Search Results (2,226)

Understanding how solvents influence the luminescence behavior of Cu(I) complexes is crucial for designing advanced optical sensors. This study reports the synthesis, structures and photophysical investigation of an 8-hydroxyquinoline-functionalized 1H-imidazo[4,5-f][1,10]phenanthroline ligand, ipqH₂, and its four Cu(I) complexes with diphosphine co-ligands. Photoluminescence studies demonstrated distinct solvent-dependent excited-state mechanisms. In DMSO/alcohol mixtures, free ipqH₂ exhibited excited-state proton transfer (ESPT) and enol-keto tautomerization, producing dual emission at about 447 and 560 nm, while the complexes resisted ESPT due to hydrogen bond blocking by PF₆⁻ anions and Cu(I) coordination. In DMSO/H₂O, aggregation-caused quenching (ACQ) and high-energy O–H vibrational quenching dominated, but complexes 1 and 2 showed a significant red-shifted emission (569–574 nm) with high water content due to solvent-stabilized intra-ligand charge transfer and metal-to-ligand charge transfer ((IL+ML)CT) states. In DMSO/DMF, hydrogen bond competition and solvation-shell reorganization led to distinct responses: complexes 1 and 3, with flexible bis[(2-diphenylphosphino)phenyl]ether (POP) ligands, displayed peak splitting and (IL + ML)CT redshift emission (501 ⟶ 530 nm), whereas complexes 2 and 4, with rigid 9,9-dimethyl-4,5-bis(diphenylphosphino)-9H-xanthene (xantphos), showed weaker responses. The flexibility of the diphosphine ligand dictated DMF sensitivity, while the coordination, the hydrogen bonds between PF₆⁻ anions and ipqH₂, and water solubility governed the alcohol/water responses. This work elucidates the multifaceted solvent-responsive mechanisms in Cu(I) complexes, facilitating the design of solvent-discriminative luminescent sensors. Full article

In this study, we report the synthesis, characterization, and performance evaluation of a series of bimetallic Pt_xRh_y/C electrocatalysts with systematically varied Rh content for glycerol electrooxidation in acidic and alkaline media. The catalysts were prepared via a polyol reduction method using ethylene glycol as both a solvent and reducing agent, with prior functionalization of Vulcan XC-72 carbon to enhance nanoparticles (NPs) dispersion. High-resolution transmission electron microscopy (HRTEM), energy-dispersive X-ray spectroscopy (EDS), and X-ray diffraction (XRD) analyses indicated the spatial co-location of Rh atoms alongside Pt atoms. Electrochemical studies revealed strong composition-dependent behavior, with Pt₉₅Rh₅/C exhibiting the highest activity toward glycerol oxidation. To elucidate the origin of raised results, density functional tight binding (DFTB) simulations were conducted to model atomic distributions and evaluate energetic parameters. The results showed that Rh atoms preferentially segregate to the surface at higher concentrations due to their lower surface energy, while at low concentrations, they remain confined within the Pt lattice. Among the series, Pt₉₅Rh₅/C exhibited a distinctively higher excess energy and less favorable binding energy, rationalizing its lower thermodynamic stability. These findings reveal a clear trade-off between catalytic activity and structural durability, highlighting the critical role of the composition and nanoscale architecture in optimizing Pt-based electrocatalysts for alcohol oxidation reactions. Full article

Cytisine, a naturally occurring alkaloid and partial agonist of nicotinic acetylcholine receptors (nAChRs), has long been used as a smoking cessation aid and serves as the pharmacophore for varenicline. Recent research has expanded its therapeutic scope to neurodegenerative and neurological disorders, motivating the development of new cytisine derivatives. Among these, N-propargylcytisine combines the biological activity of the parent compound with the synthetic versatility of the terminal alkyne group. Herein, we report the synthesis and characterization of N-propargylcytisine, and its symmetrical dimer linked through 1,3-diyne moiety obtained via a copper-mediated Glaser–Hay oxidative coupling. The products were analyzed by NMR, FT-IR, and mass spectrometry, confirming the introduction of the propargyl moiety and the formation of the diyne bridge. Solvatochromic study of both compounds were performed using UV-VIS absorption spectroscopy in solvents of varying polarity, including protic solvents capable of hydrogen bonding. The 1,3-diyne motif, commonly found in bioactive natural products, endows the resulting dimer with potential for further derivatization and biological evaluation. This study demonstrates the utility of the Glaser–Hay reaction in the functionalization of alkaloid scaffolds and highlights the prospects of N-propargylcytisine derivatives in drug discovery targeting the central nervous system. Full article

