Natural Bond Orbital Analysis Research Articles

Anion-Carbonyl Interactions.

Presented herein is the exploration of a novel non-covalent anion-carbonyl (X-···C═O) interaction using aromatic imides as receptors and halides as lone pair donors. Combined theoretical calculations and experimental methods including 13C NMR, IR, and crystallographic analyses were performed to provide the physical origin and experimental evidence of anion-carbonyl interactions. The EDA analysis (energy decomposition analysis) based on DFT calculation indicates that electrostatic terms are the dominant contributions for the binding energy while electron delocalization also significantly contributes alongside the electrostatic attraction. Orbital interaction (n → π*) involving the delocalization of halide lone pairs on the carbonyl antibonding orbitals was visualized with NBO (Natural Bond Orbital) analysis. 13C NMR and IR spectra demonstrated upfield chemical shifts and red-shift frequency of hosts upon the addition of halides, reflecting the effect of orbital overlap between the halide lone pairs and π* of carbonyl (n → π* contribution). The anion-carbonyl interactions were directly revealed by X-ray structural analysis of anion and benzene triimide complexes.

Metal-Organic Frameworks for Enhanced Hydrogen Generation from Syngas: A Density Functional Theory Approach.

Although methane poses environmental concerns, it is employed in hydrogen production processes such as steam-methane reforming (SMR), which has an issue of by-products released. Initiatives are being pursued to address CO and CO2 emissions using carbon capture methods, with the goal of minimizing environmental harm while improving pure hydrogen generation from syngas. In this study, porous coordination network (PCN-250) has been studied for its selective adsorption property towards CO, CO2 and H2O as syngas mixture to obtain pure hydrogen. For this purpose, the trimetallic cluster node Fe2M (where Fe2 represents the 3+ oxidation state and M is Cr(II), Mn(II), Fe(II), Co(II), Ni(II), and Zn(II)) has been considered. Fe(III) in combination with metal atoms like Cr(II), Co(II), or Ni(II) has been found to exhibit enhanced adsorption properties towards CO, CO2 and H2O. The molecule with the strongest interaction was found to be H2O over Fe(III)2Zn(II) cluster and weakest interaction was found between H2 and Fe(III)2Ni(II). Charge transfer, natural bond orbital (NBO) and spin density analyses reveal the electronic structural properties of this combination, leading to enhanced adsorption of CO and CO2.

New rotational rate coefficients computation of the linear NaC3N(X1Σ+) by collision with He(1S) and astrophysical implication

ABSTRACT For a better understanding of the physico-chemistry in the interstellar medium, collisional data are needed. In this work, we provide rate coefficients for the recently detected by Cabezas and collaborators in 2023 sodium cyanoacetylide molecule NaC$_{3}$N($X^{1}\Sigma ^{+}$) induced by collisions with He. A new two-dimensional potential energy surface (2D-PES) is derived by adopting the high-level theory of the explicitly correlated coupled cluster with single, double, and perturbative triple excitations (CCSD(T)-F12) in conjunction with the aug-cc-pVTZ basis sets. Our 2D-PES presents two minima: the global one with a well depth of $-86.58$ cm$^{-1}$ and the second well with a $-47.01$ cm$^{-1}$ depth. This was expected by the Natural Bond Orbital analysis showing two electrophilic zones located on Na and N linked Carbon with respective atomic charges : $+0.96575$ and $+0.28910$. This PES was used to calculate inelastic cross-sections within the framework of the close-coupling theory for total energies $\le 170$ cm$^{-1}$ and $J\le 22$. Using the Maxwell–Boltzmann distribution of kinetic energies, these cross-sections were integrated to generate the collisional (de)-excitation rate coefficients for temperatures below 30 K. In order to estimate the impact of the computed collisional rates, a non-local thermodynamical equilibrium radiative transfer calculation was performed. The new collisional data can allow accurate NaC$_{3}$N abundance determination in the interstellar medium.

Quantum Computational and Spectroscopic Investigation of 3-aminosalicylic Acid.

