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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]

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]

Promising sensor applications of graphdiyne for various gases and toxic molecules have extensively been studied; however, similar studies for the detection of chemical warfare agents (CWA) are not reported. Here, we report the adsorption of Lewisites (L1, L2, and L3), on graphdiyne nanoflake (GDY) using density functional theory (DFT) ωB97XD/6‐31+G (d,p) method. Our results show that Lewisite molecules are preferably physiosorbed at the triangular portion of GDY nanoflake. In particular, the binding of L3 (3‐chlorovinyl arsine) on GDY nanoflake is thermodynamically favorable than L1 (1‐chlorovinylarsonous dichloride) and L2 (2‐chlorovinylarsonous chloride). Symmetry adopted perturbation theory (SAPT0) analysis reveals that the least contribution of repulsive exchange component is present in case of L2@GDY complex. Further, the smallest HOMO‐LUMO energy gap, appreciable charge transfer (NBO), and largest red shift in ultraviolet‐visible (UV‐Vis) spectrum are also in accord with the higher %sensitivity of graphdiyne toward L2. Quantum theory of atom in molecule (QTAIM) analysis is performed to get insight into the noncovalent interactions. Therefore, it is predicted that the sensitivity of GDY nanoflake is potentially high for Lewisite especially for L2. [ABSTRACT FROM AUTHOR]

Chemical warfare agents (CWAs) are highly poisonous and their presence may cause diverse effects not only on living organisms but also on environment. Therefore, their detection and removal in a short time span is very important. In this regard, here the utility of graphdiyne (GDY) nanoflake is studied theoretically as an electrochemical sensor material for the hazardous CWAs including A-230, A-232, and A-234. Herein, we explain the phenomenon of adsorption of A-series CWAs on GDY nanoflake within the density functional theory (DFT) framework. The characterisation of adsorption is based on optimised geometries, BSSE-corrected energies, SAPT0, RDG, FMO, CHELPG charge transfer, QTAIM and UV-Vis analyses. The calculated counterpoise adsorption energies for reported complexes range from − 13.70 to − 17.19 kcal mol−1. These adsorption energies show that analytes are physiosorbed onto GDY which usually takes place through noncovalent interactions. The noncovalent adsorption of CWAs on GDY is also attributed by the SAPT0, RDG and QTAIM analyses. These properties also reveal that dispersion factors dominate in the complexes among many noncovalent components (exchange, induction, electrostatic, steric and repulsion). In order to estimate the sensitivity of GDY, the %sensitivity and average energy gap variations are quantitatively measured by energies of HOMO and LUMO orbitals. In terms of adsorption affinity of GDY, UV-Vis analysis, CHELPG charge transfer and DOS analyses depict an appreciable response towards these toxic CWAs. [ABSTRACT FROM AUTHOR]

Excess electron generation through doping with alkali and superalkali metals is well known to enhance NLO responses. On the contrary, superhalogen doping is an unexplored dimension. Herein, we report the first ever examples where superhalogen doping alone is introduced as a new and effective approach to impart large NLO responses. Density functional theory (DFT) calculations illustrate that superhalogen (BeF3 and BeCl3)-doped cyclic oligofurans (nCF) possess exceptionally high NLO responses (first hyperpolarizability (β0), hyper-Rayleigh scattering coefficient (βHRS), electro-optical Pockels effect (EOPE), second harmonic generation (SHG), and nonlinear refractive index (n2)), which are not trivial for organic compounds. Upon doping with superhalogens, the first hyperpolarizability (β0) of nCF increases to 3 × 105 a.u. in the BeF3@6CF complex, whereas the β0 values of the BeF3@5CF, BeCl3@5CF and BeCl3@6CF complexes are 6 × 104, 3 × 104 and 4 × 104 a.u., respectively. An enormously large third order nonlinear optical response coefficient with an electric field-induced second harmonic generation (ESHG) value of 2.1 × 109 a.u. is observed for the BeCl3@6CF complex. The remarkable NLO responses of the superhalogen-doped cyclic oligofuran complexes are due to the electron withdrawing nature of the halogen atoms, which are responsible for withdrawing electrons from the oxygen atoms of nCF to create poles. The significant hyperpolarizability (β0) of the BeF3@6CF complex is due to the most electronegative nature of fluorine. Furthermore, these results are rationalized through a two-level model. Bvec values are calculated for these complexes because they give more meaningful numbers from an experimental point of view. The stability of the complexes is judged through interaction energies, whereas electronic properties are calculated by chemical reactivity descriptors, the HOMO–LUMO gaps (Eg) and NBO charge transfer analysis. TD-DFT calculations reveal that the maximum absorbance for the BeF3@6CF complex is shifted to the longest wavelength. [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]

