Browsing by Author "Amel Messai"
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Item 1-Formyl-3-phenyl-5-(4-isopropylphenyl)-2-pyrazoline: Synthesis, characterization, antimicrobial activity and DFT studies(2016-05-13) Amel MessaiThe structure of 1-formyl-3-phenyl-5-(4-isopropylphenyl)-2-pyrazoline synthesized as single crystal was investigated by FTIR, NMR, XRD. Experimental data were complemented by quantum mechanical calculations. XRD data show that the compound crystallizes in the triclinic system (P 1) via trans isomer (a ¼ 6.4267(4) Å, b ¼ 10.9259(12) Å, c ¼ 12.4628(9) Å and a ¼ 102.894(8) , b ¼ 102.535(6) , g ¼ 101.633(7) ). Anti-microbial screening results indicate that the compound shows promising activity. The theoretically predicted and experimentally obtained parameters reveal further insight into pyrazoline systemsItem 3-Hydroxyanilinium hydrogensulfate(2017-06-13) Amel MessaiIn the title compound, C6H8NO+ HSO4ÿ, there is an intricate cation–cation, cation–anion and anion–anion three-dimensional hydrogen-bond network.Item A comparative study of two novel unsymmetrically substituted triazacyclohexanes(2017-03-06) Amel Messaiovel unsymmetrically N-substituted N,N0-R1N00-R2-1,3,5-triazacyclohexanes (1b and 2b; R1 ¼ p-chlorophenyl or p-methoxyphenyl and R2 ¼ butyl or cyclohexyl) have been synthesized in a good yield from condensation reaction by excess amine. Both triazacyclohexane rings have chair conformation. However, 1b adopts diaxial orientation of aryl groups and an equatorial form of alkyl group whereas 2b prefers an axial orientation of the alkyl group and diequatorial forms of aryl groups. 1b is consolidated by weak CH/p interactions. Intra-molecular C-H/O or C-H/N hydrogen bonds and C-H/p may be effective in the stabilization of 2b. Both compounds have showed moderate antimicrobial activity, but 1b exhibits higher activity than 2b. All experimental results are found in good support to theoretical data. Findings of research may be helpful guide for the medicinal chemists and the field is further open for pharmacokinetics studies.Item A new tetranuclear copper(II) complex using a Schiff base ligand: Synthesis, structural, and magnetic studies(2017-06-01) Amel MessaiThis paper reports on the synthesis, X-ray, and magnetic properties of tetranuclear CuII complex [CuL4] with square-like structure. A Schiff base ligand used for synthesis in this work derives from condensation of acetylacetone with DL-valine amino acid. The structure of the synthesized ligand was investigated by FTIR and NMR. Investigation of the crystal packing diagrams demonstrates extensive C–H O interactions of hydrogen bonding, causing to the production of network structures. The complex exhibits exchange interaction among the CuII ions by a bridging carboxylate pathway. Analysis of the magnetic data through spin Hamiltonians of the form H^ ¼ 2Jð^S1^ S4 þ ^S4^S2 þ ^ S2^S3 þ ^S3^ S1Þ 2J0ð^S1^S2 þ ^ S3^S4Þ (J has a positive value for a ferromagnetic interaction and negative value for an antiferromagnetic interaction) lead to the following parameters set of best-fit: J = 3.04 cm 1, J0 = 0 cm 1, g = 2.09, and ZJ = 0.109 cm 1.Item Creatinium perchlorate(2009-01-26) Amel MessaiThe title compound, C4H8N3O+ ClO4ÿ, is built up from creatininium cations and perchlorate anions. Crystal cohesion and perchlorate stability are ensured by N—H O hydrogen bonds that together with weak C—H O interactions build up a three-dimensional networkItem Hydrogen bonding in cytosinium dihydrogen phosphite(2009-04-14) Amel MessaiIn the title compound, C4H8N3O4P+ H2PO3ÿ, the cytosine molecule is monoprotonated and the phosphoric acid is in the monoionized state. Strong hydrogen bonds, dominated by N— H O interactions, are responsible for cohesion between the organic and inorganic layers and maintain the stability of this structureItem Investigation of phase transformation for ferrite–austenite structure in stainless steel thin films(2016-03-22) Amel MessaiIn this work we report on phase transformation of 304 stainless steel thin films due to heat treatment. Ex-situ annealing was applied for evaporated 304 stainless steel thin films inside an ultra-high vacuum chamber with a pressure of 3 × 10−7 Pa at temperatures of 500 °C and 600 °C. The structure of thin films was studied by X-ray diffraction (XRD) and conversion electron Mössbauer spectroscopy (CEMS) techniques. The results revealed a transformation from α-phase that exhibits a body-centered cubic structure (BCC) to γ-phase that exhibits a face-centered