Quantum chemical calculations of3-aminosalicylic acid (3ASA) (monomer and dimer forms) have been performed using DFT and TD-DFT theories with B3LYP/6-311 G(d,p) functional level in the ground and excited states. Using TD-DFT with IEF-PCM model, the electronic spectra of 3ASA in solvents were computed and correlated with the experimental data. The theoretically calculated absorption and emission maxima of 3ASA (monomer) are observed in the range of 343- 347nm (S0 → S1 transition) and 429- 448nm (S1 → S0 transition), respectively. The natural bond orbital (NBO) analysis shows that charge transfer interaction contributes significantly to stabilize the molecular system. In the case of dimer, hydrogen bonding plays a dominant role in stabilizing the molecular framework. Additionally, the obtained nonlinear optical (NLO) properties: polarizability (13.86 × 10-24 e.s.u for monomer and 29.46 × 10-24 e.s.u. for dimer), first-order hyperpolarizability (4.21 × 10-30 e.s.u for monomer and 0.18 × 10-30 e.s.u for dimer) and second-order hyperpolarizability (7.44 × 10-36 e.s.u. for monomer and 14.32 × 10-36 e.s.u. for dimer) were found to be larger than those of standard organic compounds suggesting that 3ASA has a significant NLO character for optoelectronic applications. The NLO properties of dimer may differ from monomer due to dimerization. Further, the radiative lifetime, light harvesting efficiency and band gap energy were calculated, and proposed that 3ASA may be useful in photovoltaics and wide bandgap power devices. HIGHLIGHTS: • DFT and TD-DFT theories were employed to calculate structural and molecular properties of 3ASA (monomer and dimer) in ground and excited states. • HOMO-LUMO study shows monomer and dimer of 3ASA are good reactive. • NBO analysis reflects that charge transfer interactions stabilized the 3ASA molecule. • Electronic absorption/emission spectra in solvents calculated by IEF-PCM/TD-DFT method correlate with experimental results. • Calculated NLO parameters suggested that 3ASA is a potential candidate for NLO material.

Styrene monomer as potential material for design of new optoelectronic and nonlinear optical polymers: density functional theory study.

Using density functional theory, we have studied the intrinsic properties of styrene. First, we determine the optimized structures, structural parameters and thermodynamic properties to make our simulations more realistic to experimental results and check the stability. Second, we investigate optoelectronic, electronic and global descriptors, transport properties of holes and electrons, natural bond orbital analysis, absorption and fluorescence properties. Finally, we study nonlinear optical (NLO) properties: first- and second-order hyperpolarizability, second and third-order optical susceptibilities, hyper-Rayleigh scattering hyperpolarizability, electro-optical Pockel effect, direct current Kerr effects and quadratic refractive index. The bandgap energy E g = 5.146 eV and dielectric constant show that styrene is a good insulator with an average electric field value of 4.43 × 108 Vm-1. Thermodynamic findings show that our molecule is thermodynamically and chemically stable. Electron and hole reorganization energies of 0.393 and 0.295 eV, respectively, show that styrene is more favourable to hole transport than electron transport. Styrene is transparent with linear refractive index n = 1.750 and quadratic n 2 = 1.748 × 10-20 m2 W-1. At the NLO, styrene has a non-zero value of which confirms the existence of first-order NLO activity. Globally the study shows that the styrene monomer is suitable for the architecture design of new polymer materials for NLO applications and optoelectronic by functionalization.

