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In this study, for the first time, boron oxide nanoflake is analyzed as drug carrier for favipiravir using computational studies. The thermodynamic stability of the boron oxide and favipiravir justifies the strong interaction between both species. Four orientations are investigated for the interaction between the favipiravir and the B3O3 nanoflake. The Eint of the most stable orientation is −26.98 kcal/mol, whereas the counterpoise-corrected energy is −22.59 kcal/mol. Noncovalent interaction index (NCI) and quantum theory of atoms in molecules (QTAIM) analyses are performed to obtain insights about the behavior and the types of interactions that occur between B3O3 nanoflake and favipiravir. The results indicate the presence of hydrogen bonding between the hydrogen in the favipiravir and the oxygen in the B3O3 nanoflake in the most stable complex (FAV@B3O3-C1). The electronic properties are investigated through frontier molecular orbital analysis, dipole moments and chemical reactivity descriptors. These parameters showed the significant activity of B3O3 for favipiravir. NBO charge analysis transfer illustrated the charge transfer between the two species, and UV-VIS analysis confirmed the electronic excitation. Our work suggested a suitable drug carrier system for the antiviral drug favipiravir, which can be considered by the experimentalist for better drug delivery systems. [ABSTRACT FROM AUTHOR]

Switchable nonlinear optical (NLO) materials have widespread applications in electronics and optoelectronics. Thermo-switches generate many times higher NLO responses as compared to photo-switches. Herein, we have investigated the geometric, electronic, and nonlinear optical properties of spiropyranes thermochromes via DFT methods. The stabilities of close and open isomers of selected spiropyranes are investigated through relative energies. Electronic properties are studied through frontier molecular orbitals (FMOs) analysis. The lower HOMO-LUMO energy gap and lower excitation energy are observed for open isomers of spiropyranes, which imparts the large first hyperpolarizability value. The delocalization of π-electrons, asymmetric distribution and elongated conjugation system are dominant factors for high hyperpolarizability values of open isomers. For deep understanding, we also analyzed the frequency-dependent hyperpolarizability and refractive index of considered thermochromes. The NLO response increased significantly with increasing frequency. Among all those compounds, the highest refractive index value is observed for the open isomer of the spiropyran 1 (1.99 × 10−17 cm2/W). Molecular absorption analysis confirmed the electronic excitation in the open isomers compared to closed isomers. The results show that reversible thermochromic compounds act as excellent NLO molecular switches and can be used to design advanced electronics. [ABSTRACT FROM AUTHOR]

Herein, a series of D‐π‐A conjugated molecules based on donor N‐methyl‐4,5‐diazacarbazole with a variety of acceptor end caps are quantum chemically proposed with aim of rational design of novel organic materials applicable in organic solar cells (OSCs) by using ab initio density functional theory (DFT) calculations. Herein, the optoelectronic performance of tailored molecules was explored by substituting the bay annulated indigo dye acceptor unit with a variety of molecules including 4‐(5‐methyl‐thiophene‐2‐yl)benzothiadiazole; 1, 2‐(3‐methyl‐5‐methylene‐4‐oxothiazolidin‐2‐ylidene)‐malononitrile; 2, 3‐methyl‐5‐methylene‐2‐thioxothiazolodin‐4‐one; 3, 2‐methylenemalononitrile; 4, 2‐cynaoacryli‐caidmethylester; 5, those are linked through the thiophene bridge. The DFT results encompassed the significant variations of electronic behavior of newly designed molecules (M1‐M5) with respect to the reference molecule, especially in the case of 1, 2, and 3 substitution. The designed molecules exhibit excellent electron transition due to the increasing λmax toward the higher region. The outcomes of this study proposed the designed molecules as a possible choice in designing efficient optoelectronic materials for OSCs. From the future point of view, this finding suggests that the pre‐synthesis of such hypothetical molecules using quantum mechanics is an effective strategy for designing ideal candidates for solar cell applications. [ABSTRACT FROM AUTHOR]

[Display omitted] • DFT study for B 3 O 3 quantum dot as a sensor for methyl halides. • Methyl halides@B 3 O 3 complexes are thermodynamically stabile. • NCI analysis confirmed non-covalent interactions. • NBO analysis confirmed charge transfer from the methyl halides towards B 3 O 3 quantum dot. In this study, B 3 O 3 quantum dot has been used for sensing of various methyl halides for the first time. The suitable cavity of B 3 O 3 makes it more suitable for the sensing of variety of analytes. The three, very simple and most important methyl halides (CH 3 F, CH 3 Cl and CH 3 Br) are selected to adsorb on B 3 O 3 surface. Density functional theory (DFT) method with appropriate basis set was implemented. Among the considered complexes, methyl bromide complex CH 3 Br@B 3 O 3) showed higher interaction energy of −16.90 kcal mol−1. The noncovalent interaction (NCI) analysis identified the existence of van der Waals interactions among all analytes and adsorbent. The density of state (DOS) and natural bond orbital (NBO) charges analyses identified the charge transfer and conductive properties of B 3 O 3 nanosheet after interaction with alkyl halides. Frontier molecular orbital study revealed the electronic attributes of considered complexes. It is revealed that B 3 O 3 quantum dot can be a very good choice for sensing of methyl halides and could be helpful for monitoring and reducing the environmental pollution. [ABSTRACT FROM AUTHOR]

[Display omitted] • The chiral recognition ability of CBPQT4+ is systematically studied using DFT simulations. • Chirodiastalic energy (E chir) indicates the L -enantiomer complexes are more stable than D -complexes. • The quantitative analyses of noncovalent interaction indicate the structures are stabilized by the dispersion forces. • The electronic properties analyses illustrate the high chiral response of CBPQT4+ towards small molecular amino acids. • Overall findings reveal that the CBPQT4+ macrocycle has an excellent ability to differentiate between L - and D -enantiomers. Two enantiomeric forms of amino acids in a chiral medium behave quite differently because of the different orientation of their functional groups in space. Thus, the phenomenon of chiral recognition is crucial with the focus on applications in molecular sensing and enantioselective separations. The present research work is focused on the illustration of the potential chiral recognition of a porous CBPQT4+ macrocycle for sulfur-containing amino acids, which is elucidated by the conformational energies landscape with quantitative non-covalent analysis and their electronic behaviour. Herein, we report the chiral recognition of sulfur-containing amino acids e.g., cysteine (CY), homocysteine (HCY), and methionine (MT), by tetra-protonated (4+) CBPQT macrocycle via density functional theory (DFT) calculations. Geometry optimization, thermodynamic stability, noncovalent interaction analysis, symmetry-adapted perturbation (SAPT), and electronic properties analyses are employed to characterize the chiral response of the complexes formed by CBPQT4+ with D - and L -isomers of selected amino acids. The interactive conformations of complexes indicate physisorption of amino acids through the central cavity of the macrocycle. The maximum chiral discrimination is observed in the case of D - and L -cysteine isomers, which is 3.56 kcal/mol. It is revealed that the complex; D -CY@CBPQT4+ is energetically more stable than the L -CY analogue, whereas, L -HCY and L -MT show higher stability as compared to D -type counterparts, probably due to the interaction of the thiol groups with π-electrons of macrocycle in respective stable complexes. Non-covalent interaction (NCI) analyses including, reduced density gradient-based NCI index and SAPT reveal that the methionine-based complexes show the highest attractive components e.g., electrostatic, dispersion, and induction with the lowest repulsive exchange contribution, which is followed by homocysteine and cysteine. Overall, results show that the CBPQT4+ macrocycle has an excellent ability to differentiate between L - and D -amino acids, the difference is more pronounced when the structure of amino acid is small and rigid. [ABSTRACT FROM AUTHOR]

