Natural Bond Orbital Research Articles

Four-membered heterocyclic molecules featuring boron and heavy group 14 elements that exhibit both σ-aromatic and π-aromatic properties: a new synthetic target.

In this study, we present a series of theoretically designed B2G14G14' molecules, featuring four-membered-ring heterocycles containing boron and heavy group 14 elements (G14 and G14' = Si, Ge, Sn, and Pb). Through the use of density functional theory (DFT), natural bond orbital (NBO) analysis, quantum theory of atoms in molecules (QTAIM), and electron localization function (ELF), our studies demonstrate a strong π single bond between the bridgehead G14 and G14' atoms, with minimal participation from a very weak G14-G14' σ bond. Additionally, the nucleus independent chemical shift (NICS), anisotropy of current-induced density (ACID), and adaptive natural density partitioning (AdNDP) analyses definitively establish the presence of both σ-aromaticity and π-aromaticity in these inorganic four-membered heterocyclic neutral molecules.

Synthesis, Solvent effects, Chemical reactivity, Molecular Docking and Molecular Dynamic Studies of Triazole derivative

In the present study, (E)-3-(2-(4-amino-5-mercapto-4H-1,2,4-triazol-3-yl)hydrazono)methyl)-2-bromo-6-methoxyphenol (AMTMP) is synthesized and characterized utilizing FT-IR, FT-Raman, NMR, Mass Spectra, and vibrational modes at DFT/B3LYP/6-31G (d, p) computational studies. The calculated properties were subsequently compared to the results of experiments. The absorption characteristics were assessed through the utilization of various kinds of solvents. The molecular properties of AMTMP, including the natural bond orbital (NBO), molecular electrostatic potential (MEP), and local and global reactivity descriptors, were utilized to ascertain the stability, reactivity, and reactive sites on the molecule. Using molecular docking, we have investigated the AMTMP's affinity for CA-2 as well as its potential binding mode. For the purpose of assessing the stability of AMTMP-CA-2 complexes over time, MD simulations were performed. The results suggest that AMTMP could act as CA-2 inhibitor for targeting GSC in GBM.

Host-guest interactions of coumarin-based 1,2-pyrazole using analytical and computational methods: Paper strip-based detection, live cell imaging, logic gates and keypad lock applications

A novel Coumarin-based 1,2-pyrazole, HCPyTSC is synthesised and characterized. The chemosensor has been shown to have efficient colourimetric and fluorescence sensing capabilities for the quick and selective detection of fluoride and copper ions. At 376 and 430 nm, the HCPyTSC exhibits selective sensing for Cu2+ and F− ions. By examining the natural bond orbital (NBO) analysis and the potential energy curve (PES) of the ground state for the function of the C–H bond, it has been determined from the theoretical study at hand that the deprotonation was taken from the ‘CH’ proton of the pyrazole ring. For F− and Cu2+, the HCPyTSC detection limits were 4.62 nM and 15.36 nM, respectively. Similarly, the binding constants (Kb) for F− and Cu2+ ions in acetonitrile medium were found to be 2.06 × 105 M−1 and 1.88 × 105 M−1. Chemosensor HCPyTSC with and without F− and Cu2+ ions have an emission and absorption response that can imitate a variety of logic gates, including the AND, XOR, and OR gates. Additionally, a paper-based sensor strip with the HCPyTSC was created for use in practical, flexible F− sensing applications. The paper-based sensor was more effective in detecting F− than other anions. The effectiveness of HCPyTSC for the selective detection of F− in living cells as well as its cell permeability were examined using live-cell imaging in T24 cells.

Microwave spectroscopic and computational analyses of the phenylacetylene⋯methanol complex: insights into intermolecular interactions.

