Comparative Density Functional Theory Research Articles

A comparative DFT assessment of the mechanical, elastic, electronic, and optical parametric study of perovskites CsPbX3 for opto-electronic applications

Perovskites, specifically CsPbX3 (X= F, Cl, Br, I), are gaining attention for their remarkable optoelectronic features, suitable for applications like solar cells, LEDs, and photodetectors. Utilizing Density Functional Theory (DFT), this study explores CsPbX3's electronic, mechanical, and optical properties. CsPbI3 and CsPbBr3 exhibit ideal electronic traits with a large band gap and excellent optical features, making them optimal for solar cells and LEDs. CsPbF3 stands out for superior mechanical properties, ideal for applications like scintillators. Overall, CsPbI3 and CsPbBr3 excel in electronic and optical aspects, while CsPbF3 is mechanically robust.

A Comparative DFT Investigation of the Adsorption of Temozolomide Anticancer Drug over Beryllium Oxide and Boron Nitride Nanocarriers.

Herein, attempts were made to explore the adsorption prospective of beryllium oxide (Be12O12) and boron nitride (B12N12) nanocarriers toward the temozolomide (TMZ) anticancer drug. A systematic investigation of the TMZ adsorption over nanocarriers was performed by using quantum chemical density functional theory (DFT). The favorability of Be12O12 and B12N12 nanocarriers toward loading TMZ was investigated through A↔D configurations. Substantial energetic features of the proposed configurations were confirmed by negative adsorption (E ads) energy values of up to -30.47 and -26.94 kcal/mol for TMZ•••Be12O12 and •••B12N12 complexes within configuration A, respectively. As per SAPT results, the dominant contribution beyond the studied adsorptions was found for the electrostatic forces (E elst = -100.21 and -63.60 kcal/mol for TMZ•••B12N12 and •••Be12O12 complexes within configuration A, respectively). As a result of TMZ adsorption, changes in the energy of molecular orbitals followed by alterations in global reactivity descriptors were observed. Various intermolecular interactions within the studied complexes were assessed by QTAIM analysis. Notably, a favorable adsorption process was also observed under the effect of water with adsorption energy ( reaching -28.05 and -22.26 kcal/mol for TMZ•••B12N12 and •••Be12O12 complexes within configuration A, respectively. The drug adsorption efficiency of the studied nanocarriers was further examined by analyzing the IR and Raman spectra. From a sustained drug delivery point of view, the release pattern of TMZ from the nanocarrier surface was investigated by recovery time calculations. Additionally, the significant role of doping by heavy atoms (i.e., MgBe11O12 and AlB11N12) on the favorability of TMZ adsorption was investigated and compared to pure analogs (i.e., Be12O12 and B12N12). The obtained data from thermodynamic calculations highlighted that the adsorption process over pure and doped nanocarriers was spontaneous and exothermic. The emerging findings provide a theoretical base for future works related to nanocarrier applications in the drug delivery process, especially for the TMZ anticancer drug.

A comparative DFT study of monosubstituted silabenzene and benzene structures: Effects of Si atom incorporation in benzene ring

In the present study, monosubstituted structures with 16 substitutions in the ortho, meta, and para positions of silabenzene have been comprehensively compared with similar structures in benzene. This study aimed to investigate the effect of Si atom incorporation in the benzene ring. This comparison investigated the chemical properties, including structural geometries of molecules, molecular orbitals and reactivity, ring aromaticity, and excitation energy of each monosubstituted silabenzene and benzene structure. The density functional theory (DFT) at the B3LYP/6–311G++(d,p) level of theory was used to perform all relevant calculations. In addition to changes in ring geometry values and electron donating, the results showed that the Si atom incorporation in benzene ring and its monosubstituted derivatives in different positions caused a significant decrease in LUMO, chemical hardness, ring aromaticity, excitation energy, and a significant increase in HOMO, electrophilicity, nucleophilicity, and NMR chemical shift values. Among the positions of the substituents concerning the Si atom in the ring, the ortho and para positions exhibited the most optimal values. In contrast, the meta position displayed different values compared to the ortho and para positions. This difference is attributed to the electron-withdrawing effects of the substituents. Also, among substitutions, electron-donating substitutions especially -NH2 compared to electron-withdrawing substitutions especially -NO2 decreased HOMO, electrophilicity, excitation energy, and increased LUMO, chemical hardness, nucleophilicity, and ring aromaticity.

