Cationic Molecules Research Articles

Emerging Cationic Nanovaccines

Cationic vaccines of nanometric sizes can directly perform the delivery of antigen(s) and immunomodulator(s) to dendritic cells in the lymph nodes. The positively charged nanovaccines are taken up by antigen-presenting cells (APCs) of the lymphatic system often originating the cellular immunological defense required to fight intracellular microbial infections and the proliferation of cancers. Cationic molecules imparting the positive charges to nanovaccines exhibit a dose-dependent toxicity which needs to be systematically addressed. Against the coronavirus, mRNA cationic nanovaccines evolved rapidly. Nowadays cationic nanovaccines have been formulated against several infections with the advantage of cationic compounds granting protection of nucleic acids in vivo against biodegradation by nucleases. Up to the threshold concentration of cationic molecules for nanovaccine delivery, cationic nanovaccines perform well eliciting the desired Th 1 improved immune response in the absence of cytotoxicity. A second strategy in the literature involves dilution of cationic components in biocompatible polymeric matrixes. Polymeric nanoparticles incorporating cationic molecules at reduced concentrations for the cationic component often result in an absence of toxic effects. The progress in vaccinology against cancer involves in situ designs for cationic nanovaccines. The lysis of transformed cancer cells releases several tumoral antigens, which in the presence of cationic nanoadjuvants can be systemically presented for the prevention of metastatic cancer. In addition, these local cationic nanovaccines allow immunotherapeutic tumor treatment.

Cationic amphiphilic molecules as novel sclerosants for venous malformation treatment: A study on tranexamic acid-derived low-molecular-weight gels

Venous malformation (VM) is a prevalent congenital vascular anomaly characterized by abnormal blood vessel growth, leading to disfigurement and dysfunction. Sclerotherapy, a minimally invasive approach, has become a primary therapeutic modality for VM, but its efficacy is hampered by the rapid dilution and potential adverse effects. In this study, we introduced a series of cationic amphiphilic molecules, fatty alcohol esters (TA6, TA8, and TA9) of tranexamic acid (TA), which self-assembled into low-molecular-weight gels (LMWGs) in water. The TA9, in particular, is released slowly when hydrogel is injected into the vein locally. Then, it damages the venous wall by destroying cell membranes and precipitating proteins, causing inflammation and thrombosis, thickening of the venous wall, effectively inducing irreversible vein fibrosis. Additionally, TA9 can be rapidly degraded into TA in plasma to reduce toxicity caused by diffusion. Overall, this study suggests that the cationic amphiphilic molecule TA9 is a promising sclerosant for VM treatment, offering a novel, effective, and safe therapeutic option with potential for clinical translation.

Glucose-fueled cationic nanomotors for promoting the healing of infected diabetic wounds

Hyperglycemia-promoted bacterial infection will seriously exacerbate diabetic wounds, and its current clinical treatments are suffering from the adverse effects associated with off-target, bacterial resistance, and glycemic fluctuation. Herein, we present a kind of glucose-fueled cationic nanomotors capable of remarkably enhancing antibacterial efficacy, and thus expediting diabetic wound healing. The nanomotors have positively charged surfaces, and consist of mesoporous bowl-shaped polydopamine nanoparticles grafted with quaternized polymer brushes and coupled with glucose oxidase (GOx) and catalase (CAT). Stemming from the GOx-CAT cascade reaction in diabetic wound microenvironment, they can perform robust chemotactic motion towards both high glucose regions, where bacteria proliferation predominantly occurs, and elevated H2O2 levels, which bacterial metabolism produced. This enables the nanomotors to facilitate targeted migration towards bacteria-rich regions and simultaneous downregulation of glycemic levels, as well as to significantly enhance the electrostatic interaction between antibacterial components and bacteria. Consequently, the nanomotors exhibit amplified contact-killing effects of their attached cationic molecules, leading to an almost 10-fold enhancement in antibacterial efficacy compared to previous counterparts. The in vivo experiments approved that the nanomotors demonstrated the accelerated healing of infected diabetic wounds by S. aureus and biosafety. The results herein provide an insight into the clinical treatment of infected diabetic wounds.

Evaluation of optimized conditions for the adsorption of malachite green by SnO2-modified sugarcane bagasse biochar nanocomposites.

