Solvent Media Research Articles

Cerric ammonium nitrate catalyzed eco-friendly green synthesis of chitosan Schiff base using PEG-400 as an anticancer agent against gastric cancer cells via inhibiting EGFR

The present study was conducted to scrutinize the pharmacological effect of oxazole-embedded Chitosan as an anticancer agent against gastric cancer cells. This compound was synthesized using the classical Schiff base reaction but utilizing the novel green chemical process where cerric ammonium nitrate (CAN) was used as a catalyst in the PEG-400 as solvent media. The target compound was obtained with an excellent yield at the catalyst loading of 5% CAN concentration in 15 min. The Kinase-Glo Plus luminescence kinase assay kit was used to determine the EGFR inhibitory activity of compound 1 where it showed potent activity with IC50 of 2.14 µM. Its effect was also determined on the cellular viability of the Human gastric cancer cell line (SGC7901), liver cancer cell line (HepG2), and lung cancer cell line (A549), where it exhibits potent activity against SGC7901. The compound further showed the concentration-dependent inhibitory effect on migration and invasion of SGC7901. In RT-qPCR analysis, the compound showed induction of apoptosis of SGC7901 cells possibly by restoring the expression of Bcl-2 and Bax near to normal, and inhibition of the mRNA expression of EGFR in a concentration-dependent manner. KEY WORDS: Schiff base, Chitosan, EGFR, mRNA, apoptosis, Bcl-2 Bull. Chem. Soc. Ethiop. 2024, 38(4), 1091-1101. DOI: https://dx.doi.org/10.4314/bcse.v38i4.22

Sustainable combination of ionic liquid and deep eutectic solvent for protecting and preserving of the protein structure: The synergistic interaction of enzymes and eco-friendly hybrid ionic fluids

Hybrid ionic fluids (HIFs) are one of the emerging and fascinating sustainable solvent media, a novel environment-friendly solvent for biomolecules. The HIFs have been synthesized by combining a deep eutectic solvent (DES), an ionic liquid (IL) having a common ion. The stability and activity of hen's egg white lysozyme (Lyz) in the presence of a recently designed new class of biocompatible solvents, HIFs have been explored by UV–visible, steady-state fluorescence, circular dichroism (CD), Fourier transform infrared spectroscopy (FT-IR) along with dynamic light scattering (DLS) measurements. This work emphasizes the effect of DES synthesized by using 1:2 choline chloride and glycerol [Glyn], ILs (1-butly-3-methylimidazolium chloride [BMIM]Cl and choline acetate [Chn][Ac]) and their corresponding HIFs on the structure and functionality of Lyz. Moving forward, we also studied the secondary structure, thermal stability and enzymatic activity and thermodynamic profile of Lyz at pH = 7 in the presence of varying concentrations (0.1 to 0.5) M of [BMIM]Cl, [Chn][Ac] ILs, [Glyn] DES and [Glyn][BMIM]Cl (hybrid ionic fluid1) as well as [Glyn][Chn][Ac] (hybrid ionic fluid2). Spectroscopic results elucidate that ILs affect the activity and structural stability of Lyz, whereas the stability and activity are increased by DES and are maintained by HIFs at all the studied concentrations. Overall, the experimental results studied elucidate expressly that the properties of Lyz are maintained in the presence of hybrid ionic fluid1 while these properties are intensified in hybrid ionic fluid2. This work has elucidated expressly biocompatible green solvents in protein stability and functionality due to the alluring properties of DES, which can counteract the negative effect of ILs in HIFs.

Biocatalysts engineering by varying the binary CNTs-silica composition and the physicochemical characteristics of adsorbents for the immobilization of recombinant T. lanuginosus lipase

