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Papers by Mohammad Khear Sabra
Ab initio quantum chemical methods were applied to investigate the ground state energies and geom... more Ab initio quantum chemical methods were applied to investigate the ground state energies and geometrical configurations of boron-carbon (BC) n and boron-carbon hydrides (HBCH) n chains. The boron-carbon chains were found to be unstable in one dimension. They dissociate into boron-carbon dimers or transform into two dimensional network. The boron-carbon hydride chains were found to be stable in one dimensional structure with bond alternation. The ab initio ground state energies of the conjugated (HBCH) n chains were fitted into the SSH model, in order to determine the corresponding parameters for the ground state energy. According to the SSH model, this conjugation induces a band gap of around 0.8 eV.
Journal of Alloys and Compounds, 2017
Full-potential linearized augmented plane waves (FPLAPW), density functional theory within the ge... more Full-potential linearized augmented plane waves (FPLAPW), density functional theory within the generalized gradient and local density approximations methods are used to determine the ground state structure and to calculate the elastic constants of two phases of boron hydrogen chains in monoclinic crystalline form. The ground state structures are subjected to different strains to find the thirteen elastic constants of both phases by fitting the total energies E (V 0 ,ε) with BirchdMurnaghan equation of state. Young's modulus shows that the anti-phase structure is stiffer than the in-phase one. The calculated ductility index using Pugh's (B/G) ratio found to be less than 0.5 for both phases indicating that they are brittle material.
![Research paper thumbnail of 1,1ʹ-Methylenedipyridinium tetranitratocuprate(II): A rare example of organic-inorganic hybrid salt of form [organic dication][Cu(NO3)4], synthesis, spectroscopic characterizations and molecular structural investigations](https://attachments.academia-assets.com/99738637/thumbnails/1.jpg)
](Revue Roumaine de Chimie, 2019
The ionic compound [(C 5 H 5 N) 2 CH 2 ](NO 3) 2 •H 2 O and its novel copper complex [(C 5 H 5 N)... more The ionic compound [(C 5 H 5 N) 2 CH 2 ](NO 3) 2 •H 2 O and its novel copper complex [(C 5 H 5 N) 2 CH 2 ][Cu(NO 3) 4 ] were synthesized, isolated as pure salts and characterized by multinuclear NMR, FTIR spectroscopies and elemental analysis. Their molecular structures and IR absorption frequencies were also investigated by ab initio quantum chemical calculations using Hartree-Fock theory and different basis sets. The calculated structures of [(C 5 H 5 N) 2 CH 2 ](NO 3) 2 •H 2 O and [(C 5 H 5 N) 2 CH 2 ][Cu(NO 3) 4 ], each consisting of discrete organic dication [(C 5 H 5 N) 2 CH 2 ] 2+ and two NO 3 ions or inorganic anion [Cu(NO 3) 4 ] 2respectively. For the [(C 5 H 5 N) 2 CH 2 ][Cu(NO 3) 4 ], the Cu centre has pseudo square planar geometry with Cu-O bond lengths lie in the range (1.819-1.835 Å). The calculated IR characteristic absorption bands for both salts are found to be also in good agreement with those experimentally observed.
Acta Crystallographica Section C Structural Chemistry, 2016
The design of new organic–inorganic hybrid ionic materials is of interest for various application... more The design of new organic–inorganic hybrid ionic materials is of interest for various applications, particularly in the areas of crystal engineering, supramolecular chemistry and materials science. The monohalogenated intermediates 1-(2-chloroethyl)pyridinium chloride, C5H5NCH2CH2Cl+·Cl−, (I′), and 1-(2-bromoethyl)pyridinium bromide, C5H5NCH2CH2Br+·Br−, (II′), and the ionic disubstituted products 1,1′-(ethylene-1,2-diyl)dipyridinium dichloride dihydrate, C12H14N22+·2Cl−·2H2O, (I), and 1,1′-(ethylene-1,2-diyl)dipyridinium dibromide, C12H14N22+·2Br−, (II), have been isolated as powders from the reactions of pyridine with the appropriate 1,2-dihaloethanes. The monohalogenated intermediates (I′) and (II′) were characterized by multinuclear NMR spectroscopy, while (I) and (II) were structurally characterized using powder X-ray diffraction. Both (I) and (II) crystallize with half the empirical formula in the asymmetric unit in the triclinic space groupP\overline{1}. The organic 1,1′-(ethy...
Chemical Physics Letters, 2021
Ab initio quantum Hartree-Fock and Moller–Plesset approximations used to study cis boron hydrogen... more Ab initio quantum Hartree-Fock and Moller–Plesset approximations used to study cis boron hydrogen cis-(BH)n chains. The ground-state energies, binding energies, Mulliken population and the optimal geometrical configurations of cis-(BH)n are reported in terms of the chain size n. The calculated ground-state energies in terms of chain dimerization un showed two phases cis-transoid and Trans-cisoid. The energies of these two phases at MP2 fitted into the modified Su-Schrieffer-Heeger (SSH) model in order to determine the corresponding parameters. According to this model, the dimerization induces a band gap around 0.12 eV for cis-transoid phase and 0.11 eV for the trans-cisoid one.
