d with the NO₂ group at position 4 of the benzene ring was superior to the other compounds; it showed an IC₅₀ value of 134.2 ± 4.4 µM against Hep3B cells, while compound 4h with the pyridyl moiety showed the highest cytotoxicity against Hela cells with an IC₅₀ of 85.1 ± 2.1 µM. The anticancer activity of some imidazolones was greatly enhanced by adding to them the zwitterionic properties that made them more polar and water-soluble. DNA binding studies with compounds 4a₁, 4d, and 4g indicated a docking score ranging from approximately −6.8 to −8.7 kcal/mol. This could be attributed to the outstanding interaction between the molecule and the DNA binding sites, which primarily relies on its inherent capability to establish hydrogen bonds, facilitated by the electron pair present at the oxygen atoms and the drug’s amino group. In conclusion, water-soluble imidazolone with zwitterionic functionality could be a promising tool for the development of anticancer medication. To outline the general idea and the relationships for the effect of the developed compounds under study, as well as their mechanism of action, further extensive research is also necessary. Full article

The structures and properties of hydrophobic association polymers can be controlled using micelles. In this work, we synthesize a reactive hydrophobic surfactant monomer, KS-3, from oleic acid, N,N-dimethylpropylenediamine, and allyl chloride. A strong synergistic effect between KS-3 and cocamidopropyl betaine in aqueous solution enhances the hydrophilic dispersibility of KS-3, thereby transforming spherical micelles into cylindrical micelles. KS-3 was grafted onto a polyacrylamide chain via aqueous free-radical polymerization to obtain RES, a hydrophobic association polymer. Structural analysis revealed that the RES polymers assembled in wormlike micelles were more tightly arranged than those assembled in spherical micelles, resulting in a compact network structure in water, smooth surface, and high thermal stability. Rheological tests revealed that the synthesized polymers with wormlike and spherical micelles exhibited shear-thinning properties along with different structural strengths and viscoelasticities. Therefore, controlling the micellar state can effectively regulate the polymer properties. The polymers obtained through wormlike micelle polymerization have potential applications in fields with high demands, such as drug release, water purification, and oilfield development. Full article

It is well known that beer is more than 90% water, and therefore, water can be one of the main sources of fluoride in beers. With this in mind, the goal of the present study was to determine the mass concentration of fluoride in 53 beer samples. Using the recently published standard addition method in potentiometry, the fluoride content of 28 samples of the most consumed beers in the Republic of Croatia was determined. The remaining 25 beer samples tested came from so-called microbreweries, which together account for less than 10% of the Croatian market. Fluoride concentrations in light beers ranged from 49 to 180 μg L⁻¹, with a mean value of 95 ± 34 μg L⁻¹, and from 52 to 164 μg L⁻¹, with a mean value of 89 ± 29 μg L⁻¹ in dark beers. The mean value of fluoride content in beers from large producers was 100 ± 38 μg L⁻¹ and 89 ± 38 μg L⁻¹ in beers from small producers. All values are within the recommended range and thus do not pose a risk to human health. The statistical analysis showed no correlation between the mass concentration of fluoride and pH, i.e., alcohol content in beers. Full article

Quinoxaline is a fused heterocycle system of a benzene ring and pyrazine ring. It has earned considerable attention due to its importance in the field of medicinal chemistry. The system is of extensive importance due to its comprehensive array of biological activities. Quinoxaline derivatives have been used as anticancer, anticonvulsant, anti-inflammatory, antidiabetic, antioxidant, antibacterial, anti-TB, antimalarial, antiviral, anti-HIV, and many other uses. Variously substituted quinoxalines are significant therapeutic agents in the pharmaceutical industry. This review spotlights on the chemistry, physiochemical characters, synthesis, pharmaceutical products, and medicinal chemistry of various anticancer quinoxaline derivatives that were developed in the last period. It covers the period from 2016 to 2023. Full article

