Showing papers in "Computational and Theoretical Chemistry in 2021"

Abstract: In this article, we present a stand-alone, versatile and flexible code named Shermo for calculating various thermochemistry data. This code is compatible with various mainstream quantum chemistry codes, and has many unique advantages: The output information is very clear and easy to read; thermodynamic quantities can be fully decomposed to contributions of various sources to gain a deeper insight; temperature and pressure can be conveniently scanned; two quasi-rigid-rotor harmonic oscillator (quasi-RRHO) models are supported to properly deal with contributions of low frequencies; different frequency scale factors can be simultaneously specified for calculating different thermodynamic quantities; conformation weighted thermodynamic data can be directly evaluated; the code can be easily run and embedded into shell script to automatically process large amount of systems. We hope the Shermo program will bring great convenience to quantum chemists in their daily research. The Shermo code can be freely obtained at http://sobereva.com/soft/shermo .

Abstract: In the density functional theory framework, the geometric stableness and electronic properties of square-octagon arsenene nanosheet (O-AsNS) are studied. The O-AsNS shows semiconductor nature with a bandgap of 1.348 eV. The O-AsNS is used as a base material to adsorb M-xylene and toluene vapours. The adsorption energy shows the physisorption of M-xylene and toluene on O-AsNS. Furthermore, the charge transfer, electron density, and bandgap variations of O-AsNS clearly support the chemi-resistive nature of O-AsNS. Besides, the band structure and projected density of states mapping disclose the change in the electronic properties of O-AsNS owing to M-xylene and toluene adsorption. Thus, the result reveals that O-AsNS can be deployed as a chemosensor for the detection of M-xylene and toluene vapours.

Abstract: To enhance the charge transfer properties in organic materials, four π-conjugated donor compounds, namely DR3TBDTC-M1, DR3TBDTC-M2, DR3TBDTC-M3, and DR3TBDTC-M4 are formulated and studied. The central core of the molecules is composed of benzodithiophene acridine connected with the terminal groups using three thiophene rings as a spacer. The optoelectronic analysis has indicated that from all the donors DR3TBDTC-M3 is better which has a greater λmax value of 505.4 nm than the reference molecule (DR3TBDTC) having a λmax value of 463.4 nm. Examination of the frontier molecular orbitals, the binding energy, transition density matrix, the reorganization energy, and open-circuit voltage are implemented that offered the fundamental knowledge on the transmission of charges and electronic excitation. With a small band gap (Eg = 3.97 eV), the DR3TBDTC-M3 compound excellently transfers its electron density from the HOMO to LUMO. In the reported compounds, the λe value of DR3TBDTC-M1 (0.01358 eV), DR3TBDTC-M3 (0.01680 eV), and DR3TBDTC-M4 (0.01169 eV) are found to be less than the reference having λe = 0.01795 eV. Likewise, DR3TBDTC-M3 provides the lowest λh = 0.01566 eV relative to DR3TBDTC λh = 0.01578 eV. It has been observed that the structural adaptation at the terminal modifies the charge transfer property in the molecule as all the designed molecules have shown better VOC and Eg as compared to the reference.

Abstract: Non-fullerene small acceptor molecules demonstrate promising photovoltaic properties supported the progress of organic solar cells (OSCs). In organic photovoltaics, non-fullerene small acceptor compounds are valuable than traditional fullerene-based acceptor molecules for their good contribution in organic solar cells. This research generally focusses on Bipolar Diketopyrrolopyrrole (F(DPP)2B2) based small electron acceptor compounds used for organic solar cells (OSCs). For this purpose, four newly developed A-D-A (Acceptor-Donor –Acceptor) type electron accepting compounds named as V1, V2, V3, and V4 are planned for organic solar cells to study their optoelectronic characteristics. MPW1PW91/6-31G(d,p) basis set was used for calculations of various geometric parameters. Among all these, newly designed molecules V1 is proven an appropriate compound for OSCs applications due to the photovoltaic characteristics like low band gap between HOMO and LUMO (1. 88 eV) and V3 molecule shows broader absorption λmax in the gas phase (741.62 nm) and chloroform solvent (785.95 nm). Molecule V2 exhibits the lowest value of mobility of electrons (0.0806 Eh). All the designed compounds exhibit better open-circuit voltage, fewer energies of excitations, the highest value of absorption, greater dipole moment, equivalent binding energies, well-organized transport of electron and hole as compared to reference R. Thus, these molecules are suggested to researchers for the future development of highly efficient OSCs.

