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Öğe Electronic structure perturbation induced by fluorine substitution in methylamine: a comparative DFT, spectroscopic and molecular recognition study(Springer Int Publ Ag, 2026) Fto, Ahmed Muhsin Mohammed Youns; Tahhan, Omar M. Saeed Younus; Abed, Mahmood Dahham Abed; Hssain, Ala Hamd; Kebiroglu, Mehmet Hanifi; Bulut, NiyaziThis study presents a comparative theoretical investigation of methylamine and fluoromethylamine to explain the electronic and spectroscopic consequences of single fluorine substitution. Geometry optimization and electronic structure calculations were carried out at the B3LYP/6-311G(d, p) level within the framework of density functional theory. Frontier molecular orbital analysis showed that fluorination significantly reduced the HOMO-LUMO energy gap, suggesting enhanced electronic reactivity of the fluorinated derivative. Global reactivity descriptors further revealed an increase in electrophilic character following fluorine substitution. Simulated NMR and UV-Vis spectra showed noticeable spectral changes associated with charge redistribution and fluorine-induced polarization effects. Molecular electrostatic potential and density of states analyses confirmed substantial change in the electronic environment of the molecule. In addition, molecular docking calculations were performed to evaluate the molecular recognition behavior of both compounds toward RhCG, providing insight into their possible interaction propensity. The results show that minimal structural modification by fluorination can induce measurable changes in the electronic structure, spectroscopic response, and exploratory molecular-recognition tendency of methylamine.Öğe Experimental characterization and theoretical investigation of Ce/Yb co-doped hydroxyapatites(Elsevier Science Sa, 2022) Acar, Serdar; Kaygili, Omer; Ates, Tankut; Dorozhkin, Sergey, V; Bulut, Niyazi; Ates, Burhan; Hssain, Ala HamdIn the present study, the effects of variable amounts of Yb addition on the structural, thermal, and in vitro biocompatibility properties of Ce-doped hydroxyapatite (HAp) samples synthesized via the wet chemical method were investigated. Besides, the prepared formulations were also modeled for making the theoretical investigations. The single-phase compositions were detected for all samples, and no formation of additional phases was observed. Doping with Yb was observed to produce some variations in the lattice parameters, unit cell volume, lattice strain, and lattice stress. While a decreasing trend in the crystallite size and crystallization percent with increasing Yb content was found, a gradual increase in the anisotropic energy density was observed. All samples were found to be thermally stable from room temperature to 1000 degrees C with negligible mass losses during heating. No significant morphological changes were caused by the addition of Yb. For all samples, the numerical values of (Ca + Ce + Yb)/P molar ratio were found to be close to that for stoichiometric HAp (1.67). It was observed that the increased Yb additive caused a decrease in cell viability values. A continuous decrease in the bandgap energy with the increasing amounts of Yb added to the Ce-based HAp structure was observed from the theoretical investigations. A sharp decrease in the cell viability of the Ce-based HAp was observed with the addition of Yb.Öğe Experimental characterization and theoretical investigation of Zn/Sm co-doped hydroxyapatites(Elsevier, 2022) Hssain, Ala Hamd; Bulut, Niyazi; Ateş, Tankut; Köytepe, Süleyman; Kuruçay, Ali; Kebiroğlu, Hanifi; Kaygılı, ÖmerIn this study, the wet chemical method was used to synthesize Zn-doped hydroxyapatite (HAp) samples, and the effects of varying the amount of Sm addition on structural, thermal, and biocompatibility in vitro properties were studied. In addition, a density functional theory was used for modeling the as-synthesized samples to obtain the theoretical calculation results. XRD results confirmed the formation of biphasic compositions for all samples, and FTIR data supported the formation of the functional groups of hydroxyl and phosphate. More than 98% of samples showed the formation of the HAp phase. The addition of Sm resulted in an increase in the secondary phase of the ?-TCP from 0.60% to 1.49%. The lattice parameters (aandc),unit cell volume (V), lattice strain(?), and lattice stress? varied when Sm was added as a dopant. The crystallite size and crystallinity decreased as the Sm content increased, however, the anisotropic energy density gradually increased. Thermal analysis results confirmed that all samples seemed to be thermally stable. The addition of Sm did not result in any notable morphological modifications. Cell viability values of theZn-based HAp sharply decreased as a result of an increase in the Sm additive. Theoretical studies show that when the amount of Sm in the Zn-based HAp structure increases, the bandgap energy decreases from 4.68 to 4.40eV. An increasing density and decreasing unit cell volume have been observed, as confirmed by the theoretical results. In addition, there was a decrease in crystallinity as well as an increase in anisotropic energy density.