Methylammonium Lead Iodide (MAPbI 3) is bellwether in the field of photovoltaics due to its remarkable optoelectronic properties. However, the instability of MAPbI 3 hinders its commercial scale applications. To address this issue, we have utilized the method of compositional engineering by doping A-site of MAPbI 3 with alkali metals (Na, K, Cs) availing the first principle study within the framework of density functional theory. To realize the band structure, geometry is initially optimized using GGA-PBE, GGA-PBESOL and GGA-PW91 exchange correlation functionals and then GGA + SOC technique is applied to draw the comparison for better insight of the electronic structure. Later we explored the structural, electronic, optical, elastic, and thermodynamic properties of alkali doped MAPbI 3. The results manifest improvement in the phase stability, thermodynamic stability and optical absorption of MAPbI 3 after being doped with Na, K and Cs. These properties can provide research ideas for ensuing research in A-site doped studies of MAPbI 3. [ABSTRACT FROM AUTHOR]

[Display omitted] • For the first time, DFT study of superalkalis doped C 16 Te 8 is performed. • Designed complexes have promising thermodynamic stabilities. • Static first hyperpolarizability up to 2.60 × 105 au is obtained for doped complexes. • Large nonlinear refractive index value up to 1.55 × 10−12 au is observed for doped complexes. There is a growing demand for thermodynamically stable and highly polarizable materials with excess electrons in the fields of optics. In this study, a new class of theoretically designed materials (A x Y@C 16 Te 8 (A = K, Na, Li, and x = 2, 3 4)) are explored for optoelectronic and nonlinear (NLO) applications via DFT calculations. Various superalaklis (A x Y (Y = O, N, F and x = 2, 3, 4)) are doped on C 16 Te 8 nano-surface. The outcomes of DFT revealed high thermodynamic stability of these complexes. Natural bond orbital (NBO) charge analysis illustrated that charge transfer occurred from superalkali toward Te-containing [8]circulene (C 16 Te 8). HOMO − LUMO energy gap is reduced after doping. Moreover, (A x Y@C 16 Te 8 (A = K, Na, Li, x= 2, 3 4, and Y = O, N, F) complexes exhibit remarkably large nonlinear optical (NLO) response. The static first hyperpolarizability (β o) of these complexes ranges between 3.28 × 103 – 2.60 × 105 au. The NLO response of the designed complexes is further explored by computing second hyperpolarizability (γ tot ), frequency-dependent hyperpolarizability, and nonlinear refractive index. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Benchmark theoretical study is performed for homolytic cleavage of C Sn bond. • Nineteen DFs along with four basis sets are selected. • Theoretical results are compared with the experimental data. • BLYP-D3/SDD method is the most accurate method for homolytic cleavage of C Sn bond. Abstract Stille coupling is a well-known cross coupling reaction, where the rate determination step is the dissociation of carbon stannous (C Sn) bond. The organotin compounds are also used as precursors in the manufacturing of tin oxide films, solar cells, gas sensors, flat panel display technology and low emission glass materials, etc. The reactivity of organotin compounds has direct relationship with the homolytic cleavage of C Sn bond. Therefore, accurate determination of C Sn bond has direct relevance in understanding many phenomena. The current benchmark study is aimed at finding out the accurate theoretical method for the homolytic cleavage (bond dissociation energy) of C Sn bond. In this regard, nineteen DFs from eight different classes of DFT with two effective core potential basis sets (LANL2DZ and SDD) and two Karlsruhe basis sets (def2-SVP and def2-TZVP) are selected for the BDE calculation of C Sn bond. Ten structurally diverse organotin compounds with experimentally known BDE of C Sn bond are selected from the literature. The statistical [root mean square deviation (RMSD), standard deviation (SD), Pearson’s correlation (R) and mean absolute error (MAE)] results are obtained by the comparison of theoretical data with the experimental BDE values of C Sn bond of selected organotin compounds. Among all DFT classes, GGA-D class is a batter class and BLYP-D3 functional of this class is selected as the best functional for homolytic bond dissociation energy (BDE) calculation of C Sn bond. This functional with SDD basis set shows remarkable performance in reproducing the BDE of C Sn bond with more accuracy. The SD, RMSD, R and MAE are 4.11 kcal mol−1 is 3.9 kcal mol−1 is 0.963 and −0.01 kcal mol−1, respectively. [ABSTRACT FROM AUTHOR]

[Display omitted] • The drug carrier ability of B 3 O 3 toward Foscarnet is investigated via DFT. • The interaction is characterized by the geometric, energetic, electronic, and optical analyses. • Widely accepted ωB97XD/6-31+G(d,p) method of DFT is adopted for geometric analysis whereas for electronic properties B3LYP/6-31+G (d,p) method is used. • NCI and QTAIM analyses confirmed the nature of interactions. In this study, B 3 O 3 quantum dot is investigated via density functional theory (DFT) calculations as an antiviral drug carrier toward Foscarnet. Geometric analysis is carried out to find stable orientations of interaction between Foscarnet drug and the B 3 O 3 quantum dot. As a result, three stable orientations are proposed. The E int of the most stable orientation is –32.63 kcal/mol whereas the BSSE corrected energy is −26.98 kcal/mol. Noncovalent interaction index (NCI) and quantum theory of atoms in molecules (QTAIM) analyses are employed to understand the nature and the type of interactions taking place between drug and the B 3 O 3 quantum dot. Their results indicated the presence of hydrogen bonding in the most stable complex (orientation A). The HOMO-LUMO analysis is performed to study the electronic properties of the interacting moieties. The lowest E gap is observed in case of orientation A. The value of dipole moments and chemical descriptors showed the significant activity of B 3 O 3 quantum dot toward Foscarnet drug molecule. The overall findings from this study suggest the B 3 O 3 quantum dot as a potential drug carrier system for antiviral drugs. [ABSTRACT FROM AUTHOR]

[Display omitted] • Sensing capability of aminated graphdiyne (GDY-NH 2) towards common environmental pollutants by using DFT. • GDY-NH 2 forms energetically stable complexes with acetamide, thioacetamide, benzamide, and thiobenzamide. • Adsorption of the analytes decreases the HOMO-LUMO E gap. • The analytes interact with GDY-NH 2 via non-covalent van der Waals forces. • Stability, QTAIM, NCI, FMOs, NBO, and DOS analyses are executed to evaluate the applicability of the sensing. The detection of common environmental pollutants through chemical sensors has received significant interest from the scientific community. Acetamide (AM), benzamide (BM), thioacetamide (TAM), and thiobenzamide (TBM) are hazardous chemicals to humans and can cause many diseases including cancer, chronic liver damage, and acute skin irritations. Recently, functionalized 2D carbon-based materials have been used extensively as chemical sensors. Functionalization of these materials introduces adsorption sites which facilitates the interactions with the analytes. In this study, the sensing capability of the recently synthesized aminated graphdiyne material (GDY-NH 2) is explored towards AM, BM, TAM, and TBM via density functional theory (DFT) calculations. The results revealed that GDY-NH 2 forms stable complexes with the considered analytes. The interaction energies are −10.64, −11.92, −11.19, and −13.28 kcal/mol for AM@GDY-NH 2 , BM@GDY-NH 2 , TAM@GDY-NH 2 , and TBM@GDY-NH 2 , respectively. Quantum theory of atoms in molecules (QTAIM) and non-covalent interaction (NCI) analyses revealed that the interaction between GDY-NH 2 and the analytes occurs mainly via weak non-covalent van der Waals forces. A decrease in the HOMO-LUMO energy gap after interaction corresponds to a change in conductivity of the material. Furthermore, to ensure that the analytes are properly released after the detection, the turnover time has been theoretically calculated. [ABSTRACT FROM AUTHOR]