Abstract: Nanostructures such as nanotubes and nanosheets are widely used in the medical industry for drug delivery, prevention, and treatment. These nanostructures are used as sensors or carriers by adsorbing functional groups. In this study, the adsorption rates of the bromochlorodifluoromethane (CBrClF2) molecule, which is used as an effective gaseous fire suppression agent, onto the outer surfaces of pristine, Al, Ga, P, and As-doped boron nitride nanotubes are investigated. A periodic boundary condition density functional theory method using both Perdew, Burke, and Ernzerhof exchange–correlation (PBEPBE) and B3LYP-D3 functionals together with the 6-311G (d) basis set were used. Subsequently, the B3LYP, CAM-B3LYP, ωB97XD, and M06-2X functionals with the 6-311G (d) basis set were used to consider the single-point energies. Natural bond orbital analysis and the quantum theory of atoms in molecule were considered using the PBEPBE/6-311G (d) method, and the results were compatible with the expected electronic properties, namely the Wiberg bond index, natural charge, natural electron configuration, donor–acceptor natural bond orbital interactions, and second-order perturbation energies. All the calculations and analyses denoted that the adsorption of the CBrClF2 molecule onto the surfaces of pristine boron nitride nanotubes occurred due to physical adsorption and van der Waals interactions. Among the doped nanotubes, the Al nanotube exhibited the highest adsorption energy compared to the other doped nanotubes.

Abstract: In the present study, structural, wavefunctional, electronic and charge transfer properties of 8-Quinolinesulfonamide are investigated by making the use of DFT tools Gaussian 16 W, and Gauss View 6. The optimized geometrical parameters, wavefunctional properties like reduced density gradient, chemical bonding and electron localization function are reported in monomer and dimer form. The calculated energies of HOMO and LUMO have been found to represent the electron excitation properties. Electrophilic and nucleophilic sites are found by MEP analysis. Spectroscopic wavenumbers (IR, Raman) are investigated computationally and UV–Visible spectrum was analyzed using TD-DFT method with solutions. To explain the charge transfer and stabilization energy due to inter or intra molecular interactions, the natural bond orbital analysis is performed. Furthermore, drug-likeness, ADME, molinspiration, environmental toxicity properties and the molecular docking study with monomer and dimer structure was also performed.

Abstract: The chlormethine (CM) drug adsorption on C24, B12C6N6 and B12N12 nanocages has been investigated by using density functional theory at B3LYP/6-31G(d,p) method. Also, the adsorption energy (EAd) investigation of the CM adsorbed complexes has been done by using wB97XD functional to understand the non-local dispersion interactions. Our study reveals that C24 and B12C6N6 nanocages are unfavorable (very low value of EAd) for CM drug adsorption but B12N12 is a promising adsorbent for this drug as EAd of CM/B12N12 complex is −101.70 kJ/mol (−84.77 BSSE corrected) at B3LYP method and −139.70 kJ/mol (−123.43 BSSE corrected) at wB97XD method. NBO and Mulliken charge analysis predicts that large charge transfer occurs from CM to B12N12 about 0.324|e| and 0.259|e| respectively. Also, the spontaneous and favorable interaction between CM drug and B12N12 nanocage is also confirmed by the investigation of solvation Gibbs free energy and quantum theory of atoms in molecules analysis.

