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Graphyne (GYN) has received immense attention in gas adsorption applications due to its large surface area. The adsorption of toxic ammonia and nitrogen halides gaseous molecules on graphyne has been theoretically studied at ωB97XD/6–31 + G(d, p) level of DFT. The counterpoise corrected interaction energies of NH3, NF3, NCl3, and NBr3 molecules with GYN are − 4.73, − 2.27, − 5.22, and − 7.19 kcal mol−1, respectively. Symmetry-adapted perturbation theory (SAPT0) and noncovalent interaction index (NCI) reveal that the noncovalent interaction between analytes and GYN is dominated by dispersion forces. The significant change in electronic behavior, i.e., energies of HOMO and LUMO orbitals and NBO charge transfer correspond to the pronounced sensitivity of GYN towards considered analytes, especially NBr3. Finally, TD-DFT calculation reveals a decrease in electronic transition energies and shifting of adsorption to a longer wavelength. The recovery time for NX3@GYN is observed in nanoseconds, which is many orders of magnitude smaller than the reported systems. The recovery time is further decreased with increasing temperature, indicating that the GYN benefits from a short recovery time as a chemical sensor. [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]

[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 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]

The chemical warfare agents (CWAs) are highly toxic for living systems and environment. These diverse effects of CWAs, especially blistering agents, need the development of highly selective sensors for their rapid and effective detection. Herein, by using density functional theory calculations, we explained the adsorption of nitrogen (NM) and sulphur mustard (SM) blistering agents on graphdiyne (GDY) sheet. The calculated adsorption energies illustrate the physisorption of blistering (SM & NM) agents on the graphdiyne surface. The symmetry adopted perturbation theory (SAPT) analysis predicts that the dispersion is a dominating component of interaction energy. Reduced density gradient (RDG) and quantum theory of atoms in molecules (QTAIM) analyses are performed to justify the nature of interactions. Based on QTAIM analysis, the interaction energies between graphdiyne and blistering agents are noncovalent in nature. Furthermore, RDG results reveals that the van der Waals interactions i.e., dispersion forces dominate in the complexes. The %sensitivity and average energy gap variations are illustrated by HOMO-LUMO gaps. The detection ability of graphdiyne is further studied using UV–Vis analysis, NBO charge transfer and density of state analysis. These properties depict the appreciable sensitivity of graphdiyne towards blistering agents (SM and NM). We believe that the results of this study are fruitful for experimentalist to design highly sensitive CWAs sensors using graphdiyne sheet. Unlabelled Image • The adsorption of blistering agents on GDY is studied by ωB97XD/6-31+G(d,p) method of DFT. • Adsorption behaviour is elucidated by SAPT, RDG and QTAIM analyses. • The dispersion forces dominate between BA-GDY complexes. • This study shows that GDY sheet has high sensitivity towards blistering agents. [ABSTRACT FROM AUTHOR]