European Journal of Chemistry

We report the synthesis, characterization, X-ray crystal structure and Hirshfeld surface analysis of Ni(II) perchlorate complex (1, Ni₂L₃·4ClO₄·2CH₃CN) of 1,2-bis(pyridin-2-ylmethylene)hydrazine (L) ligand. The X-ray crystallographic study of complex 1 reveals that in the presence of Ni(II) ions,the ligand L forms a dimeric triple helix with a Ni(II)-Ni(II) distance of 3.794 Å. Crystal data for C₄₀H₃₆Cl₄N₁₄Ni₂O₁₆: Monoclinic, space group P2₁/c (no. 14), a = 20.7558(19) Å, b = 13.1937(12) Å, c = 20.0181(18) Å, β = 96.9510(10)°, V = 5441.6(9) Å³, Z = 4, T = 293.15 K, μ(MoKα) = 0.965 mm^-1, D_calc = 1.498 g/cm³, 38075 reflections measured (1.976° ≤ 2Θ ≤ 43.728°), 6557 unique (R_int = 0.0695, R_sigma = 0.0466) which were used in all calculations. The final R₁ was 0.0518 (I > 2σ(I)) and wR₂ was 0.1270 (all data). The Hirshfeld surface analysis of complex 1 shows that C···H, H···H, N···H and O···H interactions of 10.9, 26.4, 6.7, and 33.4%; respectively, which exposed that the main intermolecular interactions were H···H intermolecular interactions.

In this study, the solvatochromic effect on the photophysical properties of Alexa Fluor 514 (AF514) and Alexa Fluor 532 (AF532) fluorescent dyes is examined experimentally and computationally. To explore the solvatochromism and dipole moments, the steady-state absorption and fluorescence spectra of the dyes were measured in a series of organic solvents. Various solvent correlation models, like Bilot-Kawski, Lippert-Mataga, Bakhshiev, Kawski-Chamma-Viallet, and Reichardt microscopic solvent polarity parameters, were adapted to determine the dipole moments in their ground and excited states. For the computational investigation, the ground and excited-state geometries are optimized using density functional theory (DFT) and time-dependent density functional theory (TD-DFT), respectively, in vacuum. Furthermore, semiempirical ZINDO with the IEF-PCM model is used to evaluate the absorption transition energies of these dyes, which are comparatively studied in various solvent polarity along with experimental data. Additionally, the highest occupied molecular orbital energies (HOMO) and lowest unoccupied molecular orbital energies (LUMO), chemical softness, chemical hardness, energy gap, chemical potential, electronegativity, and molecular electrostatic potential (MEP) were estimated using DFT calculations at the CAM-B3LYP/6-311G(d,p) level, in gas phase. The experimental and computational results reveal that the singlet excited state dipole moment is greater than that of the ground state for the molecules considered. The angle between ground- and singlet excited-state dipole moments are found to be 0.50 and 0.49° making them almost parallel to each other. The natural bond orbital analysis (NBO) has been employed to investigate the stability of the molecule, inter- and intra-hyper-conjugative interactions and charge delocalization within the molecule.