The microwave spectra of five isotopologues of phenylacetylene⋯methanol complex, C6H5CCH⋯CH3OH, C6H5CCH⋯CH3OD, C6H5CCH⋯CD3OD, C6H5CCD⋯CH3OH and C6H5CCH⋯13CH3OH, have been observed through Fourier transform microwave spectroscopy. Rotational spectra unambiguously unveil a specific structural arrangement characterised by dual interactions between the phenylacetylene and methanol. CH3OH serves as a hydrogen bond donor to the acetylenic π-cloud while concurrently accepting a hydrogen bond from the ortho C-H group of the PhAc moiety. The fitted rotational constants align closely with the structural configuration computed at the B3LYP-D3/aug-cc-pVDZ level of theory. The transitions of all isotopologues exhibit doublets owing to the methyl group's internal rotation within the methanol molecule. Comprehensive computational analyses, including natural bond orbital (NBO) analysis, atoms in molecules (AIM) theory, and non-covalent interactions (NCI) index plots, reveal the coexistence of both O-H⋯π and C-H⋯O hydrogen bonds within the complex. Symmetry adapted perturbation theory with density functional theory (SAPT-DFT) calculations performed on the experimentally determined geometry provide an insight into the prominent role of electrostatic interactions in stabilising the overall structural arrangement.

Preparation of a high-coordinated-silicon-centered spiro-cyclic compound.

Silicon compounds containing silicon-silicon bond with a variety of unusual oxidation states are quite important, because their high reactivity leads to the formation of a variety of silicon compounds. The isolation of such compounds with unusual oxidation states requires a resilient synthetic strategy. Herein, we report the synthesis of a silicon based spirocyclic compound containing a hyper-valent silicon atom and a silicon-silicon bond. The computational calculations employing natural bond orbital (NBO) analysis and energy decomposition analysis-natural orbitals for chemical valence (EDA-NOCV) reveal that the nature of bonding between the silicon atoms is of an electron sharing nature.

Excited state properties of an A-D-A non-fullerene electron acceptor: a LC-TD-DFTB study.

Understanding charge transfer processes is essential to estimate the performance of organic photovoltaic technologies. Although experimental production is on the rise, predictability strongly relies on theoretical modeling, which is limited to the size of semiconductors. As a computationally favorable approach, we benchmarked the long-range corrected (LC) time-dependent (TD) formulation of the semi-empirical density functional-based tight-binding method (DFTB) for three polycyclic aromatic hydrocarbons (PAHs) and studied the DTP-IC-4Ph molecule, a PAH-based non-fullerene electron acceptor (NFA) with an A-D-A backbone structure. After a thorough investigation into the long-range parameter (ω) tuning for naphthalene, anthracene and pyrene, the excitation energies, oscillator strengths and Natural Transition Orbitals (NTOs) were compared with the standard ωB97X-D/6-31G(d,p) level of theory and the ADC2/6-31G(d,p) multiconfigurational method. We estimated mobility-related properties of the NFA and considered 1000 thermally accessible configurations to qualitatively reproduce the experimental absorption profile and investigate the energetic disorder. Finally, we conducted a fragment-based analysis using the one-electron transition density matrix (1TDM) to determine the character of the excited states and investigate the effect of side chains on exciton formation. Our results are sensitive to the level of theory and highly dependent on the long-range parameter but suggest that the presence of alkyl chains promotes a higher average charge delocalization and allows for additional hopping mechanisms, favoring the charge transfer dynamics.

Precise molecular engineering for the preparation of pyridinium photosensitizers with efficient ROS generation and photothermal conversion.

Organic photosensitizers (PSs) with aggregation-induced emission properties have great development potential in the integrated application of multi-mode diagnosis and treatment of photodynamic therapy (PDT) and photothermal therapy (PTT). However, preparing high-quality PSs with both optical and biological properties, high reactive oxygen species (ROS) and photothermal conversion ability are undoubtedly a great challenge. In this work, a series of pyridinium AIE PSs modified with benzophenone have been synthesized. A wide wavelength range of fluorescent materials was obtained by changing the conjugation and donor-acceptor strength. TPAPs5 has a significant advantage over similar compounds, and we have also identified the causes of high ROS generation and high photothermal conversion in terms of natural transition orbitals, excited state energy levels, ground-excited state configuration differences and recombination energy. Interestingly, migration of target sites was also found in biological imaging experiments, which also provided ideas for the design of double-targeted fluorescent probes. Therefore, the present work proposed an effective molecular design strategy for synergistic PDT and PTT therapy.