This work deals with the synthesis of SnO2-modified sugarcane bagasse biochar (SnO2-SBB) nanocomposites using an impregnation method. XRD, FTIR, SEM, and EDX analyses were used to characterize the produced nanocomposites. Several factors influencing the removal of malachite green from wastewater via the adsorption process were explored to maximize the effectiveness of this process. These factors included the different doses of nanocomposites, pH, temperature, contact time, etc. Studies on batch adsorption were conducted to examine the impact of operational parameters, such as contact time (5 to 30 minutes), adsorbent dosage (5 to 40 mg), pH (2 to 10), and temperature (303, 323, and 353 K), on the percentage of MG dye removal. The adsorption kinetics of MG dye over SnO2-SBB nanocomposites were evaluated with the aid of the Langmuir adsorption isotherm, which provided a good fit (R 2 = 0.99) for pseudo-second-order kinetics. The thermodynamic parameters revealed spontaneous and exothermic adsorption of MG dye over SnO2-SBB nanocomposites. A maximum adsorption capacity (q max) of 52.64 ± 0.03 for 0.3 SnO2-SBB and 73.86 ± 0.05 for 0.5 SnO2-SBB nanocomposites was observed. The newly synthesized SnO2-SBB nanocomposites showed negative zeta potential, which facilitated the adsorption of hydrated cationic dye molecules due to the electrostatic force of attraction.

Metal cation and crystal lattice water molecule stabilized highly mesoporous manganese oxide network for excellent durable electrode in sodium-ion storage

Potassium birnessite is a remarkable material with a wider inter-planar spacing, which enables to accommodate more electrolytic ions to improve overall electrochemical performances. In this work, controlled synthesis of K0.46Mn2O4(H2O)1.4 (HKMO) nanosheets were interconnected mesoporous networks uniformly grown on carbon cloth (CC) via a one-step hydrothermal process. Specifically, the HKMO sample synthesized at 100 °C for 12 h (100@HKMO-12 h) exhibited a mesoporous morphology with a large specific surface area. The binder-free 100@HKMO-12 h electrode exhibits a maximum specific capacitance of 255F g−1 (323F cm−3) in 1 M NaClO4/acetonitrile electrolyte over a broad potential range of 3 V. DFT studies demonstrated the interlayer distance increased by the insertion of K+ ions into the MnO2 matrix. Bader charge analysis showed a 12.09 |e| charge difference for K-birnessite in the inter-layer region compared to the normal birnessite, supported the increase of inter-layer region in the MnO2 matrix. Significantly, the increased interlayer the distance, promoted rapid intercalation/deintercalation of Na+ ions and allowed the reversible faradic pseudocapacitance reaction to occur at a wider potential window. Moreover, the symmetric full-cell fabricated utilizing the 100@HKMO-12 h electrodes have a wide voltage of 2 V and the device delivered a maximum specific energy of 43 Wh kg−1 (28 Wh cm−3) at a minimum specific power of 556 W Kg−1 (349 W cm−3). Besides, the device showed an excellent capacitance retention of ∼94 % even after 10,000 continuous charge–discharge cycles at a current of 5 A/g, indicating it is a potential candidate for next-generation sodium energy storage devices.

Antimigratory Effect of Lipophilic Cations Derived from Gallic and Gentisic Acid and Synergistic Effect with 5-Fluorouracil on Metastatic Colorectal Cancer Cells: A New Synthesis Route.