A new spectrophotometric reagent, N,N'-bis(salicylidene)-ethylenediamine (Salen), has been synthesized and characterized through novel reaction techniques. A very simple, ultrasensitive, and nonextractive spectrophotometric method has been developed for the determination of the picotrace amount of cobalt (II) using Salen. Salen undergoes a reaction in a slightly acidic solution (0.001-0.003 M H₂S0₄) with cobalt in 20% ethanol to give a light orange chelate, which has an absorption maximum at 459 nm. The reaction is instantaneous, and the absorbance remains stable for over 24 hours. The average molar absorption co-efficient and Sandell’s sensitivity were found to be 6.04×10⁵ L/mol.cm and 5.0 ng/cm² of Co, respectively. Linear calibration graphs were obtained for 0.001-40 mg/Lof Co with a detection limit of 0.1 µg/L and RSD of 0-2 %. The stoichiometric composition of the chelate is 1:1 (Co:Salen). A large excess of over 60 cations, anions and some common complexing agents such as chloride, azide, tartrate, EDTA, SCN^- etc. do not interfere in the determination. The developed method was successfully used in the determination of cobalt in several Certified Reference Materials (Alloys, steel, bovine liver, human hair, drinking water, sewage sludge, soil, and sediments) as well as in some environmental waters (Potable and polluted), biological fluids (Human blood, urine, and milk), soil samples, food samples (Vegetables, rice, and wheat) and pharmaceutical samples and solutions containing both cobalt (II) and cobalt (III) as well as complex synthetic mixtures. The results of the proposed method for assessing biological, soil, food and vegetable samples were comparable with ICP-OES and AAS were found to be in excellent agreement. The method has high precision and accuracy (s = ±0.01 for 0.5 mg/L).

Cancer cannot be ignored since it is the most dangerous disease because it is a major cause of death globally with 15% mortality. Researchers have been attracted to the plant-based solution of this havoc. Among all plants, Syzygium aromaticum has shown tremendous results in many aspects such as anticancer, antioxidant, and others.  All the studies that took place, were done on the plant extract only. No one goes further than this. Hence, an advanced computational chemistry-based method for the characterization and identification of the bioactive ingredients isolated from cloves was developed for the first time. First, different extracts of Syzygium aromaticum plant buds were obtained using different solvents (Water, methanol, chloroform, ethyl acetate, 50% ethanol, and hexane), then each extract was evaluated for its anticancer activity against A549 and H1299 lung cancer cell lines. The fractionation of the most active extract was done using flash chromatography. After that, anticancer evaluation of every fraction was done again. One of the obtained fractions showed the highest anticancer activity. For the identification of the most active fraction the experimental IR and NMR data of it was taken and compared with the computational IR and NMR data of 19 compounds found in cloves. Furthermore, DNA binding affinity and antioxidant activity of the fraction showing the highest anticancer activity were also studied. The presented method of the isolation of the most bioactive ingredient will be the most helpful for all the scientists working in the field of separation science and phytomedicine.

An efficient and regioselective synthetic reaction friendly to the environment has been described to synthesize various derivatives of pyrazolo[1,5-a]quinozolinone. Condensation of aminopyrazole (4a-m) with formylated dimedone (3) in the presence of KHSO₄, under ultrasonic irradiation furnished 2/3-substituted 8,8-dimethyl-8,9-dihydropyrazolo[1,5-a]quinazolin-6(7H)-one (6a-m). This is a clean reaction, giving excellent yields with short reaction time. The structures were elucidated with the help of spectral and analytical data. X-ray crystallographic studies of a model compound 6a ascertained its structural configuration, crystal data for C₁₂H₁₂BrN₃O (M =294.152 g/mol): Triclinic, space group P-1 (no. 2), a = 5.872(4) Å, b = 10.870(8) Å, c = 19.523(15) Å, α = 90.013(10)°, β = 90.009(11)°, γ = 93.838(11)°, V = 1243.3(16) Å³, Z = 4, T = 296.15 K, μ(Mo Kα) = 3.293 mm^-1, Dcalc = 1.571 g/cm³, 37271 reflections measured (4.18° ≤ 2Θ ≤ 52.7°), 5073 unique (R_int = 0.2404, R_sigma = 0.2366) which were used in all calculations. The final R₁ was 0.0596 (I≥2σ(I)) and wR₂ was 0.1759 (all data).