Theoretical Studies of Xanthates in Heavy Metal Complexation: Understanding the Structural, Thermochemical, and Electronic Aspects

Heavy metals have been widely discussed as a significant cause of environmental disasters in recent decades. One of the main focuses has been exploring agents and mechanisms capable of removing these metals from nature. Under this perspective, xanthates have been studied as sequestering agents of these metals in aqueous environments. In this theoretical study, complexes of cadmium(II) and mercury(II), with different coordination modes and geometric isomers of the xanthate ligands (n-propyl, n-butyl, and n-pentyl xanthates), were evaluated using density functional theory. To verify the versatility of coordination modes of the xanthates, monodentate and bidentate structures were optimized. For these compounds, structural, thermochemical, and electronic parameters were studied. The thermochemical results showed that all complexes are formed through exothermic and spontaneous processes. Electronic analysis showed that the mercury(II) complexes have a higher covalent character of the Hg-S bond, in contrast with the cadmium(II) complexes, which exhibited a higher ionic character of the Cd-S bond. Through the analysis of the natural bond orbitals, the Lewis acid-base nature of these complexes was confirmed and corroborated by the softness calculations, with the participation of the p orbitals of the sulfur and s orbitals of the metal centers.

What can quantum information theory offer to quantum chemistry?

It is the ultimate goal of this work to foster synergy between quantum chemistry and the flourishing field of quantum information theory. For this, we first translate quantum information concepts, such as entanglement and correlation, into the context of quantum chemical systems. In particular, we establish two conceptually distinct perspectives on 'electron correlation', leading to a notion of orbital and particle correlation. We then demonstrate that particle correlation equals total orbital correlation minimized over all orbital bases. Accordingly, particle correlation resembles the minimal, thus intrinsic, complexity of many-electron wave functions, while orbital correlation quantifies their complexity relative to a basis. We illustrate these concepts of intrinsic and extrinsic correlation complexity in molecular systems, which also manifests the crucial link between the two correlation pictures. Our results provide theoretical justification for the long-favored natural orbitals for simplifying electronic structures, and open new pathways for developing more efficient approaches towards the electron correlation problem.

Sonification of molecular electronic energy density and its dynamics.

A method is proposed for sonification of the molecular electronic energy density. The characteristic energetic structures of the individual complicated electronic wavefunctions are extracted in terms of the Energy Natural Orbitals (ENO), which are the eigenfunctions of the electronic energy density operator [K. Takatsuka and Y. Arasaki, J. Chem. Phys., 2021, 154, 094103]. Then, the frequency corresponding to each ENO energy is linearly transformed to the audible range. The time-variation of the population of the ENO serves as the volume (amplitude) of the sound. We demonstrate the sonification and associated voiceprints for a couple of very basic chemical bondings, from across an avoided crossing, and from the bond dissociation of a cluster.

Insight into the nature of carbon-metal bonding for N-heterocyclic carbenes in gold/silver complexes and nanoparticles using DFT-correlated Raman spectroscopy: strong evidence for π-backbonding.

