European Journal of Chemistry

A versatile synthetic building block, 2-amino-1,10-phenanthrolin-1-ium chloride (L∙HCl) was synthesized and characterized by IR, ¹H and ¹³C NMR DEPT analysis, UV/Vis and single-crystal X-ray diffraction technique. The molecular geometry, vibrational wavenumbers and gauge including atomic orbital (GIAO), ¹H and ¹³C NMR chemical shifts values of the title compound in the ground state were obtained by using density functional theory (DFT/B3LYP) method with 6-311++G(d,p) basis set and compared with the experimental data. Electronic absorption spectrum of the salt was determined using the time-dependent density functional theory (TD-DFT) method at the same level. In the NMR and electronic absorption spectra calculations, the effect of solvent on the theoretical parameters was included using the default model with DMSO as solvent. The obtained theoretical parameters agree well with the experimental findings.

A simple, precise, reproducible and economical HPLC method for estimation of tinidazole has been developed. The wavelength of 317 nm is selected as λ_max for tinidazole in phosphate buffer (pH = 6.8). Validation parameters were tested following International Conference on Harmonization (ICH) guideline. Tinidazole shows linearity at the selected wavelength and obeys Beer’s law in the concentration range of 3.2-40.0 µg/mL with correlation coefficient of 0.9999. Recovery studies for tinidazole were performed and the percentage recovery was obtained in the range of 99.10-102.45% confirming the accuracy of the proposed method. The method showed good reproducibility and recovery with %RSD less than 2. Statistical validation of the data shows that the proposed method can be used as stability indicating method which successfully applied for the routine analysis of drug in commercial tablets.

Density functional theory was used to calculate the electronic structure of 20 selected 1,4-benzodiazepine derivatives. Certain parameters were extracted from the theoretical calculations, including the proton affinity of N1, the total energy, HOMO and LUMO energies, the total positive atomic charge, dipole moment and molecular volume. These parameters were used for the correlation with the minimum effective dose acting on human. The correlation was performed by applying linear least square method. Seven parameters were found to afford good fit. Clorazepate, one of the benzodiazepines, was studied extensively, it contains a carboxylate group, which can act as an ordinary molecule or zwitterions, where the ionisable proton migrates to N1. The energy gap between the two forms was found to be strongly dependent on the solvent dielectric constant.

A rapid and sensitive High Performance Liquid Chromatography (HPLC) method has been developed and validated as per ICH guideline for simultaneous determination of ramipril and felodipine binary mixture. Chromatographic separation was achieved on a Hyperchom C18 column (250 × 4.6 mm i.d., 5 μm) using an isocratic mobile phase of potassium di-hydrogen phosphate (pH = 3.4): methanol: acetonitrile in the ratio 15:15:70 (v:v:v). The flow rate was 1.5 mL/min, temperature of the column was maintained at 30 °C and detection was made at 210 nm. Linearity studies indicated that the drugs obey Beer’s law over the range of 10-80 μg/mL for ramipril and 5-80 μg/mL for felodipine. The proposed method is precise, accurate, linear and robust. The short retention time allows the analysis of a large number of samples in a short period of time and, therefore, considered to be cost-effective that can be used for routine analysis of both drugs in the pharmaceutical industry.

The development of alternative coating material is important for the corrosion life of metals. Improving the corrosion resistance and decorative appearance of zinc-nickel coatings is gaining importance. Related physical properties can be provided by using various chemicals. Tetraethylamine, triethanolamine, gelatin, and p-aminobenzenesulfonic are the chemicals used in this study to evaluate corrosion resistance and decorative appearance.

A one dimensional (1D) lead(II) coordination polymer, [Pb(Phen)(NO₃)(OAC)(H₂O)]_n (1) (Phen = 1,10-Phenanthroline; OAc = Acetate) was isolated in crystalline phase and characterized through different analytical techniques. Single crystal X-ray structural analysis of compound 1 revealed that the Pb(II) polymer crystallized in a monoclinic system with P2₁/c space group. Pb²⁺ ion adopted a highly distorted octahedral geometry having O3 (water) and O5 (nitrate) at axial positions (∠O3-Pb1-O5 of 145.02°) and acetate oxygen (O4), phenanthroine nitrogens (N3, N4) and oxygen (O2) atom from bridging nitrate made a distorted square plane. This Pb(II) polymer exhibited good fluorescence property in solid state. The steric arrangement of distorted square plane around Pb(II) ion by Phen, acetate and bridging nitrate ion makes a huge gap around Pb(II) ion where a stereo-active lone pair of electrons may possibly be occupied.