The high over-potential associated with water splitting hinders the wide production of hydrogen and oxygen gases. Recent advancements in this field are being made by exploring novel, low-cost and highly efficient catalysts to lower the over-potential of the water splitting reaction. Herein, we studied the novel single atom catalysts (SACs) based on late first-row transition metal doped boron phosphide (B 12 P 12) nano-cages for the electrocatalysis of the oxygen evolution reaction (OER) via density functional theory (DFT) calculations. The choice of using boron phosphide nano-cages as the support is based on the highly desirable properties within it. Namely, having many defects, excellent electrical conductivity, large surface area, and high chemical stability. The Ni@B 12 P 12 and Co@B 12 P 12 SACs exhibit high chemical stability, having interaction energies of −1.70 and −2.55 eV, respectively. Moreover, the results of quantum theory of atoms in molecules (QTAIM) analysis confirmed that the transition metals are covalently chemisorbed on the nano-cages, such strong interactions are desirable in SACs to ensure they withstand harsh chemical environments and are active for longer time period. Frontier molecular orbitals (FMOs) analysis indicates that the designed catalysts have semi-conducting capabilities which facilitate the transfer of electrons. The calculated FMOs energy gap (H-L E gap) values range from 2.01 to 2.88 eV. Results of OER activity analysis indicate that Ni@B 12 P 12 and Co@B 12 P 12 are promising OER SACs with low overpotentials (1.01 and 1.06 V, respectively). The result of this study highlights the viability of B 12 P 12 nano-cages as supports in SACs and encourage the exploration of other nano-cages in the catalysis field. [Display omitted] • Investigation of the activity of transition metal doped nano-cages as SACs for the OER using DFT. • Decorating transition metals on B 12 P 12 is energetically favorable. • The adsorption of transition metals enhances the conductivity of B 12 P 12. • Thermodynamic calculations are performed to estimate overpotential of the designed SACs toward OER. • Interaction energy, QTAIM, FMOs, NBO, and DOS analysis are performed to investigate the properties of catalysts. [ABSTRACT FROM AUTHOR]

Background: Donor acceptor moieties connected through π-conjugated bridges i.e. D-π-A, in order to facilitate the electron/charge transfer phenomenon, have wide range of applications. Many classes of organic compounds, such as cyanine, coumarin carbazole, indoline, perylene, phenothiazine, triphenylamine, tetrahydroquinoline and pyrrole can act as charge transfer materials. Phenothiazines have been extensively studied as electron donor candidates due to their potential applications as electrochemical, photovoltaic, photo-physical and DSSC materials. Results: Two phenothiazine derivatives, 2-((10-hexyl-10H-phenothiazin-3-yl)methylene)malononitrile (3a) and 2-((10-octyl-10H-phenothiazin-3-yl)methylene)malononitrile (3b) have been synthesized in good yields and characterized by various spectroscopic techniques like FT-IR, UV-vis, 1H-NMR, 13C-NMR, and finally confirmed by single crystal X-ray diffraction studies. Density functional theory (DFT) calculations have been performed to compare the theoretical results with the experimental and to probe structural properties. In order to investigate the excited state stabilities the absorption studies have been carried out experimentally as well as theoretically. Conclusions: Compound 3a crystallises as monoclinic, P2 (1)/a and 3b as P-1. The X-ray crystal structures reveal that asymmetric unit contains one independent molecule in 3a, whereas 3b exhibits a very interesting behavior in having a higher Z value of 8 and four independent molecules in its asymmetric unit. The molecular electrostatic potential (MEP) mapped over the entire stabilized geometries of the molecules indicates the potential sites for chemical reactivities. Furthermore, high first hyperpolarizability values entitle these compounds as potential candidates in photonic applications. [ABSTRACT FROM AUTHOR]

A variety of novel 5-aryl thiophenes 4a-g containing sulphonylacetamide (sulfacetamide) groups were synthesized in appreciable yields via Pd[0] Suzuki cross coupling reactions. The structures of these newly synthesized compounds were determined using spectral data and elemental analysis. Density functional theory (DFT) studies were performed using the B3LYP/6-31G (d, p) basis set to gain insight into their structural properties. Frontier molecular orbital (FMOs) analysis of all compounds 4a-g was computed at the same level of theory to get an idea about their kinetic stability. The molecular electrostatic potential (MEP) mapping over the entire stabilized geometries of the molecules indicated the reactive sites. First hyperpolarizability analysis (nonlinear optical response) were simulated at the B3LYP/6-31G (d, p) level of theory as well. The compounds were further evaluated for their promising antibacterial and anti-urease activities. In this case, the antibacterial activities were estimated by the agar well diffusion method, whereas the anti-urease activities of these compounds were determined using the indophenol method by quantifying the evolved ammonia produced. The results revealed that all the sulfacetamide derivatives displayed antibacterial activity against Bacillus subtiles, Escherichia coli, Staphylococcus aureus, Shigella dysenteriae, Salmonella typhae, Pseudomonas aeruginosa at various concentrations. Furthermore, the compound 4g N-((5-(4-chlorophenyl)thiophen-2-yl)sulfonyl) acetamide showed excellent urease inhibition with percentage inhibition activity ∼46.23 ± 0.11 at 15 μg/mL with IC50 17.1 μg/mL. Moreover, some other compounds 4a-f also exhibited very good inhibition against urease enzyme. [ABSTRACT FROM AUTHOR]

[Display omitted] • Sensing of gaseous molecules on aza-macrocyle is studied using DFT approach. • The adsorption behaviour is analyzed via geometric, energetic, and electronic properties. • The effect of applied electric field is studied for reported complexes. • The adsorption trend of is as follow: SO 3 @HA ≫ SO 2 @HA > H 2 S@HA ≫ NO 2 @HA > N 2 O@HA. The toxic gas sensing applications find immense attention in environmental monitoring. In this research, the adsorption of nitrogen and sulfur-containing gaseous molecules i.e., N 2 O, NO 2 , H 2 S, SO 2 and SO 3 on organic aza-macrocyclic hexaazabipyH 2 (HA) is analyzed through DFT simulations. The interactions of toxin analytes with HA are expressed through the interaction stabilities of optimized geometries, and electronic parameters including highest occupied and lowest unoccupied molecular orbitals energies and NBO charged transfer analysis. Our results indicate that the gaseous molecules are physisorbed onto the HA with the interaction energies of −4.80, −4.86, −7.09, −7.42 and −11.64 kcal/mol for NO 2 , N 2 O, H 2 S, SO 2 and SO 3 , respectively. The trend of interaction stability of complexes is observed as, SO 3 @HA > SO 2 @HA > H 2 S@HA > N 2 O@HA > NO 2 @HA. The adsorption of the gaseous molecule on the electronic structure of HA is significant, especially for sulfur-containing analytes. The effects of the applied electric field from the range of −0.15 to +0.15 V/Å in the direction of adsorbed molecules (Y-axis) on the interaction energies and dipole moment of complexes have been measured. It can be concluded that the HA macrocycle shows greater sensitivity towards the toxic gas molecules and therefore, can be applied for their sensing. [ABSTRACT FROM AUTHOR]

Abstract: The ultrasoft pseudopotential technique is used to explore the elastic, electronic and optical properties of cotunnite TiO2 using LDA and GGA proposed by Perdew Wang (PW91), Perdew–Burke–Ernzerhof (PBE) functional as defined by Wu and Cohen (PBEWC) and PBE functional for solids (PBESOL). The calculated elastic constants bulk modulus, shear modulus and Young’s modulus are in agreement with the previous theoretical reports. From our investigated shear anisotropy factors (A1, A2, and A3), we infer that cotunnite TiO2 is strong anisotropy in case of A1 and A2 and less anisotropy in case of A3. The value of mean sound speed and Debye temperature are calculated using the obtained values of elastic moduli. The calculated structural parameters are in accord with the reported experiment and theoretical results. Our obtained values of direct bandgaps show an improvement over the other previous theoretical reports. The values of the dielectric constant (ε 1(ω)) of cotunnite TiO2 calculated within LDA and GGA approximations are 7.655 (LDA (CA-PZ)), 7.578 (GGA (PW91)), 7.685 (GGA (WC)) and 7.655 (GGA (PBESOL)), which are slightly higher than the experimental values of rutile (6.69) and anatase (6.55) polymorphs. The obtained values of the refractive index are consistent with rutile TiO2 and higher than anatase phase. The investigated imaginary part of dielectric constant and absorption spectrum reflect that the cotunnite TiO2 is a weak photocatalytic material as compared to anatase and similar to rutile phases. [Copyright &y& Elsevier]