N-Heterocyclic carbenes (NHCs) have emerged as promising ligands for stabilizing metallic complexes, nanoclusters, nanoparticles (NPs) and surfaces. The carbon-metal bond between NHCs and metal atoms plays a crucial role in determining the resulting material's stability, reactivity, function, and electronic properties. Using Raman spectroscopy coupled with density functional theory calculations, we investigate the nature of carbon-metal bonding in NHC-silver and NHC-gold complexes as well as their corresponding NPs. While low wavenumbers are inaccessible to standard infrared spectroscopy, Raman detection reveals previously unreported NHC-Au/Ag bond-stretching vibrations between 154-196 cm-1. The computationally efficient r2SCAN-3c method allows an excellent correlation between experimental and predicted Raman spectra which helps calibrate an accurate description of NHC-metal bonding. While π-backbonding should stabilize the NHC-metal bond, conflicting reports for the presence and absence of π-backbonding are seen in the literature. This debate led us to further investigate experimental and theoretical results to ultimately confirm and quantify the presence of π-backbonding in these systems. Experimentally, an observed decrease in the NHC's CN stretching due to the population of the π* orbital is a good indication for the presence of π-backbonding. Using energy decomposition analysis - natural orbitals for chemical valence (EDA-NOCV), our calculations concur and quantify π-backbonding in these NHC-bound complexes and NPs. Surprisingly, we observe that NPs are less stabilized by π-backbonding compared to their respective complexes-a result that partially explains the weaker NHC-NP bond. The protocol described herein will help optimize metal-carbon bonding in NHC-stabilized metal complexes, nanoparticles and surfaces.

Unveiling the multifaceted potential of (E)-N-(4-Chlorophenyl)-1-(thiophen-2-yl) methanimine with special reference to solution-state fluorescence, synthesis, electronic structure, antimicrobial, antibiofilm, larvicidal activities, toxicity, docking and dynamics

Schiff bases exhibit distinctive characteristics in the realm of chemistry, physics, and medicine, rendering them highly efficacious in the field of biology. A Schiff base was synthesized by reacting 4-chloroaniline with thiophene-2-carboxaldehyde, and its structure was subsequently optimized using density functional theory (DFT). We conducted experimental simulations and validations of the IR, UV, and NMR spectra. The compound formation was confirmed through the utilization of FTIR, UV–VIS, 1HNMR, and 13CNMR analyses. The observed fluorescence intensities at wavelengths of 438.28 and 666.83 nm provided indications of its inherent fluorescence properties. A conspicuous alteration in the thermogravimetric analysis (TGA) plot within the temperature range of 250 °C to 315 °C was indicative of a chemical metamorphosis. The compound exhibited an energy gap of 3.97 electron volts (eV). In the MEP graph, the blue regions denoted electron-deficient areas, whereas the red regions represented electron-abundant regions. In the context of natural population analysis, the hydrogen atoms exhibit positive charges, which are associated with electron transfer phenomena. The optimized compound exhibited nitrogen and chlorine atoms with negative charges, functioning as electron donors. The utilization of NBO (Natural Bond Orbital) analysis and spectral analysis unveiled the occurrence of electron transfers within the molecular framework. The ELF diagrams illustrate the presence of hydrogen by utilizing the colour red, while carbon and nitrogen are represented by the colour blue. The carbon atoms exhibited a blue hue in the LOL diagram, indicating a state of electron deficiency. Non-covalent interactions were exemplified in RDG maps. It exhibited superior antimicrobial efficacy against both bacteria and fungi, surpassing that of amoxicillin The compound exhibited a moderate level of antibiofilm activity, with an IC50 value of 158.9 μg/ml. Additionally, it demonstrated larvicidal effects that were dependent on the concentration. The antimicrobial properties of the compound were confirmed through molecular docking and dynamic simulation. The insilico assessments conducted against toxicity models have revealed a notable absence of toxicity and a commendable level of tolerance.