Linear conducting polymers are extensively studied as sensors for various analytes, whereas studies on cyclic analogues are limited. In this study, sensor applications of cyclic oligothiophenes (nCTs) have been explored by means of DFT (density functional theory) calculations. Three models, namely, five (5CT)-, six (6CT)- and seven (7CT)-membered cyclic oligothiophenes are evaluated against twelve different gaseous analytes. For optimization of geometries and interaction energies, the B3LYP method including Grimme's dispersion correction (B3LYP-D3) was applied with the 6-31++G(d,p) basis set. Chemical interactions of nCTs with NH3, CO, CO2, N2H4, HCN, H2O2, H2S, CH4, CH3OH, SO2, SO3 and H2O analytes are analyzed via interaction energies, Gibbs free energies, electronic properties and UV-Vis analysis. The interaction energies are quantitatively correlated with the volume of the cyclic oligothiophene (nCT). The electronic properties are calculated at the widely accepted B3LYP/6-31G(d) level of theory; however, the TD-B3LYP/6-31G(d) method is used for the UV-Vis analysis. Symmetry-adapted perturbation theory reveals that the 5CT system is highly sensitive towards analytes as compared to the 6CT and 7CT systems. This assumption is also strengthened by the HOMO–LUMO gaps and excited state properties. ESAPT, HOMO–LUMO gaps, NCI, and NBO charge transfer suggest that nCTs are highly sensitive towards SO3 followed by SO2. The density of state spectra shows the reasonable variation in the peaks of nCTs upon interaction with SO2 and SO3 analytes. The findings of this study suggest that cyclic oligothiophenes can effectively be used for the rational design of atmospheric sensors, which are superior to the conventional sensors. [ABSTRACT FROM AUTHOR]

Polypyrrole is experimentally reported as an excellent sensor for biological molecules including urea and uric acid. DFT calculations at M05-2X/6–31++G(d,p) are performed to gain theoretical insight into the sensing mechanism of polypyrrole for urea, uric acid, acetamide and sulfonamide. Geometry optimization and electronic property calculations have been performed on a series of oligopyrrole (1, 3, 5, 7 and 9) complexes, and the properties are extrapolated to infinite polymer through 2nd degree polynomial fit. Energy decomposition analyses (SAPT0) have been performed to demonstrate the contribution of electrostatic, induction, exchange and dispersion. The trend of SAPT0 interaction energies is very much comparable to that of binding energies. The noncovalent components of SAPT0 regularly increase with oligomer chain length; however, these components become almost constant after trimer for urea, acetamide, and sulfonamide. The increase in interaction and SAPT0 energies illustrate an increase in sensitivity of polypyrrole. Charge transfer and electronic properties also illustrate the high sensitivity of polypyrrole for uric acid. Energy difference between HOMO and LUMO orbitals of polypyrrole decreases upon doping with analytes. The decrease in the HOMO-LUMO gap shows an increase in the conductivity of polypyrrole. Our results indicate that polypyrrole has the highest sensing ability for uric acid, consistent with the experimental observations. [ABSTRACT FROM AUTHOR]

The desirability of the high nonlinear response of two-dimensional (2D) materials for electronics and optoelectronic devices drove us to investigate the nonlinear optical (NLO) behavior of alkali metal atom (AA) doped lithiated boron-containing hexahydroxy-triphenylene (LiBHHTP). In this context, the geometric, electronic, optical, and NLO properties are investigated. The doped AA atoms including Li, Na, and K preferably interact via the oxygen atoms of the LiBHHTP surface. The stability of the doped complexes is revealed by the interaction energies (E int), which are −22.90, −16.10, and −16.52 kcal/mol for Li@LiBHHTP, Na@LiBHHTP, and K@LiBHHTP complexes, respectively. The alterations in the electronic behavior of LiBHHTP are observed upon doping with alkali atoms via Frontier Molecular Orbital (FMO), Natural Bond Orbital (NBO), and the Density of State (DOS) analyses. The FMO analysis reveals that these complexes are electride in nature with absorption transparency in the UV–Vis range. Finally, the NLO behavior of designed complexes is evaluated through static and dynamic hyperpolarizabilities. Among reported complexes, K@LiBHHTP exhibits significantly large static hyperpolarizability (βₒ), 2.24 × 105 au. The dynamic NLO response of doped LiBHHTP complexes is also high, where the values are ranged in between 3.67 × 105 and 6.04 × 108 au at 1064 nm. This article not only highlights the effects of alkali atom doping on the NLO behavior of materials but also presents the first Lithiated boron-containing triphenylene as a next-generation optoelectronic material. [Display omitted] [ABSTRACT FROM AUTHOR]