Investigation on molecular and biomolecular spectroscopy of the novel 2BCA molecule to analyse its biological activities and binding interaction with nipah viral protein

The molecule of 2-Biphenyl Carboxylic Acid (2BCA), which contains peculiar features, was explored making use of density functional theory (DFT) and experimental approaches in the area of quantum computational research. The optimised structure, atomic charges, vibrational frequencies, electrical properties, electrostatic potential surface (ESP), natural bond orbital analysis and potential energy surface (PES) were obtained applying the B3LYP approach with the 6–311++ G (d,p) basis set.. The 2BCA molecule was examined for possible conformers using a PES scan. The methods applied for spectral analyses included FT-IR, FT-RAMAN, NMR, and UV–Vis results. Vibrational frequencies for all typical modes of vibration were found using the Potential Energy Distribution (PED) data. The UV–Vis spectrum was simulated using the TD-DFT technique, which is also seen empirically. The Gauge-Invariant Atomic Orbital (GIAO) approach was employed to model and study the 13C and 1H NMR spectra of the 2BCA molecule in a CDCL3 solution. The spectra were then exploited experimentally to establish their chemical shifts. To predict the donor and acceptor interaction, the NBO analysis was used. The electrostatic potential surface was employed to anticipate the locations of nucleophilic and electrophilic sites. Hirshfeld surfaces and their related fingerprint plots are exploited for the investigation of intermolecular interactions. Reduced Density Gradient (RDG) helps to measure and illustrate electron correlation effects, offering precise insights into chemical bonding, reactivity, and the electronic structure of 2BCA. According to Lipinski and Veber’s drug similarity criteria, 2BCA exhibits the typical physicochemical and pharmacokinetic properties that make it a potential oral pharmaceutical candidate. According to the findings of a molecular docking study, the 2BCA molecule has promise as a treatment agent for the Nipah virus (PDB ID: 6 EB9), which causes severe respiratory and neurological symptoms in humans.

Crystal Structure and Hirshfeld Surface Analysis of a Heterometallic Hofmann-Type-Like Compound

In this study; a new heterometallic compound defined by the open formula [Cd(H2O)2Ni(CN)4]4[Cd(H2O)4Ni(CN)4]5 was synthesized in crystal form. Consisting of components such as water molecules, [Ni(CN)4]2− anions, and cadmium transition metal atoms, this new crystal structure has no analogues which might have been previously obtained, even with other transition metal atoms. It is a new compound and a unique example of a crystal. The structural properties of this heterometallic compound have been characterized by single crystal X-ray diffraction spectroscopy (SC-XRD), FT-IR spectroscopy, thermal analysis and elemental analysis methods. According to the data obtained from the SC-XRD technique, this heterometallic compound has a monoclinic crystal system and a C2/c space group. The asymmetric unit of this compound consists of five Cd(II) ions, five Ni(II) ions, eighteen cyanide ligands, and fourteen coordinated water ligand molecules. In addition, theoretical calculations have been made with the Gaussian 03 program in order to obtain more information about this heterometallic Hofmann-type-like compound. The chemical properties of this new compound have been calculated using its HOMO and LUMO values and the natural bond orbital (NBO) analyses. In addition, Hirshfeld surface analysis of the asymmetric unit of this compound has been performed with the CrystalExplorer program. As a result of the Hirshfeld surface analysis, extensive information has been obtained about the weak intramolecular and intermolecular forces that form this new crystalline compound.

Regiodivergent Synthesis of 4- and 5-Sulfenyl Oxazoles from Alkynyl Thioethers.

The regiodivergent synthesis of 4- and 5-sulfenyl oxazoles from 1,4,2-dioxazoles and alkynyl thioethers has been achieved. Gold-catalysed conditions are used to favour the formation of 5-sulfenyl oxazoles via β-selective attack of the nitrenoid relative to the sulfenyl group. In contrast, 4-sulfenyl oxazoles are formed by α-selective reaction under Brønsted acid conditions from the same substrates. The nature of stabilising gold-sulfur interactions have been investigated by natural bond orbital analysis, showing that the S→Au interactions are significantly stronger in the intermediate that favours the 5-sulfenyl oxazoles. A kinetic survey identifies catalyst inhibition processes. This study into the regiodivergent methods includes the development of telescoped annulation-oxidation protocols for regioselective access to oxazole sulfoxides and sulfones.