Gold nanoparticles (AuNPs) are attracting more and more attention in life sciences, especially due to their versatile physicochemical properties whereby their colloidal stability in water and organic solvents is crucial. In this study, a systematic comparison of different polymers, synthesis methods and solvents was carried out. The AuNPs were synthesized using the ligand exchange reaction/postsynthetic addition reaction (PAR) and the one-pot synthesis with the polymers poly(vinyl alcohol) (PVA), poly(ethylene glycol) (PEG), poly(vinylpyrrolidone) (PVP) and poly(acrylic acid) (PAA), each with different molar weight averages. Analysis of the AuNP@Polymer conjugates by transmission electron microscopy (TEM) finds essentially unchanged gold nanoparticle core sizes of 11–18 or 11–19 nm in water and ethanol, respectively. The hydrodynamic diameter from dynamic light scattering (DLS) lies largely in the range from 20 to 70 nm and ultraviolet-visible spectroscopy (UV-Vis) showed gold plasmon resonance band maxima between 517 and 531 nm over both synthesis methods and solvents for most samples. The polymer PVA showed the best colloidal stability in both synthesis methods, both in water and after transfer to ethanol. An increased instability in ethanol could only be noted for the PEG coated samples. For the polymers PVP and PAA, the stability depended more specifically on the combination of synthesis method, polymer molecular weight and solvent. Full article

The search for bioactive compounds against chronic diseases such as cancer and diabetes
includes curcuminoids as promising scaffolds. Here, we report the synthesis of a family
of curcuminoid analogue compounds with an extended unsaturated central chain, as follows:
difluoroboron complex 1, the enolised curcuminoid 2, and its homoleptic copper
complex 3, in moderate to good yields (68–90%). Additionally, their β-cyclodextrin (BCD)
association complexes, 4 and 5, were prepared through a mechanochemical method and
characterised by spectroscopic techniques. Complete ¹H and ¹³C NMR assignments and
NOESY correlations revealed unique solvent effects on the conformational disposition of
compound 2, while the copper complex 3 displayed the highest extinction coefficient (1.20
× 10⁵ M⁻¹·cm⁻¹). Furthermore, the authentication of the polymorph of 1 and the new crystal
structures of 2 and 3, determined by single-crystal X-ray analysis, were highlighted. Although
the copper complex 3 initially exhibited the lowest a-glucosidase inhibitory activity
(IC₅₀ > 100 μM), it showed a significant increase (IC₅₀ = 36.27 μM) upon association with
BCD, reaching values comparable to the free ligand (IC₅₀ = 45.63 μM). Compounds 1–5
were non-toxic to healthy cells (COS-7), but compound 5 stands out as a promising candidate
against this metabolic condition. Full article

Five-membered nitrogen heterocycles exhibit a diverse range of applications across various fields, including medicine, agrochemicals, and materials science. Worldwide industries have exploited hazardous organic solvents and catalysts to afford key bioactive heterocycles, which in turn have a devastating impact on the aqueous environment. The tremendous rise in environmental contamination has shifted the focus of the scientific community towards sustainable alternatives. In line with this, ionic liquids have received the attention of investigators and are widely preferred in organic transformations as catalysts, solvents, ligands, and co-catalysts. Ionic liquids exhibit superior physicochemical properties, such as non-volatility, excellent conductivity, low vapour pressure, non-flammability, and electrochemical and thermal stability, thereby emerging as a clean and efficient alternative to the hazardous volatile organic solvents. The ionic-liquid-assisted synthetic approach has become a popular, greener method owing to high efficiency and product yield with notable purity. Thus, the present article aimed at highlighting catalytic applications of ionic liquids in the synthesis of aromatic five-membered nitrogen heterocycles such as pyrrole, pyrazole, imidazole, 1,2,3-triazole, 1,2,4-triazole, and tetrazole. This article will provide an insight into ionic liquids for their further exploration in organic transformations and related applications. Full article

