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The detection of toxic molecules has gained imperial attention to protect living organisms and their environment. The broadly explored sensor behaviour of triazine-based C3N4 reveals their ultra-high sensitivity towards numerous toxic molecules e.g., chemical welfare agents. However, another potential analogue of C3N4 composed of heptazine exhibits remarkable electrical and optical properties but has not been much explored in sensor technology, especially for toxic pollutants. Keeping this in mind, the sensing performance of heptazine-based g-C3N4 is explored for the detection of toxic amides by using First Principles calculations. In this context, acryloyl amide (C2H3CONH2), acryloyl chloride (C2H3COCl), fluoroacetic acid (C2H3FCOOH), flouroaceta amide (C2H2FONH2), flouroacetyl chloride (C2H2FOCl) are selected as toxic pollutants; herein, for the ease of understanding, these molecules are represented as AAM, ACl, FAAc, FAA, & FACl, respectively. The electrochemical sensitivity of g-C3N4 is determined via geometric, energetic, and electronic properties analysis, whereas the photochemical sensitivity is explored by UV–Vis absorption analysis based on TD-DFT calculations. The interaction energies of studied molecules on C3N4 range between − 9.09 and - 23.39 kcal/mol depending upon the type of interactions e.g., hydrogen bonding or dispersion, which are explained on the basis of Symmetry Adopted Perturbation Theory, Non-Covalent Interaction Index, and Quantum Theory of Atoms in Molecules analyses. The density of State analysis, Frontier Molecular Orbitals and NBO charge transfer characterized that the electronic behaviour of g-C3N4 can be an effective sensor material with a semiconducting nature and significant charge transfer. Lastly, UV–Vis absorption analysis confirms the photosensitivity of g-C3N4 upon interaction with toxic molecules. [ABSTRACT FROM AUTHOR]

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]

In organic photovoltaic technology, tailoring the acceptor or donor unit to enhance intramolecular charge transfer is a well-known approach, however, the effect of modifying conjugated bridge units is an underdeveloped phenomenon. In this study, this approach has been focused, where a series of conjugated bridges including, a) electron-excessive heterocycles, b) electron-deficient heterocycles, and c) short-chain unsaturated hydrocarbons have been substituted from thiophene bridge-containing D-π-A; N-methyl-4,5-diazacarbazole (donor) and bay-annulated indigo (acceptor) molecule. This quantum chemical study aims to investigate the effect of various types of π-conjugated bridges on the electronic structure and solar cell activity of already reported material. The selected π-conjugated bridges include electron-excessive (furan, pyrrole, & thiophene) and electro-deficient (diazine, tetrazine, & pyridine) heterocycles, and short-chain hydrocarbons (ethylene & ethyne). The optimized structural parameters e.g., dihedral angles (θ), distortion energies (E dis), & bond distances (d), and electronic behaviour i.e., Frontier Molecular Orbitals (FMO), Electrostatic Potentials (ESP), Density of States (DOS) spectra, dipole moments (μ), and absorption spectra of the hypothetically designed molecules are estimated using density functional theory calculations. The solar cell proficiency is investigated with transition dipole moment (μ T), reorganization energy (RE), Transition density matrix (TDM), exciton binding energy (E b), and open circuit voltage (Voc). Our finding encompassed that our designed D-π-A molecules show significant improvement in their electronic behaviour, especially when the thiophene bridge of the reference molecule is substituted with the excess electron heterocycles, especially pyrrole. The HOMO-LUMO gap of this particular molecule (MPy) is reduced to 2.07 eV, resulting in the significant charge transfer between donor and acceptor units (0.15 e-). Moreover, the results of RE, TDM, E b , and V oc also support the high solar cell efficiency of pyrrole-containing molecules. [Display omitted] • Photovoltaic properties enhancement through variation of conjugated bridge between donor- π-acceptor groups. • B3LYP-(BJ)D3/6–31+G(d, p) level of DFT was adopted. • The significant reduction of HOMO-LUMO gap (up to 2.07 eV) was observed. • RE, TDM, E b , and V oc analyses supported the high solar cell efficiency. [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]

[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]

Conducting organic polymers (COPs) are excellent candidates for sensor application. Polypyrrole is much superior in this regard than other COPs. A few studies indicate the potential of polypyrrole for some specific analytes; however, global picture of sensitivity and selectivity of polypyrrole sensor for various common analytes remains unclear. Here, we present first comprehensive study of polypyrrole sensors for various analytes: NH3, CO2, CO, N2H4, HCN, H2O2, H2S, CH4, CH3OH, SO2, SO3, and H2O. Geometric, thermodynamic, and electronic properties are calculated for infinite polymer to realize the sensor application of polypyrrole. The strongest interaction energy is observed for nPy‐N2H4 followed by nPy‐SO2/SO3 complexes. However, the interaction energy, charge transfer, FMO analysis, density‐of‐states, and electronic transitions envision the highest response toward SO2 and SO3. Surprisingly, the electronic properties of N2H4 complexes show quite opposite behavior than interaction energy. The uneven behavior of electronic properties for hydrazine is due to the interaction from two different sites which decreases the charge transfer. The excellent geometric and electronic properties related to the oxides of sulfur reveal that polypyrrole is highly selective toward SO2 and SO3. [ABSTRACT FROM AUTHOR]

Research is actively being carried out to design new materials with exceptional nonlinear optical (NLO) responses. In this context, a systematic investigation of designing novel hypothetical materials e.g., superalkalides based on stacked Janus dimer, all- cis -1,2,3,4,5,6-hexafluorocyclohexane (C 6 H 6 F 6) 2 has been reported using high-level density functional simulations. The superalkalides are designed here by doping alkali metals on the fluorine face and superalkalis on the hydrogen face of Janus dimer. The thermodynamic stability of newly designed complexes is demonstrated by the interaction energies (E int), ranging between −13.64 and −33.12 kcal/mol. Moreover, the superalkalide nature of these complexes is proved by negative charge and HOMO on superalkalis in natural bond orbitals (NBO) and frontier molecular orbitals (FMO) analyses, respectively. Energy gaps (E g) between HOMO and LUMO orbitals of the designed complexes lie in the range of 0.63–0.83 eV. UV–Vis analysis is performed to gain idea about the transparent region of electromagnetic spectrum for nonlinear activity. The nonlinear activity of the designed superalkalide(s) is studied by static first hyperpolarizability β 0 , dynamic first hyperpolarizability β (ω) and dynamic second hyperpolarizability γ(2- ω ; ω , ω). The highest β 0 , β (ω), and γ(2- ω ; ω , ω) ranges up to 1.1 × 107, 2.9 × 106 and 2.9 × 1012 au, respectively for designed complexes. A comprehensive examination of these superalkalides based on stacked Janus dimers with exceptionally high NLO response highlights their potential for use in nonlinear optical materials. [Display omitted] • Nonlinear optical response of Stacked Janus dimer based superalkalides is investigated. • Doping of alkali metals and superalkalis on the dimer serve to reduce the energy gap of the complexes significantly. • All the designed superalkalide complexes are transparent in deep UV region. • The highest β o value of 2.9 × 107 au is observed for K-2-K 2 F complex. [ABSTRACT FROM AUTHOR]