Frontier Molecular Orbitals Research Articles

On the Nature of the Out-Of-Plane Distortions in Subporphyrins.

The field of subporphyrins has garnered great interest in recent years owing to its unique structure and associated properties. They exhibit spectroscopic features similar to porphyrins and find applications in various optoelectronic devices, photodynamic therapy etc. Most of the synthesized subporphyrins have boron coordination with an axial ligand and exhibits a bowl-shaped geometry. The first isolation of a stable free-base subporphyrin is achieved recently with mesityl groups at two of the meso positions and anthracene at the other. X-ray studies reveal a markedly non-planar structure different from the bowl shape and is attributed to the steric hindrance of the inner N-H bonds. Herein, we report a systematic quantum chemical investigation assisted by symmetry principles on molecular models to characterize the out-of-plane (OOP) distortions observed so far in subporphyrins and unveil the electronic reasons. Correlation of the frontier molecular orbital (FMO) landscape between the D4h porphyrin and D3h subporphyrin gives insight into their electronic structure relative to one another and the nature of OOP distortions. Further the effect of a π-donor cum σ-acceptor substituent at the meso/beta positions of the subporphyrin ring as well as the impact of boron incorporation in the central cavity on the OOP distortions are also discussed.

Repurposing of drug candidates against Epstein-Barr virus: Virtual screening, docking computations, molecular dynamics, and quantum mechanical study.

Epstein-Barr virus (EBV) was the first tumor virus identified in humans, and it is mostly linked to lymphomas and cancers of epithelial cells. Nevertheless, there is no FDA-licensed drug feasible for this ubiquitous EBV viral contagion. EBNA1 (Epstein-Barr nuclear antigen 1) plays several roles in the replication and transcriptional of latent gene expression of the EBV, making it an attractive druggable target for the treatment of EBV-related malignancies. The present study targets EBV viral reactivation and upkeep by inhibiting EBNA1 utilizing a drug-repurposing strategy. To hunt novel EBNA1 inhibitors, a SuperDRUG2 database (> 4,600 pharmaceutical ingredients) was virtually screened utilizing docking computations. In accordance with the estimated docking scores, the most promising drug candidates then underwent MDS (molecular dynamics simulations). Besides, the MM-GBSA approach was applied to estimate the binding affinities between the identified drug candidates and EBNA1. On the basis of MM-GBSA//200 ns MDS, bezitramide (SD000308), glyburide (SD001170), glisentide (SD001159), and glimepiride (SD001156) unveiled greater binding affinities towards EBNA1 compared to KWG, a reference inhibitor, with ΔGbinding values of -44.3, -44.0, -41.7, -40.2, and -32.4 kcal/mol, respectively. Per-residue decomposition analysis demonstrated that LYS477, ASN519, and LYS586 significantly interacted with the identified drug candidates within the EBNA1 binding pocket. Post-dynamic analyses also demonstrated high constancy of the identified drug candidates in complex with EBNA1 throughout 200 ns MDS. Ultimately, electrostatic potential and frontier molecular orbitals analyses were performed to estimate the chemical reactivity of the identified EBNA1 inhibitors. Considering the current outcomes, this study would be an adequate linchpin for forthcoming research associated with the inhibition of EBNA1; however, experimental assays are required to inspect the efficiency of these candidates.

Role of SiO2, TiO2, and Fe3O4 adsorbed on glycine for remediation of heavy metals and antibacterial activity in water.