This study presents a critical review of the experimental vapor-liquid equilibrium (VLE) data for the quaternary acetic acid-ethanol-ethyl acetate-water system and its subsystems that are reported in the literature. The thermodynamic consistency of the VLE data were verified using two integral tests: the Redlich–Kister test and the direct integration of the Gibbs–Duhem equation. The VLE data were correlated using the NRTL equation for further integration. Additionally, the reliable value of the integral derived from the direct integration of the Gibbs–Duhem equation for multicomponent systems under isothermal-isobaric conditions was estimated. This integral can be used for testing the thermodynamic consistency of experimental VLE data. Full article

Cambridge Structural Database (CSD) is the largest repository of crystal data, containing over 1.2 million crystal structures of organic, metal–organic and organometallic compounds. It is a powerful research tool in many areas, including the extensive studying of noncovalent interactions. In this review, we show how a thorough analysis of CSD crystal data resulted in recognition of novel types of stacking interactions. Even though stacking interactions were traditionally related to aromatic systems, a number of crystallographic studies have shown that nonaromatic metal–chelate rings, as well as hydrogen-bridged rings, can also form stacking interactions. Joined efforts of a CSD analysis and quantum chemical calculations showed that these new stacking interactions are stronger than stacking interactions of aromatic species and recognized them as very important attractive forces in numerous supramolecular systems. Full article

Micelle templating has emerged as a powerful method to produce monodisperse nanoparticles. Herein, we explore unconventional phase transformations in the synthesis of organo-halide perovskite nanoparticles utilizing reverse micelle templates. We employ diblock-copolymer reverse micelles to fabricate these nanoparticles, which confines ions within micellar nanoreactors, retarding reaction kinetics and facilitating perovskite cage manipulation. The confined micellar environment exerts pressure on both precursors and perovskite crystals formed inside, enabling stable phases not typically observed at room temperature in conventional synthesis. This provides access to perovskite structures that are otherwise challenging to produce. The hydrophobic shell of the micelle also enhances perovskite stability, particularly when combined with anionic exchange approaches or large aromatic cations. This synergy results in long-lasting stable optical properties despite environmental exposure. Reverse micelle templates offer a versatile platform for modulating perovskite structure and behavior across a broad spectrum of perovskite compositions, yielding unique phases with diverse emission characteristics. By manipulating the composition and properties of the reverse micelle template, it is possible to tune the characteristics of the resulting nanoparticles, opening up exciting opportunities for customizing optical properties to suit various applications. Full article

Palladium(II) complexes of the general formula [Pd(η³-C₃H₅)(L)](PF₆), where L is 4,7-diphenyl-1,10-phenanthroline (1), 2,9-dimethyl-1,10-phenanthroline (2), 2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline (3), 5-methyl-1,10-phenanthroline (4), 3,4,7,8-tetramethyl-1,10-phenanthroline (5), and 2-(2′-pyridyl) quinoxaline (6), were synthesized and characterized using high-resolution ESI-MS, NMR techniques and, in the case of (6), single-crystal X-ray diffraction methods. In addition, their photophysical properties were investigated. Complexes (1)–(6) were emitted in the greenish-blue region, with those containing methyl-substituted phenanthrolines having the higher quantum yield (≈14%) in the solid state. Full article

The metal–organic framework (MOF) is a kind of porous material with lattice materials. Due to its large surface area and structural diversity, it has made great progress in the fields of batteries, capacitors, electrocatalysis, etc. Conductive MOF (c-MOF) increases the conductivity based on the original advantages of the MOF, which is more suitable for the development of batteries, capacitors, electrocatalysis, and other fields. This review summarizes the preparation of c-MOF and the research progress of conductive MOFs in the field of electrochemical energy storage and conversion. Full article