In this study, for the first time, static and dynamic NLO responses of pure and superhalogen doped aromatic heterocyclic monomers have been investigated by using density functional theory (DFT) calculations. The thermal, electronic, linear, and nonlinear optical properties are computed at the ωB97XD/6-31+G(d,p) method. The thermodynamic stabilities of reported complexes are estimated based on interaction energies, which are in the range of −28.06 to −83.20 kcal/mol. The lowest interaction energies are observed for AlF 4 @X (X = C 4 H 4 NH, C 4 H 4 O, C 4 H 4 S, and C 5 H 5 N) complexes, which correspond to their higher stabilities. The appreciable decrease in the HOMO-LUMO energy gap (E gap) is an indicative of the increase in reactivity after doping with superhalogens. The decrease in E gap is further demonstrated with the help of density of state (DOS) analysis. The significant nonlinear optical responses of the superhalogen doped aromatic heterocyclic monomers are due to the strong electron-withdrawing nature of the fluorine atom. Overall, the results indicate the high NLO response for the AlF 4 @X complexes due to the presence of four electron-withdrawing fluorine atoms in AlF 4. The NLO results are further analyzed through the two-level model. • Superhalogen doping of aromatic heterocyclic monomers is investigated for enhancement of NLO response. • HOMO-LUMO gap significantly decreases upon complexation. • AlF 4 @X exhibit significant thermodynamic stability upto −83.20 kcal/mol. • AlF 4 @X showed excellent third order nonlinear response. [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]

The sensing affinity of C 4 N is the most fascinating topic of research due to its excellent chemical and electronic properties. Moreover, owing to the highly active porous cavity, C 4 N can easily accommodate foreign molecules. Herein, we studied the adsorption properties of carbamate insecticides (CMs) namely, Dimetalin (DMT), Carbanolate (CBT), Isolan (ISO) and Propoxur (PRO) using density functional theory calculations. All the results are calculated at widely accepted ωB97XD functional along with 6-31G(d, p) basis set. The calculated counterpoise corrected interaction energy of the reported complexes ranges between −20.05 and −27.04 kcal/mol, however, the interaction distances are found to be higher than 2.00 Å. The values of interacting parameters depict that the carbamate molecules are physisorbed via noncovalent interactions that can easily be reversible. Moreover, the binding of selected insecticides notably changes the electronic structure of C 4 N. The electronic changes are characterized by the energies of HOMO & LUMO, their energy gaps and CHELPG charge transfer. The charge density difference between C 4 N surface and carbamate pesticides are characterized by EDD and CDA analysis. Moreover, the ab initio molecular dynamic study reveals that the complexes are stable even at 500 K. The photochemical sensing properties of C 4 N are estimated by time dependent UV–Vis calculations. The high sensitivity of C 4 N towards considered analytes enable it to act as a promising sensor for toxic pesticides. [Display omitted] • The sensing of C 4 N towards carbamate insecticides is investigated within the framework of DFT. • The results are characterized by the geometric, energetic, electronic, and optical analyses. • All the results are computed at ωB97XD/6-31G (d,p) level of DFT. • The trend of thermodynamic stability of complexes is as follow; DMT@C4N > CBT@C4N > ISO@C4N > PRO@C4N. [ABSTRACT FROM AUTHOR]

