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The toxic chemical warfare agents (CWAs) are extremely harmful to the living organisms. Their efficient detection and removal in a limited time span are essential for the human health and environmental security. Twisted nanographenes have great applications in the fields of energy storage and optoelectronics, but their use as sensors is rarely described. Therefore, we have explored the sensitivity and selectivity of twisted nanographene analogues (C 32 H 16 , C 64 H 32 ) towards selected toxic CWAs, including phosgene, thiophosgene and formaldehyde. The interaction between CWAs and twisted nanographenes is mainly interpreted by considering the optimized geometries, adsorption energies, natural bond orbital (NBO), frontier molecular orbital (FMO), non-covalent interaction (NCI) and quantum theory of atoms in molecules (QTAIM) analyses. The structural geometries show that the central octagon of twisted nanographenes is the most favorable site of interaction. The interaction energies reveal the physisorption of selected CWAs on tNGs surface. The average energy gap change (%E H-L a ) and % sensitivity are quantitatively determined to evaluate the sensing capability of the twisted nanographenes. Among the selected CWAs molecules, the sensitivity of tNG analogues (C 32 H 16 and C 64 H 32 ) is superior towards thiophosgene (ThP), which is revealed by the high interaction energies of -8.19 and - 12.17 kcal/mol, respectively. This theoretical study will help experimentalists to devise novel sensors based on twisted nanographenes for the detection of toxic CWAs which may also work efficiently under the humid conditions., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2022 Elsevier B.V. All rights reserved.)

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]

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]

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]