[Display omitted] • Alkali metal substituted diamantanes are investigated for NLO response. • Alkali metal substitution increases first hyperpolarizability (upto 36,328 a.u.). • HOMO-LUMO gap is significantly reduced to 1.64 eV a.u. for K@CH a complex. • A bathochromic shift (λ max = 600 nm) is observed in the absorption spectrum. • Frequency dependent hyperpolarizabilities suggest sensitivity towards radiations. Electronic properties, absorption spectra and nonlinear optical properties of alkali metal substituted diamantanes are presented. A significant reduction in HOMO-LUMO gap has been observed by alkali metal substitution. K@CH a has the lowest H-L gap of 1.64 eV as compared to 8.88 eV for pristine diamantane. A remarkable increase in the first hyperpolarizability (β o) has been observed due to the substitution of alkali metals. Among these structures, K substituted complexes show the largest first hyperpolarizability (25526–36328 a.u). This significant increase in the first hyperpolarizability (β o) is attributed to low crucial transition energy (ΔE). K@CH a has the lowest ΔE value (2.06 eV) which results in the highest β o value (36328 a.u.) for K@CH a. Furthermore, frequency-dependent hyperpolarizability calculations have been carried out using 1906 nm and 1340 nm frequencies for commonly used lasers. The values of dynamic hyperpolarizabilities are greater than those of static ones for the majority of the substituted systems. This suggests the application of the proposed complexes under different frequencies of incident radiations. The substitution of alkali metals leads to the shift in absorption from ultraviolet to the visible region. Bathochromic shifts in the absorption spectra are observed with an increase in the size of alkali metal atom ( λ max = 600 nm for K@CH a). This study provides an efficient approach to design high-performance NLO materials having extensive applications in the field of electronics and optoelectronics. [ABSTRACT FROM AUTHOR]

Motivated by the excellent geometric and electronic properties of recently reported triphenylene (TP), for the first time, we studied the nonlinear optical responses of superalkalis (Li 3 O and Na 3 O) doped triphenylene and amino (HATP), hydroxy (HHTP) and thiol (HTTP) functionalized quantum dots by using density functional theory. The geometric stabilities of eight reported complexes are measured through the interaction energies at ωB97XD/6-31+G(d,p) level of theory. Our results reveal that Li 3 O@HATP and Na 3 O@HATP complexes are highly stable with the interaction energies of −60.36 and −57.26 kcal/mol, respectively. The HOMO-LUMO energy gaps of TP, HATP, HHTP and HTTP are significantly varied upon complexation with M 3 O which is evident by the strong charge transfer from excess electron donor superalkalis (M 3 O) to the surfaces. However, the π back donation is more pronounced in M 3 O@HATP complexes, revealed by the negative value of CHELPG charge transfer on M 3 O. Due to the donation and back donation of charges between M 3 O and HATP, the significantly high first static hyperpolarizability ( β o ) and its projection to dipole moment ( β vec ) are computed for M 3 O@HATP complexes. The β o of Li 3 O@HATO and Na 3 O@HATP complexes are 3 × 104 au. The β o of Na 3 O@HHTP complex is surprisingly high (1 × 105 au) which is justified by the two-level model. Moreover, the NLO responses of co-doped Li 3 O/Na 3 O and mixed functional groups TP-quantum dots are also computed. Among them, the maximum β o (5 × 104) is observed for the Na 3 O@AHTP complex. Finally, the TD-DFT calculations reveal that the reported complexes show excellent transparency in the ultraviolet region especially M 3 O@HATP and Na 3 O@HHTP complexes. [Display omitted] • The NLO response of superalkalis (M 3 O) doped TP, HATP, HHTP and HTTP are computed. • The NLO responses of these novel complexes are investigated in the framework of density functional theory (DFT) calculations. • The results are rationalized by analyzing the geometric, energetic, electronic, linear and nonlinear optical properties. • Theoretical results reveal that Na 3 O@HATP, Li 3 O@HATP and Na 3 O@HHTP complexes exhibit superior optical behavior. [ABSTRACT FROM AUTHOR]

To harness the full potential of electrochemical water splitting for hydrogen and oxygen production, recent efforts have focused on the development of single atom catalysts (SACs) to enhance electrocatalytic performance while maximizing metal atom utilization. In this context, we have designed and assessed the feasibility of late first-row transition metal (TM) linked 1-Azahomocubane dimer as SACs for facilitating the water splitting reaction. The effectiveness of these designed electrocatalysts has been thoroughly evaluated through density functional theory (DFT) calculations. Remarkably, the Fe containing SAC demonstrated exceptional activity towards the hydrogen evolution reaction (HER) (ΔG H = −0.06), indicating the ability of Fe metal to facilitate the adsorption of hydrogen ions and their release as hydrogen gas. Furthermore, the Fe containing SAC revealed high stability and sufficient conductivity. This investigation underscores the potential utility of the Fe containing SAC as effective precious-metal free electrocatalysts for the HER. [Display omitted] • TM linked 1-Azahomocubane dimer SAC for water the splitting reactions. • Fe@2Cubane revealed ultra-high catalytic activity toward the HER. • The Fe based SACs serves as precious-metal free, chemically stable, and sufficiently conductive SACs. [ABSTRACT FROM AUTHOR]

[Display omitted] • This study theoretically presents the sensing affinities of cyclic tetrapyrrole (CTPy) towards toxic gaseous molecules. • The sensitivity of CTPy is measured against the toxic chemicals namely NH 3 , NF 3 , NCl 3 and NBr 3. • ωB97XD/6-31+G(d, p) level of DFT has implemented to measure the sensitivity of CTPy. • DFT results proved that CTPy is highly sensitive towards the considered analytes. 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 NH 3 and nitrogen halides including NF 3 , NCl 3 and NBr 3. 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 NH 3 , NF 3 , NCl 3 and NBr 3 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 NH 3 @CTPy, NCl 3 @CTPy and NBr 3 @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 λ max is shifted to longer wavelength in UV–vis spectra. [ABSTRACT FROM AUTHOR]

[Display omitted] • DFT studies are executed for hydrogen storage on Germanium (Ge 5 −2 & Ge 9 −2) and Silicon (Si92−) Zintl clusters. • The superior adsorption behavior of Zintl ions is illustrated by comparing with neutral analogues. • The adsorption behavior is investigated by using M052X/6-31+G(d,p) method. • The storage capability is explained with the help of geometric and electronic properties. Hydrogen storage is a subject of extensive research because hydrogen is a clean and eco-friendly for future applications. New strategies are being developed simultaneously for the easy and effective storage of hydrogen gas. Herein, we report the hydrogen adsorption on the Germanium and Silicon Zintl clusters within the framework of density functional theory (DFT). The excellent adsorption of hydrogen on Ge 5 2−, Ge 9 2−, Si 9 2− based Zintl clusters is achieved in terms of adsorption energies, electronic properties such as, HOMO-LUMO gaps, natural bond orbital (NBO) charge transfer, variation in dipole moment and density of state analysis (DOS). The superior adsorption affinities of these Zintl clusters are demonstrated in comparison with the adsorption capability of Ge and Si neutral clusters. In comparison, the adsorption energies of H 2 @Zintl phase complexes are higher than those of corresponding H 2 @neutral clusters. For example, the adsorption energy of b- exo -H 2 @Si 9 2− complexes is −11.13 kJ mol−1 which is far higher than −3.47 kJ mol−1 for the neutral analogue (b- exo -H 2 @Si 9 0). The effect of hydrogen adsorption on the E H-L gaps in Zintl clusters is also more pronounced, and the higher charge transfer is observed as well. Overall, results suggest the higher adsorption strength of Zintl cluster for H 2 as compared to neutral clusters. [ABSTRACT FROM AUTHOR]

