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[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]

[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] • Drug carrying application of Triazine-based COF toward Tegafur is investigated via DFT calculations. • Boron-doping makes the Triazine-COF more applicable for Tegafur delivery. • Boron-doped Triazine-COF is more sensitive toward Tegafur. • Drug recovery time is better than previously reported carriers. The therapeutic potential of Triazines-based six-membered ring covalent organic framework (COF) and respective boron doped derivative toward anticancer drug i.e. , Tegafur (TG) is evaluated using the first principles DFT calculations. The geometric, energetic, and electronic properties of TG@Triazine and TG@TriazineB2 are computed to explore and compare the efficacy of selected COFs as drug carrier systems. The strength of the adsorption of tegafur onto the triazine-COFs is illustrated through the counterpoise corrected adsorption energies (Ecp). The computed Ecp of TG@Triazine and TG@TriazineB2 are −21.81 and −25.57 kcal/mol, which illustrate the physisorption of the drug on adsorbent. The nature of interactions i.e. , physisorption between tegafur and Triazine COFs is further illustrated via the noncovalent interaction index (NCI) plot and quantum theory of atom in molecules (QTAIM), which illustrated that the weak dispersion forces are present between the drug and COF adsorbents. In comparison, the adsorption strength is significantly high in boronated triazineB2 COF. The electronic properties, including HOMO-LUMO analysis and NBO charge transfer analysis, reveal the significant variation in the electronic behavior of triazine COF, upon doping with boron, the E g (HOMO-LUMO gap) of pristine Triazine (4.15 eV) reduced to 0.49 eV in TriazineB2 analogue. This significant decrease in the E g of Triazine on boron doping illustrates the shifting of the semiconducting behavior of pristine Triazine to the metallic nature of TriazineB2, thus the electron transportation becomes double the magnitude (0.018 |e|) on interaction with tegafur drug as compared to 0.07 |e| in TG@Triazine. Finally, the recovery time is computed to illustrate the time taken by the drug in detaching at the active site. With this study, it is confirmed that the triazine-COF can be a significant drug carrier, however, the doping of boron further enhances the therapeutic potential of the adsorbent. [ABSTRACT FROM AUTHOR]

[Display omitted] • The report compares the adsorption of small gaseous molecules including, N 2 O, NO 2 , NO, H 2 S, SO 2 , and SO 3 onto the Be 12 O 12 , Mg 12 O 12 & Ca 12 O 12 nanocages within the density functional theory framework. • Our thermodynamic analysis reveals that the gaseous molecules strongly bind with C 12 O 12 nanocage with the maximum interaction energy of ∼ 124 kcal/mol for SO 3 @Ca 12 O 12. • The general trend of adsorption of small gaseous molecules onto the selected nanocages is as follows Ca 12 O 12 > Mg 12 O 12 > Be 12 O 12. • These gaseous molecules cause a significant effect on the electronic behaviour of nanocages. The gas sensing applications of nanocages find intense attention in environmental monitoring. In this research, the adsorption of nitrogen and sulfur-containing gaseous molecules i.e., N 2 O, NO 2 , NO, H 2 S, SO 2, and SO 3 on inorganic oxide nanocages are analyzed through DFT simulations. The adsorption of gaseous molecules with Be 12 O 12 , Mg 12 O 12, and Ca 12 O 12 is illustrated through the adsorption energies, optimized geometries, and electronic properties like HOMO-LUMO energies and NBO analysis. Our theoretical analysis indicates that the molecules strongly bind with the Ca 12 O 12 nanocage. The adsorption energies of N 2 O@Ca 12 O 12 , NO 2 @Ca 12 O 12 , NO@Ca 12 O 12 , H 2 S@Ca 12 O 12 , SO 2 @Ca 12 O 12 and SO 3 @Ca 12 O 12 are −11.79, −46.53, −26.51, −50.26, −78.64 and −123.62 kcal/mol, respectively. Moreover, the HOMO-LUMO orbital analysis, density of state analysis (DOS), and natural bond orbital (NBO) analysis illustrate the significant impact of adsorption of these molecules on the electronic properties of respective nanocages, especially Ca 12 O 12. Finally, it can be concluded that the Ca 12 O 12 nanocage shows promising sensitivity towards the gaseous molecules which is followed by Mg 12 O 12 and Be 12 O 12. [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]

