Browsing by Author "Wahiba Falek"

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    A structural comparative study of charge transfer compounds: Synthesis, crystal structure, IR, Raman-spectroscopy, DFT computation and hirshfeld surface analysis
    (2019-04-24) Wahiba Falek
    The present work focuses on the crystal structure analysis, vibrational spectroscopy investigation and DFT calculation. Two new charge transfer compounds; bis (creatininium) fumarate fumaric acid (I) and creatininium 3,5-dicarboxybenzoate monohydrate (II), have been synthesized, their Raman and IR modes of vibrations have been assigned and their crystal structures have been studied by means of single crystal X-ray diffraction. Complementary Hirshfeld surface analysis were carried out to investigate and quantify the contributions of the different intermolecular interactions within the crystal. This analysis revels that the main contributions in both compounds are provided by the O/H and H/H interactions that represent ~70 (for I) and ~75% (for II) of the total contributions to the Hirshfeld surface. The results of the theoretically predicted structural parameters and vibrational frequencies are in good agreements with the experimental investigations. These results show that both compounds exhibit similar features, however the energy gap between E HOMO and E obtained from the molecular orbital analysis indicates that compound (I) is characterized by a molecular structural more favourable for charge transfer. LUMO
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    A structural comparative study of charge transfer compounds: Synthesis, crystal structure, IR, Raman-spectroscopy, DFT computation and hirshfeld surface analysis
    (2019-04-24) Wahiba Falek
    The present work focuses on the crystal structure analysis, vibrational spectroscopy investigation and DFT calculation. Two new charge transfer compounds; bis (creatininium) fumarate fumaric acid (I) and creatininium 3,5-dicarboxybenzoate monohydrate (II), have been synthesized, their Raman and IR modes of vibrations have been assigned and their crystal structures have been studied by means of single crystal X-ray diffraction. Complementary Hirshfeld surface analysis were carried out to investigate and quantify the contributions of the different intermolecular interactions within the crystal. This analysis revels that the main contributions in both compounds are provided by the O/H and H/H interactions that represent ~70 (for I) and ~75% (for II) of the total contributions to the Hirshfeld surface. The results of the theoretically predicted structural parameters and vibrational frequencies are in good agreements with the experimental investigations. These results show that both compounds exhibit similar features, however the energy gap between EHOMO and ELUMO obtained from the molecular orbital analysis indicates that compound (I) is characterized by a molecular structural more favourable for charge transfer.
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    Cytosinium–hydrogen maleate–cytosine (1/1/1)
    (Wahiba Falek, 2009-11-04) Wahiba Falek
    The title organic salt, C4H6N3O+ C4H3O4ÿ C4H5N3O, was synthesized from cytosine base and maleic acid. An intramolecular O—H O hydrogen bond occurs in the hydrogen maleate anion. The crystal packing is stabilized by intermolecular N—H O, N—H N and C—H O hydrogen bonds, giving rise to a nearly planar two-dimensional network parallel to (101)
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    Synthesis, structural elucidation, spectroscopic, Hirshfeld surface analysis and theoretical simulation of a new adeninium orthoperiodate (1−) bis(hydrate) organic–inorganic hybrid crystals
    (2020-09-06) Wahiba Falek
    One novel organic-inorganic hybrid supramolecular compound named Adeninium orthoperiodate (1−) bis(hydrate) (I) has been synthesized and characterized by FT-IR spectroscopy and single-crystal X-ray diffraction complemented with a quantum chemical study performed with DFT method at the B3LYP/3– 21G level. The title compound crystallized in the monoclinic centrosymmetric P 2 1 /n space group. In the molecular arrangement, the different entities are held together through the interplay of intermolecular O···H – N/O and N – H ···O hydrogen bonds, that found to be effective in stabilizing the three-dimensional crystal packing. The hydrogen bonds network of (I) contains an interesting cyclic homosynthon of R 2 2 (10) graph set notation involving the adeninium Hoogsteen sites (N6—H1N···N7). The role of such interactions is known to be predominant in the stabilization of the usual 1H,9H tautomer. The different intermolecular interactions of (I) were quantified and analysed using Hirshfeld surface analysis, enrichment ratio (E) and fingerprint plots. The obtained results indicate that the main contributions are ascribed to O···H and H···H interactions. Scanning electron microscopy (SEM) was used to provide an extremely enlarged image of the sample morphology of (I), as well as information on its chemical composition using an energy dispersive X-ray spectrometer (EDS) detector, which confirms that the compound was successfully synthesized. The complementary theoretical achievements were found in a good agreement with respect to the experimental data. Moreover, a natural bond orbital (NBO) analysis was performed to evaluate the nature of bonding and the strength of the intra and inter-molecular interactions. Furthermore, the calculations of HOMO and LUMO energies were carried out to investigate the charge transfer within the molecular structure. The molecular electrostatic potential maps were used to detect the possible electrophilic and nucleophilic sites in (I).