Single-crystal X-ray structure, theoretical (Hirshfeld, electronic properties, NBO, NLO, RDG), and molecular docking studies of three phthalimidoethanesulfonamide derivatives

The three N-substituted-2-phtalimidoethanesulfonamide derivatives, 2-(1,3-dioxoisoindolin-2- yl)-N-(2-isopropylphenyl)ethane-1-sulfonamide (I), N-(2,6-dimethylphenyl)-2-(1,3-dioxoiso indolin-2-yl)ethane-1-sulfonamide (II) and 2-(2-(morpholinosulfonyl)ethyl) isoindoline-1,3‑dione (III), were analyzed using a combined approach including single-crystal X-ray diffraction (SC-XRD), theoretical calculations with Density Functional Theory (DFT), and molecular docking studies. Phthalimide and sulfonamide compounds have recently attracted attention for their inhibitory properties against AChE and BChE enzymes. In this study, molecular and crystal structures of compounds have been confirmed by the SC-XRD technique. Optimized molecular geometries and vibrational modes have been examined and compared to experimental results. Frontier molecular orbital (HOMO-LUMO) energies, molecular electrostatic potential (MEP), natural bond orbital (NBO) analysis, and non-linear optical (NLO) properties have been investigated by DFT/B3LYP/6–311G++(d,p) method. The reduced density gradient (RDG) analysis has been performed to analyze the non-covalent interactions. The Hirshfeld surfaces and 2D fingerprint analyses have been used to determine the intermolecular interactions of compounds. Moreover, in silico docking studies are performed to investigate the interactions between N-substituted-2-phtalimidoethane sulfonamide derivatives and AChE and BChE enzymes.

DFT-assisted design of curcumin-based donor-π-bridge-acceptor molecular structures: Advancing nonlinear optical materials and sustainable organic solar cells

This study explores the theoretical design of novel curcumin-based structures with enhanced nonlinear optical (NLO) characteristics. By systematically substituting hydroxyl (OH) functionalities in bisdemethoxycurcumin (BdMC) with various donor and acceptor functionalities at the edges of the π-bridge backbone, we constructed 12 different derivatives. Density-functional theory (DFT) and time-dependent DFT (TD-DFT) calculations were performed at the B3LYP/6-311++G(d,p) and CAM-B3LYP/6-311++G(d,p) levels to analyze the optoelectronic properties. The introduction of donors and acceptors significantly improved NLO characteristics. Notably, BdMC-1 (N(C2H5)2-π-bridge-NO2) exhibited a remarkable enhancement in NLO responses, with the average polarizability (<α>) and the first hyperpolarizability (βtot) increasing from 465.3 to 660.9 (a.u.) and 14254.4 to 143487.6 (a.u.), respectively. UV–Vis spectroscopy showed BdMC-1 as the most red-shifted compound, with a maximum wavelength (λmax) of 431.1 nm, the lowest optical bandgap of 2.88 eV, and an ultrahigh light harvesting efficiency (LHE) of 97.4%. The designed compounds exhibited narrower HOMO-LUMO electronic bandgaps (as low as 2.08 eV) compared to BdMC (3.32 eV), contributing to the improved NLO responses. Natural bond orbital (NBO) analysis confirmed the formation of a charge separation state, facilitating effective electron migration from donors to acceptors through the π-bridge. Additionally, using BdMC-based materials as acceptors in organic solar cells (OSCs) yielded open-circuit voltages (Voc) from 1.62 to 2.23 V, fill factors (FF) above 90%, and low exciton binding energies (Ee−b) in the range of 0.08 to 0.80 eV.