• Synthesis of hydrazones derivatives of 2,1-Benzothiazines. • Crystallization and single crystal structure determination. • Hydrogen bonding interactions. • Investigation of reactivities and reactive sites as well on the basis of DFT. 2,1-Benzothiazine-4(3 H)-one 2,2-dioxide was synthesized through a multistep procedure starting with methyl anthranilate. It was reacted with hydrazine monohydrate to form corresponding hydrazine derivative which was subsequently treated with acetone and cyclopentanone respectively to get benzothiazine based hydrazones. Both the molecules were crystalized in monoclinic crystal system with P 2 1/n and P 2 1/c space groups for first and second molecules, respectively. The thiazine ring in both molecules adopted the envelope shape conformation. Moreover, both the structures were stabilized by hydrogen bonding interactions. DFT calculations were performed for the validation of geometric parameters obtained through X-ray diffraction studies. Moreover, the DFT calculations are also executed for the investigation of reactivities and reactive sites as well. Image, graphical abstract [ABSTRACT FROM AUTHOR]

The pressure induced theoretical investigations of electronic, optical and elastic constants of cubic zirconia (c-ZrO 2) are estimated under the effect of hydrostatic pressure (0–40 GPa) by employing first principles based local density approximation (LDA) functional within the framework of density functional theory (DFT). The optimized structural parameters are in excellent agreement with previous theoretical and experimental values. Our calculated bandgap (3.350 eV) at zero pressure shows excellent consistency with previous listed computational results and very favorable approach to experimentally reported bandgap (4.6 eV) with the increment of pressure. Density of states (DOS) predicts dominant contribution of oxygen electrons of 2p-orbital and zirconium electrons of 4d-orbital in valence and conduction band formation. The estimated values of dielectric constant (5.85) and refractive index (2.42) at zero pressure are in good agreement with existing theoretical data. The optical constants are less sensitive to applied pressure and offer significant stability under high pressure. Pressure based elastic parameters exhibit high mechanical stability, more hardness and stiffness, improved ductility and higher elasticity of c-ZrO 2 under high pressure. [ABSTRACT FROM AUTHOR]

• This study theoretically presents the adsorption of G-series nerve agents on graphdiyne surface. • ωB97XD/6-31+G(d,p) method is used to elucidate the binding nature of graphdiyne sheet with nerve agents. • NCI and QTAIM analyses confirmed the presence of van der Waals interactions. Easy and effective detection of health hazards chemical warfare agents (CWA) is vital for the good human health and safe environment. Here, we report the sensing of G type nerve agents, such as GA(tabun), GB(sarin), GD(soman) and GF(cyclosarin) on graphdiyne (GDY) using DFT and QTAIM analyses. The sensing results reveal the physisorption of analytes at the triangular portion of graphdiyne surface. Among all, GA shows the highest interaction energy of −16.31 kcal/mol. SAPT0 analysis reveals the least contribution of repulsive component (exchange) in GA@GDY complex. The change in HOMO-LUMO energy gap and charge transfer (NBO) also support the sensitivity of graphdiyne toward considered analytes. QTAIM and NCI analyses reveal that the type of noncovalent interactions are mainly van der Waals in nature. A short recovery time of 0.63 µs at 298 K for desorption of GF from GDY shows that GDY can act as better surface as sensor study for GF. [ABSTRACT FROM AUTHOR]

Hydrogen evolution reaction (HER) has gained a great interest in recent years because it provides the cleanest fuel (H 2). One of the most demanding things required for this reaction is an efficient and cost-effective catalyst. Single atom catalysis is one of the most remarkable strategies in this regard. Herein, transition metals adsorbed silicon carbide nanocages (TM@Si 12 C 12 ; TM = Zn, Fe, Co, Cu, Ni) are investigated as single atom catalysts in order to search less expensive electrocatalysts with excellent efficiency for HER. The pure and hydrogen adsorbed TM@Si 12 C 12 show geometric and thermodynamic stability which illustrates their practical utility. Interaction energies obtained range from −0.70 to −5.73 eV, and it is suggested that Cu@Si 12 C 12 may play an excellent role in HER due to its lowest Gibbs free energy of −0.17 eV (near to zero). In this work, we investigated electronic properties through natural bond orbital (NBO) analysis of selected TM@SiC. According to NBO calculations, it is observed that charge is transferred from adsorbed transition metals towards nanocage. After H adsorption, NBO charge is transferred to hydrogen which shows the adsorption properties of H. In case of HOMO-LUMO energy gap, it is observed that transition metal adsorbed complexes have small energy gaps between 2.17 and 2.77 eV but after adsorption of hydrogen, this energy gap increases to lie in the range of to change from 2.93 to 3.12 eV, which also verified the electronic stability of H adsorbed species. The noncovalent interactions are estimated through NCI analysis. The density of states analysis gives insight about the energy states of occupied and unoccupied orbitals of electrons. The highest thermodynamic stability and electronic conductivity of transition metal adsorbed silicon carbide suggested it as an excellent supportive surface for HER. [Display omitted] • Transition metals doped Si 12 C 12 nanoclusters are used as single atom catalyst toward HER. • Thermodynamic and electronic properties of hydrogen adsorbed TM@Si 12 C 12 are investigated via DFT method. • Cu@Si 12 C 12 has excellent HER efficiency due to very low Gibbs free energy (−0.17 eV). [ABSTRACT FROM AUTHOR]

To fully realize the potential of hydrogen and oxygen production via the electrochemical water splitting process, single atom catalysts (SACs) are recently proposed and applied with high metal % utilization. In this regard, we have designed and examined the suitability of late second-row transition metal (TM) loaded B 12 P 12 nanocages as SACs for the water splitting reaction. The viability of the designed electrocatalysts has been evaluated based on density functional theory (DFT) calculations. Outstandingly, the Rh@B 12 P 12 SACs revealed high stability (E int = −2.73 eV), which ensures that the Rh atoms can maintain single atom dispersion throughout extended periods and can withstand harsh catalytic conditions. In addition, the Rh@B 12 P 12 SACs showed excellent catalytic activity as a bifunctional electrocatalyst (ΔG H = 0.17 eV & η OER = 0.61 V) for both the hydrogen and oxygen evolution reactions (HER & OER, respectively). We hope that this study demonstrates the applicability of TM doped nanocage SACs as potential electrocatalysts. [Display omitted] • 2nd row TM loaded B 12 P 12 electrocatalysts toward hydrogen and oxygen evolution reactions. • Rh@B 12 P 12 revealed high thermal stability (E int = −2.73 eV). • Rh@B 12 P 12 showed excellent catalytic activity (ΔG H = 0.17 eV & η OER = 0.61 V) for both HER & OER, respectively. [ABSTRACT FROM AUTHOR]

In the pursuit of efficient hydrogen and oxygen production via water electrolysis, the deployment of single atom catalysts (SACs) plays a pivotal role in reducing the overpotential of this process on a large scale. Hence, the quest for suitable support materials remains imperative for the design of superior SACs. In this study, we explored the potential of the recently proposed penta-belt structure as a support matrix for anchoring late first-row transition metals (Fe - Zn). The catalytic prowess of these engineered SACs in facilitating water electrolysis is assessed through density functional theory (DFT) calculations. Remarkably, the Cu@Penta-belt SACs exhibits the highest catalytic activity for the hydrogen evolution reaction (HER), with a remarkably low ΔG H value of 0.17 eV. Additionally, Ni@Penta-belt demonstrates a competitively moderate overpotential of 0.72 V for the oxygen evolution reaction (OER). To deepen our comprehension of the bonding interactions between the metal atoms and the support structure, we introduce and apply a systematic approach for identifying and analyzing the primary binding molecular orbital. This innovative methodology can be extended to diverse doping investigations that necessitate non-periodic DFT calculations. [Display omitted] • Application of TM doped Penta-belt for the water splitting reaction. • A new method to identify and analyze the binding MOs for non-periodic systems. • Great catalytic potential towards the HER and OER of TM@Penta-belt. [ABSTRACT FROM AUTHOR]