Colorectal cancer (CRC) is the third leading cause of cancer deaths in the world. Standard drugs currently used for the treatment of advanced CRC-such as 5-fluorouracil (5FU)-remain unsatisfactory in their results due to their high toxicity, high resistance, and adverse effects. In recent years, mitochondria have become an attractive target for cancer therapy due to higher transmembrane mitochondrial potential. We synthesized gallic acid derivatives linked to a ten-carbon aliphatic chain associated with triphenylphosphonium (TPP+C10), a lipophilic cationic molecule that induces the uncoupling of the electron transport chain (ETC). Other derivatives, such as gentisic acid (GA-TPP+C10), have the same effects on colorectal cancer cells. Although part of our group had previously reported preparing these structures by a convergent synthesis route, including their application via flow chemistry, there was no precedent for a new methodology for preparing these compounds. In this scenario, this study aims to develop a new linear synthesis strategy involving an essential step of Steglich esterification under mild conditions (open flask) and a high degree of reproducibility. Moreover, the study seeks to associate GA-TPP+C10 with 5FU to evaluate synergistic antineoplastic effects. In addition, we assess the antimigratory effect of GA-TPP+C10 and TPP+C10 using human and mouse metastatic CRC cell lines. The results show a new and efficient synthesis route of these compounds, having synergistic effects in combination with 5FU, increasing apoptosis and enhancing cytotoxic properties. Additionally, the results show a robust antimigratory effect of GATPP+C10 and TPP+C10, reducing the activation pathways linked to tumor progression and reducing the expression of VEGF and MMP-2 and MMP-9, common biomarkers of advanced CRC. Moreover, TPP+C10 and GA-TPP+C10 increase the activity of metabolic signaling pathways through AMPK activation. The data allow us to conclude that these compounds can be used for in vivo evaluations and are a promising alternative associated with conventional therapies for advanced colorectal cancer. Additionally, the reported intermediates of the new synthesis route could give rise to analog compounds with improved therapeutic activity.

Synthesis of porous carbons for the fixing of cationic molecules in aqueous solution

In Africa, the calyxes of the Hibiscus sabdariffa are widely used to produce a fresh fruit juice, known in Benin as bissap. The stems from this production have no potential use and are therefore an environmental problem. The parietal composition of these stalks revealed a high level of lignin (31 ± 1 %) and cellulose (35 ± 1 %). They can therefore be converted into activated carbon for various applications. In this study, the stems were transformed into activated carbons at moderate temperature using orthophosphoric acid (H3PO4) as the activating agent. The physicochemical, structural, and textural properties were determined. Adsorption kinetics and isotherms were studied and modelled. Porous carbons give specific surface areas equal to 1066 and 1053 m2.g−1 respectively for 2:1 and 4:1 ratios according to the B.E.T-Rouquerol model. Similarly, the said porous carbons give specific surface areas equal to 991 and 975 m2.g−1 respectively for 2:1 and 4:1 ratios according to the 2D-NLDFT model. Using the latter model, the pore size distribution is predominantly microporous, with the Vµ/VT (%) ratio increasing to 56 %. Thermogravimetric analysis of the porous coals showed favourable fixed carbon levels (≈ 60 %). The adsorption kinetics of methylene blue on activated carbons is governed by the pseudo-second order kinetic model indicating that the dye adsorption process is globally controlled by chemisorption. The results of the modelling of the methylene blue adsorption isotherms shown that the Langmuir model is the most credible model that best describes these experimental results, with 588 and 526 mg.g−1. These activated carbons are good candidates for the development of bio-sourced filters for the treatment of industrial wastewater.

Cationic Biocides Tend to Embed into the Inner Layer of the Model Outer Membrane Vesicles of Gram-negative Bacteria: Computational Insights

The outer membrane vesicles (OMVs), produced by many pathogenic bacteria, play a significant role in bacterial pathogenesis. They promote bacterial resistance to antibiotics and act as natural protective barriers. The study of OMVs is essential both for understanding the general mechanisms of bacterial pathogenicity and for the development of the antibacterial drugs. In this paper, we created model vesicle that imitate the OMVs of Gram-negative bacteria using molecular modeling techniques. To investigate the interaction of the cationic antimicrobial compounds with the outer lipopolysaccharide (LPS) monolayer and the inner phospholipid monolayer of the OMV membrane, we performed molecular dynamics simulations by placing molecules of the cationic antiseptic octenidine on the outside or inside of model vesicles. The interaction of octenidine with the outer and inner monolayer was significantly different: octenidine interacted weakly with the outer LPS surface of the model OMV, but exhibited high affinity for the phospholipids of the inner monolayer. To study the translocation of cationic antimicrobial molecules within model OMV, we performed steered molecular dynamics simulations. For all three cationic biocide molecules, antiseptic octenidine, photosensitizer octakis(cholinyl)zinc phthalocyanine, and dye methylene blue, it turned out that, along with the LPS of the outer membrane of the OMV, the phosphates of lipid A molecules represent the final barrier to their penetration into the model OMV.