Biocatalytic engineering was carried out by varying monotonically the binary CNTs-silica composition and, accordingly, the physicochemical characteristics of adsorbents developed for immobilization of recombinant T. lanuginosus lipase (rPichia/lip). The adsorbents based on composite carbon-silica materials (CCSMs) were produced by impregnating finely dispersed multi-walled carbon nanotubes with silica hydrosol followed by calcination in argon at 350°C; the mass ratio of the hydrophobic and the hydrophilic components varied over a wide range. Biocatalysts (BCs) for green low-temperature synthesis of various esters in a non-aqueous medium of organic solvents were prepared by adsorption of rPichia/lip with subsequent drying under ambient conditions. The characteristics of the CCSMs and BCs were characterized by thermogravimetry, nitrogen porosimetry and electron microscopy. The catalytic properties of BCs, such as enzymatic activity, substrate conversion and specificity, as well we their operational stability depending on the chemical composition of CCSMs were extensively studied in the esterification of saturated monocarboxylic acids (C4, C7, C18) and primary aliphatic alcohols (C2, C4, C16) in hexane at 20°C. It was found that the esterifying activity manyfold decreased with increasing the silica content primarily due to a decrease in adsorption ability of CCSMs toward rPichia/lip. The substrate specificity and operational stability of the lipase-active BCs did not greatly depend on the composition of CCSMs. Biocatalysts retained more than half of their initial esterifying activity after 10 reaction cycles.

Synthesis and OER catalytic activity of quasi zeolitic imidazolate Framework-67 having two and three dimensional morphology

Zeolitic imidazolate framework-67 (ZIF-67), in two and three dimensional (2D/3D) morphologies have been synthesized at room temperature using different solvent media, and annealed at 350 and 920 °C to derive the modified ZIF-67 based catalysts. All the ZIF-67 based catalysts were characterized using powder X-ray diffraction, Fourier transform infrared spectroscopy, Raman spectroscopy, X-ray photoelectron spectroscopy, Scanning electron microscopy, Thermogravimetric analysis, N2 gas adsorption method, and Positron annihilation lifetime spectroscopy. It has been observed that catalytic activity of the ZIF-67 based catalysts towards oxygen evolution reaction (OER) depends on the morphology and annealing-induced modifications in active sites. Among different morphologies of as-synthesized ZIF-67, 2D ZIF-67 (nanosheet and disc like morphology) exhibits the best electrocatalytic activity in as-synthesized as well as in the annealed form in comparison to 3D ZIF-67 (rhombic dodecahedron) owing to their better electronic properties. All the types of ZIF-67 annealed at 920 °C show the lower Tafel slopes suggesting higher OER rate.

An insight into the nonlinear optical properties of dihydroxyphenyl chalcone derivative: Combined assessment by DFT, solvatochromism and z-scan technique

The current research reports the nonlinear optical features of a chalcone derivative, (E)-1-(2,4-Dihydroxyphenyl)-3-(3,4-dihydroxyphenyl)-2-propen-1-one which are examined through theoretical and experimental approaches. The spectra from the NMR, FT-IR, FT-Raman, and UV–Vis were retrieved and studied. Density functional theory computations were executed to confirm the experimental findings. Ground-state and excited-state dipole moments were assessed by solvatochromism. Also, the nonlinear optical characteristics were examined using two-level solvatochromic model and theoretically by hybrid functionals - B3LYP and CAM-B3LYP. By employing the z-scan technique, the third-order NLO characteristics as well as the limiting threshold of the chalcone in polar and nonpolar solvent media were studied. The z-scan results demonstrate the chalcone as a desirable candidate for designing optoelectronic and photonic devices.

Regioselective amination of 4-methylene-5,7-dinitroquinazoline: a mechanistic consideration on non-conventional N-H—π interactions between amine and ethylene moiety

ABSTRACT Pi (π) interactions originating from the N-H bond of amine and ethylene moiety have been explored on the mechanism of aromatic nucleophilic substitution (ArSN) of the nitro group of 4-methylene-5,7-dinitroquinazoline with methylamine in the gas phase and solvent media within DFT framework. The free energy profiles confirmed that the amination should take place at peri-position and calculations support the one-step mechanism through a transition state with no intermediate in the reaction route. Stabilisation of peri-transition state by intramolecular weak interaction akin to hydrogen bonding N-H—CH2 = C leads to the regioselective amination at peri-position of 4-methylene-5,7-dinitroquinazoline. The intramolecular hydrogen bond interactions at N-H—CH2 = C in the peri-transition state are strongly supported by a red shift in N-H stretching vibrations in simulated IR spectra and are confirmed by studying energetics of amination of structural/electronic analogues of 4-methylene-5,7-dinitroquinazoline. The present study established that ethylene plays an important role as an efficient H-bond acceptor in fixing the regioselectivity at peri-position in the amination of 4-methylene-5,7-dinitroquinazoline. This is the first-ever report for the exploration of the role of ethylene moiety as a hydrogen bond acceptor in mediating the regioselectivity of organic reactions.