C 4 N is a novel porous two-dimensional material with fascinating electronic and chemical properties. Thereby, the sensing ability of C 4 N is the most aspect topic of research nowadays. In this study, potential application of C 4 N nanoflake as a chemical sensor for the toxic pesticides has been investigated using density functional theory calculations. The sensing ability of C 4 N for pesticides is evaluated through the interaction energy, noncovalent interaction index (NCI), quantum theory of atoms in molecule (QTAIM), molecular orbitals and CHELPG charge transfer analyses. The first principle calculations on ωB97XD/6-31G(d, p) level of DFT show that the C 4 N is selectively sensitive to Dichlorodiphenyltrichloroethane (DDT), Fenitrothion (FNT), Dimethoxy (DMDT), Ronnel (RN) and Fenthion (FT). The interaction of pesticides leads to the significant changes in the electronic structure of C 4 N. The observed sequence of interaction energy of our reported complexes is DDT@C 4 N > FNT@C 4 N > DMDT@C 4 N > RN@C 4 N > FT@C 4 N. The electronic structure changes can be demonstrated from two aspects: the strong interaction between pesticide molecule and C 4 N, the variation in HOMO-LUMO orbital energies and charge transfer from C 4 N to pesticide. The charges distribution between analytes and C 4 N nanoflake on interaction is analyzed by the electron density differences (EDD) and charge decomposition analysis (CDA). Our results reveal the potential application of C 4 N in electronic and sensor devices especially for the detection of toxic chemicals. [Display omitted] • The sensing of C 4 N nanoflake toward pesticides is investigated theoretically. • The results are based on the geometric, energetic, and electronic analyses. • ωB97XD and M052X-D3/6-31G (d,p) levels of DFT are implemented to measure the sensing affinity of C 4 N. • The thermodynamic stability is in the order of DDT@C 4 N > FNT@C 4 N > DMDT@C 4 N > RN@C 4 N > FT@C 4 N. [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]

[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]

Although, the sensor applications of straight chain conducting polymers are well explored, but, the cyclic analogues are not much explored in this regard. The density functional theory calculations are performed to study the interaction behaviour of tetracyclic oligomers such as tetrapyrrole (4CP), tetrafuran (4CF) and tetrathiophene (4CT) for the detection of harmful gases like, phosgene, thiophosgene and formaldehyde. The most stable interaction configurations, interaction energies (E int), interaction distance (D int), SAPT0 energies, NCI, NBO charge transfer, HOMO-LUMO gaps and maximum absorbance are evaluated to understand the sensitivity and selectivity of these cyclic analogues toward poisonous gases. The results of all these properties illustrate that 4CP exhibits the highest sensitivity towards analytes with the sequence of formaldehyde > phosgene > thiophosgene. The interaction energies are −10.91, −9.03 and −7.58 kcal mol−1 for fd@4CP, ph@4CP and tph@4CP complexes, respectively. SAPT0 results depict that the electrostatic forces have strong influence in these complexes which indicate the presence of strong hydrogen bond between 4CP and analytes. However, this is not the case in other oligomer-analyte complexes especially in 4CT based complexes. The highest sensitivity of 4CP enables it to act as promising sensing material for formaldehyde, phosgene and thiophosgene as compared to 4CF and 4CT. Image 1 • Sensing affinities tetracyclic analogues have been investigated. • Toxic chemicals namely phosgene, thiophosgene and formaldehyde are investigated. • ωB97XD/6-31 + G (d, p) method of DFT has implemented. • Tetracyclic pyrrole has high sensitivity over furan and thiophene analogues. [ABSTRACT FROM AUTHOR]

Nonlinear optical (NLO) switchable materials play a crucial role in the fields of electronics and optoelectronics. The selection of an appropriate switching approach is vital in designing such materials to enhance their NLO response. Among various approaches, thermos-switching materials have shown a 4-fold increase in NLO response compared to other photo-switching materials. In this study, we computationally investigated the geometric, electronic, and nonlinear optical properties of reversible lactone-based thermochromic compounds using the ωB97XD/6-311+G (d,p) level of theory. Molecular orbital studies are employed to analyze the electronic properties of the close and open isomers of these compounds, while time-dependent density functional theory (TD-DFT) analysis is utilized to evaluate their molecular absorption. Our findings reveal that the π-electronic conjugation-induced delocalization significantly influences the ON-OFF switchable nonlinear optical response of the lactone-based thermochromic compounds. Notably, among all compounds, the open isomer of lactone 2 exhibits the highest hyperpolarizability value (6596.69 au). Furthermore, we extended our analysis to investigate the frequency-dependent second and third-order hyperpolarizabilities. The most pronounced frequency-dependent NLO response is observed at 532 nm. Additionally, we calculated the refractive index of these thermochromic compounds to further assess their nonlinear optical response. The open isomer of lactone 1 demonstrates the highest refractive index value (3.99 × 10−14 cm2/W). Overall, our study highlights the excellent potential of reversible thermochromic compounds as NLO molecular thermos-switches for future applications. [Display omitted] • NLO response of lactone based thermochromic compounds is studied. • The open isomer of lactone exhibits higher static first hyperpolarizability than the close isomer. • Frequency dependent NLO increases with increasing frequency. • The open isomer of lactone 1 has the highest refractive index value of 3.99 × 10−14 cm2/W. [ABSTRACT FROM AUTHOR]

