Search Results (413)

The present study aimed to design, synthesize, and evaluate a new series of thieno[3,2-d]pyrimidin-4(3H)-one-based Schiff bases as potential antileishmanial agents against Leishmania major (L. major). A series of twenty thieno[3,2-d]pyrimidine Schiff base derivatives were synthesized and characterized using FTIR, NMR, and HRMS techniques. Their antipromastigote activities were evaluated in vitro against L. major, while cytotoxic effects were assessed on HUVECs to determine selectivity indices. The most active compound was further investigated using molecular docking against several L. major proteins. Among the tested compounds, compound 12, bearing a 2-hydroxy-5-bromophenyl moiety, exhibited the most potent activity against L. major promastigotes with an IC₅₀ value of 13.7 µM, along with a favorable selectivity index (SI = 17.5), outperforming the reference drug miltefosine (IC₅₀ = 31 µM and SI = 0.2). Docking studies demonstrated that compound 12 showed the strongest binding affinity toward phosphodiesterase B1, supported by a docking score of −9.042 kcal/mol and an MM-GBSA value of −67.21 kcal/mol. This study highlights thieno[3,2-d]pyrimidin-4(3H)-one as a promising scaffold in the context of in vitro antileishmanial screening and suggests the role of ortho-phenolic substitution in enhancing activity and selectivity. Compound 12 emerges as a promising lead, warranting further optimization and biological evaluation in future studies. Full article

Raw lacquer, a natural polymer derived from the bast of lacquer trees (Toxicodendron vernicifluum), is renowned as the “King of Coatings” due to its exceptional film-forming properties, abrasion resistance, corrosion resistance, and biocompatibility. However, its inherent limitations—including stringent drying conditions, slow curing rates, deep coloration, and difficult application—have severely restricted its modernization and widespread adoption. This review systematically summarizes recent research advances in the modification and application of raw lacquer, focusing on four major modification strategies: (1) Nanocomposite modification—incorporating functional nanofillers such as Al₂O₃, cellulose nanofibrils (CNF), polydopamine (PDA) melanin-like nanoparticles, and SiO₂ to significantly enhance film hardness, compactness, UV-aging resistance, and drying kinetics. (2) Chemical structure modification—employing molecular design strategies including aminoanthraquinone grafting, tung oil blending, water-based emulsification, and terpene/allyl group functionalization to improve hydrophobicity, flexibility, fast-drying properties, and achieve dual photo/oxygen curing. (3) Biomass synergistic composites—utilizing natural polymers such as chitosan and lignin, along with bio-inspired adhesion mechanisms (e.g., PDA), to confer advanced functionalities including antibacterial and antifouling properties. (4) Curing behavior regulation—precisely controlling drying kinetics through inorganic salt ion microenvironment engineering, nonionic surfactants, and salicylaldehyde Schiff base-based driers. Building upon these foundations, this review further expands on the emerging high-value applications of modified lacquer in preventive conservation of cultural heritage, advanced functional coatings (anti-corrosion, super-hydrophobicity, flame retardancy), biomedical materials (hemostasis, antibacterial activity, drug-controlled release, water treatment adsorption), and intelligent responsive flexible electronics. Finally, addressing challenges including weak fundamental research, bottlenecks in green industrialization, and lack of standardization, future development directions are proposed encompassing interdisciplinary innovation, sustainable modification strategies, integration of multifunctional intelligent systems, and big data-driven research paradigms, aiming to provide theoretical guidance and technical references for the high-value utilization and modernization of lacquer resources. Full article

Imidazolidin-2-thiones are versatile sulfur-containing heterocycles with broad biological relevance. The synthesis of (3aR,7aR)-1,3-bis(4-aminobenzyl)octahydro-2H-benzo[d]imidazole-2-thione (an imidazolidin-2-thione derivative) from trans-(R, R)-diaminocyclohexane is presented via a three-step sequence: formation of a Schiff base from 1,2-diamine and 4-nitrobenzaldehyde, followed by reduction with NaBH₄; thiocarbonylation under microwave irradiation (MW) to generate the imidazolidin-2-thione core; and reduction of the nitro substituents to amines using an iron/CaCl₂ system. The structure of the final compound was confirmed by detailed ¹H and ¹³C NMR analyses, demonstrating the preservation of the bicyclic backbone and the successful conversion of the nitro functional group. The overall yield of the sequence was 28%, with the reduction of the nitro group identified as the rate-limiting step. This protocol represents a viable synthetic strategy for obtaining functionalized imidazolidin-2-thiones useful for the development of novel bioactive sulfur-containing heterocycles. Full article