cubic (FCC) due to annealing. In addition, the percentage of γ-phase structure increased with the increase of annealing temperature. Annealing thin films increased the crystal size of both phases (α and γ), however, the increase was nonlinear. The results also showed that phase transformation was produced by recrystallization of α and γ crystals with a temporal evolution at each annealing temperature. The texture degree of thin films was investigated by XRD rocking curve method, while residual stress was evaluated using curvature methodItem Investigation of Proton Diffusion Coefficient for PbO2 Prepared from Intermediate Oxides(2018-08-27) Amel MessaiLead dioxide was extracted from used batteries, and used to synthesize the following intermediate oxides by heating at different temperatures: Pb12O19, Pb12O17, and Pb3O4. Each of the prepared intermediate oxide was subject to sulfuric acid with 1.28 g.cm–3. X-ray diffraction (XRD) results showed that the sample prepared from Pb12O19 only had a pattern similar to that of the starting PbO2 with α-PbO2 and β-PbO2 phases. The measurements of H+ proton diffusion coefficient (DH+) of the different samples showed that the sample prepared from Pb12O19 had better electrochemical performances than the starting PbO2. This kinetics reflects the proton insertion mechanism in PbO2, i.e. the sample prepared from Pb12O19 has a large amount of structural water in OH- hydroxyl form. This amount contributes more in the PbO2 reduction mechanism. In addition, the DH+ value of the sample prepared from Pb12O19 is significantly higher than that of starting PbO2, which confirms this hypothesis. X-ray diffraction analysis, thermogravimetric and differential thermogravimetry analysis, and cyclic voltammetry reduction at different scanning rates were used to investigate the samples. This work contributes to environment preservation by recycling of used lead dioxide and reduction of the hazard of its disposal on water.Item New Cu(II) coordination polymer by chiral tridentate Schiff base ligand(2017-02-16) Amel MessaiThe present research reports the synthesis, X-ray, magnetic and electronic properties for novel coordination polymer based upon copper (II) with chiral tridentate Schiff base ligand synthesized at condensation of acetylacetone and L-leucine amino acid. The investigation was also conducted by quantum mechanical calculations. The large energy gap indicates a high kinetic stability. Magnetic measurement gives predominant antiferromagnetic interactions within the chain. Results reveals further insight into copper(II) chiral tridentate Schiff base complexes.Item New model of metalloantibiotic: synthesis, structure and biological activity of a zinc(II) mononuclear complex carrying two enrofloxacin and sulfadiazine antibiotics(2018-08-06) Amel MessaiA new model of the Zn-based complex, [Zn(LH)(Erx)(ErxH)]ClO4 (sulfadiazine: LH and enrofloxacin ErxH), has been synthesised with two different, but complementary antibiotics (sulfonamide and quinolon) following an easy procedure. To evaluate the synergetic effect of this multicomponent molecule, the mononuclear complexes [Zn(L)2(H2O)(NH3)] and [Zn(Erx)3]ÿ which each include only one of the two antibiotics (sulfadiazine: LH or enrofloxacin ErxH) were synthesized. All three compounds were characterized, including crystal structure determination by single-crystal X-ray diffraction. For all of the complexes, enrofloxacin is coordinated to Zn(II) by pyridinone and one oxygen atom of the carboxylate group in a monodente mode. The antibacterial activity, determined by the minimum inhibitory concentration on specific bacteria, has been studied on free ligands, on the corresponding mononuclear complexes and on our model.Item New unsymmetrically substituted triazacyclohexanes: Synthesis, characterisation, antimicrobial properties and DFT study(2016-09-21) Amel MessaiNew five unsymmetrically substituted 1,3,5-triazacyclohexanes compounds, carrying aliphatic as well as aromatic substituent, were synthesized and structural analyses were performed by FTIR, 1H NMR and single crystal X-ray techniques. Experimental research was complemented by quantum mechanical calculations. The present triazacyclohexane rings adopt a chair conformation by both R1 substituents in axial positions and R2 group in an equatorial form. Further, all compounds were screened for their antibacterial and anti-fungal properties. By revealing further insight into triazacyclohexanes systems, the data theoretically predicted and