RNA polymerases are essential enzymes that catalyze DNA transcription into RNA, vital for protein synthesis, gene expression regulation, and cellular responses. Non-template-dependent RNA polymerases, which synthesize RNA without a template, are valuable in biological research due to their flexibility in producing RNA without predefined sequences. However, their substrate polymerization mechanisms are not well understood. This study examines Poly (A) polymerase (PAP), a nucleotide transferase superfamily member, to explore its substrate selectivity using computational methods. Previous research shows PAP’s polymerization efficiency for nucleoside triphosphates (NTPs) ranks ATP > GTP > CTP > UTP, though the reasons remain unclear. Using 500 ns Gaussian accelerated molecular dynamics simulations, stability analysis, secondary structure analysis, MM-PBSA calculations, and Markov state modeling, we investigate PAP’s differential polymerization efficiencies. Results show that ATP binding enhances PAP’s structural flexibility and increases solvent-accessible surface area, likely strengthening protein–substrate or protein–solvent interactions and affinity. In contrast, polymerization of other NTPs leads to a more open conformation of PAP’s two domains, facilitating substrate dissociation from the active site. Additionally, ATP binding induces a conformational shift in residues 225–230 of the active site from a loop to an α-helix, enhancing regional rigidity and protein stability. Both ATP and GTP form additional π–π stacking interactions with PAP, further stabilizing the protein structure. This theoretical study of PAP polymerase’s substrate selectivity mechanisms aims to clarify the molecular basis of substrate recognition and selectivity in its catalytic reactions. These findings offer valuable insights for the targeted engineering and optimization of polymerases and provide robust theoretical support for developing novel polymerases for applications in drug discovery and related fields. Full article

Traditional synthetic methods, often limited by inefficiency, are increasingly being replaced by sustainable alternatives. This study presents a green approach combining microwave irradiation with in situ FTIR spectroscopy for real-time monitoring and optimising nitrogen-heterocycle synthesis, focusing on quinoxalines. Although both microwave-assisted synthesis and time-resolved FTIR are established techniques, their combined application remains underexplored, limiting their synergistic potential. The methodology was applied to synthesising 2,3-diphenylquinoxaline, a compound of interest in medicinal chemistry. Optimisation of the condensation between benzil and 1,2-phenylenediamine was achieved by exploiting the accelerated kinetics of microwave irradiation and continuous monitoring via in situ FTIR. Three catalytic systems were evaluated—hydrochloric acid (Brønsted acid), Montmorillonite K10 (heterogeneous catalyst), and molecular iodine (halogen/Lewis acid)—alongside a range of solvents, including ethanol, methanol, water, acetonitrile, ethyl acetate, dimethyl sulfoxide, and dichloromethane. Iodine proved to be the most efficient catalyst, while acetonitrile and ethyl acetate provided the most effective solvent systems. This integrated monitoring strategy reduces reliance on trial-and-error optimisation and establishes a streamlined, scalable, and efficient protocol. The dual-technique approach highlights a versatile pathway for advancing green synthetic methodologies with applications across the chemical and pharmaceutical industries. Full article