Study of chemical, kinetic, and theoretical sorption properties of activated carbons obtained from agroindustrial origin, comparison of anionic and cationic model molecules: Part II—ZnCl2 activation

Study of chemical, kinetic, and theoretical sorption properties of activated carbons obtained from agroindustrial origin, comparison of anionic and cationic model molecules: Part II—ZnCl2 activation

Facile fabrication of superhydrophilic copper foam for rapid and efficient filtration of cationic dyes from water

Rapid and efficient separation of dyes from water is a formidable challenge due to the trade-off between separation selectivity and permeability. Here, a novel superhydrophilic copper foam (CF) enabling the rapid and efficient filtration of cationic dyes from water is reported. The fabrication involves brushing a coating consisting of attapulgite (APT), poly(vinyl alcohol) (PVA), TiO2 and glutaraldehyde (GA) onto copper foam and then heating. The obtained copper foam (CF-PVA/GA@APT/TiO2) is superhydrophilic and negatively charged with dye adsorption capability. The interconnected cage-shaped porous structure endows the foam with long tortuous permeation channels and large pore size. It is able to separate various cationic dyes with a separation efficiency reaching to 99.93 % and a permeation flux up to 1671 ± 189 L m-2h−1 under gravity. Furthermore, the CF-PVA/GA@APT/TiO2 can realize the selective separation and recovery of various cationic dyes from rhodamine B (RhB)-mixed dye solutions. Molecular dynamics-based computational modeling and experimental studies revealed that the interaction energy between the surface of CF-PVA/GA@APT/TiO2 and methylene blue (MB) is much stronger than that of the former and RhB, leading to adsorption of MB in the permeation channel, while RhB gradually migrates through the permeation channel and passes through the channel with water. The tortuous permeation channels of CF-PVA/GA@APT/TiO2 increase the contact area and absorption opportunities for cationic dye molecules on the surface, and its large pore size maintains the filtration flux. These properties provide the as-prepared foam with excellent potential applicability for industrial dye wastewater treatment.

Enhancing the Phase Crystallinity of Buried Layer Perovskites through Organic Salt Molecule‐Assisted Crystal Growth

The performance and stability of perovskite solar cells rely crucially on the purity of their active perovskite phase. While the two‐step method has emerged as a well‐known technique for fabricating high‐performance cells, it suffers from significant PbI2 phase impurities at the buried layer due to inefficient diffusion of cationic molecules into the preprepared PbI2 layer. Herein, a simple yet highly effective method is presented to boost phase purity within the buried layer by introducing formamidinium iodide (FAI) seed molecules into the underlying PbI2 layer. X‐Ray diffraction analysis result reveals that this process significantly reduces the PbI2 phase and enhances the purity of the perovskite's phase. It is also observed that this technique can produce perovskite layer with a remarkably smooth surface structure and large interconnected crystal grains, forming a continuous layer. These characteristics are subjected to further enhancement when hexamethylenetetramine molecules are concurrently introduced with FAI into the PbI2 layer. Solar cells fabricated using this method, with an active area of 0.1 cm2, achieve a remarkable power conversion efficiency of up to 24.52% with Voc as high as 1.18 V, representing a substantial improvement over cells produced using the standard two‐step method, which attains only 22.18% efficiency. With its simple yet impactful approach, the present method should find widespread adoption in the production of high‐performance perovskite solar cells.

Host-Guest Interactions of Ruthenium(II) Arene Complexes with Cucurbit[7/8]uril.

Cucurbit[n]urils (CB[n]s) have been recognized for their chemical and thermal stability, and their ability to bind many neutral and cationic guest molecules makes them excellent hosts in a range of supramolecular applications. In drug delivery, CB[n]s can enhance drug solubility, improve chemical and physical drug stability, and allow for triggered and controlled release. This study aimed to investigate the ability of CB[7] and CB[8] as molecular hosts to bind ruthenium(II) arene complexes that are current anticancer lead structures in the area of metallodrugs. Both, experimental and computational methods, led to insights into the binding preferences and geometries of [RuII(cym)Cl2]2 (1; cym = η6-p-cymene), [RuII(cym)(dmb)Cl2]) (2; cym = η6-p-cymene; dmb = 1,3-dimethylbenzimidazol-2-ylidene), and [RuII(cym)(pta)Cl2] (3, RAPTA-C; cym = η6-p-cymene; pta = 1,3,5-triaza-7-phospha-adamantane) with CB[7] and CB[8]. Competition experiments by mass spectrometry revealed clear preferences of 2 for CB[8] and 3 for CB[7]. Based on a comparison of the associated interaction energies from quantum chemical calculations as well as experimental data, 3@CB[7] clearly prefers a binding mode, where the pta ligand is located inside the cavity of the host, and the metal ion interacts with two of the carbonyl groups on the rim of CB[7]. In contrast, complex 2 binds in two different orientations with interaction energies similar to those of both CB[n]s, with the cym ligand being either inside or outside of the cavity. These findings suggest that ruthenium(II) arene complexes are able to form stable host-guest interactions with CB[n]s, which can be exploited as drug delivery vehicles in further metallodrug development to improve their chemical stability.