Abstract: In this research, we explored black phosphorene nanotube’s ability to the detection of DDT (dichlorodiphenyltrichloroethane) and heptachlor present in the polluted water. The formation energy of the designed black phosphorene nanotube delineates its stable configuration. The adsorption properties for the target molecules assimilation over black phosphorene nanotube have been scrutinised concerning adsorption energy, which shows the physisorption type of adsorption on the black phosphorene nanotube. The electronic characteristics of black phosphorene nanotube constituted by the energy band specifications (spectrum of energy bands and PDOS maps) and the contours of electron density differences are visualised for the pristine and adsorption complexes. Those attributes validate the change in the electronic properties of black phosphorene nanotube following the adsorption. Moreover, the variation in the energy gap of black phosphorene nanotube, which is perceived upon adsorption of DDT and heptachlor shows chemi-resistive nature. The calculated adsorption energy, Bader charge transfer, and electron density difference of black phosphorene nanotube owing to adsorption of target molecules suggest the use of black phosphorene nanotube as a chemical sensor for DDT and heptachlor.

Abstract: The potential application of pristine and Au-decorated BC3 nanosheet (Au@BC3N) was studied in mercaptopurine (MC) drug detection using density functional theory calculations. The MC drug was physically adsorbed onto the pristine BC3N with the binding energy (Eb) of −7.5 kcal/mol. The electronic properties of the pristine BC3N are not affected by the MC drug, and the sensing response is 6.6 at 298 K. After the Au-decoration, the MC formed an η6-Au half-sandwich with Eb of −33.2 kcal/mol, and the sensing response dramatically increased to 384.0. A short recovery time of 1.26 s was obtained for the MC desorption from the Au@BC3N surface. The water solvent reduces the Eb or the sensing response to −27.0 kcal/mol or 328.5. We concluded that the Au@BC3N may be a promising sensor for the MC detection.

Abstract: Using density functional theory (DFT) method, we showed that gamma-butyrolactone (GBL) is adsorbed weakly on the pristine Hexa-peri-hexabenzocoronene (HBC). The HOMO and LUMO levels of Al- and Si-doped HBCs are less stable than those of pristine HBC causing more negative Eadsorption values. The electrical conductance of AlHBC and SiHBC become 2.6 × 1011 and 343 times higher upon GBL adsorption. SiHBC benefits from a short GBL recovery time (2.67 × 10−2 s), compared to the AlHBC (5.10 × 1012 s). The adsorption of GBL on Al- and Si-doped graphene was also explored to compare the HBC nanographene and graphene (G) as GBL sensors. It was revealed that AlG and SiG nanosheets suffer from a long recovery time. Based on our calculations, Adsorption of GBL produces an electrical signal selectively in the presence of gamma-hydroxybutyrate (GHB) but ecstasy (ECS) is an interfering molecule that affects the detection of GBL molecule.

Abstract: The adsorption of hexane and heptane on delta arsenene nanoribbon (delta-AsNR) are studied with regard to the density functional theory method. Firstly, the structural stability of delta-AsNR is ascertained with formation energy. The band structure of delta-AsNR shows semiconductor behaviour. The delta-AsNR is used as a sensing substrate for hexane and heptane molecules. Based on the energy of assimilation, average band gap alteration, and Bader charge transference, the surface assimilation of hexane and heptane molecules on delta-AsNR are explored. The density of states variation of delta-AsNR upon hexane and heptane adsorption also shows the variation in electronic properties of delta-AsNR. Thus, based on the results it is evident that delta-AsNR can be deployed as a novel chemosensor for hexane and heptane molecules evolved from the sewage.