experimentally obtained in current research may be helpful guide for the medicinal chemists.Item Novel copper (II) and zinc (II) complexes with enrofloxacin and oxolinic acid: synthesis, characterization, Hirshfeld surface and DFT/CAM-B3LYPD3BJ studies: NBO, QTAIM and RDG analysis(2025-02-15) Amel MessaiThis study aimed to investigate the crystal structure of the synthesized complexes of Cu (II) and Zn (II) with enrofloxacin and oxolinic acid. The characterization of the complexes was carried out using single– crystal x-ray diffraction, Hirshfeld surface and 1H NMR spectroscopy. In addition, a DFT/6-31g(d) investigation was conducted to assess the performance of two exchange-correlation functionals CAM-B3LYP and CAM-B3LYPD3BJ to predict both covalent and non-covalent bonds lengths, and the vibrational frequencies of the metallic complexes. The main findings of this study indicate that the interaction between each metallic ion and the corresponding ligand leads to significant modifications in bond lengths, Mulliken charge distribution and electrostatic potential values in the complex molecules as compared to the ligands alone. To gain further insights into these complexes, several calculations were performed, such as Natural Atomic orbitals (NAO), Natural Bond orbitals (NBO), and Quantum Theory of Atoms in Molecules (QTAIM) analysis. The non-covalent interactions were explored and visualized in two and three-dimensional spaces with the help of the Reduced electron Density Gradient (RDG) approach.Item Structural, mechanical, and magnetic properties of ferrite–austenite mixture in evaporated 304 stainless steel thin films(2015-08-31) Amel MessaiIn this paper, we investigate the structure, composition, magnetic, and mechanical properties of stainless steel thin films formed by thermal evaporation technique. These thin films reveal novel structural and physical properties where they were found to consist of nanocrystals that are *90 % body-centred cubic crystal structure which holds ferromagnetic properties (a-phase), and *10 % face-centred cubic crystal structure which is paramagnetic at room temperature (c-phase). The presence of the above phases was quantified by X-ray diffraction, transmission electron microscopy, and conversion electron Mo¨ssbauer spectroscopy. The magnetic properties were evaluated by a superconducting quantum interference device magnetometer, and they confirmed the dual-phase crystal structure of the stainless thin films, where the presence of c-phase reduced the magnetization of the produced thin films. In addition, the fabricated stainless steel thin films did not contain micro-cracks, and they exhibit a tensile stress of about 1.7 GPa, hardness of 7.5 GPa, and elastic modulus of 104 GPa.Item Synthesis, Characterization and Antimicrobial Screening of Some Novel 3-(Naphtalen-1 and 2-yl) -5- Aryl-2- Pyrazolines Synthesized by Condensation of Hydrate Hydrazine to Appropriate α, β-Unsaturated Ketones(2015-02-14) Amel MessaiSome new pyrazoline derivatives were synthesized by reacting appropriate α, β-unsaturated ketones with hydrate hydrazine in the presence of alcohol. The synthesized compounds were identified by spectral data and screened for antimicrobial activity. Some of these compounds showed moderate to considerable antimicrobial activityItem Synthesis, Characterization and properties studies of new magnetic materials(2015) Amel MessaiWe are interested in molecular polymetallic species having high spin and nuclearities in relation to the field of so call single-molecule magnets (SMMs). The goal is to find a way to synthesis metal clusters which may have application in magnetism and nanosciences. With this purpose, we decided to investigate the coordination chemistry of the Schiff base.Along this way we were able to create cubane-like complexes and elaborate new Single Molecule-Magnets. The idea was to use Schiff base ligands and different metals to generate high nuclear complexes. Complexation of Shiff base with copper has been investigated. Tetranuclear complex with a cubane like core have been synthesised with (Sciff base), with the same base and cobalt we obtains an other single magnetic complex completely different.Item SYNTHESIS, CRYSTAL STRUCTURES, HYDROGEN BONDING GRAPH-SETS AND THEORETICAL STUDIES OF NICKEL (+II) CO-ORDINATIONS WITH PYRIDINE-2,6-DICARBOXAMIDE OXIME(2017-01-01) Amel MessaiThe pyridine-2,6-dicarboxamide oxime, C7H9N5O2, was Synthesis and characterises with 1H NMR and FTIR spectroscopy . The reaction of this ligand with