Thermal Truncation of Heptamethine Cyanine Dyes.

Cyanine dyes are a class of organic, usually cationic molecules containing two nitrogen centers linked through conjugated polymethine chains. The synthesis and reactivity of cyanine derivatives have been extensively investigated for decades. Unlike the recently described phototruncation process, the thermal truncation (chain shortening) reaction is a phenomenon that has rarely been reported for these important fluorophores. Here, we present a systematic investigation of the truncation of heptamethine cyanines (Cy7) to pentamethine (Cy5) and trimethine (Cy3) cyanines via homogeneous, acid-base-catalyzed nucleophilic exchange reactions. We demonstrate how different substituents at the C3' and C4' positions of the chain and different heterocyclic end groups, the presence of bases, nucleophiles, and oxygen, solvent properties, and temperature affect the truncation process. The mechanism of chain shortening, studied by various analytical and spectroscopic techniques, was verified by extensive ab initio calculation, implying the necessity to model catalytic reactions by highly correlated wave function-based methods. In this study, we provide critical insight into the reactivity of cyanine polyene chains and elucidate the truncation mechanism and methods to mitigate side processes that can occur during the synthesis of cyanine derivatives. In addition, we offer alternative routes to the preparation of symmetrical and unsymmetrical meso-substituted Cy5 derivatives.

Carboxylated pillar[5]arene cavity accommodates organic cations in the host-guest complexes

The electron-rich cavity of carboxylated pillar[5]arene efficiently encapsulates cationic guest molecules within supramolecular assemblies. In this study we provide evidence of the host-guest complexation between carboxylated pillar[5]arene and benzamidine, a competitive inhibitor of serine proteases. We show the unexpected inclusion of the polar amidinium functionality within the central cavity of the macrocyclic host sustained by N+-H···π and cation···π interactions. In addition to the in-cavity complexation, simultaneous external binding of bipyridinium guests with varying stoichiometries has been observed. The interesting aspect is the inclusion of a hydrogen bonded pair of 1,2-bis(4-pyridyl)ethylene guests into pillar[5]arene cavity. Additional insights into inclusion characteristics are provided by NMR and ion mobility mass spectrometry (IM-MS) studies, offering information for the solution/gas phase and enabling a comprehensive description of the complexation process across different phases. This work expands the portfolio of cationic guest molecules capable of being encapsulated by carboxylated pillar[5]arene, showing new promises and directions for their inclusion and self-assembly behavior.

Evolution of polyamine resistance in Staphylococcus aureus through modulation of potassium transport.

Microbes must adapt to diverse biotic and abiotic factors encountered in host environments. Polyamines are an abundant class of aliphatic molecules that play essential roles in fundamental cellular processes across the tree of life. Surprisingly, the bacterial pathogen Staphylococcus aureus is highly sensitive to polyamines encountered during infection, and acquisition of a polyamine resistance locus has been implicated in spread of the prominent USA300 methicillin-resistant S. aureus lineage. At present, alternative pathways of polyamine resistance in staphylococci are largely unknown. Here we applied experimental evolution to identify novel mechanisms and consequences of S. aureus adaption when exposed to increasing concentrations of the polyamine spermine. Evolved populations of S. aureus exhibited striking evidence of parallel adaptation, accumulating independent mutations in the potassium transporter genes ktrA and ktrD. Mutations in either ktrA or ktrD are sufficient to confer polyamine resistance and function in an additive manner. Moreover, we find that ktr mutations provide increased resistance to multiple classes of unrelated cationic antibiotics, suggesting a common mechanism of resistance. Consistent with this hypothesis, ktr mutants exhibit alterations in cell surface charge indicative of reduced affinity and uptake of cationic molecules. Finally, we observe that laboratory-evolved ktr mutations are also present in diverse natural S. aureus isolates, suggesting these mutations may contribute to antimicrobial resistance during human infections. Collectively this study identifies a new role for potassium transport in S. aureus polyamine resistance with consequences for susceptibility to both host-derived and clinically-used antimicrobials.