DNA as an intriguing organic ligand has been widely employed for synthesizing metal nanoclusters and engineering their properties. This review aims to present recent progress on DNA-encoded metal (Ag, Cu, Au, Ag/Pt, Cu/Ag, etc.) nanoclusters (DNA-MNCs), focusing on their applications in the fields of analysis, logic operation, and therapy based on properties including fluorescence, electrochemiluminescence (ECL), and antibacterial and catalytic activity, and summarizes the attractive features of the latest research. The key points are briefly described as follows. (1) Analytical systems have been constructed based on fluorescence regulation, and nuclease-assisted and enzyme-free amplification strategies have been extensively adopted with fluorescent DNA-MNCs for amplified analysis. (2) DNA-MNCs may play more than one role (emitter, quencher, or catalyst) in ECL-based analytical systems. (3) Apart from antibacterial activity, DNA-MNCs also possess apparent catalytic capability, such as enzyme-like activity (i.e., nanozymes), which has been applied in colorimetric systems. (4) Reversibly regulating the catalytic activity of DNA-MNCs has been attained with DNA systems. It is believed that through in-depth investigation of the relationship between atomic structure and property, more novel DNA-MNCs will be explored and applied in the future. Full article

Maintaining the confidentiality and integrity of the messages during a transmission is one of the most important aims of encrypted communication systems. Many achievements were made using biomolecules to improve the quality of the messages in communication. At the same time, it is still a challenge to construct cooperative communications based on the interactions between biomolecules to achieve the confidentiality and integrity of the transmitted messages. DNA-based encrypted communications have been developed, and in particular, DNA-origami-based message encryption can combine steganography and pattern encryption and exhibits extremely high confidentiality. Nevertheless, limited by biological characteristics, encrypted messages based on DNA require a strict storage environment in the process of transmission. The integrity of the message encoded in the DNA may be damaged when the DNA is in an unfriendly and hard environment. Therefore, it is particularly significant to improve the stability of DNA when it is exposed to a harsh environment during transmission. Here, we encoded the information into the DNA strands that were condensed for encryption to form a nanosphere covered with a shell of SiO₂, which brings high-density messages and exhibits higher stability than separated DNA. The solid shell of SiO₂ could prevent DNA from contacting the harsh environment, thereby protecting the DNA structure and maintaining the integrity of the information. At the same time, DNA nanospheres can achieve high throughput input and higher storage density per unit volume, which contribute to confusing the message strand (M-strand) with the interference strand in the stored information. Condensing DNA into the nanosphere that is used for DNA origami cryptography has the potential to be used in harsh conditions with higher confidentiality and integrity for the transmitted messages. Full article

A one-pot multi-component reaction was employed for the stereoselective synthesis of a novel set of dispiro-oxindolopyrrolizidines analogs incorporating a thiazolo[3,2-a]benzimidazole scaffold based on the [3 + 2] cycloaddition (32CA) reaction approach. The desired novel dispiro-oxindolopyrrolizidines 9a–d were achieved using the 32CA reaction of new ethylene derivatives based on thiazolo[3,2-a]benzimidazole moiety seven with thiazolidine derivatives eight and different substituted isatin compounds 5a–d (R = H, Cl, NO₂, and Br). The final dispiro-oxindolopyrrolizidines cycloadducts were separated, purified, and fully characterized by means of a set of spectroscopic tools including IR, HNMR, CNMR, and MS. The Molecular Electron Density Theory (MEDT) was applied to explain the mechanism and stereoselectivity in the of the key 32CA reaction step. The reactive pseudo(mono)radical electronic structure of the in situ generated azomethine ylides and the high polar character of the corresponding 32CA reactions account for the low computed activation Gibbs free energies and total endo stereoselectivity of this kinetically controlled exergonic reaction. The computed relative Gibbs free activation energies of competitive reaction paths and regioisomers ratio distribution of 80:20 justify the major formation of 9a via the most favorable ortho/endo reaction path. Full article

The replacement of carbon with a heteroatom within the structure of a fullerene gives the possibility of obtaining compounds with adjustable properties. The influence of aza-substitution on C₂₄ fullerenes was investigated and a comparison of HF and DFT calculations was performed. Various substitution patterns were proposed and the characterization of C₂₂N₂ and C₂₀N₄ structures was performed. Global reactivity descriptors like chemical potential, hardness, HOMO–LUMO gap and singlet–triplet gap were computed. Aromaticity descriptors like delocalization indices and NICS(0) index were employed for the characterization of each six-membered ring of the studied fullerenes. The possible use of aza-fullerenes as drug delivery systems for two adamantane-derived antivirals was evaluated through molecular docking studies. The best results were obtained for the fullerenes with a pronounced hydrophobic character, the favored configuration of the antiviral drugs being the one oriented toward the side consisting of carbon atoms of the fullerenes. Full article