Study of the Crystal Structure and Hydrogen Bonding during Cold Crystallization of Poly(trimethylene 2,5-furandicarboxylate).

Here, we present a detailed description of the in situ isothermal crystallization of poly(trimethylene 2,5-furandicarboxylate)(PTF) as revealed by real-time Fourier transform infrared spectroscopy (FTIR) and grazing incidence wide-angle X-ray scattering (GIWAXS). From FTIR experiments, the evolution of hydrogen bonding with crystallization time can be monitored in real time, while from GIWAXS, crystal formation can be followed. Density functional theory (DFT) calculations have been used to simulate FTIR spectra for different theoretical structures, enabling a precise band assignment. In addition, based on DFT ab initio calculations, the influence of hydrogen bonding on the evolution with crystallization time can be understood. Moreover, from DFT calculations and comparison with both FTIR and GIWAXS experiments, a crystalline structure of poly(trimethylene 2,5-furandicarboxylate) is proposed. Our results demonstrate that hydrogen bonding is present in both the crystalline and the amorphous phases and its rearrangement can be considered as a significant driving force for crystallization of poly(alkylene 2,5-furanoate)s.

Coverage-dependent stability of RuxSiy on Ru(0001): a comparative DFT and XPS study.

This work investigates the interaction of silicon with ruthenium, extending from Si-defect centers in ruthenium bulk to the adsorption of Si on the Ru(0001) surface. Using density functional theory (DFT) we calculate the interaction energies of up to 2 monolayers (MLs) of Si with this surface, uncovering the initial formation of ruthenium silicide (RuxSiy). Our results demonstrate that Si readily forms substitutional defects (SiRu) in bulk ruthenium. These defects are further stabilized on the Ru(0001) surface, resulting in a distinct propensity for forming Ru-SiRu mixed layers - which can thus be described by stoichiometry RuxSiy. Overlayers of surface-adsorbed Si adatoms and RuxSiy mixed layers are iso-energetic at 0.5 ML, with the latter becoming increasingly energetically favored at higher Si coverages. We further examine the influence of RuxSiy formation with respect to oxide formation, focusing on coverage-dependent energy differences. Our results show RuxSiy layers are energetically favored with respect to the forming oxide for silicon and oxygen coverages above 1.1 ML, respectively. In addition, the formation of RuxSiy and the subsequent oxidation of Ru and RuxSiy were also investigated experimentally using in situ XPS. This confirmed the DFT prediction, with negligible oxide formation on the RuxSiy sample, whereas the unprotected Ru surface showed extensive RuO2 formation under the same conditions. Our study not only enhances the understanding of Ru surface chemistry but also suggests a straightforward computational approach for screening the oxidation resistance of surface coatings.

A Comparative DFT Investigation on the Structural, Electric, Thermodynamic, and Optical Properties of the Pristine and Various Metals and Nonmetals (Li, Be, B, N, O, and F) Doped Graphene and Silicene Nanosheets

In recent times 2D nanosheets have come to the fore of the attention of researchers due to their unique properties. In this work, the comparative studies between graphene and silicene nanosheets before and after doping with different metals and nonmetals doping have been performed using a quantum mechanical approach, density functional theory (DFT) employing B3LYP functional along with the LanL2DZ. For Li, Be, B, N, O, and F dopants, periodic changes have been observed for both graphene and silicene nanosheets. Li doping causes increasing surface area and higher reactivity which suggests its feasibility in sensor development. On the other hand, N causes higher structural, and thermodynamical stability along with favorable electric properties. So, based on purposes, both Li and N-doped graphene and silicene nanosheets are suitable for real-life applications, especially in emerging technologies including supercapacitors, optoelectronic sensing devices, energy storage devices, and so on.