Öğe Investigation of the effects of Ni-doping on the structural and thermal properties of ZnAl2O4 spinels prepared by wet chemical method(Springer, 2021) Ercan, Filiz; Ateş, Tankut; Kaygılı, Ömer; Bulut, Niyazi; Köytepe, Süleyman; Alahmari, Fatimah; Ercan, İsmail; Hssain, Ala Hamdn this study, a more detailed characterization of the un-doped and Ni-doped ZnAl2O4 spinel structures prepared via a facile wet chemical route was carried out. Significant effects of the additive of Ni on the ZnAl2O4 structure were observed. For all the samples, the ZnO phase was detected as the second phase, and the third phase of NiO was observed for two samples having the highest Ni content. X-ray diffraction (XRD) results showed that the crystallinity percent, lattice parameter, and volume of the unit cell decreased continuously with adding of Ni. Fourier transform infrared (FTIR) spectra verify the formation of the ZnAl2O4 structure for all the samples. The thermal behaviors, including the recrystallization temperature and mass losses, of the ZnAl2O4 structure, were also affected by the amount of Ni. The morphology varied with adding of Ni. These properties were not reported before.Öğe Mg-Dopant Effects on Band Structures of Zn-Based Hydroxyapatites: A Theoretical Study(Springer Int Publ Ag, 2023) Bulut, Niyazi; Kaygili, Omer; Hssain, Ala Hamd; Dorozhkin, Sergey V.; Abdelghani, Benahmed; Orek, Cahit; Kareem, Rebaz ObaidThe band structures of Zn-based hydroxyapatites co-doped with Mg at varying amounts from 0 to 2.0 at. % have been investigated theoretically in more detail. The calculations were done to obtain the band structure, density of states, and band gap for all the modeled structures to study their electronic properties. It was seen that the co-doping has an effect on the structural and electronic properties of all the as-investigated structures. The bandgap energy for all samples in each group was found to be reduced gradually with varying doping rates of Mg into Zn-doped HAp. The band gap decreased from 4.54 to 3.84 eV for samples of 0.4Zn-0.4 Mg-HAp and 2.0Zn-0.4 Mg-HAp with the same amount of Mg, respectively, as a result of increasing the doping levels of Zn from 0.4 to 2.0 at.%. The lattice parameters, unit cell volume, and density decrease with increase in doping of Zn-containing HAp and in addition of second dopant Mg at varying amounts 0.4, 0.8, 1.2, 1.6, and 2.0 at. % in all of the modeled sample group. Furthermore, it is observed that the declining values of the aforementioned parameters are significantly impacted by the increasing Zn doping rates.Öğe NTCDA compounds of optoelectronic interest: Theoretical insights and experimental investigation(Elsevier, 2021) Hssain, Ala Hamd; Gündüz, Bayram; Majid, Abdul; Bulut, NiyaziStructural, electronic, and spectroscopic properties of 1,4,5,8-naphthalene-tetracarboxylic dianhydride organic semiconductor molecule are reported based on experimental and computational methods. The spectroscopic investigations were carried out via H1 and C13 NMR chemical shifts and UV–VIS spectroscopy. The effects of solvation of NTCDA molecule into different solvents were investigated to explore the effect of polarities of solvents on the absorption peak of the compound. Positive charges on the Carbon atom side were discovered to be more prominent, leading to the conclusion that the NTCDA molecule could be suited for optoelectronic applications with mid-range optical band gaps.Öğe Sr/Smco-doped hydroxyapatites: experimental characterization and theoretical research(Springer, 2022) Hssain, Ala Hamd; Bulut, Niyazi; Ates, Tankut; Koytepe, Suleyman; Kurucay, Ali; Kebiroglu, Hanifi; Kaygili, OmerThis paper goes into extensive detail about the theoretical and experimental characterization of Sr doped hydroxyapatite (HAp) samples that have been doped with Sm in various amounts. To accomplish this, five HAps containing a constant 0.133at.