The preparation of a new class of six bifunctional thiourea organocatalysts having a D-fructose scaffold and a primary amino group was demonstrated. In the present study, the novel organocatalysts exhibited excellent enantio- and moderate diastereoselectivities in the asymmetric Michael addition of aliphatic ketones and 1,3-diketone to substituted nitroolefins at room temperature. In addition, the direct asymmetric aldol reaction between cyclic aliphatic ketone and aromatic aldehydes was also studied in the presence of the saccharide-thiourea organocatalysts giving excellent yield with moderate enantioselectivity. Full article

One of the biologically beneficial oils against many ailments is Achillea fragrantissima essential oil (EO). The current study focused on the comprehensive comparative chemical characterization of A. fragrantissima EOs, which were gathered from Saudi Arabia and Egypt, as well as evaluation of their allelopathic, antioxidant, and antibacterial functions. With a respective total oil mass of 96.9% and 96.1%, 40 compounds were found in the EOs from Saudi Arabia (38 compounds) and Egypt (26 compounds). Terpenes represented the main constituents including mono- (52.6% and 75.4% from Saudi Arabia and Egypt, respectively) and sesquiterpenoids (42.1% and 19.7%, respectively). The α-thujone (12.0%), myrcenyl acetate (10.3%), alloaromadendrene oxide-(1) (5.9%), artemisia ketone (4.9%), β-thujone (4.7%), lavandulol (4.2%), and santolina alcohol (4.0%) represented the main components of the overall oil of the Saudi Arabian plant-derived EO. However, the main constituents of the EO of the Egyptian plant were 4-terpineol (17.4%), myrcenyl acetate (9.1%), artemisia ketone (9.0%), α-thujone (8.6%), yomogi alcohol (6.2%), santolina alcohol (6.2%), and β-thujone (5.8%). The chemometric analysis exhibited a strong association between the two EOs from Saudi Arabia and Egypt in addition to the samples collected from Jordan. The Saudi and Egyptian A. fragrantissima’ EOs were found to have significant allelopathic potencies against the weed C. murale. The seed germination, seedling shoot growth, and root growth of C. murale were all reduced by the EO of the Saudi ecospecies by 79.9, 56.7, and 68.6%, respectively, with IC₅₀ values of 66.5, 68.0, and 69.2 µL L⁻¹, respectively. The two oils from Saudi Arabia and Egypt exhibited potent antioxidant activity against the DPPH free radicals, with IC₅₀ values of 30.94 and 28.72 mg/L, respectively. In addition, the two oils from Saudi Arabia and Egypt exhibited strong abilities to scavenge ABTS radicals with respective IC₅₀ values of 39.02 and 37.13 mg/L. Additionally, the two EOs showed a much higher antibacterial activity than the antibiotics tested against all bacterial strains, with the exception of Enterobacter cloacae. The two oils exhibited antibacterial activity against the examined strains, except Bacillus subtilis and Salmonella typhimurium, for which the Egyptian species shown greater inhibition. The results revealed that Escherichia coli and Staphylococcus epidermidis were more sensitive, while Enterobacter cloacae was more resistant. Full article

The bio-based solvent dihydrolevoglucosenone (Cyrene) is a green and sustainable alternative to petroleum-based dipolar aprotic solvents. Cyrene can be prepared from cellulose in a simple two-step process and can be produced in a variety of yields. Cyrene is compatible with a large number of reactions in the chemical industry and can be applied in organic chemistry, biocatalysis, materials chemistry, graphene and lignin processing, etc. It is also green, non-mutagenic and non-toxic, which makes it very promising for applications. In this paper, we have also screened all articles related to Cyrene on the Web of Science and visualised them through Cite Space. Full article