Electronic and optical properties of bare and functionalized M2C and M2CO2 (M= Ti, Zr, Sc) MXene nanotubes: A comparative DFT study

By means of the density functional theory (DFT), this work studies the structural, electronic and optical properties of (12,12) M2C and M2CO2(M= Ti, Zr, Sc) MXene nanotubes and compares them with those of monolayer counterparts. Despite bare M2C monolayers, M2C nanotubes show dielectric property when incident light is perpendicular to their axis (E||x), and show metallic property when it is parallel to their axis (E||z). The studied M2CO2monolayers and nanotubes are semiconductors. Despite Sc2CO2, the electronic band gaps of Ti- and Zr-based nanotubes are larger than those of monolayers. Bare M2C nanotubes have higher dielectric constants than monolayers, compared with M2CO2nanotubes. In the visible region, the M2CO2monolayers show higher absorption coefficients and efficiencies than the nanotube ones. Most of the reflections in Ti2CO2and Zr2CO2nanotubes occur in the visible region, inspiring their potential applications in sensor devices. The main reflection features of the Sc2CO2monolayer and its nanotube are in the ultraviolet region, indicating their practical applications in UV-blocking coating. Moreover, semiconducting nanotubes show lower reflectivity than monolayers in the visible region. Results show that electronic and optical properties of MXenes can be engineered by switching from monolayer to nanotube.

The surface chemistry of norbornadiene and norbornene on Pd(111) and Pd(100): a comparative DFT study.

The interaction of norbornadiene (NBD) and norbornene (NBE) with the palladium (111) and (100) surfaces have been investigated using density functional theory (DFT). Five configurations of adsorbed NBD may be formed on Pd(111): endo-tetra-σ, endo-di-σ,π, endo-di-π, exo-di-σ, and exo-π. The NBE molecule adsorbed on Pd(111) may exist in 4 configurations: endo-di-σ, endo-π, exo-di-σ, and exo-π. On Pd(100), a smaller number adsorption configurations of NBD and NBE are formed, since the double bonds of these molecules in the endo-orientation are bound only in a di-σ mode. The adsorption energy of NBD and NBE molecules on Pd(100) is noticeably higher compared to Pd(111), which is due to the surface geometry of Pd(100). The most stable configurations on both Pd facets are endo-tetra-σ for NBD and exo-di-σ for NBE. However, due to smaller adsorption area of the exo-di-σ configuration on Pd(111), a larger number of NBD molecules may adsorbed on the same surface area. Energetically favorable endo-tetra-σ (NBD) and exo-di-σ (NBE) configurations are very mobile on Pd(111). On Pd(100), only NBE molecules can migrate, while NBD migration is hindered due to the high activation barrier. All DFT calculations were performed using the Perdew-Burke-Ernzerhof density functional (PBE) with the relativistic SBK effective core potential and TZ2P basis set in the PRIRODA program.

Pt-and Pd-doped carbon nanotubes with different diameters as CO sensors: A comparative DFT study

The density functional theory (DFT) is employed to assess the electronic characteristics and vibrational frequencies of CO adsorbed by several Zigzag carbon nanotubes with different diameters that are substitutionally doped using Pt and Pd. Computations were based on the Quantum Espresso (PBE) and Gaussian 16/6-31G(d,p) or LanL2DZ basis sets. The formation energy, adsorption energy, and interaction distances between CO and carbon nanotube as a function of the tube diameter were evaluated for Pt- and Pd- doped carbon nanotubes. Such doped nanotubes have relatively higher adsorption energy at smaller diameters, amounting to −2.784 eV and −2.635 eV for Pd-doped and Pt-doped carbon nanotubes, respectively. The adsorption energies of CO gas on Larger tubes Pt and Pd doped carbon nanotube are −2.207 eV, and −2.583 eV eV, respectively. Following CO adsorption, the smaller diameter Pt-doped carbon nanotube has a relatively greater change in electrical conductivity and chemical reactivity than other Pd- or Pt-doped nanotubes with relatively higher diameters. These changes are attributed to energy gaps concerning the alpha and beta HOMO and LUMO molecular orbitals. The computed Raman active mode frequencies extensively depend on diameter pre- and post-adsorption on the Pd- and Pt -nanotubes. This work offers several scientific suggestions concerning the use of Pt and Pd doped carbon nanotubes with different diameters for CO molecule sensor use cases. Such sensor materials having charge movement-based sensing might be employed as acceptors or donors.

Adsorption Features of Tetrahalomethanes (CX4; X = F, Cl, and Br) on β12 Borophene and Pristine Graphene Nanosheets: A Comparative DFT Study.