Penaeus sp. shells (shrimp) were used to extract chitosan using acid and basic treatments, which were characterized by IR spectroscopy, Raman spectroscopy, potentiometric titration, and elemental analysis. The degrees of deacetylation were determined to be 71.8%, 75.6%, 53.4%, and 68.6%, respectively. Likewise, viscosimetry measurements were carried out, determining an average molecular weight of chitosan 1 of 1521467.919 (g/mol). The obtained chitosan was used as a substrate in condensation reactions with 10 para-substituted benzaldehydes. The products obtained were characterized by IR, Raman, and ¹H-NMR spectroscopy, AE (Elemental Analysis), TGA (Thermogravimetric Analysis), and DSC (Differential Scanning Calorimetry). For the obtained polymers, biological assays of cytotoxicity using RAW macrophage cells and leishmanicidal activity on promastigotes of Leishmania mexicana were performed. The results show that the synthesized products do not present in vitro cytotoxicity, and that 1 (Chitosan) and 3i (Schiff Base) present leishmanicidal activity. Selected derivatives were incorporated into polyvinyl alcohol-based films and evaluated for surface topography and gas permeability. AFM revealed nanometric roughness patterns, while gas exchange studies demonstrated selective CO₂/O₂ permeability, supporting passive modified atmosphere formation in packaged carrots. Mechanical characterization revealed that the incorporation of Schiff base derivatives significantly influences tensile strength and flexibility, with certain films exhibiting enhanced elongation and mechanical performance compared to pure PVA, highlighting their potential for packaging applications. These findings confirm that chemical functionalization enhances the versatility of chitosan, allowing the design of tailored biopolymers. The synthesized derivatives show promising characteristics for the development of biodegradable films with potential applications in food packaging and antiparasitic material development. Full article

Lubricants contain various types of additives, with corrosion and rust inhibitors being some of the most important. Due to the importance of 2,5-Dimercapto-1,3,4-thiadiazole (DMTD) in the field of corrosion inhibitors, we used it as a key intermediate to synthesize a series of 4-thiazolidinone and 4-imidazolidinone derivatives. This work also includes performing the reaction of DMTD with ethyl chloroacetate, which produced the corresponding ester, followed by the conversion into a hydrazide derivative using hydrazine hydrate. The next step is the condensing of the yielded hydrazide with various aromatic aldehydes yielding Schiff bases, which were subjected to cyclization by means of mercapto acetic acid and ethyl glycinate to produce the target 4-thiazolidinone and 4-imidazolidinone derivatives, respectively. FT IR, ¹H NMR, and ¹³C NMR spectroscopies were involved to confirm the structures of these derivatives. The synthesized derivatives have been evaluated as copper corrosion and rust inhibitors for medium lubricants in accordance with ASTM-D130 and ASTM-D665 standards. Interestingly, some lubricant blends of the synthesized derivatives showed good performance as copper corrosion and rust inhibitors. Full article

A synergistic approach to the photodegradation of polydimethylsiloxane-based composites upon photoaging was implemented by using La(III) complexes of Schiff base ligands with a silicon-containing spacer as fillers. The analysis methods were spectral, nanomechanical, and morphological. The results show that the accelerated oxidative degradation of the polydimethylsiloxane matrix is due to the combined actions of radicals, fragments, and photoproducts derived from the photolysis of the La(III) complexes and the water vapors in the photoaging chamber. Compared to the undoped polydimethylsiloxane, the photo-excited radical intermediates and photoproducts of the La(III) complexes, with aromatic or quinone structures, in ground or in excited state, have acted as photocatalysts and as new sources for reactive intermediates and for the generation of reactive oxygen species. Infrared, electron spin resonance, and nanomechanical investigations revealed that the chemistry of the photoaged surfaces comprises oxygen–containing species, photoreaction products, and an extended siloxane network with embedded ligand fragments. The key role of La(III) complexes in promoting the generation of reactive species is described. The study highlights the unexplored potential of La(III) complexes of Schiff base ligands bearing a silane/siloxane spacer as potential catalysts in the photodegradation of polymers and plastics. Full article