Structural characterization and keto-enol tautomerization of 4-substituted pyrazolone derivatives with DFT approach

The synthesis of two pyrazolone derivative compounds, PYR-I(4-Acetyl-1-(4-chlorophenyl)-3-isopropyl-1H-pyrazol-5(4H)-one) and PYR-II1-(4-Chlorophenyl))-3-isopropyl-5-oxo-4,5-5-dihydro-1H-pyrazole-4-carbaldehyde, their characterization by FT-IR, NMR, UV–Vis and GC-MS techniques, and the evaluation of the keto-enol tautomerization process of the structures along with the DFT approach and spectral data were reported in this paper. Spectral findings indicated that PYR-I was stable at the keto state. The IR spectrum recorded in solid form showed that the PYR-II structure was stable in the enol state, while the NMR spectrum in the solution medium showed that it was stable in the keto state. DFT-based analyses were realized with the B3LYP hybrid functional and the 6–311++G(d,p) basis set. The modelled keto, transition and enol state molecular geometries of structures were optimized in the gas phase and different solvent media and the total energy and dipole moment values were investigated at the specified theoretical level. The possible keto-enol tautomerism mechanism of the structures was evaluated through some thermodynamic parameters such as the difference in free Gibbs energy (ΔG), enthalpy (ΔH), entropy (ΔS), and predictive tautomeric equilibrium constants (Keq), acidity constants (pKa) and percentages of tautomers at 298.15 K and 1 atm pressure. The results of these analyses based on the DFT approach indicated that the keto-enol tautomer equilibrium heavily favours the keto form for PYR-I and the enol form for PYR-II in all cases. Moreover, natural bond orbital (NBO) analysis was performed for the tautomers, and the chemical reactivity profiles of the most stable tautomers were examined with the values of frontier molecular orbital energy and some reactivity descriptors.

Exploring the structural and electronic characteristics of phenethylamine derivatives: a density functional theory approach

Accurate structure elucidation of biologically active molecules is crucial for designing and developing new drugs, as well as for analyzing their pharmacological activity. In this study, density functional theory calculations are applied to explore the electronic structure and properties of phenethylamine derivatives, including Amphetamine, Methamphetamine, and Methylene Dioxy Methamphetamine(MDMA). The investigation encompasses various aspects such as geometry optimization, vibrational analysis, electronic properties, Molecular Electrostatic Potential analysis, and local and global descriptor analysis. Additionally, the study utilizes Natural Bond Orbital analysis and Quantum Theory of Atoms in Molecules to investigate the chemical bonding and charge density distributions of these compounds. Experimental techniques such as Fourier transform infrared (FT-IR) and Raman spectroscopic analysis are employed in the range of 4000-400 cm-1\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$cm^{-1}$$\\end{document} and 4000-50 cm-1\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$cm^{-1}$$\\end{document}, respectively. Theoretical vibrational analysis with Potential Energy Distribution(PED) assignments is conducted, and the resulting frequencies are compared to experimental spectral data, revealing good agreement. By correlating various structural parameters with the pharmacological activity of each derivative, computational structure elucidation aids in understanding the unique actions of phenethylamine derivatives. The obtained results offer a comprehensive understanding of the molecular behavior and properties of these drugs, facilitating the development of new drugs and therapies for addiction and related disorders.

Effect of intermolecular interactions and pharmacokinetic profile of antidiabetic agent (E)-N,N‑diethyl-2-(5(3‑hydroxy-4-methoxybenzylidene)-2,4-dioxothiazolidin-3-yl) acetamide

Diabetes is a prevalent disease in South India, posing a severe threat to public health. To tackle this issue, researchers are focusing on developing multi-targeted ligands, and one promising candidate is (E)-N,N‑diethyl-2-(5(3‑hydroxy-4-methoxybenzylidene)-2,4-dioxothiazolidin-3-yl)acetamide (DMDA). Geometry optimization of DMDA was carried out using density functional theory with 6–311+G(d, p) basis set to develop a theoretical model close to the previously synthesized and reported DMDA. Natural Bond Orbital analysis was conducted to scrutinize the phenomena of charge delocalization and electronic exchange interactions governing both intermolecular and intramolecular associations. Moreover, the vibrational characteristics of the molecule were elucidated through FT-IR and FT-Raman spectra. Lowest Unoccupied Molecular Orbital and Highest Occupied Molecular Orbital have also been explored to enhance understanding of the molecule's electronic structure and reactivity. Hirshfeld surface analysis was utilized to investigate the interactions between molecules within the crystalline lattice. Absorption, distribution, metabolism, excretion, and toxicity (ADMET) analysis elucidates the potential pharmacokinetic profile of DMDA. Molecular docking was performed to predict the binding site responsible for various interactions with the targeted protein. By combining these techniques, a comprehensive molecular description of DMDA has been generated.There are three prominent intramolecular interactions within the ambit of van der Waals radii, leading to stability of the molecule. The presence of a broad and shallow band with a significant red shift provides evidence for the strong intermolecular OH hydrogen bonding. DMDA complies with Lipinski's Rule of Five, highlighting its favorable characteristics for pharmaceutical efficacy. The negative binding energies determined by docking studies ascertain the potential sites of ligand-protein interaction leading to inhibition of α-amylase and α-glucosidase enzyme.