This review summarizes the applications of vinyl sulfonate and vinyl acetate as green alternatives for vinyl bromide in cross-coupling reactions. In the first part, the preparation of vinyl sulfonates and their cross-coupling reactions are briefly discussed. Then, a brief review of vinyl acetate cross-coupling reactions, including cyclization reactions, the Fujiware–Moritani reaction, and transvinylation reactions are described. Full article

The current study aimed to produce a material that has dual effects of healing and anti-inflammatory activity. For this purpose, a κ-carrageenan/polyacrylamide film loaded with cetrimide (κ-CAR/PAAm/CI) was developed using the manual casting technique. Definite concentrations of κ-CAR and AAm were heated at 80 °C for 2 h, and CI and glycerol were added. The solution was cast without using an initiator or crosslinker. The reaction of the sulfonic acid group -SO₃H of κ-CAR with the –CONH₂ group of PAAm lead to the formation of a sulfonamide (–SO₂NH–) group. The characteristics of the produced films were investigated based on FT-IR, TGA, the contact angle, and mechanical properties. An improvement in the thermal stability of the κ-CAR/PAAm/CI₂ film containing 1.5% CI was achieved, compared to the film with 0.5% CI (κ-CAR/PAAm/CI₁). The contact angle measurement proved that the films were hydrophobic, enhanced by increasing the CI content. The tensile strength and elongation percent values are considered adequate for materials used in wound care. The κ-CAR/PAAm/CI₂ (1.5% CI) film showed superior antimicrobial activity against P. aeruginosa, moderate activity against S. aureus, and low activity against E. coli. The κ-CAR/PAAm/CI₂ film effectively inhibited heat-induced hemolysis and showed wound contraction activity at a level of 100% after 19 days of excision wound treatment. The prepared films may offer a promising approach for the development of effective wound dressings. Full article

Essential oils (EOs) are advised by traditional medical systems for the treatment of a variety of disorders worldwide. In many ancient medical systems around the world, Polygonum herbs have been employed as remedies including P. equisetiforme Sm. The EO profile of P. equisetiforme and its bioactivities have yet to be discussed in depth. As a result, the current study aims to investigate the chemical profile and free radical scavenging capacity of P. equisetiforme EO. Hydrodistillation was used to obtain the EO from P. equisetiforme, and gas chromatography–mass spectrometry (GC-MS) was used for analysis. A total of forty-three compounds, including terpenes and sesquiterpenes as the main components (76.13% and 69.06%, respectively), were identified in the oil using the GC-MS analysis. The main constituents of the oil were hexahydrofarnesyl acetone (29.45%), 7-epi-selinene (14.45%), isospathulenol (8.35%), and n-docosane (6.79%). The chemosystematic significance of the plant was established via multivariate assessing, comprising principal component analysis (PCA), hierarchical clustering, and constellation plot, of the EO principal components of the various Polygonum plants. The P. equisetiforme exhibited different associations with the studied Polygonum spp. Then, the scavenging of the free radicals 2,2-diphenyl-1-picrylhydrazyl (DPPH) and 2,2′-azinobis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) was used to evaluate the radical scavenging abilities of EO compared with those of vitamin C, a reference antioxidant. P. equisetiforme EO exhibited the scavenging capacity of the DPPH and the ABTS free radical with respective IC₅₀ values of 470.01 and 113.74 mg L⁻¹ compared with vitamin C, and with IC₅₀ values of 39.06 and 26.09 mg L⁻¹, respectively. The in silico studies revealed that the oxygenated sesquiterpenes, especially ar-turmerone, hexahydrofarnesyl acetone, and 5E,9E-farnesyl acetone, exhibited the best fitting with hematopoietic cell kinase (Hck) and human Peroxiredoxin 5 proteins with ΔG values of −6.14 and −4.93, −6.83 and −5.34, and −7.08 and −5.47 kcal/mol, respectively. The major components’ combined or individual effects may be responsible for the antioxidant properties. Therefore, additional extensive studies are advised to characterize the essential compounds as radical scavenger agents, either individually or in combination. Full article