In this study, a novel composite hydrogel was developed based on oxidized sodium alginate (OSA), synthesized via sodium periodate oxidation, and incorporated into a carboxymethyl chitosan (CMCS) matrix. Scallop active peptides (SAPs), a marine-derived bioactive component with outstanding antioxidant and pro-regenerative activities, was introduced to endow the hydrogel with enhanced biological functions, which is of great significance for breaking the functional limitations of traditional single-component hydrogels. The construction of a dynamic covalent network, driven by the Schiff base reaction, was confirmed through structural characterization using FT-IR and ¹H-NMR. The hydrogel exhibited favorable physicochemical properties, including shear-thinning behavior, significant self-healing capability, and a uniform porous microstructure that effectively mimics the extracellular matrix (ECM). In vitro evaluations revealed excellent biocompatibility and potent pro-angiogenic potential, as evidenced by enhanced HUVEC migration and tube formation. In a rat model of full-thickness skin wounds, the CMCS/OSA/SAPs hydrogel significantly accelerated wound closure and promoted re-epithelialization and organized collagen deposition. Furthermore, immunohistochemical analysis confirmed upregulated VEGF and α-SMA expression, alongside reduced inflammatory levels (decreased iNOS), indicating potent tissue-regenerative and immunomodulatory functions. Overall, this work presents a multifunctional hydrogel system that integrates antioxidant, anti-inflammatory, and tissue-regenerative properties, offering a promising strategy for deep-wound healing. This study highlights the significant potential of marine-derived bioactive proteins/peptides in the development of advanced biomedical materials. Full article

Self-healing materials have attracted increasing attention as a strategy to enhance durability, extend service life, and reduce maintenance in advanced material systems. Among these, cellulose-based self-healing materials represent a sophisticated intersection between sustainable macromolecular chemistry and adaptive materials science. This review provides a synthesis of recent advancements in the field, systematically categorizing materials derived from cellulose raw materials. We evaluate the fundamental chemical strategies employed to achieve autonomous repair, distinguishing between extrinsic mechanisms—utilizing cellulose-based micro/nano-capsules to sequester healing agents—and intrinsic mechanisms governed by dynamic covalent chemistry (Schiff-base, boronic ester, Diels–Alder) and supramolecular interactions (hydrogen bonding, metal–ligand coordination, and host–guest assemblies). The analysis highlights how cellulose’s hierarchical structure and abundant surface functionality are leveraged to overcome the traditional trade-off between mechanical toughness and healing efficiency. Particular emphasis is placed on the transition from simple structural hydrogels to sophisticated multifunctional systems. These include ultra-stretchable strain and pressure sensors for e-skin applications, biocompatible and injectable matrices for chronic wound management and stem cell delivery, and advanced anti-freezing eutectogels for performance in extreme environments. Furthermore, we explore the integration of cellulose into traditional sectors, such as self-healing concrete utilizing microbe-induced calcification and smart, eco-friendly coatings for corrosion protection. Finally, we discuss critical challenges, including environmental stability, scalability, and the development of standardized evaluation protocols, providing a roadmap for the next generation of bio-derived, sustainable and intelligent materials. Full article

Moxifloxacin-based Schiff-base ligands provide a useful platform for tuning the coordination and biological properties of fluoroquinolone derivatives. Here, a moxifloxacin–salicylaldehyde hydrazone ligand (MOX-S) was prepared and coordinated with cobalt(II), nickel(II), copper(II), oxovanadium(IV), and gadolinium(III) ions to obtain a series of metal complexes. Citrate-stabilized gold nanoparticles (AuNPs) were also prepared and functionalized with MOX-S and the Cu(II) complex to evaluate the effect of nanoformulation on biological performance. The compounds were characterized using complementary analytical, spectroscopic, magnetic, thermal, and microscopic techniques. The combined data support 1:2 metal-to-ligand formulations for the complexes and indicate coordination mainly through the azomethine nitrogen and oxygen donor sites of MOX-S. In antimicrobial screening, the activity was strongly metal- and organism-dependent. Cu–MOX-S and VO–MOX-S showed the most pronounced activity against Gram-positive bacteria, with inhibition zones of up to 30 mm, while Cu–MOX-S displayed MIC values of 19.53 and 39.06 µg mL⁻¹ against Bacillus subtilis and Staphylococcus aureus, respectively. Cytotoxicity assays showed that MOX-S was more active than moxifloxacin against MCF-7 and HepG2 cells, while Cu–MOX-S showed enhanced potency, particularly toward HepG2 cells, with an IC₅₀ of 0.98 µM and a selectivity index of 5.97. AuNP formulations further increased the apparent antiproliferative potency in the tested cancer cell lines, giving sub-micromolar IC₅₀ values. Computational analyses, including DFT-based electronic descriptors and molecular docking, provided qualitative support for the experimentally observed coordination and cytotoxicity trends. Overall, metal coordination and AuNP formulations provide complementary strategies for modulating the physicochemical and in vitro biological behavior of this moxifloxacin-derived hydrazone scaffold. Full article