Decrypting the critical point of internal rotation of formaldehyde: A rotational study of the acrolein-formaldehyde complex.

The rotational spectrum of an acrolein-formaldehyde complex has been characterized using pulsed jet Fourier transform microwave spectroscopy complemented with quantum chemical calculations. One isomer has been observed in pulsed jets, which is stabilized by a dominant O=C⋯O tetrel bond (n → π* interaction) and a secondary C-H⋯O hydrogen bond. Splittings arising from the internal rotation of formaldehyde around its C2v axis were also observed, from which its V2 barrier was evaluated. It seems that when V2 equals or exceeds 4.61 kJ mol-1, no splitting of the spectral lines of the rotational spectrum was observed. The nature of the non-covalent interactions of the target complex is elucidated through natural bond orbital analysis. These findings contribute to a deeper understanding on the non-covalent interactions within the dimeric complex formed by two aldehydes.

Theory guided engineering of zeolite adsorbents for acaricide residue adsorption from the environment.

Zeolites have attracted attention for their potential in adsorbing environmental contaminants. However, contaminants, such as acaricides used extensively in livestock production to control ticks and mites, have received limited exploration regarding their adsorption onto zeolite surfaces. This study aimed to identify the most appropriate zeolite frameworks for the adsorption of acaricide residues, deduce the mechanism underlying the adsorption process, and evaluate the impact of surface modification on the adsorption capabilities of zeolites. Grand Canonical Monte Carlo (GCMC) was used to screen the entire zeolite database to analyze their adsorption properties, where the cloverite zeolite framework (CLO) exhibits the highest adsorption capacity (percentage weight, 54%). Machine learning was employed to rank structural feature importance on adsorption. Density and helium void fraction appeared to be the most important structural features. Thus, engineering these features is of utmost significance in harvesting the desired acaricides. The second step involved engineering the structural and electronic properties of the shortlisted zeolite frameworks via cation substitution with suitable atoms. DFT calculations involving natural bond orbital (NBO) analysis and quantum theory of atoms in molecules (QTAIM) have been done to understand the influence of cation substitution on the electronic structure.

Synthesis, spectroscopic characterization, biological evaluation studies on 6-methoxy-8-nitroquinolinium picrate: A potent lung cancer drug

The compound 6-Methoxy-8-Nitroquinolinium Picrate was synthesized and characterized using FT-IR, FT-Raman, and UV–Vis spectroscopic techniques. Vibrational wavenumbers were calculated and compared with experimental values, while UV–Vis analysis revealed electronic transitions within the molecule. Frontier molecular orbitals, molecular electrostatic potential surface, Mulliken atomic charge distribution, and Natural bond orbitals analyses confirmed the molecule's bioactivity and validated the intramolecular charge transfer within the molecule. Antibacterial testing exhibited activity against Klebsiella pneumoniae, while in vitro cytotoxicity experiments demonstrated higher inhibition of A549 cancer cell lines compared to HeLa cell lines. Molecular docking supported the in vitro cytotoxicity findings, suggesting the potential for developing new lung cancer treatments based on this research.