Excessive consumption of fossil fuels and CO 2 emissions exacerbate global environmental concerns. Unfortunately, fossil fuel reserves are dwindling and fossil fuel energy is unsustainable, non-renewable, and costly. Due to these concerns, there is an imperative demand for eco-friendly energy conversion electrochemical systems. Hydrogen (H 2) is ubiquitously regarded as a fossil fuel substitute and a potential sustainable energy source. Water electrolysis powered by renewable resources is being considered as a sustainable approach to produce H 2. To cater the need, electrocatalysts with non-precious single metal atoms supported on a covalent organic framework (TM@COF SACs) have been proposed for HER. Single atoms of Co, Ni, Cu, and Zn were introduced onto the COF substrate. The thermodynamic stability, HOMO, LUMO energies, HOMO-LUMO energy gaps, DOS spectra, and change in the Gibbs free energy of adsorbed atomic hydrogen (ΔG H ∗) on the catalyst's surface are used to evaluate the catalytic performance of designed complexes for HER. Among all the considered complexes, Zn@COF demonstrated the highest potential to act as a single atom catalyst, with an E int value of −0.11 eV. Density functional theory (DFT) findings suggest that single Zn atom doped on the surface of the covalent organic framework with ΔG H ∗ value of −0.88 eV has a substantial effect on the performance of the HER. This research opens up new possibilities for the advancement and utilization of highly efficient, stable, and cost-effective single-atom catalysts for HER, thereby laying the foundation for future developments in this field. [Display omitted] • Theoretical investigation of designed 3d-transition metal atoms doped COF complexes. • HER activity of all the reported complexes is calculated. • Zn@COF catalyst shows the excellent HER performance with the ΔG H∗ value of −0.88 eV. [ABSTRACT FROM AUTHOR]

Nowadays, the pursuit of finding suitable supports for single atom catalysts (SACs) is rising in interest. Novel carbon-based nanostructures are most promising due to their unique properties such as high surface area, excellent stability, large degree of functionalization, and high electric conductivity. In this work, we investigated the potential application of late first-row transition metal doped cyclo [12]carbon (C 12) nanoring and its isoelectric analogues (Al 6 N 6 , and B 6 N 6) as SACs towards hydrogen evolution reaction (HER), via DFT calculations. Among all studied systems, Co@C 12 , Ni@C 12 , Cu@C 12 , and Ni@Al 6 N 6 showed the highest electrocatalytic potential towards the HER, as they show excellent stabilities with high interaction energies of −3.41, −2.40, −1.19, and −3.05 eV, respectively. Furthermore, the results of the electronic properties analysis revealed that these systems are sufficiently conducting with small band gaps. The activities of the proposed catalysts were evaluated by computing the Gibbs free energy of hydrogen evolution (ΔG H*), which is the main activity descriptor of the HER. The best catalytic activities were obtained for Co@C 12 , Ni@C 12 , Cu@C 12 , and Ni@Al 6 N 6 , having ΔG H* values of −0.23, 0.23, −0.14, and 0.18 eV, respectively. This study will help in finding novel, noble metal-free, and highly efficient catalysts for producing high purity hydrogen gas. [Display omitted] • Transition metal doped nanorings are evaluated for HER. • Anchoring Fe, Co, Ni, and Cu atoms on the nanorings is energetically favorable. • Calculated Gibbs free energies of hydrogen evolution are close to the optimum value. • Stability, spin state, thermodynamic, QTAIM, DOS, and FMO analyses are performed to investigate applicability of the designed SACs. [ABSTRACT FROM AUTHOR]

The hydrogen evolution reaction (HER) is a promising process to produce high purity hydrogen gas. However, the overpotential of this reaction hinders its practical applications. Single atom catalysts (SACs) are recently investigated by the scientific community to facilitate the HER. Herein, we studied the doping of late first-row transition metals on the B 12 P 12 and Al 12 P 12 nano-cages as SACs via density functional theory (DFT) calculations. Results show that all transition metals are chemisorbed on the support, with interaction energies ranging from −0.65 to −3.85 eV. The calculated Gibbs free energies of hydrogen evolution are −0.01, −0.06 and −0.20 eV for Ni@Al 12 P 12 , Ni@B 12 P 12 , and Co@B 12 P 12 , respectively, which are close to the optimum value of 0.00 eV, and comparable to the highly active Pt-based catalysts in literature. Our results indicate that the designed Ni@Al 12 P 12 , Ni@B 12 P 12 , and Co@B 12 P 12 SACs are excellent candidates as noble metal-free, sufficiently stable, and highly efficient electrocatalysts for HER. [Display omitted] • DFT investigation on the application of TM doped nano-cages toward the HER. • Doping of late first-row TMs on B 12 P 12 and Al 12 P 12 is energetically favorable. • Calculated ΔG H∗ are close to the optimum value of zero. • Thermodynamic, QTAIM, DOS, FMO, and NBO analyses are employed to analyze the SACs. [ABSTRACT FROM AUTHOR]

Barium tungstate (BaWO 4) has fascinating applications in the area of laser technology, solar cell, super capacitor, electronic devices and in photoluminescence. Electronic and optical behavior of BaWO 4 is the reasons behind all of these fascinating applications. This research work provides the evaluation of electronic and optical properties of BaWO 4 at the optimized cut-off energy value of 1200 eV by the implementation of Density Functional Theory (DFT) within the framework of CASTEP in Material STUDIO. The direct band gap and diamagnetic behavior of semiconductor BaWO 4 have been evaluate by band structure, PDOS and TDOS calculation. O 2p of V.B and W, Ba 5d of C.B are the occupied electronic states of BaWO 4. The highest band gap value of BaWO 4 corresponds to highest loss function and smallest value of dielectric constant. Absorption spectrum exhibits that BaWO 4 is an excellent UV absorber so it suitable for the formation of sensor, filter and for transparent conducting film for window layers on solar cell, solar control, and warming coatings. High refractive index value of BaWO 4 makes it useful for detector for dark matter and for scintillators. •Electronic and optical properties of BaWO4 calculated by CASTEP. •BaWO4 is an excellent UV absorber so it is helpful for filter and transparent conducting film for window layers on solar cell. •It is effective eco-friendly as it use as photocatylst for the degradation of water. •Useful for detector for dark matter and for scintillators because of high refractive index. •Help in electronic packing material and also as substrate material. [ABSTRACT FROM AUTHOR]

Designing of anode nanomaterials with an optimum cell voltage is an important challenge for high-performance lithium (Li) ion batteries. In this study, we have investigated the electrochemical potential of pristine and Li-doped magnesium oxide (Mg 12 O 12) and zinc oxide (Zn 12 O 12) fullerenes through density functional theory (DFT) simulations, with a focus on their potential applications in lithium-ion batteries. Specifically, we investigated the halide ion encapsulated oxide nanocages as a means to achieve this improvement. We examined both unaltered and halide encapsulated Mg 12 O 12 and Zn 12 O 12 with Li atom/lithium cation (Li/Li+). Our investigation delves into the geometric and electrochemical characteristics of Li/Li+ interactions with Mg 12 O 12 and Zn 12 O 12 nanocages. We analyzed adsorption energies (E ad) and frontier molecular orbitals (FMOs) of Li/Li+ ions with these nanocages to gain insights into how neutral or ionic Li affects their geometric and electrochemical properties. The initial cell voltages of bare Mg 12 O 12 and Zn 12 O 12 are found to be 0.61 and 0.57 V, primarily due to marginal distinctions in the adsorption energies of Li and Li+ bound systems. Notably, the encapsulation of various halides into Mg 12 O 12 and Zn 12 O 12 nanocages significantly enhanced the cell voltage. Among the considered halides, the encapsulation of fluoride anion (F −) into Mg 12 O 12 and Zn 12 O 12 stands out, leading to a remarkable increase in cell voltage of 4.05 and 3.55 V for lithium-ion batteries, respectively. Moreover, the use of toluene solvent further increased the E ad values of Li cation with pure and halides encapsulated oxides (Mg 12 O 12 and Zn 12 O 12) nanocages. Ultimately, the Gibb's free also decreased along with the decrease in the cell voltage which is encountered in the acceptable range. The most suitable anode nanomaterial is suggested to be Li doped F−@Mg 12 O 12 which has the most acceptable cell voltage of 1.59 V. The work also leads to more research work on the designing of halides encapsulated oxides fullerenes based secondary batteries for use in electrochemical energy storage devices. This work is a full-length guideline for the experimentalist to synthesize such systems to overcome the energy crises. [Display omitted] • Theoretically models of magnesium and zinc oxides nanocages are analyzed for use as anode in Na-ion batteries. • The electrochemical performance is enhanced by encapsulating halides inside magnesium and zinc oxides nanocages. • The energy gaps of both oxides nanocages are decreased by halides encapsulation and making them conductors. • The highest cell voltages of L i / F − @Mg 12 O 12 and L i / F − @Zn 12 O 12 are 4.05 and 3.55 V, respectively. [ABSTRACT FROM AUTHOR]