Fluorine-Containing Ionogels with Stretchable, Solvent-Resistant, Wide Temperature Tolerance, and Transparent Properties for Ionic Conductors.

Stretchable ionogels, as soft ion-conducting materials, have generated significant interest. However, the integration of multiple functions into a single ionogel, including temperature tolerance, self-adhesiveness, and stability in diverse environments, remains a challenge. In this study, a new class of fluorine-containing ionogels was synthesized through photo-initiated copolymerization of fluorinated hexafluorobutyl methacrylate and butyl acrylate in a fluorinated ionic liquid 1-butyl-3-methyl imidazolium bis (trifluoromethylsulfonyl) imide. The resulting ionogels demonstrate good stretchability with a fracture strain of ~1300%. Owing to the advantages of the fluorinated network and the ionic liquid, the ionogels show excellent stability in air and vacuum, as well as in various solvent media such as water, sodium chloride solution, and hexane. Additionally, the ionogels display impressive wide temperature tolerance, functioning effectively within a wide temperature range from -60 to 350 °C. Moreover, due to their adhesive properties, the ionogels can be easily attached to various substrates, including plastic, rubber, steel, and glass. Sensors made of these ionogels reliably respond to repetitive tensile-release motion and finger bending in both air and underwater. These findings suggest that the developed ionogels hold great promise for application in wearable devices.

A Thermally Stable SO2-Releasing Mechanophore: Facile Activation, Single-Event Spectroscopy, and Molecular Dynamic Simulations.

Polymers that release small molecules in response to mechanical force are promising candidates as next-generation on-demand delivery systems. Despite advancements in the development of mechanophores for releasing diverse payloads through careful molecular design, the availability of scaffolds capable of discharging biomedically significant cargos in substantial quantities remains scarce. In this report, we detail a nonscissile mechanophore built from an 8-thiabicyclo[3.2.1]octane 8,8-dioxide (TBO) motif that releases one equivalent of sulfur dioxide (SO2) from each repeat unit. The TBO mechanophore exhibits high thermal stability but is activated mechanochemically using solution ultrasonication in either organic solvent or aqueous media with up to 63% efficiency, equating to 206 molecules of SO2 released per 143.3 kDa chain. We quantified the mechanochemical reactivity of TBO by single-molecule force spectroscopy and resolved its single-event activation. The force-coupled rate constant for TBO opening reaches ∼9.0 s-1 at ∼1520 pN, and each reaction of a single TBO domain releases a stored length of ∼0.68 nm. We investigated the mechanism of TBO activation using ab initio steered molecular dynamic simulations and rationalized the observed stereoselectivity. These comprehensive studies of the TBO mechanophore provide a mechanically coupled mechanism of multi-SO2 release from one polymer chain, facilitating the translation of polymer mechanochemistry to potential biomedical applications.

Efficient antidermatophytic agents to fight clinical Tinea spp. using Salvia multicaulis and Hypericum scabrum-based sustainable NCs

Increased problems associated with side effects and microbial resistance of chemical drugs have promoted the research focus of herbs and herbs-based medicines as renewed interest. The present study studied the antifungal potential of Hypericum scabrum (H. scabrum), Salvia multicaulis (S. multicaulis) plants and their derived sustainable NCs against dermayophyton species. These plants were used as free-toxic solvent media and phytogradiant reductants to fabricate nanoformulations as alternative antimycotic drugs. Analysis of antifungal activity showed a noticeable inhibition of the trychophyton mycelial growth when cultured on SDA mixed with different doses of the plant extract, particularly 50% H. scabrum that stopped mycelial growth of T. mentagrophytes and T. verrcuosum thoroughly after 10-day incubation by of 100 % MGI, followed by Ag@Fe3O4@SiO2 with particle size around 20 to 60 nm, that record ( 67.64 and 63,.33 % of MGI) by 50 µg ml−1 application respectively. The lowest effect of H. scabrum and Ag@Fe3O4@SiO2 at high concentrations was against T. simii (44.44 % and 16 % MGI). The maximum antifungal activity of 50 % Salvia multicaulis and 50 µg ml−1 CuO@SiO2 NC with an average diameter of 60 nm was found against T. mentagrophytes and T. verrcuosum with (66.66 and 51.47 % MGI), respectively, while the minimum activity was found against T. quinckeanum and T. simii (33.33 and 13.33 % MGI), respectively. Thus, these plant extracts and NCs could be used to develop a new medication for dermatophytosis.