The synthesis, characterization, and theoretical studies of the title compound has been reported in this study. The molecular structure has been characterized by room-temperature single-crystal X-ray diffraction study which reveals that it has an angular shape with intramolecular and intermolecular hydrogen bonding. Crystal data for the title compound, C₂₇H₂₂N₂O₂ (M =406.46 g/mol): monoclinic, space group C2/c (no. 15), a = 36.371(10) Å, b = 4.6031(12) Å, c = 12.192(3) Å, β = 94.972(6)°, V = 2033.5(9) Å³, Z = 4, T = 100 K, μ(MoKα) = 0.084 mm^-1, Dcalc = 1.328 g/cm³, 8812 reflections measured (2.248° ≤ 2Θ ≤ 49.734°), 1773 unique (R_int = 0.0323, R_sigma = 0.0239) which were used in all calculations. The final R₁ was 0.0411 (I > 2σ(I)) and wR₂ was 0.1165 (all data). In crystal structure, the molecule exits in the enol form and is located on a two-fold axis of symmetry; where the central methylene carbon atom of the diphenylmethane moiety is displaced from the aromatic ring planes. The Hirshfeld surface analysis of the title compound shows that H···H, C···H, and O···H interactions of 53.3, 13.2, and 5.4%; respectively, which exposed that the main intermolecular interactions were H···H intermolecular interactions. The HOMO-LUMO energy gap in the title compound is 2.9639 eV. Molecular electrostatic potential of the investigated compound has also been studied.

Oxidative stress, caused by reactive oxygen species, is known to cause oxidation of biomolecules, leading to cell damage and oxidation of important enzymes, resulting in an unstable pathophysiological state. The antioxidant capacity of leaves, stems, and roots of Cordyla pinnata was determined by measuring the inhibition of the absorbance of 2,2-diphenyl-1-picryl-hydrazyl (DPPH) and 2,2'-azino-bis-(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) radicals by spectrophotometry. The polyphenol contents were determined with the same technique. The mineral contents were evaluated by atomic absorption spectrometry. The strongest inhibition of the DPPH radical after that of the control antioxidant (IC₅₀ = 0.014 mg/mL) was obtained with the ethyl acetate fraction of the leaf hydroethanolic extract (IC₅₀ = 0.201 mg/mL). For ABTS, the ethyl acetate fraction of the stem extract was more active (IC₅₀ = 0.884×10^-3 mg/mL) than the other extracts and ascorbic acid (IC₅₀ = 0.915×10^-3 mg/mL). The polyphenol content of the leaves, stems and roots extracts is between 66.33 and 142.67; 55.33 and 69.33; 67.67 and 116.00 EAT/g of dry extract, respectively. The contents of Fe, Na, Zn, K, Mg, and Ca are 0.0005, 0.0006, 0.0020, 0.0897, 0.0247, and 0.0273% for leaves, respectively. They are 0.0001, 0.0010, 0.0015, 0.0557, 0.0131, and 0.1357% for the stems, respectively. The mineral contents of the roots in the same order are 0.0002, 0.0013, 0.0013, 0.0140, 0.0096, and 0.0267%. Strong inhibition of free radicals and the chemical composition of various plant materials would justify the use of C. pinnata in the management of certain pathologies and nutritional deficiencies.

Iron(II) and manganese(II) complexes of N'-(1-(pyridin-2-yl)ethylidene)nicotinohydrazide (LH) have been synthesized and characterized by elemental analysis, IR, and ¹H NMR spectroscopy. The crystal structure of the ligand has been determined by single crystal X-ray diffraction and electronic spectroscopic techniques. Crystal data for LH, C₁₃H₁₂N₄O: Orthorhombic, space group Pbcn (no. 60), a = 18.0824(3) Å, b = 7.86555(14) Å, c = 16.1614(3) Å, V = 2298.60(7) Å³, Z = 8, T = 103 K, μ(Mo Kα) = 0.093 mm^-1, Dcalc = 1.388 g/cm³, 36729 reflections measured (5.042° ≤ 2Θ ≤ 54.966°), 2633 unique (R_int = 0.0224, R_sigma = 0.0124) which were used in all calculations. The final R₁ was 0.0383 (F²>2σ(F²)) and wR₂ was 0.0988 (all data). The ligand was found to chelate to the metal ions through the azomethine nitrogen and amide oxygen atoms in a bidentate manner. The anti-tubercular activity of the ligand, its iron (II) and manganese (II) complexes were studied against Mycobacterium tuberculosis (ATTC 27294). The results revealed higher activity of the iron (II) complex with MIC value of 8.00±0.83 µM and a moderate activity of the manganese (II) complex having MIC value of 14.20±1.40 µM, compared to the reference drugs having MIC values of 9.41±0.92, 10.74±1.02, 25.34±2.6 µM and parent ligand with MIC value of 17.60±1.80 µM.