The potentiality of the β12 borophene (β12) and pristine graphene (GN) nanosheets to adsorb tetrahalomethanes (CX4; X = F, Cl, and Br) were investigated using density functional theory (DFT) methods. To provide a thorough understanding of the adsorption process, tetrel (XC-X3∙∙∙β12/GN)- and halogen (X3C-X∙∙∙β12/GN)-oriented configurations were characterized at various adsorption sites. According to the energetic manifestations, the adsorption process of the CX4∙∙∙β12/GN complexes within the tetrel-oriented configuration led to more desirable negative adsorption energy (Eads) values than that within the halogen-oriented analogs. Numerically, Eads values of the CBr4∙∙∙Br1@β12 and T@GN complexes within tetrel-/halogen-oriented configurations were -12.33/-8.91 and -10.03/-6.00 kcal/mol, respectively. Frontier molecular orbital (FMO) results exhibited changes in the EHOMO, ELUMO, and Egap values of the pure β12 and GN nanosheets following the adsorption of CX4 molecules. Bader charge transfer findings outlined the electron-donating property for the CX4 molecules after adsorbing on the β12 and GN nanosheets within the two modeled configurations, except the adsorbed CBr4 molecule on the GN sheet within the tetrel-oriented configuration. Following the adsorption process, new bands and peaks were observed in the band structure and density of state (DOS) plots, respectively, with a larger number in the case of the tetrel-oriented configuration than in the halogen-oriented one. According to the solvent effect affirmations, adsorption energies of the CX4∙∙∙β12/GN complexes increased in the presence of a water medium. The results of this study will serve as a focal point for experimentalists to better comprehend the adsorption behavior of β12 and GN nanosheets toward small toxic molecules.

Assessment of the adsorption mechanism of amantadine drug onto pristine, Si- and Ge-doped Al12N12, and Al12P12 nanocages: A comparative DFT study

In the current study, the adsorption characteristics of pristine and doped (Si and Ge)- Al12N12 (AlN) and Al12P12 (AlP) nanocages towards the amantadine (AM) drug have been investigated in the gas phase by employing density functional theory (DFT). The study outcomes indicated that the amantadine drug interacts with the hexagonal ring of AlN and AlP nanocages through its H atoms and –NH2 group. The values of the adsorption energies on the pristine nanocages vary from −2.31 to −31.55 kcal/mol in the vacuum environment. However, after swapping out one of the central Al atoms with a Si or Ge atom, the adsorption energy of the doped AlN and AlP significantly increases towards the AM drug. From a thermodynamic perspective, the adsorption process of AM drug over Al12N12 and Al12P12 nanocarriers had a spontaneous and exothermic nature. The crucial and essential characteristics of the atoms in molecule (AIM) analysis, the negative and positive amounts of the total electron energy density and Laplacian parameters, respectively, illustrate that the examination interactions are a partial covalent nature. Charge transfer occurs from the AM molecule to the AlN and AlP nanocages, according to the Natural Bond Orbital (NBO) analysis. Taken altogether, these findings propose that the doped AlN and AlP nanocarriers are efficient aspirants for the development of the AM drug delivery process.

Elastic, anisotropic, lattice dynamics and electronic properties of XNiM and XNi2M (X = Ti, Zr, Hf; M = Sn, Ge, Si): DFT comparison study

The ab-initio calculations were performed using density functional theory (DFT) as implemented in the Quantum ESPRESSO (QE) code. Lattice parameter mismatch was minimal (2.5 % - 3 %) in TiNiSn/TiNi2Sn, ZrNiSn/ZrNi2Sn, and HfNiSn/HfNi2Sn compounds. Half-Heusler compounds had shorter bond lengths and smaller bulk moduli than their full-Heusler counterparts. Directional dependencies of the Young’s and shear moduli were investigated using elastic constants. TiNiGe, HfNiSn, and ZrNiSn had a greater universal anisotropy index among the half-Heusler compounds. Half-Heusler, TiNi2Sn, TiNi2Si, ZrNi2Sn, and HfNi2Sn compounds are reported to be dynamically stable. The electronic structure computations show that TiNiSn, ZrNiSn, and HfNiSn compounds have the least indirect energy gaps of 0.4508 eV, 0.5019 eV, and 0.3847 eV respectively. TiNiSn, ZrNiSn, and HfNiSn compounds are good candidates for minimizing the thermal conductivity of thermoelectric devices. TiNi2Sn, ZrNi2Sn, and HfNi2Sn are good candidates as possible contact electrodes for TiNiSn, ZrNiSn, and HfNiSn.