Design of Azomethine based Metalloorganic Complexes and their Binding Interactions with Nucleic Acid and Protein

Mononuclear nickel, copper, and zinc complexes based on salen type (ONNO) donor acting as a tetradentate ligand obtained by the condensation of 4-methyl-o-phenylenediamine and 5-fluoro salicylaldehyde in 1:2 ratios. The compounds are characterized using UV-visible, FT-IR, 1H, 13C-NMR, HR-MS, Elemental (CHN) analyses ESR spectral techniques, and single crystal X-ray diffraction studies (SC-XRD). The binding interactions of the metal complexes with deoxyribonucleic acid (DNA) and bovine serum albumin (BSA) are monitored using UV absorption titration and tryptophan emission quenching techniques, respectively. The complexes possess strong binding propensities with DNA and prefer groove binding, as indicated by the hyperchromic effect. The complexes quench the intrinsic fluorescence of BSA with increasing amounts of the complex concentration in a dose-dependent manner. The gel electrophoresis was carried out against pBR322 to analyze the cleaving ability of the complexes. The results of the NBO (natural bond orbitals) analysis performed in combination with the Time-dependent Density Functional Theory (TD-DFT) calculations provided a good explanation of their electronic and structural characteristics. Further, the predictions of molecular docking studies support the experimental observations. The Gel electrophoresis study reveals the cleaving ability of the complexes by their interactions with DNA. In addition, the cell viability of the complexes is assessed based on MTT assay and the results indicate that they have a good antiproliferative activity only on liver cancer cell-line HepG-2 and does not show cytotoxic effect on normal vero cell lines with 90% viability.

Ab initio investigation of the competition of pnicogen, halogen, and hydrogen bonds resulting from the interactions between cyanophosphine and hypohalous acids.

The complexes formed as a result of the interactions between cyanophosphine (CP, H2PCN) and hypohalous acid molecules (HOX, X = F, Cl, Br, and I) were studied by employing ab initio computations conducted at the MP2/aug-cc-pVTZ level. Three types of complexes were acquired (I, II, and III) as a result of the (O∙∙∙P) pnicogen bond, the (N∙∙∙H) hydrogen bond, and the (N∙∙∙X) halogen bond interaction, respectively. The results of harmonic vibrational frequency calculations with no imaginary frequencies confirmed the structures as minima. In addition, given the interaction energy of the complexes, hydrogen bond complexes of structure II have the highest stability compared to other structures. In all studied complexes, the strength of the interactions depended on the electronegativity of the halogen atoms. The characteristics and nature of the whole three types of complexes were examined and evaluated with natural bond orbital (NBO), atom in molecules (AIM), molecular electrostatic potential (MEP) maps, non-covalent interaction (NCI) index, and electron density difference (EDD) analyses. The optimization of all complexes and corresponding monomers was conducted through the ab initio method, employing the MP2 level along with the aug/cc-pVTZ basis set for all atoms, except for the iodine (I) atom, for which the aug-cc-pVTZ (PP) basis set was employed. Subsequent frequency calculations were executed to ascertain the minimum energy state of the complexes at the MP2 level and the aug/cc-pVTZ basis set, utilizing Gaussian09 software. The MEP maps of the monomers were generated using the analysis-surface suite (WFA-SAS) software package. To probe the orbital interactions within the studied complexes, NBO analysis was performed employing NBO software. The assessment of bond nature, topological features, and electron density values at critical points for the studied complexes was undertaken using AIMAll software. The NCI index was derived utilizing Multiwfn software, and its three-dimensional representation was rendered using VMD software.

In Silico Investigation of the Mechanism of Disulfide Bond Dissociation by New Frustrated Lewis Pairs.

Understanding the mechanism of disulfide bond cleavage is important in various scientific disciplines including organic synthesis, catalysis, and biochemistry. In this study, an in silico investigation has been carried out for the dissociation of disulfide bonds using newly designed frustrated Lewis pairs (FLPs). The study revealed that the cleavage of the disulfide bond by the FLP P(tBu)3/B(C2NBSHF2)3 can also be used like the conventional FLP (tBu)3P/B(C6F5)3. It has been observed that the reaction is almost thermoneutral in the gas phase but exothermic in nonpolar solvents, such as toluene, heptane, and hexane. Furthermore, the natural bond orbital (NBO) describes insights into the role of FLPs in facilitating this reaction. Additionally, reaction force and force constant studies shed light on the energy requirements for completing the reaction and the synchronous nature of the dissociation process, respectively. Reaction electronic flux (REF) and its separations give the pattern of electronic activity during the chemical reaction. Extended transition state-natural orbitals for chemical valence (ETS-NOCV) and principal interacting orbital (PIO) analysis provide valuable information about the orbital interactions during the chemical reaction.