[Display omitted] • The adsorption of hazardous CH 3 X (X = F, Cl & Br) molecules on C 4 H 4 NH, C 4 H 4 O, C 4 H 4 S and C 6 H 6 monomer units has been studied. • The adsorption behaviors are evaluated by the geometric conformations, adsorption energies, SAPT and QTAIM topological analyses. • The effect of fluorination on the adsorption behavior is quantified. • The increase in adsorption strength is observed for the fluorinated adsorbents. Despite the numerous publications describing the synthesis and electronic properties of fluorinated furan, thiophene and pyrrole, the systematic overview of their adsorption applications is still lacking. In this study, the effect of fluorination on the adsorption properties of furan (C 4 H 4 O), thiophene (C 4 H 4 S), pyrrole (C 4 H 4 NH) and benzene (C 6 H 6) are investigated with the help of density functional theory (DFT) calculations. Herein, the adsorption energies of CH 3 X (X = F, Cl & Br) on C 4 H 4 O, C 4 H 4 S, C 4 H 4 NH and C 6 H 6 and their fluorinated analogues are calculated using ωB97XD/6-31+G(d, p) level of theory. The results of the adsorption energies and symmetry adapted perturbation theory (SAPT0) reveal that the adsorption affinity of adsorbent is enhanced upon fluorination due to the increasing dispersion forces. To comprehensively investigate the variation in the electronic properties of nonfluorinated and fluorinated systems, the HOMO, LUMO orbitals and NBO charges are analyzed. The isosurfaces of orbitals show that the electron density is more localized onto the fluorinated adsorbents which are probably due to the presence of multiple electronegative fluorine atoms. Owing to the electron-withdrawing nature of fluorine, the electronic charges are transferred from CH 3 X to fluorinated adsorbents while the charges are shifted from nonfluorinated adsorbents to CH 3 X. Furthermore, the TD-DFT calculations reveal that the electronic transition energies are significantly decreased in most of the fluorinated complexes especially, CH 3 X@C 4 F 4 S and CH 3 X@C 4 F 4 NH. With these findings, it can be postulated that fluorine substitution can significantly surge the electronic and adsorption properties of sensor materials. [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]

• The structural, electronic parameters and sensitivity towards DNA bases of cyanine dyes are studies theoretically. • Significant change in electronic properties is observed upon interaction with DNA base pairs (adenine, cytosine, guanine and thymine). • Sensitivity of cyanine dyes towards DNA bases decreases with the increase in methine chain. In the current study, the DFT calculations are performed to investigate the binding properties of nonsymmetric cyanine dyes (1a, 1b, 1c and 1d) for DNA base pairs. The effect of change in methine chain between two heterocycles on reactivity is explored through chemical reactivity descriptors (Global) including ionization potential (IP), electron affinity (EA), hardness (η) , softness (S), electronegativity (χ) and MEP (molecular electrostatic potential). The results of reactivity descriptors reflect the increase in the sensitivity of cyanine by increasing methine chain. Interaction behavior of cyanine dyes 1a to 1d with DNA nitrogenous bases is rationalized by comparing the electronic and geometric parameters. The interaction energies calculated at M05-2X/6-31++G(d,p) level of theory, suggest stronger interaction of cyanine dyes with DNA nitrogenous bases. The choice of density functional for UV–Vis is obtained through a benchmark study against available experimental data. Red shift in UV–Vis spectrum is obtained upon interaction with nucleic bases. [ABSTRACT FROM AUTHOR]