Kinetics of three commercial textile dyes decomposition by UV/H2O2 and UV/acetone processes: An experimental comparative study and DFT calculations

Acetone photolysis was investigated and compared with the UV/H2O2 process for the removal of three commercial textile dyes, Reactive Red 184 (RR184), Reactive Orange 4 (RO4), and Direct Red 80 (DR80), in aqueous solution at 254 nm, pH = 6.5–6.8, and T = 20 ± 2 °C. The removal efficiency of RR184, RO4, and DR80 by UV/H2O2 was 35 %, 59 %, and 69 %, respectively, whereas UV/acetone exhibited a removal efficiency of 81 %, 99 %, and 88 %, within 30 min ([Dye]0 = 0.1 mM and [acetone]0 = [H2O2]0 = 50 mM). However, as the initial doses of H2O2 and acetone were increased, the decolorization increased, and the experimental kinetic data always agreed with the pseudo-first-order reaction model (R2 = 0.94–0.99). Additionally, UV/acetone was consistently shown to be significantly more efficient than UV/H2O2 under all conditions tested. For instance, the rate constant ratios kUV/acetone/kUV/H2O2 are 3.19, 1.95, and 1.67 for RR184, RO4, and DR80, respectively ([Dye]0 = 0.1 mM and [acetone]0 = [H2O2]0 = 50 mM). Scavenging tests using specific probes revealed that •OH and •CH3 radicals were the main responsible for dyes degradation (greater than80 %) in the UV/H2O2 and UV/acetone processes, respectively. In both systems, the dyes' reactivity order was found to be RO4 > DR80 > RR184, indicating that chemical structure is an important factor in evaluating the efficiency of the degradation process. This reactivity order was supported by the density functional theory (DFT)-based thermodynamic calculations used to explain the HO•-initiated degradation of the studied azo dyes in the UV/H2O2 process.

Comparative Mössbauer and first principles calculations for selected iron oxides and ferrites nanoparticles

Magnetic ferrites and related iron oxides, such as Fe3O4 and γ -Fe2O3, are widely explored due to their commercial and scientific importance. While typical ferrites exhibit cubic structures, maghemite (γ-Fe2O3) has two probable phases at room temperature, namely cubic (C) and the lately discovered tetragonal (T) structures. Here, we explore the structural and electronic properties of these two distinct maghemite phases using density functional theory (DFT). To assure the reliability of our DFT calculations, we perform comparative calculations on the most stable inverse spinal structure, namely NiFe2O4, and the cubic magnetite (Fe3O4). We also explore the systematic oxidation of Fe3O4 into γ-Fe2O3 when a portion of Fe+2 ions, at octahedral sites, are oxidized into Fe+3 by controlling the vacancies ratio from one to three vacancies per cell. The obtained calculations are supported by X-ray diffraction (XRD), UV–visible, and Mössbauer spectroscopies measured for partially-oxidized magnetite, maghemite, and NiFe2O4 nanoparticle samples of different size, prepared by the conventional chemical methods. Comparative DFT calculations for C γ-Fe2O3 phase and Fe3O4, with tunable vacancies, showed that the smooth conversion of Fe3O4 into γ-Fe2O3 involves a slight reduction in the lattice parameters with increasing maghemite vacancy ratio, in agreement with the experimental XRD results for the prepared samples. Likewise, a clear signature of the successful fabrication of partially-oxidized Fe3O4 and γ-Fe2O3 phases was confirmed from Mössbauer results. The energy gap obtained from the calculated band structures for γ-Fe2O3 and NiFe2O4 were consistent with the values obtained from UV–visible spectroscopy. The present work demonstrates the effectiveness of DFT methods to predict and explain fine structural and physical properties of magnetic materials and iron oxides of different structures and complexity.