Abstract: The feasibility of detecting diazomethane (CH2N2) in the gas phase by adsorption onto the exterior surface of inorganic-based X12O12 (where X can be Be, Mg, or Ca) nanocages is investigated here using DFT. All the structures, including those of the pristine CH2N2 and of the nanocages, as well as of the CH2N2/nanocage systems, have been optimized using the B3LYP-D3, M06-2X, ωB97XD, and CAM-B3LYP functionals, in conjunction with 6-311G(d) basis set. NBO, NCI, and QTAIM analyses results are in good agreement with each other. Furthermore, the Density Of States (DOSs), the natural charges, the Wiberg Bond Indices (WBI), and natural electron configurations were considered to investigate the nature of intermolecular interactions. The energy calculations indicate a strong size-dependent adsorption, with the nanocages comprised of large atoms being able to attract CH2N2 more strongly, and hence bind with it more effectively. The adsorption incurs also significant changes to HOMO and LUMO energies.

Abstract: The site of the greatest electronic density of the highest occupied molecular orbital (HOMO) is often taken to be the location of the most energetic electrons in a molecule, and thus the most likely site for reaction with an electrophile. However we show, by reference to the average local ionization energy on a molecular surface, that the HOMO alone often does not locate the most energetic electrons. This is because the HOMO, unlike the average local ionization energy, does not take explicit account of the fact that any molecular site has a significant probability of being occupied by electrons in lower-lying, less energetic molecular orbitals.

Abstract: Structural, elastic, electronic, and thermoelectric properties of KLaX (X = C, Si, Ge and Sn) half Heusler compounds have been studied using the full potential linearized augmented plane wave (FP-LAPW) method within density functional theory (DFT). It is shown that the KLaX half Heusler compounds are energetically and mechanically stable. The calculated band structure estimates with modified Becke-Johnson (mBJ) potential, indicates a semiconducting nature with direct band gaps of 0.76 eV, 0.79 eV, and 0.81 eV for KLaC, KLaSn, and KLaX (X = Si and Ge) respectively. The valence band of KLaX is more influenced by spin-orbit coupling than in the conduction band. The Seebeck coefficient (S), electronic conductivity (σ), electronic thermal conductivity (κe), figure of merit (ZT) and the power factor (PF) have been investigated using the semi-classical Boltzmann transport theory with rigid band theory. The KLaX half Heusler compounds exhibit high thermopower values and p-type charge carriers for their thermoelectric performance than electron doping. Including the spin-orbit coupling in our calculations increases the flatness of the valence band from X = Si to Sn. The high values of ZT and PF of KLaX half-Heusler compounds make it promising materials for thermoelectric applications.

Abstract: Non-fullerene small molecules are more attractive due to their adjustable energy levels, easier synthesis, and low cost of production. Novel non-fullerene acceptor designed materials retain the advantages of fullerene derivatives, as well as overcome the disadvantages of fullerene materials. Modification of novel molecules of end-capped groups was involved to improve the optoelectrical properties of acceptor molecules of OSCs. Herein, the optoelectronic properties of four small new acceptor molecules (PA1-PA4), configured according to the A-D-C-D-A scheme, were studied after the modification of the recently synthesized molecule R (IEICO-4F). The newly designed molecules (PA1-PA4) are comprised of 4,4,9,9-tetra-p-tolyl-4,9-dihydro-s-indaceno[1,2-b:5,6-b']dithiophene (as central core), 3-methoxy thiophene as a donor, which is directly attached with different end-capped acceptors. Some geometric parameters like density of states, binding energy, transition density matrix, absorption maxima, charge transfer analysis and frontier molecular orbitals are performed in order to examine the photovoltaic characteristics of newly designed molecules. Designed molecule (PA1) showed the lowest energy band gap (3.30 eV) with a red-shift in the absorption spectrum (λmax = 870.222 nm) in chloroform which revealed a perfect relationship between end-capped acceptor with large electron-withdrawing character through extended conjugation. PA4 exhibited the highest value of Voc (2.73) among all designed molecules to PTB7-Th donor material. Further, molecular electrostatic potential analysis confirmed the efficient designing of newly designed molecules. Results of all analysis suggested that designed molecules are efficient candidates for high performance organic solar cells.