Herein, we present the detailed comparative study on geometric, electronic, optical and non-linear optical response of alkalis and superalkalis doped twisted graphene. The results illustrate that alkali metals and superalkalis interact with the central ring of the twisted graphene through non-covalent interactions which demonstrate the stability of the resultant complexes. NBO charges indicate the transfer of electrons from dopant (alkali metal atoms and superalkalis) towards twisted graphene sheet. Superalkalis doped twisted graphene complexes exhibit higher first hyperpolarizability values compared to alkali metals analogues. Among superalkalis doped complexes, K 3 O@C 104 H 52 shows the highest β o value of 1.68 × 105 au. In frequency dependent first hyperpolarizability analysis, strong second harmonic generation (SHG) response of K 3 O@C 32 H 15 complex is observed at both selected resonance frequency values (532 nm and1064 nm) whereas EOPE value of K 3 O@C 32 H 15 complex shows higher induced response at 1064 nm wavelength. The static hyperpolarizability (β o) further increases under the influence of applied electric field. Among all complexes, Li 3 O@C 32 H 15 graphene complex has the highest β o value (1.40 × 105 au) under applied electric field along x axis when sheet is in y - z plane. This analysis will be an important guideline for future studies on twisted graphene based NLO materials. Image 1 • Alkalis and superalkalis doped twisted nanographene (TGP) are theoretically analyzed. • Electronic and NLO properties of all doped complexes are investigated. • Reduced G HL suggests the change in conducting properties via doping. • Hyperpolarizability of superalkalis doped complexes are more as compared to alkalis doped complexes. [ABSTRACT FROM AUTHOR]

The barriers for the encapsulation and decapsulation of hydrogen ions (cationic hydrogen and hydride), atom, and molecule through silicon carbide nanotube are thoroughly studied. DFT method is selected to measure the kinetic barriers for the passage of hydrogen atom, ions and molecule through nanotube via scanning potential energy surface. The kinetic barriers for the passage (encapsulation and decapsulation) of hydrogen are very important to understand the mechanism of hydrogen storage and release. The barriers for the permeation of H, H+ and H− across SiC nanosheet are lower compared to hydrogen molecule (H 2). The exohedral and endohedral adsorption of hydrogen ions (cation and anion), atom and exohedral hydrogen molecule on silicon carbide are exothermic in nature. Whereas the encapsulation of hydrogen molecule in silicon carbide is endothermic. Electronic properties are analyzed through measurement of energy gap between highest occupied and lowest unoccupied molecular orbitals gap (G H-L) and the density of state (DOS) spectra. The G H-L analysis reveals that endohedral complexes have more pronounced effect on electronic properties compared to exohedral complexes. The SiC nanotube has highly favorable properties for storage and release of hydrogen ions, and atom. Image 1 • Storage of hydrogen molecule, atom and ions inside the pristine silicon carbide nanotube is studied via DFT. • The kinetic barriers of encapsulation and decapsulation are analyzed. • The permeation barriers for hydrogen atom are ions are lower than the molecular hydrogen. [ABSTRACT FROM AUTHOR]

[Display omitted] • Superalkalis doped bowel shaped silicon carbide complexes are studied via DFT method. • All complexes have electronic and thermodynamic stability. • First hyperpolarizability (β o) has increased up to 5979.99 au. • Superalkalis doping remarkably tunned the NLO response of all complexes. • Electronic excitation between superalkali and nanocluster is responsible for enhancement of NLO response. In the current study, the effect of superalkalis (Li 3 O, Na 3 O, and K 3 O) doping over bowl shaped silicon carbide (b- SiC) for geometrical, electronic and nonlinear properties has been investigated using DFT theory. The results revealed that doped b- SiC nanoclusters possess high thermodynamic stability as revealed from interaction energy up to −165.85 kcal/mol. The frontier molecular orbitals illustrate the occupation of electronic density in orbitals. Natural bond orbital charge analysis confirms the charge transfer from superalkalis to the b- SiC nanocluster. Furthermore, the electronic properties are rationalized from total density of states spectra. The highest first hyperpolarizability value (5979.99 au) is observed for isomer O of K 3 O@ b- SiC complexes. The electronic excitation is analyzed through UV–VIS analysis. Two-level model describing the internal factors responsible for enhancement of NLO response is also studied. The present work gives a guideline for the synthesis of nonlinear optical materials with greater efficiencies which can be used as building blocks in the modern world of optoelectronics. [ABSTRACT FROM AUTHOR]

Herein, we report the synthesis, characterization and biological evaluations of two novel organotin(IV) carboxylates (1 and 2). The structures of both complexes are confirmed by single crystal X-rays diffraction analysis. Density functional theory (DFT) studies are also executed to compare experimental (X-ray as well as spectroscopic) results with theoretical ones. Excellent correlation is observed between theoretical and experimental results. Furthermore, organotin(IV) carboxylates are evaluated against different bacterial stains (E. coli, S. aureus, K. pneumoniae and B. subtilis) and fungal stains (F. solani, A. fumigatus and A. niger). The complex 1 shows good antibacterial activity against B. subtilis (17 ± 0.32 mm), whereas complex 2 shows good antibacterial activity against E. coli (18 ± 0.41 mm) and B. subtilis (18 ± 0.41 mm). The complex 1 shows significant activity against A. fumigatus (28 ± 0.45 mm) and 2 shows good activity against A. fumigatus (16 ± 0.37 mm). To determine the interaction of organotin(IV) carboxylates with DNA, the interaction studies with salmon sperm DNA (SS-DNA) are also carried out through UV–vis absorption spectroscopy. The Gibbs free energies (ΔG) (−28.02 kJ/mol for complex 1 and -28.43 kJ/mol for complex 2) and high values of binding constants (K) (8.15 × 104 M−1 for complex 1 and 9.62 × 104 M−1 for complex 2) indicate that strong interactions are developed between organotin(IV) carboxylates and SS-DNA. Image 1 • Two new organotin(IV) carboxylates have been synthesized. • The structures are confirmed by spectroscopic as well as single crystal X-ray diffraction studies. • Promising antibacterial and antifungal activities of both complexes are observed. • High binding constant values are observed against SS-DNA. [ABSTRACT FROM AUTHOR]