Chemotherapy is one of the most valuable and widely available option in cancer treatment. However, a method of delivering the drug to achieve a therapeutic effect still a considerable challenge. Therefore, this study seeks to identify the non-bonding interaction of 5-fluorouracil anticancer drug with a single walled carbon nanotube and a Cellulose bio-fiber using density functional theory and molecular mechanics simulations. To do that, adsorption locator and DMol3 modules were utilized to determine the electronic and optical properties of carriers before and after adsorption processes. The interaction energies indicate that the 5-fluorouracil molecule can physically adsorb and the optimized geometries are stable. The charge transfer occurs between N4-H10 bond of the 5-fluorouracil molecule and the cellulose carrier by a synergistic effect of hydrogen bond formation and van der Waals forces. This effect smoothly transforms into van der Waals interactions by O3, N4, and N5 atoms in the case of single-walled carbon nanotubes. There is a clear difference in the absorption peak and a significant narrowing of the molecular energy gap of a cellulose complex because of the shifting of the electron accepting center to a drug molecule. The conductor-like screening model shows the affinity of the complexes toward hydrogen bond acceptor, which enhances their solubility in biological systems. A remarkable influence in the case of the cellulose complex works as a starting point to use natural polymers as drug delivery carriers.

Water pollution caused by heavy metals is of great concern because of rapid industrialization, lack of wastewater treatment, and inefficient removal of these metals from wastewater. The present project was designed to develop a green adsorbent from rice straw and to investigate it for the removal of chromium from chromium-contaminated water. Rice straw biochar was prepared and then modified with FeCl₃·6H₂O and FeSO₄·7H₂O to enhance its Cr removal efficiency. Modified and unmodified biochar were characterized by Scanning Electron Microscope (SEM), Energy Dispersive X-ray Spectroscopy (EDS), and Fourier Transform Infrared Spectroscopy (FTIR). Batch sorption experimentations were performed to inquire about adsorption kinetics, isotherms, and Cr(VI) adsorption mechanism onto iron-modified rice straw biochar (FMRSB). The results specified that the apex adsorption capability of the adsorbent for chromium was 59 mg/g and the maximum removal efficacy was 90.9%. Three isotherm models, Sips, Freundlich, and Langmuir models were applied to the experimental data. Among them, the Sips isotherm model reveals the most excellent fitting with a maximum correlation coefficient (R² = 0.996) that was adjusted to the experimental data. Regarding kinetic studies, the Pseudo second-order (PSO) exhibits the best fitting with a higher correlation coefficient (R² = 0.996). The kinetic equilibrium data expressed that the adsorption of Cr(VI) on the FMRSB surface was chemisorption. The mechanism of adsorption of Cr(VI) on FMRSB was predominantly regulated by anionic adsorption through adsorption coupled reduction and electrostatic attraction. The present study demonstrated that the use of modified biochar prepared from agricultural wastes is an environmentally safe and cost-effective technique for the removal of toxic metals from polluted water.