This study reports the synthesis and characterization of a novel benzimidazole-derived Schiff base (BIMPB) via the condensation of (1H-benzo[d]imidazol-2-yl)methanamine with 1-phenylbutane-1,3-dione. The structure was confirmed using ¹H-NMR, ¹³C-NMR and FT-IR spectroscopy. Photophysical properties were extensively evaluated, revealing a strong S₀ → S₂ transition at 212 nm and fluorescence emission peaks at 396 and 410 nm, corresponding to π → π* and n → π* transitions. BIMPB demonstrated significant sensitivity to pH variations, exhibiting blue shifts of 11–23 nm across different environments. Furthermore, the compound acts as a fluorescent chemosensor for Cu²⁺ and Ca²⁺ ions, where coordination leads to a substantial reduction in fluorescence intensity accompanied by a distinct blue shift. The interaction between BIMPB and DNA was investigated using UV-Vis and fluorescence titration. The results showed a hypochromic effect and a minor shift in the absorption peak from 342 nm to 340 nm, suggesting a binding mechanism dominated by intercalation or electrostatic interactions. A high binding constant (K_b = 2.1 × 10⁵ M⁻¹) and a fluorescence quenching efficiency of 58.9% confirm the formation of a stable complex. Stern–Volmer analysis indicated a static quenching mechanism. These experimental findings, supported by molecular docking studies (binding energy = −8.3 kcal/mol), highlight the potential of BIMPB as a sensitive molecular probe for DNA-targeting and chemical sensing applications. Full article

The search for new anticancer agents with improved efficacy and reduced toxicity has intensified interest in metal-based compounds. In this study, two novel palladium(II) complexes, synthesized from Schiff base ligands derived from 5-chloro-salicylaldehyde and p-hydroxybenzylamine or tyramine, were chemically characterized and biologically evaluated. Both complexes exhibited significant cytotoxic activity against the MCF-7 breast cancer cell line in a dose- and time-dependent manner, with Pd2 showing slightly higher potency. Morphological analysis of treated cells indicated that apoptosis is the predominant mechanism of cell death. To gain deeper insight into the potential mechanisms underlying the observed anticancer activity, several biologically relevant targets were investigated. Enzyme kinetics revealed that the complexes act as uncompetitive inhibitors of liver catalase, suggesting a possible role in the induction of oxidative stress. Fluorescence studies demonstrated that Pd2 interacts with CT-DNA through combined intercalative and minor groove binding modes and exhibits significant binding affinity toward human serum albumin, predominantly at Sudlow’s site I. Molecular docking analysis further supported favorable interactions with catalase, estrogen receptor α, and B-form DNA, providing structural insight into the experimentally observed biological effects. Overall, the study explores multiple potential mechanisms of anticancer action, underscoring the promising therapeutic potential of these palladium(II) complexes, while antitumor activity has been initially assessed using a MCF-7 cell line as a preliminary model. Full article

Excessive accumulation of copper ions (Cu²⁺) in the environment and biological systems poses severe risks to ecological balance and human health, necessitating accurate detection and monitoring of Cu²⁺. Schiff base derivatives with favorable optical properties provide an efficient strategy for copper ion recognition. In this paper, fluorescent probe L (5-methyl-2-hydroxybenzaldehyde-(7-diethylaminocoumarin-3-formyl) hydrazone) was synthesized through a three-step reaction using 4-diethylaminosalicylaldehyde and diethyl malonate as starting materials. The structure of probe L was confirmed by melting point analysis, infrared spectroscopy, and nuclear magnetic resonance. Single-crystal X-ray analysis revealed that probe L crystallized into a triclinic lattice with space group $P_1^{-}$. Optical investigations, including UV–Vis spectroscopy, fluorescence spectroscopy, and aggregation-induced emission studies, demonstrated highly sensitive and selective fluorescence “turn-off” behavior of probe L towards Cu²⁺ ions in DMSO, with negligible interference from other metal ions. Job’s plot and crystallographic analysis revealed a 1:1 binding stoichiometry between probe L and Cu²⁺, forming the complex [Cu(L)]. Fluorescence titration experiments revealed a binding constant (K_b) of 5.2 × 10⁶ L/mol and a detection limit of 7.8 × 10⁻⁷ mol/L, indicating excellent sensitivity. These results suggest that probe L has considerable promise for Cu²⁺ detection in aqueous environments, with potential applications in environmental monitoring and public health protection. Full article