Abstract: Zinc oxide nanosheet (ZnONS) is a favorable road to deliver numerous drug molecules in the human body. The electronic properties of the 5-FU/pristine ZnONS and 5-FU/metal-doped ZnONS are studied by using DFT method, which implemented in the quantum espresso package. Metal impurities are utilized to recognize the suitability and optimization of the adsorption 5-FU on the ZnONS superficial. For metal-doped ZnONS and 5-FU/metal-doped ZnONS, we observed that the shape of the electronic band structure is changed. So, the electronic band gap and Fermi level are reduced and shifted up, respectively compared to the pristine ZnONS, but they still have semiconductor behaviors. Moreover, all complex structures become more stable and lower reactive due to the total energy increased. Results disclosed a weaker interaction between the pristine ZnONS and 5-FU, but there is a stronger interaction between the 5-FU and metal-doped ZnONS. We detected very exciting results. The adsorption process is depended on the type of the impurities and the distance between the 5-FU molecule and metal-doped ZnONS. So, it became stronger when we made the distance between this molecule and metal-doped ZnONS is smaller. Additionally, all structures have a lower and higher electron affinity and chemical hardness, respectively. That means these structures needed a higher energy to donating/accepting an electron to be cation/anion. Besides, there is a great interaction between the pristine ZnONS and 5-FU molecule in the present (Cu, Au, and Ag) impurities between them, but other metal impurities made a weak interaction between them. Then, we can utilize the new substrate (metal-doped ZnONS structures) as a carrier to the 5-FU drug molecule.

Abstract: We determined the structural firmness of delta phosphorene nanosheet (del-PNS) and investigated the adsorption behaviour of hazardous halogenated compounds such as trichloropropane (TCP) and tetrachloroethylene (TCE) on del-PNS based on the framework of density functional theory. The stability of del-PNS is ensured with a formation energy of −3.81 eV/atom. Also, the energy gap of isolated del-PNS is observed as 0.22 eV indicating semiconductor behaviour. Particularly, three different preferential adsorption sites including bridge, hollow and top site of TCP and TCE molecules on del-PNS were studied with the influence of adsorption energy, Bader charge transfer, and average band gap changes. Further, the calculated adsorption energy of preferential adsorption sites is noticed to be in the range of −0.09 eV to −0.60 eV supporting the physisorption type of adsorption of chief halogenated compounds on del-PNS. The variation of electronic properties such as band gap variation, electron difference density, and charge transfer are noticed owing to adsorption of TCP and TCE on del-PNS. The overall outcomes suggest that the del-PNS can be practically used to detect TCP and TCE halogenated compounds.

Abstract: A quantum chemical analysis of four star-shaped anisotropic acceptor molecules (A1-A4) having acceptor-acceptor′-acceptor (A-A′-A) architecture has been performed for solar cell applications. The designed acceptors consist of cyano benzene as central core, thiophene as π-bridge and 2-methylenemalononitrile (A1), 6-methylene-2-thioxo-1,3-thiazinan-4-one (A2), 2-(2-methylene-3-oxo-2,3-dihydro-1H-inden-1ylidene) malononitrile (A3) and 5-methylene-2-thioxothiazolidin-4-one (A4) as peripheral acceptor units. DFT and TD-DFT calculations were performed using selected MPW1PW91 to assess optical, electronic and charge transfer properties of acceptors (A1-A4) which were further characterized through frontier molecular orbitals (FMOs), DOS, reorganization energies, TDM and open-circuit voltage analysis. The results dictated that the substitution of different acceptor units on the three sides of cyano benzene core forming star-shaped molecules can fine tune the FMO energies, absorption properties (between 470 and 524 nm), band gap energies and reorganization energies in accordance with R. Among all acceptors, A3 exhibited exclusively high absorption value (524 nm), lowest band gap (2.46 eV) and lowest hole reorganization energy (0.0037 eV). Moreover, the acceptor molecules have comparable values of open-circuit voltage to R making them quite suitable for photovoltaic applications in OSCs. The electron-deficient core-based acceptors, in this study, open a new door for designing high-performance OSC acceptors.