Recently, significant progress is observed in the design and synthesis of nonlinear optical materials due to their optoelectronic and biomedical applications. In this report, a series of inorganic electrides (Li 2 F@Al 12 P 12 , Li 3 O@Al 12 P 12 and Li 4 N@Al 12 P 12) are designed by doping of Al 12 P 12 nanocluster with superalkalis (Li 2 F, Li 3 O and Li 4 N) and studied through density functional theory (DFT) for their geometrical, electronic and nonlinear optical properties. Computational results indicated that these superalkalis doped complexes possess high stability and low HOMO-LUMO gaps. Interaction energies reveal that adsorption of Li 4 N on Al top site of Al 12 P 12 results in highly stable structure (isomer J), where superalkali is strongly chemisorbed on the nanocage (E int. = −105.13 kcal mol−1). Moreover, the lowest HOMO-LUMO gap is also observed for J isomer of Li 4 N@Al 12 P 12 (0.44 eV), compared to 0.94 eV for alkali metal doped Al 12 P 12 nanocage and 3.36 eV for pure nanocage. Doping of superalkali on aluminum phosphide nanocage can bring considerable increase in first hyperpolarizabilities (β o) response of the nanocage along with deep ultraviolet transparency. The first hyperpolarizability (β o) for isomer J of Li 4 N@Al 12 P 12 is 6.25 × 104 au. This study may provide an effective strategy to design high performance NLO materials from stable inorganic electrides. Unlabelled Image • Li 2 F@Al 12 P 12 , Li 3 O@Al 12 P 12 and Li 4 N@Al 12 P 12 complexes are investigated for electronic and NLO properties. • FMOs and charge analyses reveal that the resultant inorganic electrides are transparent in deep UV region. • HOMO-LUMO gap of Li 4 N@Al 12 P 12 is decreased up to 0.44 eV, which suggests its conductivity comparable to metals. • Polarizability and hyperpolarizability values of Li 4 N@Al 12 P 12 are 899.06 au and 6.25 × 104 au , respectively. [ABSTRACT FROM AUTHOR]

Abstract Spectroscopic studies-based on 1D (1H NMR, 13C NMR), 2D-NMR (COSY, HMBC, HSQC), UV–visible, FTIR techniques and quantum chemical studies established on the density functional theory (DFT) were carried out for the natural withanolide glycosides, isolated from Withania Coagulans Dunal. The new glycoside withanolide named as (20R,22R)-14α,17,20β,27-trihydroxy-1-oxowitha-5,24-dienolide-27β-(O-β- d -glucopyranoside) (1), and a known withanolide (20R,22R)-14α-20β,27-trihydroxy-1-oxowitha-5,24-dienolide-3β-(O-β- d -glucopyranoside) (2) are reported here from W. coagulans. The molecular mass of these compounds were confirmed through Fast Atom Bombardment Mass Spectrometry (FAB-MS). Geometric and spectroscopic detailed were obtained from DFT calculations. 1H and 13C NMR theoretical values were found a little higher than the experimental values, but the trend in the chemical shift correlates well with the experimental values. The RMSD values of 1H and 13C NMR of 1 and 2 were 0.4 and 0.38, and 4.94 and 5.02 respectively. The calculated band gap was found 4.93 and 5.00 eV for 1 and 2 respectively which indicated the stable nature of these compounds towards redox reactions. Graphical abstract Image 1 Highlights • Isolation of a new and known withanolide glycosides from withania coagulans. • IR, UV–vis. 1D- and 2D- NMR data of the isolated compounds. • Quantum chemical calculation based on DFT studies. • DFT study proposes high resistivity towards redox reaction. • Similar location in both compounds of HOMO and LUMO with high band gap. [ABSTRACT FROM AUTHOR]

Removal of commonly used dyes from water bodies has recently gained great interest from the scientific community. Presence of the methylene blue (MB) dye in drinking water poses harmful effects on the human health. The large-scale removal of MB is achievable through highly efficient, inexpensive, renewable, and biodegradable adsorbents. Our research group has recently synthesized a sodium alginate-based hydrogel and explored its application towards the removal of MB. Previous results have shown that the synthesized hydrogel exhibits a high adsorption capacity of 51.34 mg/g under basic conditions. Herein, we employed the density functional theory (DFT) calculations to explore the mechanism of MB removal by using sodium alginate hydrogel at various pH levels. Results of this study have shown that under acidic/neutral conditions the removal of MB is endergonic (ΔG int = 6.10 kcal/mol). Whereas under basic conditions it is highly exergonic (ΔG int = −97.58 kcal/mol). Moreover, the QTAIM and NCI analyses have shown that the MB dye is chemisorbed to the absorbent via strong covalent-like interactions between the polymer's carboxylate groups and the hydrogens in MB. Furthermore, preferability of basic conditions have been confirmed by the large charge transfer (0.104 |e|), as compared to no charge being transferred in the acidic/neutral conditions. [Display omitted] • Removal of methylene blue by using alginate is validated in basic conditions via DFT calculations. • The interaction of methylene blue and alginate is highly exergonic. • ΔG int of MB@alginate is −97.58 kcal/mol. • QTAIM and NCI analyses proved the existing of electrostatic interactions. [ABSTRACT FROM AUTHOR]

In this study, oxygenated triarylmethyl (oxTAM) is investigated by DFT calculations as a drug carrier framework for Nitrosourea (NU) and Fluorouracil (FU) drugs. Based on the adsorption analysis i.e. , energies and distances between interacting atoms, it is found that oxTAM exhibits excellent carrier abilities for the delivery of FU (−1.53 eV & 2.00 Å) and NU (−1.33 eV & 2.12 Å) drugs. NCI and QTAIM results indicate the presence of hydrogen bonding in drug-carrier complexes. The values of dipole moment and global chemical descriptors show the significant reactivity of oxTAM for NU and FU drugs. Based on electronic property analysis, FU@oxTAM has a higher adsorption trend for complexation with oxTAM as compared to NU@oxTAM. Moreover, FU can easily release from the carrier due to the decreasing adsorption stability after protonation under an acidic environment as well as a short recovery time observed for the oxTAM carrier surface. Keeping in view all the above parameters, we inferred that oxTAM can serve as a potential drug delivery system for anticancer drugs including, Nitrosourea and Fluorouracil drugs. [ABSTRACT FROM AUTHOR]

Four new 3-(2-(3-Phenyl-5-substituted phenyl-4,5-dihydropyrazol-1-yl)thiazol-4-yl)-2H-chromen-2-one derivatives ( 1–4) were synthesized and fully characterized by spectroscopic techniques. The final structures of all chromenone analogues ( 1 – 4 ) were confirmed by single crystal X-ray diffraction analysis. Quantum chemical studies were performed to compare the results from the theoretical studies with the experimental (X-ray as well as spectroscopic) ones. The theoretically simulated geometric parameters and other spectroscopic properties agreed nicely with the experimental data. All compounds were evaluated for biological activity (acetyl cholinesterase inhibition potential). Compound 3 emerged as the most potent derivative in acetylcholine esterase (AChE) inhibition assay with IC 50  = 27.29 μM. The IC 50 of compound 3 is greater than the standard drug galantamine (IC 50  = 44.02 μM). To rationalize the potencies, molecular docking studies were also carried out. These docking results revealed a good correlation between binding energies values and in vitro AChE inhibition assay. [ABSTRACT FROM AUTHOR]

Synthesis, molecular structures and DFT investigations of two new complexes of Ni(II) and Co(III) with ( Z )-3-(3,3-dimethylbutanoyl)-1,1-diethyl-2-thiobiuret ligand are reported. Characterization of these complexes was achieved by spectroanalytical techniques (FT-IR, UV–vis and 1 H NMR), and the structures were finally confirmed unequivocally by single crystal X-ray diffraction analysis. The obtained data of UV–vis, FT-IR and 1 HNMR were compared with the literature values which satisfactorily confirmed the synthesis of ligand and their complexes. X-ray studies revealed the square planar and octahedral geometry of both Ni(II) and Co(III) complexes, respectively. Density functional theory (DFT) studies were performed to compare the theoretical results with experimental (X-ray as well as spectroanalytical) results, and good correlation was observed. Frontier molecular orbitals (FMOs) and molecular electrostatic potential (MEP) analyses revealed the reactivity and charge distribution in both complexes. [ABSTRACT FROM AUTHOR]