Search Results (1,096)

This study synthesizes and comparatively investigates two squaric acid-based phthalocyanine-like dyes, SNF and its long-chain alkylated derivative LNF, to systematically elucidate the influence of peripheral hydrophobic groups on their third-order nonlinear optical (NLO) properties. The NLO characteristics were comprehensively characterized using femtosecond Z-scan and I-scan techniques at both 800 nm and 900 nm. Both dyes exhibited strong saturable absorption (SA), confirming their potential as saturable absorbers. Critically, the comparative analysis revealed that SNF exhibits a significantly greater nonlinear absorption coefficient (β) compared to LNF under identical conditions. For instance, at 800 nm, the β of SNF was approximately 3–5 times larger than that of LNF. This result conclusively demonstrates that the introduction of long hydrophobic alkyl chains attenuates the NLO response. Furthermore, I-scan measurements revealed excellent SA performance, with high modulation depths (e.g., LNF: 43.0% at 900 nm) and low saturation intensities. This work not only clarifies the structure–property relationship in these D-A-D dyes but also presents a clear strategy for modulating the NLO properties of organic chromophores for applications in near-infrared pulsed lasers. Full article

This study explores a series of 3,4-dihydroisocoumarins as potential inhibitors of fatty acid oxidation through rational design, synthesis and in vitro evaluation. The compounds studied were designed as structural analogs of the natural substrates of carnitine acetyltransferase (CAT) and other enzymes in the carnitine transferase family, which play a crucial role in fatty acid metabolism. Comparative in vitro analyses revealed that the presence of an alkyl substituent at position 3 of the heterocyclic core, along with its chain length, significantly influences inhibitory activity, yielding IC₅₀ values in the micromolar range. Kinetic studies of one of the most potent compounds—cis- and trans-3-decyl-6,7-dimethoxy-3,4-dihydroisocoumarin-4-carboxylic acids—demonstrated mixed inhibition of CAT, with K_i values of 130 μM and 380 μM, respectively. These findings underscore the therapeutic potential of the compounds under investigation in modulating fatty acid catabolism, with possible applications in treating metabolic disorders. Full article

The recent global coronavirus pandemic highlighted the ever-present threat of respiratory virus outbreaks and the consequent need for ongoing research into antiviral therapy. To this end, structural analogues of the guanidinium-based drug camostat mesylate have been synthesised to probe their potential inhibition of Transmembrane Serine Protease 2 (TMPRSS2), a human protease that is essential for infection by many respiratory viruses, including Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2). Our in vitro fluorescence-based protease assays and supporting computational docking studies suggest that C-terminal camostat analogues retain TMPRSS2 inhibition potencies (IC₅₀ = 1–3 nM, BE = −6.6 to −7.0 kcal/mol) that match or exceed that of the parent drug. Analogues 1c and 1d emerge as lead candidates in this regard, thereby validating the rationale behind C-terminal structural modifications and highlighting these derivatives as promising scaffolds for the future development of targeted antiviral therapeutics. Replacement of camostat’s ester functionality with peptide linkages largely preserves non-covalent binding but disrupts in vitro protease inhibition, findings consistent with the parent drug’s known role as an acylating suicide inhibitor. Docking studies confirm that the replacement of aromatic residues with flexible, equivalent-length alkyl chains is detrimental to drug binding. These function and binding data offer new directions for the synthesis of further analogues of camostat and of other guanidinium-based protease inhibitors that have yet to be refined via structure–activity relationship studies. Further investigation will support tailoring this class of drugs for repurposing in antiviral therapy. Full article

A group of sulfonium and selenonium salts bearing diverse benzylidene acetal substituents on their side chain moiety were designed and synthesized. Compared with our previous study, structural modifications in this study focused on multi-substitution of the phenyl ring and bioisosteric replacements at the sulfonium cation center. In vitro biological evaluation showed that selenonium replacement could significantly improve their α-glucosidase inhibitory activity. The most potent inhibitor 20c (10.0 mg/kg) reduced postprandial blood glucose by 48.6% (15 min), 52.8% (30 min), and 48.1% (60 min) in sucrose-loaded mice, outperforming acarbose (20.0 mg/kg). Docking studies of 20c with ntMGAM presented a new binding mode. In addition to conventional hydrogen bonding and electrostatic interaction, amino residue Ala-576 was first identified to contribute to binding affinity through π-alkyl and alkyl interactions with the chlorinated substituent and aromatic ring. The selected compounds exhibited a high degree of safety in cytotoxicity tests against normal cells. Kinetic characterization of α-glucosidase inhibition confirmed a fully competitive inhibitory mode of action for these sulfonium salts. Full article