An experimental and computational exploration on noncovalent interactions, spectroscopic and nonlinear optical properties of novel creatininium cyanoacetate single crystal

A novel creatininium cyanoacetate (CCA) single crystal is synthesized by the slow evaporation technique and characterized by various experimental techniques such as FT-IR, FT-Raman and UV–visible spectral methods. Similar techniques are also investigated by the computational methods using Gaussian 09 software. The structural parameters, natural bond orbital (NBO), frontier molecular orbital (FMO), molecular electrostatic potential (MEP) and nonlinear optical (NLO) investigations are performed utilizing the DFT method with B3LYP/6-311G(d,p) basis set. The polarizable continuum model (PCM) has been used to identify the effect of various solvents (DMSO, ethanol, methanol, water) on the energy gap, excitation and NLO properties of CCA molecule. Fukui analysis is performed to identify the sites prone to nucleophilic and electrophilic attacks. Different topological methods including electron localization function (ELF), localized orbital locator (LOL), independent gradient model (IGM) and interaction region indicator (IRI) has been performed to quantify the noncovalent interaction and to analyse the weak interaction region. The UV–visible analysis indicates that the CCA crystal was optically transparent and has lower cut-off wavelength. The hole-electron analysis is performed to identify the characteristics of six excitations. The third-order NLO activity of the CCA compound is performed using the Z-scan technique and is compared with some related NLO materials. The substantial NLO response suggests that the CCA molecule can be significant for its utilization in advanced NLO applications.

Sensing ability of carbon nitride (C6N8) for the detection of carbon monoxide (CO) and carbon dioxide (CO2)

Carbon nitride (C6N8) is explored as an adsorption material for harmful industrial gases such as carbon monoxide (CO) and carbon dioxide (CO2). The complexation of CO and CO2 with C6N8 (analyte@C6N8) is deeply studied by the analyses of interaction energy (IE), frontier molecular orbital (FMO), non-covalent interactions (NCI), natural bond orbital (NBO), Bader’s quantum theory of atoms in molecules (QTAIM), density of state (DOS), reduced density gradient (RDG), and electron localization function (ELF). The results of interaction energy (−18.870 kJ/mol to −14.991 kJ/mol) showed the adsorption strength of CO and CO2 gases on the C6N8 surface. NCI and QTAIM investigations demonstrated that non-covalent interactions occurred in CO2 @C6N8 and CO@C6N8 complexes. The NCI and RDG analyses indicated surface interaction with CO and CO2 gases. The emergence of novel energy levels in the DOS spectrum highlighted the system's susceptibility to contaminants and the development of new excited states in the PDOS spectrum demonstrated the chemical reactivity of complexes. Moreover, the results of QNBO show that surface (C6N8) extracted a relatively greater amount of charge from CO (0.018 e−1) as compared to CO2 (0.006 e−1). At 300 K, the analyte@C6N8 complexes recovery time (4.06 ×10−10 s and 1.92 ×10−9 s) showed sensing behavior of surface for CO and CO2 gases. Our results suggested that the C6N8 surface is a superb option for CO and CO2 gases.