nickel (II) perchlorate yielded green crystals of formula [Ni(C7H9N5O2)2]2+,2[ClO4]-, which crystallized in the monoclinic space group C2/c with a = 14.915(2), b = 0.895(2), c = 8.205(1) Å, β = 114.69(1), and Z = 4. The complex consists of discrete cations (+II) and one perchlorate anion, the cations existing in a slightly distorted octahedral complex with bonding through the heterocyclic and oxime nitrogen atoms. The structure is held together through N-H…O, O-H…O and C-H...O hydrogen bonds occurring between the coordinated oxime molecules and the perchlorate counter-ion. Computational investigations of nickel(II) complex are done by using M062X method with 6-31+G(d)(LANL2DZ) basis set in vacuoItem Synthesis, Crystal Structures, Hydrogen Bonds and Antibacterial Activity of New Quinoline Derivatives(2015-06-03) Amel MessaiTwo new quinolines derivatives where crystallized from the acetylation reaction in low temperature ; between Baylis–Hillman products which had themselves been prepared from the Meth Cohn method and catalyzed by 1,4- diazabicyclo (Fatiha et al. in J Chem Crystallogr 42:989–996, 2012) octane and silicon dioxide or in pyridine and chloroform. Chemical structures have been established by spectral techniques of FTIR, 1H NMR and X-ray single crystal in low temperature. The crystal structure of (1a) crystallizes in triclinic space group P-1, a = 7.9145(12) A˚ , b = 9.1412(11) A˚ , c = 10.7286(16) A˚ , a = 94.760(11) , b = 105.988(13) , c = 101.818(11) , while (2a) crystallizes inorthorhombic non- centrosymmetric space group Pna21, a = 7.7237(12) A˚ , b = 20.2539(28) A˚ , c = 8.7164(12) A˚ , and its cohesion was found to be assured by O–HO and C– HO hydrogen bonds. Antimicrobial activity (in vitro) was evaluated by Gram-positive and Gram-negative bacteria. The compounds have shown good biological activity with Grampositive bacteria (Staphylococcus aurous and Staphylococcus coagulase-negative). Graphical Abstract Two new Quinoline derivatives have been prepared with good products yields; these products constitute original compounds, of great interest biological activityItem SYNTHESIS, QUANTUM CHEMICAL COMPUTATIONS AND X-RAY CRYSTALLOGRAPHIC STUDIES OF A NEW COMPLEX BASED OF MANGANESE (+II)(2017-05-01) Amel MessaiThe ligand oxime, C7H9N5O2, was Synthesis and characterises with different characterization methods such as 1H NMR and FTIR spectroscopy. The complexation of this ligand with manganese (II) perchlorate yielded pink crystals of formula [Mn (C7H9N5O2)2]2+, 2[ClO4]-, which crystallized in the monoclinic space group P21/n with a = 12.824(3), b=13.799(2), c=15.441(4)Å, β = 100.17(2), and Z = 4. The complex consists of cations (+II) and two perchlorate anions, the cations part existing in a slightly distorted octahedral complex. Computational investigations of manganese (II) complex are done by using the DFTmethod with B3LYP functional in conjunction with the 6-31G(d,p) and lanl2dz basis sets in the gas phase imposing the C1 and C2v symmetries.Item ИССЛЕДОВАНИЕ КОЭФФИЦИЕНТА ДИФФУЗИИ ПРОТОНОВ В PbO2, ПРИГОТОВЛЕННОМ ИЗ ОКСИДОВ ПРОМЕЖУТОЧНОЙ ВАЛЕНТНОСТИ(2018-08-27) Amel MessaiОксиды свинца с промежуточной валентностью (Pb12O19, Pb12O17 и Pb3O4) синтезированы из диоксида свинца, извлеченного из использованных аккумуляторов, путем его нагревания при различных температурах. Каждый из приготовленных промежуточных оксидов был обработан серной кислотой (1.28 г см–3). Результаты рентгенодифракционного анализа показали, что только образец, приготовленный из Pb12O19, имеет дифрактограмму, подобную дифрактограмме исходного PbO2 и содержит фазы α-PbO2 и β-PbO2. Измерения коэффициента диффузии протона H+ в различных образцах показали, что этот образец демонстрирует лучшее электрохимическое поведение, чем исходный PbO2. Кинетика процесса отражает механизм внедрения протонов в PbO2, другими словами, образец, приготовленный из Pb12O19, содержит большее количество структурной воды в форме гидроксила OH–. Эта вода дает вклад в механизм восстановления PbO2. К тому же величина коэффициента диффузии протона в образце, приготовленном из Pb12O19, значенио больше, чем в исходном PbO2, что подтверждает высказанную гипотезу. Приготовленные образцы охарактеризованы методами рентгенодифракционного анализа, термогравиметрического и дифференциального термогравиметрического анализа и восстановительной циклической вольтамперометрии. Настоящая работа – вклад в охрану окружающей среды, она предлагает способ утилизации отработанного диоксида свинца и уменьшения его вредного воздействия.