Mixed-valence complexes contain two metals with different formal oxidation numbers and, therefore, show mixed properties that are influenced by the electronic coupling between the two metals, which is, in turn, regulated by a bridging ligand. This is an attractive point for many researchers. Oxalate is widely used as a bridging ligand for preparing polynuclear complexes. More than 1000 complexes have been reported until now. However, dithiooxamidate, which is an oxalate analog, is less popular as a bridging ligand. Here, a new dithiooxamidate-bridged Ni-diphosphine dinuclear complex with the formula [(μ₂-toxa){Ni(dppe)}₂](BF₄)₂ (toxa = dithiooxamidate; dppe = 1,2-bis(diphenylphosphino)ethane) was prepared and characterized via single-crystal X-ray diffraction. When using 1,3-bis(diphenylphosphino)propane (dppp) instead of dppe, dinuclear, trinuclear, and tetranuclear complexes were obtained, i.e., [(μ₂-toxa){Ni(dppp)}₂](BF₄)₂, [{μ₂-Ni(toxa)₂}{Ni(dppp)}₂](BF₄)₂, and [{μ₃-Ni(toxa)₃}{Ni(dppp)}₃](BF₄)₂, respectively. Bidentate toxa ligands in dinuclear complexes coordinate each Ni atom as κ(S,N). However, the trinuclear and the tetranuclear complexes have the toxa ligands with κ(N,N) and κ(S,S) coordination. The [(μ₂-toxa){Ni(dppe)}₂](BF₄)₂ complex undergoes four reversible redox processes, whose analysis via a controlled-potential absorption spectrum reveals the presence of a Ni(II)-Ni(I) mixed-valence state at ∆E_1/2 = 0.22 V with a comproportionation constant of 6.1 × 10³. Full article

Natural dyes, obtained without the use of chemical treatment, are derived from naturally occurring sources, such as plants, animals, insects, and minerals. The usage of natural substances and their medicinal properties dates back to the origins of human civilization. The purpose of this review is to highlight the medicinal importance of selected natural colors, which sheds light on the critical role played by these dyes in the pharmaceutical industry. The objective is to showcase the health benefits of each color that can be obtained from nature for medicinal purposes based on their chemical structure. The review presents the reasons for utilizing natural resources in addressing various health issues, with a focus on three specific problems: microbial infections, cancer, and oxidative stress. Our review highlights the potential of natural resource structures, particularly anthocyanins, genipin, carotenoids, phycocyanin, and chlorophylls, in combating these ailments, emphasizing the need to explore their resources further for medicinal purposes. While most reviews provide a survey about colorful crude plant extracts in relation to one or a few categories of human health, our review focuses on the specific chromophore extracted not only from plants but also from any natural resource to provide a specific chromophore effect in a whole resource. The review highlights the significant role performed by organic pigments in the medicinal domain, with organic colorants acting as an essential element of the pharmaceutical sector’s weaponry. Hence, it is of paramount significance to actively promote and stress the adoptions of naturally existing chromophores in diverse everyday commodities, while simultaneously acknowledging and valuing their substantial importance and worth in the vast realm of the pharmaceutical industry. Full article

Sustainable water desalination and purification membrane processes require new practical pathways to improve their efficiency. To this end, the inclusion of two-dimensional materials in membrane structure has proven to have a significant impact in various applications. In particular, in processes such as membrane distillation and crystallization, these materials, thanks to their characteristics, help to increase the recovery of clean water and, at the same time, to improve the quality and the production of the recovered salts. Therefore, a fundamental aspect of obtaining 2D materials with certain characteristics is the technique used for the preparation. This review provides a broad discussion on the preparation and proprieties of 2D materials, including examples of organic structures (such as graphene and structures containing transition metals and organic metals). Finally, the critical challenges, future research directions, and the opportunities for developing advanced membranes based on 2D materials are outlined. Full article