Cancer is hallmarked by uncontrolled cell proliferation and enhanced cell survival, driven by a complex interplay of factors—including genetic and epigenetic changes—that disrupt metabolic and signaling pathways and impair organelle function. While the roles of mitochondria and the endoplasmic reticulum in cancer are widely recognized, emerging research is now drawing attention to the involvement of peroxisomes in tumor biology. Peroxisomes are essential for lipid metabolism, including fatty acid α- and β-oxidation, the synthesis of docosahexaenoic acid, bile acids, and ether lipids, as well as maintaining redox balance. Despite their critical functions, the role of peroxisomes in oncogenesis remains inadequately explored. Prostate cancer (PCa), the second most common cancer in men worldwide, exhibits a unique metabolic profile compared to other solid tumors. In contrast to the glycolysis-driven Warburg effect, primary PCa relies primarily on lipogenesis and oxidative phosphorylation. Peroxisomes are intricately involved in the metabolic adaptations of PCa, influencing both disease progression and therapy resistance. Key alterations in peroxisomal activity in PCa include the increased oxidation of branched-chain fatty acids, upregulation of α-methylacyl coenzyme A racemase (a prominent PCa biomarker), and downregulation of 1-alkyl-glycerone-3-phosphate synthase and catalase. This review critically examines the role of peroxisomes in PCa metabolism, progression, and therapeutic response, exploring their potential as biomarkers and targets for therapy. We also consider their relationship with androgen receptor signaling. A deeper understanding of peroxisome biology in PCa could pave the way for new therapies to improve patient outcomes. Full article

Background/Objectives: Naegleria fowleri is a free-living amoeba that invades brain tissues causing fatal primary amoebic meningoencephalitis (PAM). An effective and tolerable therapeutic agent is still lacking. Methods: A series of conformationally restricted analogs of miltefosine with varied restriction positions, stereochemical configuration and lengths of alkyl chain was investigated to discover more effective and less toxic agents than miltefosine. Results: Among tested compounds, derivatives 2a, 3b and 3d featuring 1,2- or 2,3-positional restriction with trans-configuration and tridecyl or behenyl alkyl chains were discovered as more potent and less cytotoxic agents. Compounds 2a, 3b and 3d elicited 3.49-, 3.58- and 6.03-fold relative potencies to miltefosine and 7.53, 3.90 and 3.49 selectivity indices, respectively. Furthermore, compounds 2a and 3b showed IC₉₀ values for N. fowleri lower than CC₅₀ against glial C6 cells. Compounds 2a, 3b and 3d induced morphological changes and programmed cell death of N. fowleri via the apoptosis-like pathway. The induced death of N. fowleri involved DNA fragmentation along with the loss of mitochondrial membrane potential. Conclusions: The current research presents compounds 2a and 3b as more potent, selective and effective agents than miltefosine against N. fowleri for further development. Full article

Overheating in miniaturized electronic devices can reduce their useful life, where conventional heat sinks are insufficient. The utilization of ionenes as solid–solid phase change materials is proposed to enhance thermal dissipation without the risk of leakage. In this work, a series of imidazolium ionenes with structural modifications in their aromatic core and aliphatic chain length were synthesized. The synthesis was carried out using the respective monomers diimidazole and alkyl dibromide, followed by counterion bromide exchange using lithium bis(trifluoromethanesulfonyl)imide, with yields over 90% in all cases. Thermal characterizations showed that all ionenes are heat-resistant, with degradation temperatures between 421 °C and 432 °C; moreover, they all presented only a solid–solid transition (Tg) as a phase change, between 59 °C and 28 °C, which varied depending on the aromatic core used and the length of the aliphatic chain. The obtained ionenes were introduced into an experimental device with an operating temperature of 40 °C, to be evaluated as solid–solid phase change materials in heat sinks. These demonstrated an average decrease in operating temperature of 9 °C compared to the device without ionenes. On the other hand, the stability of the ionenes was analyzed over 10 thermal cycles at 40 °C at a heating rate of 5 °C/min. This analysis demonstrated that the ionenes did not present changes or degradation during the evaluated cycles. These findings demonstrate that imidazolium ionenes are promising solid–solid phase change materials for use as efficient and self-repairing heat sinks in compact electronic devices. Full article