Abstract: The study of non-Newtonian fluids flow over diverse geometries with significant physical implications has numerous applications in the manufacturing and engineering field. On the other hand, carbon nanotubes (CNT) have wide-ranging applications in nanotechnology, energy storage, industry, chemical sensors, conductive plastics, optics, and structural composite materials. Hence, the flow of Maxwell nanoliquid embedded with SWCNT/MWCNT over a stretching sheet with the consideration of thermal radiation and magnetic dipole is examined. The partial differential equations (PDEs) specifying the flow of liquid are transformed into ordinary differential equations (ODEs) with the assistance of suitable similarity transformations. The reduced ODEs are numerically solved by using Runge-Kutta Fehlberg 45 order (RFF 45) method with the aid of shooting scheme. Major result outcome unveils that, fluid velocity decreases with an upsurge of ferromagnetic interaction parameter thermal distribution enhances rapidly for heightening of Biot number and thermal radiation parameter. Rate of heat transfer growths with higher values of Biot number and thermal radiation parameter. Surface drag force enhances with heightens values of solid volume fraction but decreases for viscous dissipation parameter.

Abstract: First-principles calculations based on DFT have been carried out to investigate the adsorption behavior of cisplatin (CP) drug on the pristine BN (PBN), Al-doped BN (AlBN) and Ga-doped BN (GaBN) nanosheets in gas and water media. The calculated adsorption energy for CP/PBN complex is about −0.87 eV and −0.41 eV in gas and water media respectively. But after doping Al and Ga atom on BN nanosheet separately, the adsorption energies are greatly enhanced to −2.12 eV (gas phase) and −1.62 eV (water media) for CP/AlBN complex, −1.9 eV (gas phase) and −1.47 eV (water media) for CP/GaBN complex respectively. The electronic properties such as HOMO-LUMO energy gaps drastically decrease about 48.28% and 47.95% in gas phase and 42.27% and 38.41% in water media after adsorption of CP on the AlBN and GaBN respectively. The quantum molecular descriptors predict that AlBN and GaBN show high sensitivity and reactivity than PBN nanosheet.

Abstract: Toxic gas sensors with ultrahigh sensitivity are highly desirable and those can be achieved with the help of infinite π-conjugation of cyclic conducting polymers. In this DFT study, we demonstrate the adsorption performance of tetracyclic oligopyrrole (CTPy) towards NH3 and nitrogen halides including NF3, NCl3 and NBr3. The CTPy possesses infinite conjugation and highly active cavity which provides an excellent platform for the adsorption of upcoming gas molecules. Thermodynamically, the observed interaction energies of NH3, NF3, NCl3 and NBr3 analytes with CTPy at ωB97XD/6-31+G(d,p) level of theory are −13.14, −3.00, −6.00 and −7.50 kcal/mol, respectively. In addition, the molecular dynamic simulations are performed at GFN2-xTB method to confirm the stability of CTPy and respective complexes. The SAPT0 and NCI analyses reveal that dispersion forces play a significant role to stablize these complexes. Moreover, the electrostatic component also contributes in stabilizing the NH3@CTPy, NCl3@CTPy and NBr3@CTPy complexes. The variation in the electronic properties including HOMO-LUMO gaps of complexes along with the significant NBO charge transfer indicate the increasing conductivity of CTPy upon complexation with reported analytes. The prominent charge transfer on interaction might be due to the increasing π to π* transition, thus the λmax is shifted to longer wavelength in UV–vis spectra.

Abstract: Initial degradation of methyl propionate (MePr) through its reaction with triplet molecular (3Σg−) O2 was investigated using density functional theory (DFT) and ab initio CBS-QB3 calculations over temperature range 700–1600 K. Thermochemistry and kinetics of three hydrogen atom abstractions have been studied. These reactions encounter energy barriers of 44.17–48.10 kcal mol−1 at CBS-QB3. Rate coefficients of the studied channels were evaluated from transition state theory (TST) with tunneling correction. From kinetic and thermodynamic perspectives, the most favorable process is H-atom abstraction from the Cα position, followed by Cμ, and then Cβ position. This order is partially different for the reaction of MePr with singlet (1Δg) O2 where H-atom abstraction from the Cμ atom is the most preferable pathway, followed by Cα position, then Cβ position. The atom in molecules (AIM) theory in critical point and natural bond orbital (NBO) analysis was used to explain the existence of covalent interactions.