Ab initio quantum chemical methods were applied to investigate the ground state energies and geom... more Ab initio quantum chemical methods were applied to investigate the ground state energies and geometrical configurations of boron-carbon (BC) n and boron-carbon hydrides (HBCH) n chains. The boron-carbon chains were found to be unstable in one dimension. They dissociate into boron-carbon dimers or transform into two dimensional network. The boron-carbon hydride chains were found to be stable in one dimensional structure with bond alternation. The ab initio ground state energies of the conjugated (HBCH) n chains were fitted into the SSH model, in order to determine the corresponding parameters for the ground state energy. According to the SSH model, this conjugation induces a band gap of around 0.8 eV.
Journal of Alloys and Compounds, 2017
Full-potential linearized augmented plane waves (FPLAPW), density functional theory within the ge... more Full-potential linearized augmented plane waves (FPLAPW), density functional theory within the generalized gradient and local density approximations methods are used to determine the ground state structure and to calculate the elastic constants of two phases of boron hydrogen chains in monoclinic crystalline form. The ground state structures are subjected to different strains to find the thirteen elastic constants of both phases by fitting the total energies E (V 0 ,ε) with BirchdMurnaghan equation of state. Young's modulus shows that the anti-phase structure is stiffer than the in-phase one. The calculated ductility index using Pugh's (B/G) ratio found to be less than 0.5 for both phases indicating that they are brittle material.
Revue Roumaine de Chimie, 2019
The ionic compound [(C 5 H 5 N) 2 CH 2 ](NO 3) 2 •H 2 O and its novel copper complex [(C 5 H 5 N)... more The ionic compound [(C 5 H 5 N) 2 CH 2 ](NO 3) 2 •H 2 O and its novel copper complex [(C 5 H 5 N) 2 CH 2 ][Cu(NO 3) 4 ] were synthesized, isolated as pure salts and characterized by multinuclear NMR, FTIR spectroscopies and elemental analysis. Their molecular structures and IR absorption frequencies were also investigated by ab initio quantum chemical calculations using Hartree-Fock theory and different basis sets. The calculated structures of [(C 5 H 5 N) 2 CH 2 ](NO 3) 2 •H 2 O and [(C 5 H 5 N) 2 CH 2 ][Cu(NO 3) 4 ], each consisting of discrete organic dication [(C 5 H 5 N) 2 CH 2 ] 2+ and two NO 3 ions or inorganic anion [Cu(NO 3) 4 ] 2respectively. For the [(C 5 H 5 N) 2 CH 2 ][Cu(NO 3) 4 ], the Cu centre has pseudo square planar geometry with Cu-O bond lengths lie in the range (1.819-1.835 Å). The calculated IR characteristic absorption bands for both salts are found to be also in good agreement with those experimentally observed.
Acta Crystallographica Section C Structural Chemistry, 2016
The design of new organic–inorganic hybrid ionic materials is of interest for various application... more The design of new organic–inorganic hybrid ionic materials is of interest for various applications, particularly in the areas of crystal engineering, supramolecular chemistry and materials science. The monohalogenated intermediates 1-(2-chloroethyl)pyridinium chloride, C5H5NCH2CH2Cl+·Cl−, (I′), and 1-(2-bromoethyl)pyridinium bromide, C5H5NCH2CH2Br+·Br−, (II′), and the ionic disubstituted products 1,1′-(ethylene-1,2-diyl)dipyridinium dichloride dihydrate, C12H14N22+·2Cl−·2H2O, (I), and 1,1′-(ethylene-1,2-diyl)dipyridinium dibromide, C12H14N22+·2Br−, (II), have been isolated as powders from the reactions of pyridine with the appropriate 1,2-dihaloethanes. The monohalogenated intermediates (I′) and (II′) were characterized by multinuclear NMR spectroscopy, while (I) and (II) were structurally characterized using powder X-ray diffraction. Both (I) and (II) crystallize with half the empirical formula in the asymmetric unit in the triclinic space groupP\overline{1}. The organic 1,1′-(ethy...
Chemical Physics Letters, 2021
Ab initio quantum Hartree-Fock and Moller–Plesset approximations used to study cis boron hydrogen... more Ab initio quantum Hartree-Fock and Moller–Plesset approximations used to study cis boron hydrogen cis-(BH)n chains. The ground-state energies, binding energies, Mulliken population and the optimal geometrical configurations of cis-(BH)n are reported in terms of the chain size n. The calculated ground-state energies in terms of chain dimerization un showed two phases cis-transoid and Trans-cisoid. The energies of these two phases at MP2 fitted into the modified Su-Schrieffer-Heeger (SSH) model in order to determine the corresponding parameters. According to this model, the dimerization induces a band gap around 0.12 eV for cis-transoid phase and 0.11 eV for the trans-cisoid one.