In the methylation of pseudocumene with methanol over IM-5 zeolite, the yield of durene can be enhanced. However, poorer stability of the catalytic activity was observed, especially at a higher methanol/pseudocumene ratio. In this paper, conventional characterization methods (XRD, XRF, TGA, SEM, physical adsorption, OH-IR, NH₃-TPD, and Py-IR) were used to characterize fresh and deactivated IM-5 zeolite and ZSM-5. FT-IR, XPS, TG-MS, GC-MS, FT-ICR MS, and NMR were employed to characterize deactivated IM-5 zeolite. It was found that the deactivation of IM-5 zeolite was mainly due to the severe coverage of acidic sites and pore channels by carbon deposits. The carbon deposits within the internal surface had a higher abundance, mainly in the form of linear unsaturated chain-like structures with a high degree of unsaturation. The carbon deposits on the external surface were mainly polycyclic aromatic hydrocarbons with alkyl side chains and a high degree of saturation, accompanied by unreacted methanol. Moreover, graphitized carbon existed on both the internal and external surfaces, which made the conventional coke-burning regeneration method unable to restore the activity of the post-reaction IM-5 zeolite. This work had certain reference significance for modulating the acidity and pore channels of zeolite catalysts, thus improving the activity and stability of the catalysts and extending their service life. Full article

Ionic liquids (ILs) have attained considerable attention as cellulose solvents. Nevertheless, the detailed mechanism of cellulose dissolution in ILs is not clearly defined. It is crucial to recognize the role of the individual components of the ILs to fully understand this mechanism. During this study, the effect of alkyl chain length in imidazolium cation was examined using synthesized ILs which are composed of common acetate anion and imidazolium cations with different alkyl substituents. This study also aimed to investigate the odd–even effect of alkyl chain carbons. Furthermore, whereas most published investigations on cellulose dissolution in ILs used microcrystalline cellulose (MCC), which has a far lower degree of polymerization, in this study, cotton cellulose was used. During the dissolution experiments, cotton cellulose (5% w/w) was added to each IL, and the progress of the dissolution was monitored using polarized light microscopy (PLM). The regeneration of cellulose was performed by using water as the anti-solvent, and the regenerated cellulose was characterized by Fourier-transform infrared (FTIR) spectroscopy and scanning electron microscopy (SEM). During these experiments, it was noted that ILs with odd C3 and C5 carbon chains were less effective at dissolving cellulose than those with even C2 and C4 alkyl chains. Additionally, after regeneration, biomaterials for a variety of applications could be produced. Full article

Ionic liquids (ILs) can ideally reduce defects and improve the film stability of emissive metal halide perovskite films. In this work, we measure how the structure and emission of methylammonium lead tribromide (MAPbBr₃) perovskite films is modulated by long alkyl chain-containing pyridinium, imidazolium, or pyrrolidinium ILs. Two different film deposition methods are compared, with the resultant films characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), and photoluminescence (PL) spectroscopy. For the latter, the differences in PL intensity of the perovskite are quantified using photoluminescence quantum efficiency (PLQE) measurements. It is found that a spin coating method in conjunction with the use of an imidazolium-containing IL (for a given precursor concentration) produces the strongest emissive perovskite. This optimal enhancement is attributed to a function of accessible surface charges associated with the heterocyclic cation of a given IL and perovskite defect passivation by bromide, the latter elucidated with the help of density functional theory. Proof-of-concept device fabrication is demonstrated for the case of a light emitting diode (LED) with the IL present in the emissive perovskite layer. Full article

The limited understanding of intermolecular interactions in deep eutectic solvents (DESs) has restricted their rational design and broader application. In this study, a series of hydrophobic DESs (HDESs) were prepared using lidocaine as the hydrogen bond acceptor and various carboxylic acids as hydrogen bond donors. Their physicochemical properties, including density, viscosity, and thermal stability, were systematically characterized. Interactions between components were evaluated through excess molar volume, viscosity deviation, and Grunberg–Nissan parameters. Strong hydrogen bonding between lidocaine and carboxylic acids was confirmed, which weakened with increasing alkyl chain length of the acids. Furthermore, as the acid content in the mixture increased, lidocaine’s ability to disrupt the intrinsic hydrogen-bonding network of the carboxylic acids decreased, thereby weakening the hydrogen bonding interactions between the components. The extraction capability of the HDESs for cobalt ions was evaluated in aqueous systems. Cobalt, a key material in lithium-ion batteries and advanced alloys, is in rising demand due to clean energy development. The lidocaine/decanoic acid (1:2) system exhibited nearly 100% extraction efficiency, surpassing conventional extractants. The hydrophobic nature of the HDESs facilitated effective phase separation and reduced solvent loss. These findings provide theoretical insights and design principles for developing high performance HDESs tailored for environmentally friendly metal recovery, particularly in battery recycling and treatment of industrial wastewater. Full article