Abstract: The numerical values which play a significant role in QSAR and QSPR studies are topological indices. Out of many existing topological indices, the fundamental type of such indices depend on Shannon’s entropy measures that characterizes the graphs by analysing the structural information of graphs and networks. The graph entropy measures take part in various problem domains such as graph theory, biology and chemistry. Here, the chemical graph of porous graphene of graphite structure is discussed. Several degree-based topological indices are computed using definitions viz., First Zagreb, Second Zagreb, Randic, Reciprocal Randic, Atom-bond connectivity, Geometric arithmetic, Harmonic, Sum-connectivity, ABC 4 and GA 5 indices. Using the calculated values of topological indices, degree and edge weighted entropy of graph, the entropy measures are calculated viz., First Zagreb entropy, Second Zagreb entropy, Randic entropy, Reciprocal Randic entropy, Atom-bond connectivity entropy, Geometric arithmetic entropy, Harmonic entropy, Sum-connectivity entropy, ABC 4 entropy and GA 5 entropy for the porous graphene structure.

Abstract: The adsorption of alkali and alkaline earth ions onto the exterior surface of inorganic nanocages X12Y12 (X = B, Al, Ga and Y = N, P, As) was investigated by using the density functional theory (DFT). All of the configurations, including the pristine ions or nanocages, as well as the ion adsorbed nanocage systems, were optimized using B3LYP-D3 functional and DEF2-TZVP basis sets. Comparative single point energy calculations were performed using different functionals viz. B3LYP-D3, M06-2X, ωB97XD and CAM-B3LYP, together with DEF2-TZVP and DEF2-QZVP basis sets. The results of natural bond orbital (NBO), quantum theory of atoms in molecules (QTAIM), and non-covalent interaction (NCI) analyses were compatible with the results of electronic properties. Total density of states (TDOSs), the natural charge, Wiberg bond index (WBI), natural electron configuration, donor–acceptor NBO interactions and second-order perturbation energies are obtained. Strong interaction between the ions and the nanocages is observed and the tendency of the ions to adsorb onto the surfaces of the mentioned X12Y12 nanocages is in the order Be++ > Mg++ > Ca++ > Li+ > Na+ > K+. These nanocages may be potential sensors for these alkali and alkaline earth ions.

Abstract: In this work, we have performed density functional theory calculations to examine the adsorption behaviors of some gas molecules (NO, N2O and NO2) on the carbon nitride (C3N) nanosheets adsorbed with transition metals (Au, Ag, Pd and Pt). Based on our calculated results, among the considered noble metals, the highest adsorption energy belongs to the adsorption of Pt atom on the C3N nanosheet, indicating the strong interaction between C3N and Pt adatom. The band structure diagrams show that Pt and Pd-adsorbed C3N nanosheets represent semiconductor property, while Au and Ag-adsorbed systems exhibit metallic character. The possible adsorption positions of NO, N2O and NO2 gas molecules on Pt-C3N nanosheets were also described. Besides, the considered gas molecules are chemisorbed on the Pt site of Pt-C3N nanosheets. The results obtained in this work suggest the Pt-functionalized C3N nanosheet as a favorable material for gas sensing in the environment.