Light- and Solvent-Responsive Bilayer Hydrogel Actuators with Reversible Bending Behaviors.

Light-responsive hydrogel systems have gained significant attention due to their unique ability to undergo controlled and reversible swelling behavior in response to light stimuli. Combining light-responsive hydrogels with nonresponsive polymers offers a unique self-folding feature that can be used in soft robotic actuator designs. However, simple formulation of such systems with rapid response time is still a challenging task. Herein, we demonstrate a simple but versatile bilayer polymeric design combining light-responsive spiropyran-polyacrylamide (SP-PAAm) with polyacrylamide (PAAm) hydrogels. The photochromic spiropyran in our polymer design is a closed-ring, hydrophobic compound and turns into an open-ring, hydrophilic merocyanine isomer under light irradiation. The swelling degree of SP-PAAm and PAAm hydrogels was evaluated using LED lights with different wavelengths and solvent media (e.g., water, ethanol, DMF, and DMSO). We observed that SP-PAAm hydrogels reached a swelling ratio of ∼370% with the illumination of the blue LED in the DMF medium. By combining light-responsive SP-PAAm hydrogels with nonresponsive PAAm, a proof-of-concept demonstration was performed to demonstrate the applicability of our fabricated platforms. Although fabricated one-armed bilayer hydrogels possessed self-folding ability with a folding angle of ∼40° in 30 min, the four-armed bilayer platforms demonstrated more efficient and rapid folding behavior and reached a folding angle of ∼75° in ∼15 min. Given their simplicity and efficiency, we believe that such polymeric designs may offer new avenues for the fields of polymeric actuators and soft robotic systems.

Pseudo-Stilbene- and Azobenzene-Type Systems for Optical Frequency Conversion: Estimating the First-Order Molecular Hyperpolarizability

This study investigates the potential of a set of pseudo-stilbene and azobenzene molecular structures to become optical frequency converters for optical communications based on a detailed exploration of the first-order molecular hyperpolarizability (βHRS), which is the microscopic counterpart of second harmonic generation (SHG). βHRS values were obtained via quantum chemical calculations using the Gaussian 16 software package in solvent and gas-phase media at different wavelengths, i.e., 1064 nm, 1310 nm, and 1510 nm. The latter two wavelengths are of particular interest for optical communications. Our study focused on discerning how the molecular structure influences the βHRS response, explicitly highlighting the influence of the azomethine group (CH=N). The results revealed that the molecular planarity, affected by this group, plays a crucial role in modulating the optical properties. The highest βHRS value in a solvent medium using the CAM-B3LYP/6-311+G(2d,p) level of theory achieved in this work was around 1400 ×10−30cm4startvolt−1, four orders of magnitude higher than KDP (0.2 ×10−30cm4startvolt−1), which is a reference in SHG experiments at 1064 nm. The highest calculated βHRS value at the same level of theory and solvent at 1310 nm and 1550 nm was 631 × 10−30cm4startvolt−1 and 456 × 10−30cm4startvolt−1, respectively. All these values belong to molecular structures with azo-coupling with donor (4-NMe2) and acceptor (4′-NO2) peripheral groups, designated as AB-3.