A comparative DFT study on Al- and Si- doped single-wall carbon nanotubes (SWCNTs) for Ribavirin drug sensing and detection

In this work, we have presented a comparative study on Ribavirin (RBV) drug sensing and detection on the pristine and functionalized single-wall carbon nanotubes (f-SWCNTs) by Density Functional Theory (DFT) method. The pristine and metal-doped zigzag (4,0) and (6,0) SWCNTs were first considered for the RBV adsorption. All the probable positions of RBV adsorption were investigated to find which one is energetically favourable. The topology analysis of the Quantum theory of atoms in a molecule (QTAIM) with non-covalent interactions (NCI-RDG), Frontier molecular orbitals (FMO), Density of states (DOS), and non-linear optical (NLO) analysis were carried out to understand the molecular structure, electrical, electronic and optical properties of complexes. The charge analysis indicates that charge transfer is from the adsorbed RBV to the pristine and metal-doped (4,0) and (6,0) SWCNTs. The highest values of adsorption energies for Al-, Si-doped and pristine (4,0) SWCNTs were determined as −34.688, −87.999 and −10.382 kcal/mol, respectively, whereas corresponding values for metal-doped and pristine (6,0) SWCNTs are about −43.592, −20.661 and −12.414 kcal/mol, respectively. The results suggest that those bare and metal-doped (4,0) SWCNTs and (6,0) Si-SWCNTs can serve as promising sensors in practical applications to detect, recognize and carrier RBV drug for its medicinal drug delivery applications. Based on the NLO properties of (6,0) Si-SWCNTs and pristine (6,0) SWCNT (with an acceptable recovery time of 279s and first hyper polarizability value of β = 229.25 × 10−30 cm5 esu−1), those nanotubes may be possible candidates to be used as the optoelectronic sensor for RBV drug. The appropriate short length of nanotubes was obtained.

Adsorption of multiple NO molecules on Au10- and Au9Zn- planar clusters. A comparative DFT study.

The doping of atomic clusters with transition-metal atoms modifies to a lesser or greater extent the catalytic properties of the pure forms. Here we study by means of density functional theory (DFT) the adsorption of up to six NO molecules on Au10- and Au9Zn- clusters, both with well-tested D3h planar geometry, to learn how precise modifications of the atomic and electronic environment, namely one atom and a valence electron, affect the bonding of multiple NO molecules to anionic gold clusters. First, we confirm that these clusters have D3h symmetry as determined by L. S. Wang and coworkers using photoelectron spectroscopy experiments [Kulichenko et al., J. Phys. Chem. A, 2021, 125, 4606]. Second, we verify that Au10(NO)n- with n ≤ 6 does not form adsorbed (NO)2 dimers, as realized by the experiments of Ma and coworkers [Ma et al., Phys. Chem. Chem. Phys., 2020, 22, 25227] using a mini flow-tube reactor at 150 K. Third, we discover that the ground state of the doped Au9Zn(NO)6- compound forms a (NO)2cis-dimer bridging two non-corner Au atoms of the Au9Zn(NO)4- compound. The discussion of adsorption energies, spin multiplicities, bond lengths, charge trends, vibrational strength frequencies of adsorbed NO's, and projected density of states (PDOS), brings additional testable differences between Au10(NO)n- and Au9Zn(NO)n- compounds (n ≤ 6).

The role of covalency in enhancing stability of Eu and Am complexes: a DFT comparison of BTP and BTPhen.

We compare the stabilities and bonding nature of [Eu/Am(BTPhen)2(NO3)]2+ complexes to those previously reported for [Eu/Am(BTP)3]3+, and investigate whether more accurately reflecting the reaction conditions of the separation process by considering [Eu/Am(NO3)3(H2O)x] (x = 3, 4) complexes instead of aquo complexes increases the selectivity of the separation ligands BTP and BTPhen for Am over Eu. The geometric and electronic structures of [Eu/Am(BTPhen)2(NO3)]2+ and [Eu/Am(NO3)3(H2O)x] (x = 3, 4) have been evaluated using density functional theory (DFT) and used as the basis for analysis of the electron density through the application of the quantum theory of atoms in molecules (QTAIM). Increased covalent bond character for the Am complexes of BTPhen over Eu analogues was found, with this increase more pronounced than that found in BTP complexes. BHLYP-derived exchange reaction energies were evaluated using the hydrated nitrates as a reference and a favourability for actinide complexation by both BTP and BTPhen was found, with the BTPhen ligand found to be more selective, with relative stability ≈0.17 eV greater than BTP.