Precise Regulation the Multiemission Based on Soft Double Salt for Information Encryption.

Manipulation of multiemissive luminophores is meaningful for exploring luminescent materials. Herein, we report a soft double salt assembly strategy that could result in well-organized nanostructures and different luminescence based on multiple weak intermolecular interactions thanks to the existence of electrostatic attraction between the anionic and cationic platinum(II) complexes. The cationic complexes B1 and B2 can coassemble with anionic complex A, respectively, and the emission switches from monomeric and excimeric emission to the triplet metal-metal-to-ligand charge transfer (3MMLCT) along with morphology changes from 0-dimensional (0-D) nanospheres to 3-dimensional (3-D) nanostructures. It is demonstrated that an isodesmic growth mechanism is adopted during the spontaneous self-assembly process, and the relative negative ΔG values make the anionic and cationic complex molecules prefer to form aggregates based on π-π stacking, Pt···Pt interactions, and electrostatic interactions. The coassembly strategy between anionic and cationic complexes endows them with multicolor luminescent and apparent color as optical materials for advanced information encryption.

Bis-butoxyphenyl dipyridine cation with high affinity for PF6−: Enhancement of solid fluorescence and inhibits Escherichia coli and Staphylococcus aureus activity through anion-π+ interactions

The contamination of anions and the overuse of antibiotics pose significant hazards to human health. Excess anions can cause serious damage to organisms and the natural environment, while the misuse of antibiotics has led to the emergence of multi-drug resistant bacteria. Therefore, it is important to develop multifunctional fluorescent sensing devices that integrate the rapid and sensitive detection of specific anions and that exhibit excellent antimicrobial activity against multi-resistant bacteria. This study describes the synthesis of three water-soluble cationic fluorescent molecules, DPPT-R (R = 5C, 6C, 7C). Their structures were characterized using 1H NMR spectroscopy, HRMS, and single crystal X-ray diffraction. Spectroscopic properties of the probes were recorded using UV–visible absorption and fluorescence spectroscopy. The recognition mode and mechanism of the fluorescent probes towards PF6− were investigated. Under aqueous solution conditions involves the PF6− induced aggregation of the probe via strong electrostatic interactions, leading to fluorescence quenching. Adjusting the alkyl chain length of the probe can enhance the sensitivity for the detection of the target anions. The detection limits are 0.892 μM, 0.786 μM and 0.444 μM for R = 5C, 6C, 7C, respectively. In addition, DPPT-R and DPPT-R@PF6 exhibit good inhibitory activity and fluorescence imaging capability against methicillin-resistant Staphylococcus aureus and multidrug-resistant Escherichia coli. Among them, the side chain of DPPT-R@PF6 with an almost 90° bend may be more advantageous for membrane insertion, thus enhancing its antimicrobial activity. In particular, after DPPT-R and PF6− form the DPPT-R@PF6 complex, the complex enhances its solid-state fluorescence, intensity of bacterial fluorescence imaging, and antibacterial activity through anion-π+ interactions. Therefore, this study can provide a new strategy and theoretical basis for the design and application of multifunctional fluorescent sensing materials and antibacterial molecules based on electrostatic interactions and anion-π+ interactions.