Bis(N,N-bis(thiophen-2-ylmethyl)dithiocarbamato-S,S’)zinc(II) complex (1) and (2,2’-bipyridine)chlorobis(N,N-bis(thiophen-2-ylmethyl)dithiocarbamato-S,S’)zinc(II) complex (2) were synthesized. Complex 2 (final product) was structurally characterized by single crystal X-ray diffraction studies. Complex 2 (C₂₁H₁₈ClN₃S₄Zn) crystallized in triclinic crystal system with space group P-1 (no. 2), a = 8.7603(4) Å, b = 10.7488(6) Å, c = 13.0262(7) Å,    α = 103.965(2)°, β = 91.913(2)°, γ = 104.944(2)°, V = 1144.07(10) Å³, Z = 2, T = 302(2) K, μ(MoKα) = 1.569 mm^-1, Dcalc = 1.572 g/cm³, 14892 reflections measured (4.838° ≤ 2Θ ≤ 56.52°), 5570 unique (R_int = 0.0188, R_sigma = 0.0230) which were used in all calculations. The final R₁ was 0.0810 (I > 2σ(I)) and wR₂ was 0.2788 (all data). Complex 2 displays distorted square pyramidal coordination geometry. Crystal structure analysis of complex 2 shows that the crystal packing is mainly stabilized by C-H···π (chelate) and C-H···Cl interactions. Hirshfeld surface analysis was carried out to explore deeply into the nature and type of non-covalent interactions. The molecular and electronic structures of complexes 1 and 2 were also studied by DFT quantum chemical calculations.

The use of renewable, sustainable, and biocompatible products without chemical side effects is increasing day by day in antibacterial applications instead of materials that harm nature and humans. In biomedicine, antibacterial nanofiber composite surfaces with generally produced from materials with antibacterial properties such as chitosan, hyaluronic acid, collagen, and silver nanoparticles. In this study, olive leaf, terebinth, and fumitory plants and biocompatible, biodegradable, and environmentally friendly polylactic acid (PLA) polymer were used to obtain nanofiber structures with 100% plant extracts. Viscosity and conductivity of solutions prepared with optimum properties were analysed, the nanofiber material was produced in solution with electrospinning method, and the morphological evaluation and mechanical measurement of the nanofiber material were performed. Finally, bacterial exchange analyses were performed before and after incubation in the UV-VIS spectrophotometer. As a result of the study, the thinnest and the most uniform fiber materials were found in CFO (consist of PLA (C1) and fumitory (FO)) coded nanofiber material, the best strength values were found in COE (consist of PLA (C1) and olive leaf (OE)) coded nanofiber structure, and the highest bacterial exchange was observed in CFO coded nanofiber material. Based on these results, it has been suggested that the CFO coded nanofiber structure can be used in biomedicine. It has been observed that olive leaf, terebinth, and fumitory plant extracts, which can be grown easily in every region in Turkey, have a significant level of bacterial resistance. In conclusion, fumitory and terebinth plants can be used in antibacterial agent applications since they allow obtaining smooth and uniform nanofiber structures, and thanks to their high bacteria nullification properties.

Schiff bases are a proven moiety in antitubercular drug discovery and the antitubercular drug development. Drug discovery is a never-ending process due to evolving drug resistance by the bacteria, as a result, there is a need of developing new antitubercular drugs. In this continuous process of antitubercular drug discovery, new series of Schiff bases are synthesized using quinoline carbohydrazide upon coupling with different aldehydes in ethanolic media through multistep synthesis. These synthesized compounds were purified and characterized by different spectroscopic techniques. The molecules were in vitro screened for antifungal and antibacterial potential by Agar well diffusion assay, antitubercular activity by using microplate Alamar blue assay, and an attempt has been made to study the in-silico relationship between new Schiff base derivatives 4a-f and the crystal structure of M. tuberculosis (5V3Y) protein by molecular docking studies. Synthesized compounds 4a-f show good interaction with the crystal structure of M. tuberculosis protein (5V3Y) and fulfill ADMET characteristics in silico experiments. Among the compounds tested, compound 4d was found to be active against bacteria and fungi. Compound 4b was found to be sensitive against M. tuberculosis at 50 µg/mL concentration.