Novel acyl pyrazolone and thio-Schiff base of acyl pyrazolone ligand HL (2-((4-chlorophenyl)(1-(3-chlorophenyl)-3-methyl-5-oxo-4,5-dihydro-1H-pyrazol-4-yl)methylene) hydrazine-1-carbothioamide) has been synthesised and characterized by FT-IR and ¹H NMR techniques. This unusual coordinated complex [Zn(L)(CH₃C00)(H₂O)]CH₃CH₂OH has been synthesized and characterized by FT-IR, thermogravimetric analysis (TGA), UV-Vis spectroscopy and single crystal X-ray diffraction. ¹H NMR confirms the structure of the thio-Schiff base used in the study. The structural data reveal that mononuclear Zn(II)complex has distorted square pyramidal geometry. S-S interaction, Inter molecular and intra molecular H-Bond found in crystal packing of the complex. The complex has been screened for MTT assay against A549 cell lines. The Zn(II) complex is cytotoxic against the screened cell line at low concentration.

The Schiff base 3-(2-hydroxy-phenylimino)-1,3-diphenyl-propan-1-one (L), was prepared and characterized by elemental analysis, IR, ¹H NMR and mass spectral techniques. The crystal and molecular structures were determined by using the single crystal X-ray diffraction data. The crystal was triclinic with unit-cell dimensions: a = 9.051(3) Å, b = 10.245(3) Å, c = 11.016(3) Å, α = 69.28(2)°, β = 81.66(2)°, γ = 64.25(2)°, space group is Pī and Z = 2. The structure was refined by least squares method. The single crystal was prepared by supersaturating method using tetramethoxysilane as gelling agent. Energy minimization for locating stable conformations and single point energy calculations for comparing the obtained and calculated conformations of the same molecule were carried out using molecular mechanics method (MM2 force field). The bond lengths and the bond angles were calculated and compared with the values obtained from the single crystal analysis. The obtained results were discussed and evaluated. Generally, the calculated parameters are in good agreement with the corresponding X-ray diffraction values. The obtained results reveal that, the amine-imine tautomerism is more preferable than keto-enol form and the intra-hydrogen bond stabilize the amine-imine tautomerism.

One of the highly soluble protein presents in circulatory system of bovine body is bovine serum albumin (BSA). Bupropion hydrochloride (BRN) served to treat prime smoking cessation and disorder due to depressive. BRN binding to BSA was studied by molecular docking and lots of spectroscopic (UV-vis, emission, synchronous, 3D fluorescence, CD and FT-IR) methods at pH = 7.40. Static quenching with strong binding was obtained for BSA-BRN system by forming complex. Secondary structures, conformations and microenvironments of BSA were altered after BRN interaction. Distance between BRN and BSA was also achieved. Biologically active metal ions (Cu²⁺, Ca²⁺, Mg²⁺, Fe²⁺ and Zn²⁺) were also influenced on the BSA-BRN complex. Bonds of hydrogen and Van der Waals were major binding forces to stabilize BSA-BRN complex at site I (IIA) of BSA. Hence, binding of BRN to transport protein (BSA) is of prominent importance and these findings could be helpful for BRN pharmacology and potential clinical research.

In this research, calixpyrrole modified silica (III) was synthesized and characterized by Fourier transform infrared spectroscopy (FTIR), thermal gravimetric analysis (TGA) and scanning electron microscope (SEM) techniques. The synthesized material was used as an extractant for the removal of 4-chlorophenol from aqueous solution. Its efficiency was examined through both batch and column extraction methods. The effects of temperature, pH, initial chlorophenol concentration and mass of the adsorbent were examined using removal efficiencies. Initial concentration and quantity of adsorbent show a noticeable influence on the uptake capacity of the adsorbent. The kinetics and thermodynamics of chlorophenol removal from aqueous media were also investigated. Kinetic studies indicated that the extraction data can be best represented by pseudo second order model. Column extraction data were analyzed through Thomas, Yoon-Nelson and Yan et al. models to calculate kinetic coefficients and maximum sorption capacity of the modified silica (III). The adsorbent silica was regenerated by acid treatment without changing its properties.