Synthesis, quantum chemical studies, molecular docking, molecular dynamics simulation and ADMET studies on 2-(2,3-dihydrobenzo[b][1,4]dioxin-6-yl)-1, 4,5-triphenyl-1H-imidazole derivatives

A novel 2-(2,3-dihydrobenzo[b][1,4]dioxin-6-yl)-1,4,5-triphenyl-1H-imidazole (DDTI) molecule was synthesised and characterised by FT-IR and NMR (1H and 13C) spectral techniques. The molecular structure was optimised using the density functional theory (DFT) method with B3LYP/6-311 G (d, p) basis set. Natural bonding orbital (NBO) analysis was used to determine the electron densities of donor (i) and acceptor (j) bonds as well as the hyperconjugative interaction energy (E ( 2) ). In highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) calculations, the smaller energy gap value was discovered. Molecular electrostatic potential has been analysed. The Mulliken atomic charges of the carbon, nitrogen and oxygen atoms were calculated at the same level of theory. The dipole moment, polarizability and first-order hyperpolarizability demonstrate the good nonlinear optical (NLO) feature of the title molecule. Molecular docking studies are implemented to analyse the binding energy of the DDTI compound against standard drugs such as the crystal structure of ADP ribose phosphatase of NSP3 from SARS-CoV-2 in complex with MES, SARS-CoV-2 main protease with an unliganded active site (2019-nCoV, corona virus disease 2019, COVID-19) and the crystal structure of COVID-19 main protease in complex with an inhibitor N3 found to be considered having better antiviral agent. Molecular dynamics simulation was performed for COVID-19 main protease (Mpro: 6WCF/6Y84/6LU7) to understand the elements governing the inhibitory effect and the stability of interactions under dynamic conditions. Virtual ADMET studies were carried out as well and a relationship between biological, electronic and physicochemical qualifications of the target compound was determined. Toxicity prediction by computational technique for the title compound was also carried out.

Synthesis, Crystal Structure, Hirshfeld Surface Analysis, and DFT Calculations of the Novel Binuclear Copper(I) Complex Containing 2-Benzimidazolethiole and Triphenylphosphine Ligands.

The reaction of 2-benzimidazolethiole (2-BIT) with copper dichloride in the presence of two equivalents of triphenylphosphine led to a binuclear complex of the type [Cu(µ-S-2-BIT)2(Ph3P)2Cl2]: dichloridobis(μ-1,3-dihydro-2H-benzimidazole-2-thione)bis(triphenylphosphi ne)-di-copper. The Cu(I) compound has been fully identified by elemental analysis, molar conductivity, FT-IR, UV/Vis, and single-crystal X-ray diffraction (XRD). The XRD study reveals that the complex has distorted tetrahedral geometry around the Cu(I)center, which contains two bridge sulfur atoms. The Hirshfeld surface mappedover dnorm, shape index, and curvature revealed important H...H, H... C/C...H, and H... Cl/Cl...H intermolecular interactions as the main contributors to crystal packing. The natural bond orbital (NBO) was applied to understand the strength of nucleophilic and electrophilic attack between ligands and Cu(I)ions. Furthermore, density functional theory (DFT) was employed to demonstrate the molecular reactivity and stability of the ligands and coppercomplex.

Theoretical study about the thermal stability and detonation performance of the nitro-substituted derivatives of 4-(1H-1,2,4-triazol-1-yl) pyrimidine

The nitro groups are introduced into 4-(1H-1,2,4-triazol-1-yl) pyrimidine to substitute the hydrogen atoms successively, through which a total of 31 derivatives are constructed to look for high energy density compounds (HEDCs). To probe the thermal stabilities, the heats of formation (HOFs) are calculated by using the G3MP2 method. To explore the dynamic stability, the natural bond orbital (NBO) analysis is performed to confirm the trigger bond, for which the bond dissociation energy is calculated using the B3PW91 method with the 6-311 + G(d,p) basis set. Furthermore, the detonation velocity (D), the detonation pressure (P), the molecular density (ρ), the explosive heat (Q), and character height (H50) are also predicted. Based on our calculation, it is confirmed that D1, D2, D5, and E are potential high-energy-density compounds with sufficient stability and excellent detonation performance.