Two Zn(II) coordination compounds based on glaucine-derived Schiff bases were synthesized and investigated as potential materials for dye-sensitized solar cells (DSSCs). The structures of all compounds were established by X-ray diffraction analysis and quantum chemical modeling (DFT/TD-DFT). Their photophysical properties (absorption and luminescence spectra in solution and the solid state), electrochemical characteristics, and photovoltaic parameters in DSSC devices were studied. The highest power conversion efficiency (PCE ~5.18%) was demonstrated by the free ligands, which is attributed to their favorable absorption spectrum and optimal alignment of energy levels relative to the conduction band of TiO₂ and the redox couple of the electrolyte. The Zn(II) coordination compounds exhibited significantly lower efficiency (~2.1%). Impedance spectroscopy results indicated more efficient charge transfer at the TiO₂/dye/electrolyte interface for the organic derivatives. Full article

Pyridoxine-dependent epilepsy due to ALDH7A1 deficiency (PDE-ALDH7A1) is a rare but treatable epileptic encephalopathy caused by disruption of lysine catabolism and secondary depletion of pyridoxal-5′-phosphate (PLP). Although seizures are often controlled with pyridoxine supplementation, many patients continue to experience neurodevelopmental impairment, underscoring the importance of early diagnosis and improved therapeutic strategies. Central to both diagnosis and pathophysiology is the accumulation of lysine-derived metabolites, most notably α-aminoadipate semialdehyde (α-AASA), its cyclic Schiff base Δ¹-piperideine-6-carboxylate (P6C), and pipecolic acid. These metabolites have become the biochemical hallmarks of PDE-ALDH7A1, linking ALDH7A1 pathogenic variants to PLP inactivation and neuronal dysfunction. However, their chemical instability and analytical requirements pose challenges for universal diagnostics and newborn screening. This review summarizes current understanding of lysine catabolism in health and disease, critically evaluates the diagnostic utility and limitations of classical biomarkers, and discusses emerging insights into their pathophysiological roles. We further highlight recent discoveries of novel, chemically stable biomarkers, including 6-oxopiperidine-2-carboxylic acid (6-oxo-PIP), 2-oxopropylpiperidine-2-carboxylic acid (2-OPP), and 6-hydroxy-2-aminocaproic acid (HACA), identified through advanced metabolomics approaches. These metabolites show promise for newborn screening and provide new mechanistic links between metabolic stress, seizure susceptibility, and ongoing neurological morbidity despite pyridoxine treatment. Collectively, advances in biomarker discovery are reshaping diagnostic strategies for PDE-ALDH7A1 and offering new perspectives on disease mechanisms, paving the way for earlier detection and the development of more effective, mechanism-based therapies. Full article

The fluorescence properties of organic molecules are largely determined by molecular architecture, π-conjugation, and electronic substituent effects. In this study, three novel pyrene-chromone Schiff base derivatives were designed and synthesized to investigate substituent-driven modulation of photophysical behavior. The compounds were obtained via condensation of 1-aminopyrene with three different chromone-based aldehydes and fully characterized by FT-IR, ¹H-NMR, and mass spectrometry. The molecular design involves a donor-π-acceptor architecture: pyrene donates electrons, while the chromene moiety accepts them, enabling charge transfer upon excitation. UV-Vis and fluorescence spectroscopy revealed intense absorption in the 430–440 nm range and tunable emission in the 540–565 nm region, corresponding to large Stokes shifts (107–125 nm). Substituent effects significantly influenced optical band gaps and emission intensities, with the nitro-substituted derivative exhibiting a reduced band gap and pronounced fluorescence quenching due to enhanced intramolecular charge transfer. Concentration-dependent absorption studies demonstrated linear Beer–Lambert behavior, indicating the absence of aggregation within the investigated range. These results establish clear structure–property relationships in pyrene-chromene Schiff bases and highlight their potential as promising candidates for optoelectronic and fluorescence-based sensing applications. Full article