Poly(styrene-co-1-octene) behavioral differences in aliphatic and aromatic solvents: molecular dynamics simulation and DFT-D quantum calculations

Copolymerizing aromatic and aliphatic comonomers helps to create efficient superabsorbents to remove oil from seawater. In this work, the best sequence of styrene and 1-octene at different 1-octene molar percentages (x) was found for poly(styrene-r−1-octene) (CP-x) using neural network potential. According to the calculated characteristics of CP-x using molecular dynamics simulation, increasing the x amount up to 6% in the chain aromatic structure caused the chain expansion by ∼ 20% and the reduction of its diffusion coefficient in n-heptane by ∼ 70%. The determined Helmholtz free energy via thermodynamic integration formula showed a decrease from −2762.7 to −3818.3 kcal mol−1 (∼ 38% reduction) and entropy changes illustrated an increase from 5.12 to 8.21 kcal mol−1.K (∼ 60% increase) indicating a partial conversion of the copolymer nature from aromatic to aliphatic with raising x. This issue led to a ∼ 15% enhancement in the interaction energy between the chain and solvent media meaning a better tendency to n-heptane and the increment of the interfacial density of the solvent molecules around the copolymer chain with higher x. The quantum calculations also proved that toluene with the chain styrene ring, and n-heptane with the chain 1-octene have created a parallel orientation, due to the charge transfer energy arising from an occupied C-H bonding orbital to an adjacent one. This phenomenon moved the electron density to the boundary area between them and changed the chain conformation in the media. Compression of the CP-x characteristics in n-heptane and toluene unmasked the contrariwise behaviors of the copolymer in aliphatic and aromatic solvents, except CP-4, which is the best candidate to use in the oil absorption from water surfaces. The performed theoretical investigation of the CP-x has revealed the hidden molecular insights into the copolymer chain which can help experimentalists reduce their trial and error to manufacture efficient supper oil absorbents.

Dispersion Polymerization of N‐Vinyl‐2‐Pyrrolidone in Supercritical Carbon Dioxide in the Presence of Thiol‐Terminated Poly(vinyl acetate‐co‐vinyl propionate)

AbstractLiquid carbon dioxide (LCO2) or supercritical carbon dioxide (ScCO2) can be used as an important solvent medium for preparing polymer particles through dispersion polymerization. However, based on the weak solvent characteristics of CO2, the development of stabilizers used in dispersion polymerization has always been an important challenge. These stabilizers are progressing toward the low‐cost, pollution‐free, and simple synthesis routes, et al. In this research, pentaerythritol tetra (3‐mercaptopropionate) (PTMP) is used to control the homopolymerization or copolymerization of vinyl acetate (VAc)/vinyl propionate (VPr), the homopolymers or copolymers with thiol group are synthesized by the one‐pot method. These homopolymers or copolymers are used as the stabilizers to stabilize the dispersion polymerization of N‐vinyl‐2‐pyrrolidone (NVP) in ScCO2. The results show that the structural unit proportion of the stabilizers, the concentration of stabilizers or 2, 2´‐azobis(isobutyronitrile) (AIBN), and the time interval for dispersion polymerization have significant impacts on the conversion percentage of NVP and the molecular weight of polymers. The maximum conversion percentage of NVP can get to 95%, and the molecular weight of poly(N‐vinyl‐2‐pyrrolidone)(PNVP) can reach 22.3 kPa. SEM analysis indicates that the PNVP obtained has regular spherical characteristics.

Polystyrene Waste-ZnO nanocomposite film for energy harvesting via hydrophobic triboelectric nanogenerator: Transforming waste into energy

This research aimed to generate electricity from polystyrene waste materials combined with zinc oxide (ZnO) nanomaterials. Developing alternative polystyrene waste materials for generating electricity in triboelectric nanogenerator (TENG) could be beneficial in a circular economy and sustainable development. With the motivation to reduce environmental pollution by using polystyrene waste, a recycled polystyrene-ZnO nanocomposite film (rPS-ZnO NF) was synthesized and served as a triboelectric material for energy harvesting applications. ZnO nanopowder was produced by a low-temperature solution immersion method in conjunction with a simple film-casting method to prepare the rPS-ZnO NF. The effects of varying amounts of toluene as a solvent medium and the immersion time in stearic acid (SA) solution treatment on the structural properties, wettability behavior, surface morphology, chemical bonding properties, surface characteristics, and TENG performance were investigated. In this work, rPS film, rPS-ZnO NF, and SA-treated rPS-ZnO NF were paired with Kapton film as the opposite triboelectric material in constructing the vertical contact-separation mode TENG. Compared to rPS TENG, the rPS-ZnO TENG exhibited a two-fold enhancement in performance (8.2 V) in output voltage and ∼4.5 fold enhancement (28.1 μW/cm2) in power density. Furthermore, following SA treatment, the triboelectric performance further improved, reaching the highest open circuit voltage of ∼8.8 V and the highest power density of 32.0 μW/cm2 for repeated 2 N-solenoid tapping force. The hydrophobic behavior was also improved with the highest water contact angle of 134.7 (when the SA treatment immersion time was 1 h). These findings demonstrate that SA-treated rPS-ZnO NF could be a promising candidate for efficient mechanical energy harvesting with high electrical output and excellent surface wettability. This research not only exhibits an excellent output performance of SA-treated rPS-ZnO TENG, but it also sheds new light on the sustainable approach of converting polystyrene waste into energy-harvesting material.