% of Sr were additionally doped with Sm at varied amounts and synthesized by a method of wet chemical. In addition, the density functional theory (DFT) was used to model all of these samples. According to theoretical results, the bandgap energy declined continuously from 4.6297 to 4.4034eV. The linear absorption coefficient increased with increasing amounts of Sm in all samples, while this parameter decreased with increasing photon energy. There was a reduction in both the lattice parameter a and the volume of the unit cell, but there was also an increase in the lattice parameter c and theoretical density. Accordingly, the experiment's results were as follows:HAp phase (above 98% for all of the samples) and beta-tricalcium phosphate beta - TCP were both confirmed as the major phase and minor phase, respectively, by X-ray diffraction (XRD), FT-Raman spectroscopy and the Fourier transform infrared (FTIR) measurements. The addition of Sm increased in the beta - TCP phase from 0.62 to 0.86%. Same as theoretical results, it was also found that density was increasing and the volume of the unit cell decreased. An increase in anisotropic energy density and a decrease in crystallinity were discovered. The values are calculated based on the molar ratio, which was discovered to be close to those for stoichiometric HAp in all samples (1.67). Based on the results of the thermal study, all samples were confirmed to be thermally stable. Sm content was discovered to have an effect on cell viability.Öğe The experimental and theoretical investigation of Sm/Mg co-doped hydroxyapatites(Elsevier, 2022) Hssain, Ala Hamd; Bulut, Niyazi; Ates, Tankut; Koytepe, Suleyman; Kurucay, Ali; Kebiroglu, Hanifi; Kaygili, OmerThis study presents an extensive experimental and theoretical analysis of Mg -doped hydroxyapatite (HAp) samples with additional Sm doping at varying amounts. A wet chemical method was used to synthesize Mg-containing HAps at a constant amount of 0.133 at. %, and in addition the second dopant of Sm was utilized at varying amounts of 0.133, 0.266, 0.399, 0.532, and 0.665 at. %. All of these samples were investigated experimentally and theoretically by using the X-ray diffraction (XRD) analysis, Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM), Raman spectroscopy, differential thermal analysis (DTA), thermogravimetric analysis (TGA), in-vitro cell viability tests, and density functional theory (DFT) calculations. The bandgap energy was found to have reduced from 4.6115 eV to 4.3870 eV. The linear attenuation (or absorption) coefficient increased as the amount of Sm in the sample increased, and this parameter decreased as the photon energy increased for all samples. Both the lattice parameter and the theoretical density increased, whereas the unit cell volume and the lattice parameters declined. The XRD and FTIR results revealed that the HAp phase (over 98 percent for all samples) was a major phase formed, while the beta -TCP phase (beta-tricalcium phosphate) was a minor phase. The beta-TCP phase increased from 0.91 to 1.57 percent with an increasing amount of Sm. The volume of the unit cell trended in the same direction as predicted by the obtained results theoretically. Increased anisotropic energy density and a decrease in crystallinity have been observed. All samples were found to be thermally stable. Due to the presence of Sm content, cell viability was observed to be affected.Öğe Theoretical and experimental characterization of Pr/Ce co-doped hydroxyapatites(Elsevier, 2021) İbrahimzade, Lala; Kaygılı, Ömer; Dündar, Serkan; Ateş, Tankut; Dorozhkin, Sergey V.; Bulut, Niyazi; Köytepe, Süleyman; Ercan, Filiz; Gürses, Canbolat; Ercan, Filiz; Hssain, Ala HamdThis study presents a more extensive report on the experimental and theoretical characterization of the Ce-doped hydroxyapatite (HAp) samples additionally doped with Pr at varying amounts. To achieve this goal, four Ce-containing (a constant amount of 0.35 at.%) HAps additionally doped with Pr at various amounts (0.35, 0.70, 1.05, and 1.40 at.%) were synthesized via a combustion method. Besides, all these samples were modeled theoretically by using a density functional theory (DFT). Theoretical results showed that the bandgap energy decreased continuously from 4.5156 to 4.3097 eV. For all samples, the linear attenuation (or absorption) coefficient increased with the increasing amount of Pr and this parameter had a decreasing trend with the increase in the photon energy. An increase in the theoretical density and the lattice parameter c and a decrease of both the lattice parameter a and the unit cell volume were found. After analyzing the experimental data, the following results were observed: X-ray diffraction (XRD) and Fourier transform infrared (FTIR) data verified the formation of HAp phase (above 94% for all the samples) as the major phase and beta-tricalcium phosphate (?-TCP) as the minor one. The amount of ?-TCP phase was found to increase from 3.4 to 5.9% with the addition of Pr. Similar to the theoretical findings, an increasing trend for the density and decreasing one for the unit cell volume were detected. Both a decrease in the crystallinity and an increase in the anisotropic energy density were found. The results of the thermal analysis supported the thermal stability of all the samples. The cell viability was found to be affected by Pr-content.