Cellulose nanofibers (CNFs) are highly promising nanocarrier materials, boasting excellent drug adsorption and loading potential due to their tunable hydrophilic/lipophilic interfaces. This study is the first to report the successful synthesis of maleic anhydride-modified CNFs (MA-CNFs) via the esterification of CNFs using a solvent-free molten maleic anhydride (MA) system, and it systematically evaluates MACNFs’ dual adsorption performance for water-soluble and lipophilic drugs. A new characteristic peak at 1723 cm⁻¹ in FT-IR confirms the formation of ester bonds, proving the successful grafting of MA onto CNFs. XRD analysis shows that the crystallinity slightly increases from 72.56% to 74.06%, indicating the reaction mainly occurs in the amorphous region. After modification, the material’s hydrophobicity is significantly enhanced (water contact angle: ~63.3° for CNFs vs. ~74.9° for MA-CNFs), and its BET specific surface area rises sharply from 5.03 to 26.29 m²/g. These structural advantages collectively enable MA-CNFs to have adsorption capacities for folic acid (FA, water-soluble) and vitamin E acetate (VEA, lipophilic) that are 1.15 and 2.04 times those of CNFs, respectively. The results demonstrate MA-CNFs are high-performance functional materials fabricated via a green method, with good biocompatibility. Full article

p-toluenesulfonic acid (pTSA) was used for the synthesis of porous silica xerogels while applying different synthesis conditions. Key parameters included acid concentration, drying temperature and the method of acid removal. The resulting organic–inorganic composites were investigated by nitrogen physisorption, X-ray powder diffraction (XRD), solid-state NMR and thermal analysis. The results demonstrated that both the drying temperature and quantity of the pTSA significantly influenced the pore structure of the xerogels. The utilization of such strong acids like pTSA yielded high surface area and pore volume, as well as narrow pore size distribution. Environmentally friendly template removal by solvent extraction produced materials with superior textural properties compared to traditional calcination, enabling the recovery and reuse of pTSA with over 95% efficiency. A selected mesoporous silica xerogel was modified by a simple two-step post-synthesis procedure with 1-(2-Hydroxyethyl) piperazine (HEP). High CO₂ adsorption capacity was determined for the HEP-modified material in dynamic conditions. The isosteric heat of adsorption revealed the stronger interaction between functional groups and CO₂ molecules. Total CO₂ desorption could be achieved at 60 °C. Leaching of the silica functional groups could not be detected even after four consecutive adsorption cycles. These findings provide valuable insights into the sustainable synthesis of tunable piperazine-modified mesoporous silica xerogels with potential applications in CO₂ capture. Full article

The main objective of the study was to choose the best salicylic acid-based monomers through in silico research to improve the antibacterial effects of dental prostheses, refine the synthesis process of such monomers, and examine their antibacterial and antifungal properties in vitro, forecast the long-term stability in an oral biological environment using molecular docking software and synthesizing new copolymers. Based on their strong antibacterial activity and low toxicity compared to other derivatives, the allyl ester of salicylic acid (AESA) and the allyl ester of acetylsalicylic acid (AEASA) were chosen as the study objects. Salicylic and acetylsalicylic acids were esterified with allyl alcohol and allyl bromide in a variety of solvents and temperatures to synthesize AESA and AEASA. The optimal conditions were identified with a yield of 78%. IR spectroscopy was used to confirm the chemical structure of synthesized molecules. In the presence of peroxybenzoyl, the regularities of the polymerization process between the obtained monomer and oligoethylene macromonomer (PEMM) were examined. To obtain new antibacterial oligomers containing a salicylic group and to study their physico-chemical properties, a technology for obtaining the copolymers of AESA with PEMM was developed, and their physical, mechanical, and antimicrobial properties were studied. Full article

A novel process for the synthesis of binder-free, porous nickel/polythiophene-functionalized sulfur (Ni/S-PTh) composite cathodes for lithium–sulfur (Li–S) batteries is introduced in this paper. Initially, a polyvinyl butyl polymer scaffold is 3D printed, then coated with a graphite-based conducting layer, and, finally, it is pulse-plated for nickel deposition to produce a high-surface-area, mechanically stable current collector. S-PTh particles are afterwards co-deposited into the Ni matrix through composite electrodeposition. After the dissolution of the polymer template, the resulting self-standing electrodes still maintain porous structure with uniform sulfur distribution and a distinct transition between the dense Ni layer and the Ni/S-PTh composite layer. Electrochemical characterization of the Ni/S-PTh composite cathodes by galvanostatic cycling at C/10 rate results in an initial specific discharge capacity of ~1120 mAh·g⁻¹ and a specific capacity of ~910 mAh·g⁻¹ after 200 cycles, resulting in a high capacity retention of ~81 %. For our novel approach, no steps at high temperatures or toxic solvents are involved and the need for polymer binders and conductive additives is avoided. These results demonstrate the potential of composite electrodeposition in combination with 3D printing for producing sustainable, high-performance sulfur cathodes with tunable architecture. Full article