Visible Light-Induced Metal-free Arylation of Coumarin-3-carboxylates with Arylboronic Acids.

The present work represents a novel methodology for the selective arylation of coumarin-3-carboxylates with arylboronic acids via a photochemical route, marking the first-ever attempt for the direct alkenyl C-H arylation using rose bengal as a photocatalyst, which is a readily available and cost-effective alternative to transition metal catalysis. The reaction proceeds smoothly in MeOH/H2O solvent media in the presence of radical initiator affording the arylated products in good yields (60-80 %). The reaction parameters such as visible light, radical initiator, oxidant, anhydrous solvent, and inert atmosphere play a crucial role for the success of this methodology. The substituents present on the substrate show a significant effect on the conversion. This study provides a valuable contribution to the field of organic synthesis offering a new and efficient approach to the arylation of coumarin-3-carboxylic acid esters with a broad substrate scope and high functional group tolerance. It is a versatile method and provides a direct access to biologically relevant 4-arylcoumarin-3-carboxylates.

Cytotoxicity evaluation of sub-10-nm silver colloid prepared by electrolytic synthesis procedure

Silver nanoparticles with smaller scales tend to exhibit higher cytotoxicity. In the present work, a mild electrolytic synthesis procedure is proposed and implemented for the preparation of sub-10-nm silver colloids in polarity organic solvent media by using the nonionic polymer as a stabilizer. The synthesized silver nanoparticles can be stably dispersed in salt, acid, and alkali dispersion media. The cell viability and cytotoxicity are investigated by fluorescein diacetate/propidium iodide double staining and thiazolium blue colorimetry in vitro. Under concentration-gradient and time-gradient tests, the synthesized silver nanoparticles exhibit significant cytotoxicity against the human hepatocellular carcinoma cells of HepG2 and the human non-small cell lung cancer cells of A549 at the exposure dose of 1.6 and 2.0 ug mL−1, respectively.

Spirolactam ring locking and unlocking tuned solvent regulated unique Hg(II) sensing by a novel AIE active Rhodamine −1, 2 diamino propane-based Schiff chemosensor and its pH sensor performance

The present study highlights the development, identification, and solvent-regulated chemosensing property of a Schiff base chemosensor (E)-2-(2-((5-chloro-2-hydroxybenzylidene)amino)propyl)-3′,6′-bis(diethylamino)spiro[isoindoline-1,9′-xanthen]-3-one (RBAS). The Schiff base RBAS is developed by the simple condensation of 5-chloro salicylaldehyde and rhodamine-1,2 diamino propane derivative (RBAP). Interestingly this probe can optically as well as fluorometrically exhibit pH sensor activity and the spirolactam ring opening and the conversion from enol to keto form in lower and higher pH regions respectively are the main key factors to show pH sensor activity. Several spectroscopic, Dynamic Light Scattering (DLS), and scanning electron microscopy (SEM) studies confirm the AIE active property of the probe in 2:8 DMSO-water and ethanol-water mediums where the probe exhibits strong luminescence properties. Interestingly in ethanol-water and DMSO-water medium, it can detect Hg(II) via turn-on and off fluorescence respectively. Actually, in different solvent mediums, the presence of Hg(II) plays a crucial role in the spirolactam ring opening and closing of the developed probe. Simultaneously in an ethanol-water medium, it can detect picric acid by turning off fluorescence. By using mass and NMR spectrum analysis, the 1:1 stoichiometric addition of the probe and target analytes has been verified and the density functional theory (DFT) study is implemented in optimizing the probe-analyte structure. The live cell imaging study gives the approval of the biosensing ability of the probe. Impressively the probe can be successfully used to detect Hg(II) in real soil samples.