Abstract: Reaction and electronic structural analysis of transition metal carbonyls [TM(CO)3] and corresponding gallylene complexes [(CO)3TM(GaX)] were investigated theoretically at the DFT/B3LYP/6-31G*/LANL2DZ level of theory. From the NBO analysis, the orbital interactions of metal to gallium, and the partial atomic charges were analysed. From the EDA analysis, various parameters like ΔEPauli, ΔEorb and ΔEelstat were calculated for the transition metal to GaX bonds. And we have predicted the increasing order of TM, Pd

Abstract: Gas phase detection of explosive molecules is a sensing application of wide interest. Light weight, low power sensors are needed for mobility and wide dissemination, however low vapor pressures and the presence of similar functional groups in a variety of explosive molecules make the development of sensitive and selective detection systems difficult. Experimental research has reported some success in the development of carbon nanotube (CNT) based explosives sensors, however safety considerations and strict controls on the distribution of explosive materials hamper experimental progress. Ab initio modeling of functionalized carbon nanotubes suggests that chemiresistive sensor arrays employing hydroxyl, carboxylic acid, oxygen, and amine groups can distinguish common background gases from both nitroaromatic and nitramine explosives, distinguish between nitroaromatic and nitramine explosives, and distinuguish similar nitramine explosives from each other. The modeling results on functionalized CNT sensing arrays suggest that they offer important opportunities for future experimental research.

Abstract: In this work, we investigated the optimized structures and electronic properties of novel C3N monolayers doped with carbon atoms at the central hexagon site. The C3N monolayer is an indirect band gap semiconductor with a small band gap at the Fermi level. After substituting carbon atoms, the electronic properties and structures of the nanosystems can be modulated. Interestingly, the new carbon doped C3N structure shows semiconducting behavior. The total electron density profiles show the distribution of charge densities over the whole domain doped nanostructures. The adsorption energy of NO2 molecule on the doped C3N system is higher than that of NH3 molecule, indicating that NO2 molecule strongly interacts with the C3N system. The electron density difference plots show that the charge densities were mainly accumulated at the central carbon doped hexagon site. Both NH3 and NO2 gas molecules are weakly adsorbed on the carbon substituted C3N monolayers.

Abstract: The noncovalent interaction between chlorine oxyanions, namely: (hypochlorite (ClO−), chlorite (ClO2−), chlorate (ClO3−), and perchlorate (ClO4−), and benzene block is explicitly investigated and analyzed theoretically. The performance of a variety of DFT functionals and their dispersion-corrected DFT-D3 functionals as well as various wavefunction-based SAPT methods for the prediction of noncovalent interaction energies of C6H6–ClOx− (x = 1–4) complexes is justified in comparison with the benchmark CCSD(T)/CBS method. The results showed that benzene can form stable hydrogen-bond complexes of moderate strength with chlorine oxyanions. Moreover, the existence of favorable anion-π interactions between chlorine oxyanions and benzene π-system was demonstrated, which is predominantly attributed to attractive dispersion effects that depend on both the anion polarizability and the binding distance. It is worth mentioning that the origin of the binding energy in the studied complexes was found to be attributed in 68–74% to dispersion interaction. The sSAPT0/aVDZ method is found to perform qualitatively well for the prediction of the variation trends for the interaction energy components, compared to the computationally expensive, though provided the most accurate performance, SAPT2+(CCD)δMP2/aVTZ method. The D3-corrected DFT functionals showed good overall performance, particularly those of M06-2X, TPSS, PBE, and B3LYP.

Abstract: Agonists and antagonists of dopamine are drugs commonly used to control psychosis. The action mechanism of these drugs is however, contrary. Agonists bind to the receptor and activate it, whereas antagonists interact and block the receptor. Even though the effects of these treatments on patients have been documented, the mechanism of action of these drugs is not fully understood. In this investigation, we perform quantum chemical calculations for risperidone (antagonist), aripiprazole (partial agonist), pramipexole (agonist) and dopamine, within the cavity at the binding site of the dopamine D2 receptor. Risperidone is the only molecule that is able to replace dopamine at its receptor. This may explain the efficiency of this drug for controlling the symptoms of schizophrenia and likewise its adverse effects. The greater the electron acceptor capacity of the ligand, the more it interacts with the dopamine cavity. This information will help elucidate the action mechanism of these molecules.