Investigating antimicrobial behavior of thymol/Zn encapsulated hierarchically structured zeolite and thymol release kinetics

A new bioactive material was proposed by encapsulating thymol molecules and Zn2+ cations within the post-modified intracrystalline voids of hierarchical zeolite X crystals. To enhance the accessibility of thymol molecules within zeolite X crystals, commercial zeolite samples underwent post-synthesis treatment involving consecutive aqueous KCl, NH4Cl, and Na2H2EDTA solutions. The gas adsorption method utilized the encapsulation of both Zn2+ cation and thymol molecules into the resulting hierarchical zeolite X framework, which demonstrated improved antimicrobial activity. While sole thymol-encapsulated zeolite X exhibited no antimicrobial activity against S. aureus, Zn2+ encapsulated zeolite X (ZnX), thymol encapsulated post-treated zeolite X (HX-thy), and both Zn2+ and thymol encapsulated post-treated zeolite X (ZnHX-thy) displayed zone of inhibition values of 18.7 mm, 25.0 mm, and 37.5 mm, respectively. Adding Zn2+ and creating a hierarchical pore system in the zeolite X framework altered the release profiles. The Higuchi kinetic release model has the highest R2 value to describe the process of thymol release from X-thy, whereas the Elovich release model has the best fitting profile of thymol release kinetics from ZnX-thy, HX-thy, and ZnHX-thy. Results indicate that thymol and Zn2+ containing hierarchical porous materials could be beneficial tools for obtaining enhanced antibacterial activity and stability with reduced degradation and volatility of thymol with extended protection against microbial attack due to the controlled release. These findings highlight an innovative approach to designing sustainable and green materials, utilizing modified porous networks that encapsulate natural antibacterial compounds with environmentally benign metal ions.

Design and synthesis of S-citalopram-imprinted polymeric sorbent: Characterization and application in enantioselective separation

The current work describes the efficient creation and employment of a new S-citalopram selective polymeric sorbent, made from poly(divinylbenzene-maleic anhydride-styrene). The process began by using suspension polymerization technique in the synthesis of poly(styrene-maleic anhydride-divinylbenzene) microparticles. These were then modified with ethylenediamine, developing an amido-succinic acid-based polymer derivative. The S-citalopram, a cationic molecule, was loaded onto these developed anionic polymer particles. Subsequently, the particles were post-crosslinked using glyoxal, which reacts with the amino group residues of ethylenediamine. S-citalopram was extracted from this matrix using an acidic solution, which also left behind stereo-selective cavities in the S-citalopram imprinted polymer, allowing for the selective re-adsorption of S-citalopram. The attributes of the polymer were examined through methods such as 13C NMR, FTIR, thermogravemetric and elemental analyses. SEM was used to observe the shapes and structures of the particles. The imprinted polymers demonstrated a significant ability to adsorb S-citalopram, achieving a capacity of 878 mmol/g at a preferred pH level of 8. It proved efficient in separating enantiomers of (±)-citalopram via column methods, achieving an enantiomeric purity of 97 % for R-citalopram upon introduction and 92 % for S-citalopram upon release.

Comparing the crystal structures and spectroscopic properties of a p-hydroxy styrylquinolinium dye with those of its p-dimethylamino analogue

Two previously synthesized styrylquinolinium dyes, namely (E)-1-butyl-4-(4-(dimethylamino)styryl)quinolinium iodide (D36) and (E)-1-butyl-4-(4-hydroxystyryl)quinolinium iodide (D34), were compared in terms of their properties by single-crystal X-ray diffraction (XRD), Hirshfeld surface analysis, Fourier transform Raman (FT-Raman), Fourier transform infrared (FT-IR), fluorescence, and ultraviolet–visible (UV–Vis) spectroscopy, and 1H- and 13C-NMR methods. Both dyes D36 and D34 crystallized in the triclinic and monoclinic systems in the centrosymmetric space groups P-1 and P21/n, respectively. The unit cell of D36 contains two molecules of the dye, participating in weak intermolecular interactions, whereas that of D34 contains four formula units. The phenolic hydroxy group of D34 participates in the formation of a hydrogen bond with the iodide anion. The 4-styrylquinolinium moieties of the cationic dye molecules are nearly planar. The dihedral angle between the mean planes through the ten-membered quinolinium system and the benzene ring is 7.5° in D36 and 5.9(1)° in D34. The structural parameters planarity and bond length alternation (BLA) are discussed, which are important for the evaluation of the first hyperpolarizability β at the molecular level, even in a centrosymmetric crystal. The UV–visible spectra of the dyes in 14 solvents of different polarities were investigated. The reversible solvatochromic behavior of the dyes is demonstrated experimentally and compared with known “binuclear dyes” by evaluating the Rezende model. Dye D36 does not fluoresce, and D34 has a very low emission in the solvents tested.