Comparative experimental and DFT analysis of novel indole tagged [1,3,4]thiadiazolo[3,2-a]pyrimidin-5-one hybrid

A novel indole tagged [1,3,4]thiadiazole-pyrimidin-5-one was synthesized using the [4+2] cycloaddition reaction between the 1,3,4-thiadiazole-tethered 1,3-diazabuta-1,3-diene and indole-ketene. The compound was structurally elucidated using different spectroscopic techniques (NMR, IR, and HRMS). The single-crystal X-ray diffraction analysis revealed that the molecule (6) (C19H11BrN4OS) was crystallized in a monoclinic space group with the unit cell factors, a = 14.6166(7) Å, b = 7.1516(4) Å, c = 17.1037(9) Å, α =g = 90°, b = 111.893(2)°, V = 1658.95(15) Å3 and Z = 4. The Hirshfeld analysis further disclosed that the H…H, C…H/H…C, and BR…H/H…BR contacts were the most significant contributors among the interacting atoms in the X-ray structure. Additionally, the geometrical and electronic properties of the molecular conjugate computed at the density functional theory (DFT) level in its ground state displayed a good linear correlation with the single-crystal XRD data. Additionally, the UV absorption band of 6 was observed to be due to the n→π* transition.

Borophene and Pristine Graphene 2D Sheets as Potential Surfaces for the Adsorption of Electron-Rich and Electron-Deficient π-Systems: A Comparative DFT Study.

The versatility of striped borophene (sB), β12 borophene (β12), and pristine graphene (GN) to adsorb π-systems was comparatively assessed using benzene (BNZ) and hexafluorobenzene (HFB) as electron-rich and electron-deficient aromatic π-systems, respectively. Using the density functional theory (DFT) method, the adsorption process of the π-systems on the investigated 2D sheets in the parallel configuration was observed to have proceeded more favorably than those in the vertical configuration. According to the observations of the Bader charge transfer analysis, the π-system∙∙∙sB complexes were generally recorded with the largest contributions of charge transfer, followed by the π-system∙∙∙β12 and ∙∙∙GN complexes. The band structures of the pure sheets signaled the metallic and semiconductor characters of the sB/β12 and GN surfaces, respectively. In the parallel configuration, the adsorption of both BNZ and HFB showed more valence and conduction bands compared to the adsorption in the vertical configuration, revealing the prominent preferentiality of the anterior configuration. The density-of-states (DOSs) results also affirmed that the adsorption process of the BNZ and HFB on the surface of the investigated 2D sheets increased their electrical properties. In all instances, the sB and β12 surfaces demonstrated higher adsorptivity towards the BNZ and HFB than the GN analog. The findings of this work could make a significant contribution to the deep understanding of the adsorption behavior of aromatic π-systems toward 2D nanomaterials, leading, in turn, to their development of a wide range of applications.

A comparative DFT study of some N-based aromatic ligand metal complexes as anticancer agents and analysis of their mode of interaction with DNA base pair

Metal complexed anticancer agents interact with DNA nucleobase pairs (AT and GC) through different types of binding mode such as intercalation, groove binding, covalent binding, etc. Minor and major groove binding mechanism of DNA base pair is the key factor for all kinds of anticancer agent; as metal complexes have a great affinity to bind with DNA nucleobase either through minor or major groove. Ligands in metal complexes also play a vital role during the interaction with DNA base pairs; these ligands directly interact with DNA through different interacting modes. Generally, anticancer agents with less sterically hindered N-based aromatic and planar ligands are the key component for DNA binding; as the structure of such ligands are quite compatible for following intercalation and groove binding mechanism. Since, the experimental investigation for drug-DNA nucleobase complexes are extremely complicated, therefore; quantum mechanical calculations might be very helpful for computing the actual interactions in drug-DNA complexes. Quantum mechanical approaches such as density functional theory (DFT) might be a very important and useful tool to investigate the actual mode of interaction of metal complexed antitumor agents with DNA nucleobase. Herein, we have taken some metal complexes with N-based aromatic ligands as antitumor agents to investigate the proper mode of interaction between drug-DNA complexes.