Study of Interactions of Nucleoside Anticancer Drugs, Capecitabine and Gemcitabine, with SWNT and BNNT using Molecular and Quantum Mechanical Calculations

Abstract: Using single-wall carbon nanotubes (SWCNTs) and boron nitride nanotubes (BNNTs), this study evaluated the interactions between Capecitabine (CAP) and Gemcitabine (GEM). Molecular mechanics and quantum mechanics were used in the analysis. : The interaction between CP and GM with SWCNTs and BNNTs under various solvents was analyzed using the self-consistent reaction field (SCRF) as a model and DFT as the analytical method. Additionally, the effect of temperature on the stability of the molecule interactions during the experiment was examined. The thermodynamic properties of the title compounds were analyzed based on theoretical calculations. It included the calculation of Frontier Molecular Orbitals (FMOs) and Total Density of States (DOS). In addition to studying the ionization potential (I), we also examined the other molecular properties of the structures, such as electrophilicity (ω), electron affinity (A), chemical hardness (η), and electronic chemical potential (μ). To investigate the interaction between CAP and GEM with SWCNTs and BNNTs, molecular mechanics methods (MM) including AMBER, OPLS, CHARMM, and MM+ force fields, were employed. Monte Carlo simulation techniques were used to calculate the results at different temperatures. : The effects of the liquid phase and mixed solvent media with varying dielectric constants (Water, DMSO, Methanol, and Ethanol) on the interaction between CAP and GEM using the force fields described above were examined in this study. The correlation between data generated by Monte Carlo, Quantum Mechanics, and Molecular Mechanics was demonstrated. There was a striking similarity in the thermodynamic properties and conformer populations of all three materials.

Exploring Pyrimidine-Based azo Dyes: Vibrational spectroscopic Assignments, TD-DFT Investigation, chemical Reactivity, HOMO-LUMO, ELF, LOL and NCI-RDG analysis

Theoretical computations of pyrimidine-based azo dyes were performed by the DFT approach using the B3LYP/6 − 31G(d,p) basis set. The molecules were optimized based on the same basis set by calculating the minimum energy. FMOs, DOS and GCRD were computed for kinetic stability and chemical reactivity of the selected compounds. The MEP surface was studied to locate nucleophilic and electrophilic attack zones. The energy gap was carefully studied for pyrimidine-based azo dyes. Vibrational spectroscopy was studied in the most prominent regions with respect to PED assignments. Similarly, the UV–Vis absorption technique was calculated using the TD-DFT approach in different solvent media. The electronic structure of each atom in a molecule was examined via the electron localization function (ELF) and localized orbital locator (LOL). Non-covalent interactions were explored using reduced density gradient analysis. The combination of experimental and theoretical data allowed us to correlate the structural modifications with the observed photophysical properties, facilitating the design of azo dyes with tailored characteristics. This work contributes to the fundamental understanding of azo dyes and offers a foundation for the development of new materials with enhanced photophysical and electronic properties.

A non-extraction sequential injection method for determination of loratadine using formation of its ion-association complex with bromocresol purple in acetonitrile

The formation of an ion-association complex (IA) between sulfonephthalein dye and basic nitrogen-containing compound in an organic solvent medium has been for the first time used to develop an automated SIA method. In highly polar aprotic solvents, the tautomeric equilibrium for such dyes is strongly shifted towards the colorless lactonic form. The addition of a basic nitrogen-containing substance leads to the formation of IA with a highly colored quinonoid form, which is accompanied by an increase in the absorbance of the dye band at approximately 400 nm. Protonation of pyridine nitrogen in loratadine, structure and binding places of IA were shown using quantum-chemical calculations. The very simple, direct and non-extraction spectrophotometric SIA method with high throughput of 43 h−1 was developed based on the formation of IA between loratadine and bromocresol purple in the medium of acetonitrile used both as solvent and carrier. The calibration graph was linear in the concentration range from 1.0 to 20 mg L−1 with correlation coefficient of 0.9992. The developed method was successfully applied to the analysis of pharmaceutical formulations.