This study analyzed the compression isotherms of 7β-alkyl cholic acid derivatives and compared them to those of cholic and deoxycholic acids to elucidate their orientation and molecular interactions (acidic aqueous substrate—pH 2; NaCl concentration—3 M; temperature—T = 298.15 K). It was found that the compression isotherm of the 7β-octyl derivative of cholic acid in the monomolecular layer is most similar to the compression isotherm of deoxycholic acid. In 7β-alkyl derivatives of cholic acid, the hydrophobic interaction energy in their aggregates from a monomolecular film increased with the length of the alkyl chain. However, this energy did not increase linearly with C atoms, suggesting the existence of a conformational equilibrium. In binary mixtures of the tested bile acids and lecithin, only the 7β-octyl derivatives of cholic acid and deoxycholic acid had orientations in which the steroid skeleton had a “vertical” position, i.e., only the C3 OH group was immersed in the aqueous substrate, which resulted in the maximum hydrophobic interaction with lecithin. In 7β-octyl derivatives, part of the octyl chain probably also participated in the interaction with lecithin. In 7β-propyl and 7β-butyl derivatives, C7 alkyl groups sterically shielded the C7 α-axial OH group. However, in the 7β-ethyl derivative the C7 OH group was not additionally sterically shielded, so this derivative, similarly to cholic acid, partially dissolved in the aqueous substrate after the collapse point. Full article

Novel derivatives of imidazolium-based ionic liquids with varying alkyl chains, IL-1, IL-2, and IL-3, were evaluated as corrosion inhibitors for mild steel in 1 M HCl solution. The experimental investigations used Electrochemical Impedance Spectroscopy (EIS) and potentiodynamic polarization (PDP) techniques. The results demonstrated exceptional corrosion inhibition efficiency (>90%), as classified by electrochemical analyses, which identified these corrosion inhibitor compounds as mixed-type. The ionic liquids’ adsorption complied with the Langmuir adsorption isotherm. The characterization of the surface via SEM and EDX confirmed the development of a protective adsorbed inhibitor layer on the steel substrate. Furthermore, the theoretical DFT method (at B3LYP/6-311G (d, p)) was conducted to describe the electronic properties and reactivity of the molecules. The Monte Carlo simulation on the surface of Fe(1 1 0) was assessed to provide in-depth understanding of the adsorption mechanisms and interactions responsible for the corrosion inhibition between the molecules and the surface of the mild steel. Full article

Liquid crystals exhibit unique properties that can be tailored in response to external stimuli. Significant research is directed toward the development of luminescent materials exhibiting liquid crystallinity for various applications. The present work reports Au(I) complexes featuring N-heterocyclic carbene and phenyl acetylide ligands. Metal complexes enable the utilization of the triplet excitons through their inherent spin–orbit coupling, promoting intersystem crossing from singlet (S_n) to triplet (T_n) states to observe room-temperature phosphorescence (RTP). The strong bonds between carbene and Au enhance the thermal stability, and the substituted benzimidazole ring alters the thermodynamic and photophysical properties of the complexes. Incorporating the acetylide ligands with long alkoxy chains led to the formation of liquid crystalline (LC) phases, which exhibited stability over a wide temperature range. Additionally, the luminescence behavior was affected by the ethynyl ligands, and high quantum yields of RTP were observed. This study establishes the development of LC Au(I) complexes with a thermodynamically stable LC mesophase over a wide temperature range for applications in the field of light-emitting functional materials. Full article

A traditional dairy product from northern Colombia is suero costeño (SC), typically handmade through artisanal processes involving the natural fermentation of raw cow’s milk (RM); it is characterized by a creamy texture and a distinctive sensory profile, with a sour/salty taste and rancid odor. This study aimed to determine the chemical identity (using GC-FID/MSD) of SC and RM samples (from eight locations in the department of Córdoba-Colombia) by analyzing volatile components (trapped by HS-SPME and SDE) and fatty acid content. Consequently, the most notable results were as follows: (a) myristic (7–12%), stearic (12–17%), oleic (13–23%), and palmitic (21–29%) acids were the most abundant constituents [without significant differences among them (p > 0.05)] in both RM and SC fats; these were also expressed as polyunsaturated (2–5%), monounsaturated (26–36%), saturated (59–69%), omega-9 (19–30%), omega-6 (0.5–1.6%), and omega-3 (0.2–1.2%) fatty acids; (b) differences in the composition (p < 0.05) of the volatile fractions were distinguished between RM and SC samples; likewise, the SC samples differed (from each other) in their volatile composition due to the preparation processes applied (processes with raw milk and natural fermentation had less variability); nonetheless, it was possible to determine the volatilome for the artisanal product; and (c) the major components responsible for the chemical identity of SC were ethyl esters (of linear saturated and unsaturated acids, short/medium chains), aliphatic alcohols (linear/branched, short/long chains), aliphatic aldehydes (long chains, >C₁₄), alkyl methyl ketones (long chains, >C₁₁), sesquiterpenes (caryophyllane/humulane types), monoterpenes (mono/bi-cyclics), short-chain fatty acids, and aromatic alcohol/acid, among others. Full article