A chemical platform for post-polymerization methods was developed, starting from the ecodesign and enzymatic synthesis of safe and sustainable bio-based polyesters containing discrete units of itaconic acid. This unsaturated bio-based monomer enables the covalent linkage of molecules that can impart desired properties such as hydrophilicity, flexibility, permeability, or affinity for biological targets. Molecular descriptor-based computational methods, which are generally used for modeling the pharmacokinetic properties of drugs (ADME), were employed to predict in silico the hydrophobicity (LogP), permeability, and flexibility of virtual terpolymers composed of different polyols (1,4-butanediol, glycerol, 1,3-propanediol, and 1,2-ethanediol) with adipic acid and itaconic acid. Itaconic acid, with its reactive vinyl group, acts as a chemical platform for various post-polymerization functionalizations. Poly(glycerol adipate itaconate) was selected because of its higher hydrophilicity and synthetized via solvent-free enzymatic polycondensation at 50 °C to prevent the isomerization or crosslinking of itaconic acid. The ecotoxicity and marine biodegradability of the resulting oligoester were assessed experimentally in order to verify its compliance with safety and sustainability criteria. Finally, the viability of the covalent linkage of biomolecules via Michael addition to the vinyl pendant of the oligoesters was verified using four molecules bearing thiol and amine nucleophilic groups: N-acetylcysteine, N-Ac-Phe-ε-Lys-OtBu, Lys-Lys-Lys, and glucosamine. Full article

This work focuses on the synthesis and the comprehensive characterization of polydianiline (PDANI) polymer, obtained via oxidative polymerization of dianiline, a low-toxicity and more environmentally friendly starting monomer for polyaniline (PANI) formation. Despite the structural similarity to PANI, PDANI remains underexplored, especially regarding the effect of different synthesis conditions. Here, we investigate how chloride, sulfate, and camphor sulfonate dopants, combined with green solvents such as water and DMSO, modulate the final properties of PDANI in the emeraldine salt configuration. The produced materials were extensively characterized using a multi-technique approach. FTIR, Raman, EPR, and UV-Vis spectroscopies provided insights into chemical structure, molecular order, and polaron population. Electrical conductivity was disclosed via current-voltage (I-V) measurements, while cyclic voltammetry (CV) and coulovoltammetry (QV) were employed to evaluate redox activity and charge reversibility. The resulting PDANI displays structural and functional features comparable to those of PANI synthesized under similar conditions. Notably, the nature of the dopant and acidic medium was found to crucially govern the oxidation level, molecular organization, and electrochemical performance, boosting PDANI as a tunable and sustainable alternative for applications ranging from electronics to energy storage. Full article

An efficient and practical procedure for the synthesis of (E)-α,β-unsaturated amides incorporating α-aminophosphonates, derived from readily accessible phosphonoacetamides, via the Horner–Wadsworth–Emmons (HWE) reaction was developed. The influence of reaction parameters, including base, solvent, and temperature, as well as the scope of the method with different aldehydes, was examined, affording the target compounds in good yields and with high (E)-selectivity. The required phosphonoacetamides were conveniently prepared through a Kabachnik–Fields reaction of aldehydes, benzylamine and dimethyl phosphite followed by hydrogenolytic cleavage of the N-Bn bond, acylation with bromoacetyl bromide, and a subsequent Arbuzov reaction. This HWE protocol provides straightforward access to a broad range of (E)-α,β-unsaturated amides incorporating α-aminophosphonates under mild conditions, offering valuable scaffolds with potential pharmacological relevance as anticancer agents. Full article