Efficient synthesis of non-annulated 2-amino-4H-pyrans and 2-amino-8-oxo-4,8-dihydropyrano[3,2-b]pyran derivatives, which are biologically relevant heterocycles is achieved, utilizing a domino three-component reaction of ethyl acetoacetate or kojic acid with aromatic aldehydes and malononitrile catalyzed by Zn(L-proline)₂ as reusable organometallic catalyst. The process exhibits high atom economy, short reaction time, simple work up, high yields and environmentally friendly nature. Excellent yields of the targeted molecules have been obtained.

The reaction between an atropoisomeric diphosphine, Bitianp and [Ni(CO)₄] was achieved by direct condensation in CH₃Cl to afford complexes of general formula [Ni(CO)₂(Bitianp)]. This compound was characterized by elemental analysis, IR, ¹H-, ¹³C- and ³¹P-NMR spectroscopies. The structure of nickel complex has been determined by X-ray crystal-lography. Crystal data for C₄₂H₂₈NiO₂P₂S₂ (M = 749.41 g/mol): triclinic, space group P-1 (no. 2), a = 10.539(2) Å, b = 11.811(2) Å, c = 15.994(3) Å, α = 83.93(3)°, β = 88.18(3)°, γ = 65.24(3)°, V = 1797.6(7) Å³, Z  = 2, T  = 294(2) K, μ(MoKα) = 0.781 mm^-1, Dcalc =1.385 g/cm³, 22744 reflections measured (2.56° ≤ 2Θ ≤ 64.726°), 11837 unique (R_int = 0.0157, R_sigma = 0.0215) which were used in all calculations. The final R₁ was 0.0360 (I > 2σ(I)) and wR₂ was 0.1088 (all data). The coordination sphere of the Ni center is best described as a tetrahedral geometry.

Synthetically modified green fluorescent protein chromophore derivative was prepared, its crystal structure and spectral properties were studied. Crystal data for C₁₉H₁₈N₂O₄: triclinic, space group P-1 (no. 2), a = 8.2506(17) Å, b = 11.934(2) Å, c = 17.461(4) Å, α = 102.89(3)°,   β = 94.62(3)°, γ = 96.68(3)°, V = 1654.5(6) ų, Z = 4, T = 173(2) K, μ(MoKα) = 0.096 mm^-1, D_calc = 1.358 g/cm³, 7227 reflections measured (4.722° ≤ 2Θ ≤ 53.996°), 7227 unique (R_int = 0.0453, R_sigma = 0.0662) which were used in all calculations. The final R1 was 0.0561 (I > 2σ(I)) and wR2 was 0.1658 (all data). The single crystal structure showed, the benzylidine moiety adopts Z-conformation in solid state and the molecules were associated by various O−H···O and C−H···O non-covalent interactions. The UV absorption-emission spectral analysis indicated that a significant red shift of emission observed at alkaline pH indicating its utility for live cell imaging applications.

In order to build a metal-organic framework with mixed ligands (acid-acid), a 3D coordination network based on manganese metal center was obtained [Mn₃(BTC)₂(DMSO)₄]_n; where BTC = Benzene-1,3,5-tricarboxylic acid and DMSO = Dimethylsulfoxide. The crystal structure was determined by single crystal X-ray diffraction, showing the assembly of a tridimensional 3,6-connected non-entangled polymeric network, with RTL topology. The secondary building unit (SBU) acts as a node of the 3-periodic expansion and involves carboxylate- and oxo-bridged metals. The DMSO employed in the synthesis is chemically involved in the coordination as a µ₂-O bridge between distinct manganese metal centers. The structural characterization of the material was supported by spectroscopic (infrared absorption and Raman scattering), thermal (TG, DTG, and DTA) and elemental analysis.