Investigation of transition metals (Ag, Au, Pd, Pt and Ru)-doped boron nitride nanocarrier for drug delivery process of favipiravir: An intuition from DFT

The scientific community is keenly interested in developing efficient drug delivery systems using B12N12, particularly for carrying anti-influenza drugs like Favipiravir (FAV) against life-threatening RNA virus infections. This study delves into the exploration of transition metal-doped B12N12 nanostructures as potential carriers for drug delivery. Using density functional theory (DFT) calculations at the wB97XD/6-311++G(d,p) level of theory, the research specifically investigates the efficacy of transition metal-doped (Ag, Au, Pd, Pt, and Ru) boron nitride nanocages as effective agents for delivering the FAV drug. The systematic exploration of adsorption energy, electronic features, and thermodynamic properties (ΔG and ΔH) of FAV interacting with B12N12 and transition metals-doped (Ag, Au, Pd, Pt, and Ru) nanocages reveals a significant improvement in drug-carrying capacity, marked by notable physisorption capabilities as evident from negative adsorption energies. The confirmation of FAV’s interaction with doped-B12N12 nanocages was supported by a comprehensive analysis encompassing frontier molecular orbitals, adsorption energy, fractional charge transfer, molecular electrostatic potential (MEP), non-covalent interaction(NCI), and natural bond orbital (NBO) assessments. The frontier molecular orbitals (FMO), density of states (DOS), and natural bond orbital (NBO) analyses reveal nanocages as charge acceptors and drug as charge donor during the adsorption process. The band gap energies decreased upon FAV adsorption on both pristine and doped nanocages except Au and Pd doped nanocages. Among the doped cases, the Ag-doped B12N12 nanocage exhibits the most significant reduction in the HOMO-LUMO energy difference, and therefore should be the most effective nanocarrier for FAV. The results of this study offer novel insights for the development of B12N12 nanocages as carriers for the FAV drug.

Theoretical studies for the detailed electronic structure of organotin(IV) derivatives of 4-fluoroanthranilic acid, X-ray structure of n-dibutyltin bis(4-fluoroanthranilate)

The present study describes the detailed DFT-based electronic structure calculations without any symmetry constraints being performed on di- and triorganotin derivatives of 4-fluoroanthranilic acid (AFA), viz. Me2SnL2 (1), n-Bu2SnL2 (2), Me3SnL (3), and Ph3SnL (4) (where L= monoanion of AFA). The structural and atomic charge analysis have confirmed the previously reported our experimental results, i.e. bicapped tetrahedral and distorted tetrahedral geometry for di- and triorganotin derivatives, respectively, and all the complexes 1–4 contain a positively charged central tin atom surrounded by a negatively charged system. The single crystal X-ray structure of complex 2 (n-Bu2SnL2) also suggests that AFA acts as a monoanion and bidentate ligand resulting a bicapped tetrahedral environment around tin. Various population analysis such as Mulliken (MPA), Hirshfeld (HPA), and natural population analysis (NPA) have been employed to calculate the charges at all the atoms. A finite difference approximation method has been used to explain the charge distribution within the studied complexes 1–4 based on the conceptual global and local reactivity DFT-based descriptions, frontier molecular-orbital analysis (FMOA), and molecular electrostatic potential maps (MEP). Further, the conceptual DFT-based global reactivity descriptors and frontier molecular orbital analysis show that the interactions between CT-DNA and complexes 1–4 may be groove binding or electrostatic. The integral equation formalism-polarizable continuum model (IEF-PCM) has been employed to calculate the UV–visible spectra of 1–4 in the solvent field, whereas the same in the gas phase has been obtained with the help of time-dependent DFT (TD-DFT) at the same level of theory. The intramolecular charge distribution in 1–4 has been investigated with the help of natural bond orbital (NBO) analysis. The topological and energetic parameters at the selected bond critical points in the coordination sphere of complexes 1–4 have been calculated using atoms-in-molecules (AIM) theory. The analysis of different kinds of non-covalent interactions (NCI) in complexes 1–4 has also been investigated.