Despite the numerous publications describing the photocatalytic and electronic properties of heptazine-based C 3 N 4 , the systematic study on the sensing behavior of pure heptazine-C 3 N 4 toward harmful chemical warfare agents (CWAs) is still lacking. Herein, we performed DFT calculations to investigate the adsorption behavior of C 3 N 4 toward various harmful and toxic CWAs including formaldehyde (OCH 2), thioformaldehyde (SCH 2), phosgene (OCCl 2), and thiophosgene (SCCl 2). ωB97XD functional of DFT along with 6–31G (d, p) basis set is used for all calculations for accurate estimation of noncovalent interactions. The CWAs are physiosorbed onto the C 3 N 4 having calculated interaction energy between −16.01 and −11.00 kcal/mol. Noncovalent interactions are further analyzed by symmetry-adapted perturbation theory (SAPT0), noncovalent interaction index (NCI), and quantum theory of atoms in molecules (QTAIM) analyses. The electronic behavior is characterized by the HOMO and LUMO energies, their energy gaps, and natural bond orbital (NBO) charge transfer. The charge transportation either donation or back donation is characterized by energy density difference (EDD) and charge decomposition analysis (CDA) analyses. The results demonstrate the trend of sensitivity of C 3 N 4 for toxic gases is OCH 2 @C 3 N 4 > SCH 2 @C 3 N 4 > OCCl 2 @C 3 N 4 > SCCl 2 @C 3 N 4. This theoretical work suggests that the C 3 N 4 can act as a good electrochemical sensor for a variety of toxic gaseous molecules. [Display omitted] • The sensing abilities of C 3 N 4 towards toxic molecules have been characterized by using ωB97XD/6-31G(d, p) level of DFT. • The sensing behavior of C 3 N 4 is studied through interaction geometries, energies, and electronic properties. • Among designed structures, OCH 2 @h-g-C 3 N 4 exhibits the strongest interaction due to electrostatic interactions. • C 3 N 4 exhibits significant sensitivity towards toxic molecules. [ABSTRACT FROM AUTHOR]

The development of anode materials with an optimum cell voltage and better stability is an important challenge for high-performance Li-ion batteries. In this study, we have investigated the electrochemical potential of pristine and Li-doped C 60 fullerene through density functional theory (DFT) simulations, with a focus on their potential applications in lithium-ion batteries. Our findings reveal that exohedral doping with a more electronegative counter anion can significantly increase the cell voltage. Particularly, when lithium cations are encapsulated within C 60 fullerene with antimony hexachloride (SbC l 6 −) as the counter anion, the highest cell voltage of 2.06 V is achieved. Furthermore, we have explored the impact of substituting carbon atoms with boron, nitrogen, phosphorus, and silicon on the Gibbs free energy change and cell potential. These substitutions led to an acceptable cell voltage compared to pristine C 60 fullerenes where the most suitable cell voltage of 1.75 V is observed for SbCl 6 /Li@C 59 B. This enhancement occurs because boron increases the electron deficiency of C 60 fullerene, thereby promoting stronger interactions with electronegative counter anions. These systems with a cell voltage of 1.75 V are deemed ideal candidates in lithium-ion batteries. [Display omitted] • The electrochemical potential of C 60 fullerenes doped with counter anion is studied. • The cell potential is enhanced by substitution of carbon atom with hetero-atoms. • The most suitable cell voltage of 1.75 V is observed for SbCl 6 /Li@C 59 B. [ABSTRACT FROM AUTHOR]