[Ni(pyrdtc)(PPh₃)(NCS)] (1), [Ni(pyrdtc)(4-MP)(NCS)] (2), [Ni(pyrdtc)(PPh₃)(CN)]·H₂O (3), [Ni(pyrdtc)(PPh₃)₂]ClO₄ (4), and [Ni(pyrdtc)(P͡P)]BPh₄·2H₂O (5) [where pyrdtc: Pyrrolidine carbodithioate/S͡S, PPh₃: Triphenylphosphine, 4-MP: Tri(4-methylphenyl)phosphine, dppe/P͡P: 1,2-Bis(diphenylphosphino)ethane] have been prepared from the parent bis-dithiocarbamate, [Ni(pyrdtc)]₂ (6). The prepared compounds were characterized by electronic, IR, ¹H, ¹³C, and ³¹P NMR spectra. In the IR spectra of the compounds, thioureide bands are observed at higher wavenumbers for the mixed ligand complexes 1-5 (1528-1540 cm^-1) than the parent compound (1490 cm^-1). Cyclic voltammetry showed an increasing order of reduction potentials: 5 << 1 ~ 2 < 3 < 4 << [Ni(pyrdtc)₂] indicating an alleviation of electron density on nickel in the mixed complexes compared to the parent compound. Single crystal X-ray structure of the complexes displayed planar geometry around nickel which is in keeping with their diamagnetism. Bond Valence Sums calculated with the corrected R_ij indicated the divalent nature of nickel with predominant covalent interactions. Continuous shape measure analysis of the mixed ligand chromophores stipulates a planar square environment around central nickel atom and deviation to tetrahedral or trigonal bipyramidal variants are absolutely negated. In this study, CSM analysis of cis-platin, a clinical anti-cancer agent, showed a comparable shape measure as those of the mixed ligand complexes 1-5. Hence, pyrrolidinecarbodithioate acts as a ‘chuck’ in compounds 1-5 to stabilize the planar square shape of the nickel chromophores and provides a suitable template to synthesize analogues of cis-platin.

Mononuclear complexes of VO(IV), Cr(III), Fe(III), MoO₂(VI), WO₂(VI), and UO₂(VI) with pyrazinecarbohydrazone ligand (N'-(1-(5-chloro-2-hydroxyphenyl)ethylidene)pyrazine-2-carbohydrazide) were synthesized and the prepared complexes were characterized by elemental analysis, magnetic susceptibility, powder X-ray analysis, various spectroscopic techniques (IR, ¹H NMR, ¹³C NMR, and Mass spectra), SEM, and thermal analysis. VO(IV) complex was additionally characterized by ESR study. The ligand behaves as a dibasic tridentate, coordinating through the phenolate oxygen, azomethine nitrogen, and enolate oxygen atoms towards the central metal ion. The analytical data suggest 1:1 metal to ligand stoichiometry for all complexes. The physicochemical data suggested octahedral geometry to Cr(III), Fe(III), MoO₂(VI), WO₂(VI), and UO₂(VI) complexes while square pyramidal to VO(IV) complex. The SEM analysis indicated the presence of well-defined crystals free from any shadow of the metal ion on their external surface with particle sizes of greater than 10 μm. Various kinetics and thermodynamic parameters are calculated using Coats-Redfern method and on the basis of half decomposition temperature the thermal stability order of complexes was found to be Cr(III) < WO₂(VI) < Fe(III) < MoO₂(VI) <  VO(IV) < UO₂(VI). The solid-state electrical conductivity of compounds was measured in their pellet form in the temperature range form 313-373 K. The conductivity data vary exponentially with the absolute temperature and obey Arrhenius equation indicating their semiconducting behavior. The antibacterial as well as antifungal activities of ligand and its metal complexes were evaluated in vitro against Gram positive bacteria (S. aureus and B. subtilis) and Gram-negative bacteria (E. coli and S. typhi.) and fungal strains (C. albicans and A. niger). The activity data revealed metal complexes are found to be more active than the ligand.