Hexa-peri-hexabenzocoronene as a vector sensing and delivery of Carmustine anticancer drug: A density functional theory study

We conducted research on the adsorption of carmustine (BCNU) on the surface of pristine, N-doped, and BN-doped Hexa-peri-hexabenzocoronene (HBC) nanographene using density functional theory calculations. We used the B3LYP functional in conjunction with 6-31+G(d) and 6-311+G(d,p) basis sets to perform geometrical optimization calculations, vibrational frequencies, and natural bond orbitals (NBO) analysis. The dispersion correction term of Grimme-D3 was incorporated to account for the dispersion interactions. We found that the geometry of the nanographenes remains unchanged after the drug molecule adsorption. The calculated adsorption energies (Eads) were −17.1 kcal.mol−1 for HBC-BCNU, −17.0 kcal.mol−1 for NHBC-BCNU, and −17.9 kcal.mol−1 for BNHBC-BCNU when using the 6-31+G(d) basis set. The corresponding values calculated employing the 6-311+G(d,p) basis set were −17.9, −17.3, and −19.1 kcal.mol−1, respectively. Analysis of frontier molecular orbitals (HOMO and LUMO) showed that the electronic properties of NHBC were significantly affected by the presence of BCNU. We used NBO analysis to investigate the distribution of partial atomic charges in different systems. Finally, using the transition state equation and the smaller basis set, we found that the required time for BCNU to release from HBC, NHBC, and BNHBC is approximately 3.3, 1.8, and 13.0 s, respectively. The obtained values are 13.0, 4.6, and 96.0 s, respectively, for the higher level of calculations. The recovery time for all nanographenes is within a reasonable range, while NHBC exhibits the highest sensitivity for drug detection.

1D-Coordination Polymer of Copper(I) thiocyanate complex with metronidazole: Synthesis, crystal structure, Hirshfeld surface analysis, PXRD, Spectroscopic properties, MEP, QTAIM, π(CN)···tetrel interaction, RDG, and thermal analysis

Within 24 h of slow evaporation of the solution containing CuCl2·2H2O, metronidazole, and NH4SCN, a red-like crystalline Cu(I) complex titled [Cu(SCN)(mnz)]n (1), [where mnz = metronidazole; SCN = thiocyanate], was synthesized. The presence of SCN− during the synthesis induces reduction of the Cu(II) to Cu(I) giving rise to novel 1D coordination polymer. The compound was characterized by single crystal X-ray diffraction, powdered X-ray diffraction, spectroscopic proprieties, and Hirshfeld surface analysis. [Cu(SCN)(mnz)]n crystallizes in the monoclinic space group P21/c. The complex possesses a 1D layer structure constructed by linking the staircase-like [CuSCN]n chains. Intermolecular interactions in the crystals investigation via Hirshfeld surface analysis reveals the major contribution is from O···H/H···O interaction (22.9 %), which is due to the presence of hydrogen bonds of the O − H···O type. The thermal properties were investigated using DTA-TGA and DSC. The study comprises the interpretation of non-covalent interactions through Quantum Theory of Atoms in Molecules (QTAIM), Natural Bond Orbital (NBO) analyses, and Reduced Density Gradient (RDG). The results show the role of interactions between SCN− and mnz through multiple connections involving the oxygen, nitrogen, and sulfur lone pairs and π-bonds for constructing the unit cell. The non-covalent arrangements include very weak hydrogen bonds that cooperatively stabilize the crystal. Along with SCN− bridging copper atoms, growth in the ab plane is favored by an uncommon π···π interaction between SCN− and the imidazole ring of mnz. In this interaction, the π(SN) and π(CN) orbitals perturb the imidazole π(CN) orbital with energies of 0.36 and 0.22 kcal/mol, respectively. In the c direction, a hydrogen bond between the hydroxyl group and CH- fragment from different mnz molecules assists structure stabilization. It is accompanied by a rarely observed π(CN)···tetrel interaction, wherein SCN− donates π-electron density to the antibonding σ(CH) orbital of the methyl carbon.