Metals have a tendency to accumulate in the environment and can have carcinogenic effects. Accordingly, this study used density functional theory (DFT) calculations to investigate the adsorption of different metal ions on the glycine surface. Glycine has attracted a lot of research interest because of its remarkable metal-binding properties and cost effectiveness. Accordingly, to improve glycine's adsorption capacity, it has been combined with SiO2, TiO2, and Fe3O4, creating a glycine-metal oxide nanocomposite through hydrogen bonding. After optimizing the structures at their energy minima at the B3LYP/6-31G(d, p) level of theory, the following analyses were carried out: total dipole moment (TDM), frontier molecular orbitals (FMOs), reactivity indexes, and molecular electrostatic potential (MESPs). The study of TDM, FMOs, reactivity indexes, density of states (DOS), and UV-Vis absorption analysis demonstrated the improved reactivity of glycine due to functionalization with SiO2. Additionally, the results showed that, compared to the glycine, the glycine/SiO2 surface experiences a greater degree of charge redistribution as a result of more hydrogen bonds being formed with adsorbate molecules. Thus, the study successfully extracted Cr, Fe, Co, Ni, Cu, As, Cd, and Pb from wastewater by demonstrating their selectivity for the glycine/SiO2 nanocomposite. The findings show that Ni had a stronger adsorption for glycine/SiO2 than the others as TDM increased (34.040 Debye), band gap energy decreased significantly (0.249eV), and reactivity indices got improved. Additionally, the IR spectra were calculated and compared to the experimental data, which revealed remarkable frequency changes due to intermolecular interactions. HR-TEM scans validated the dispersion of SiO2 NP on the glycine surface with minimal aggregation. Furthermore, the antibacterial activity of glycine-amino acid-based surfactants was assessed, and the results show that glycine/SiO2 nanocomposites exhibited antibacterial efficacy against Gram-positive and Gram-negative microorganisms. These findings highlight the glycine/SiO2 nanocomposites for remediation of heavy metals and have antibacterial activity for treating pathogenic bacteria.

Crystal structure, Hirshfeld surface analysis, DFT and molecular docking studies of ethyl 5-amino-2-bromoisonicotinate

In the title compound, C8H9BrN2O2, the C—O—C—C torsion angle between isonicotine and the ethyl group is 180.0 (2)°. Intramolecular N—H...O and C—H...O interactions consolidate the molecular structure. In the crystal, N—H...N interaction form S(5) zigzag chains along [010]. The most significant contributions to the Hirshfeld surface arise from H...H (33.2%), Br...H/H...Br (20.9%), O...H/H...O (11.2%), C...H/H...C (11.1%) and N...H/H...N (10%) contacts. The topology of the three-dimensional energy frameworks was generated using the B3LYP/6–31 G(d,p) model to calculate the total interaction energy. The net interaction energies for the title compound are E ele = 59.2 kJ mol−1, E pol = 15.5 kJ mol−1, E dis = 140.3 kJ mol−1 and E rep = 107.2 kJ mol−1 with a total interaction energy E tot of 128.8 kJ mol−1. The molecular structure was optimized by density functional theory (DFT) at the B3LYP/6–311+G(d,p) level and the theoretical and experimentally obtained parameters were compared. The frontier molecular orbitals HOMO and LUMO were generated, giving an energy gap ΔE of 4.0931 eV. The MEP was generated to identify active sites in the molecule and molecular docking studies carried out with the title compound (ligand) and the covid-19 main protease PDB ID: 6LU7, revealing a moderate binding affinity of −5.4 kcal mol−1.

The molecular structure, electronic properties, and decomposition mechanism of FOX-7 under external electric field were calculated based on density functional theory.

Based on the density functional theory (DFT), we analyzed the changes of the FOX-7 molecule under external electric field (EEF) from multiple perspectives, including molecular structure, electronic structure, decomposition mechanism, frontier molecular orbitals (FMOs), and density of states (DOS). The results revealed that as the intensity of the positive EEF increased, the detonation performance of the FOX-7 molecule was significantly enhanced, while its thermal stability was also improved. This discovery challenges the traditional concept that explosives are inherently dangerous under external electric fields and provides new insights for research in related fields. To further explore the impact of EEF on the thermal stability of FOX-7, we conducted a thorough analysis of the mechanism by which EEF affects the decomposition process. Our findings indicate that applying a positive EEF significantly increases the energy required to overcome intramolecular hydrogen transfer and C-NO2 bond rupture, while having a relatively minor effect on the nitro isomerization process. This observation further demonstrates that the appropriate application of a positive EEF can enhance the detonation performance of FOX-7 without compromising its thermal stability. Further research revealed that as the intensity of the positive EEF increased, the electronegativity of the nitro group gradually enhanced, leading to an increase in the electronegativity of the oxygen atoms within it. This made the oxygen atoms more prone to participating in chemical reactions. This phenomenon also explains why the energy barrier required for nitro isomerization in FOX-7 gradually decreases as the intensity of the positive EEF increases. Based on the density functional theory (DFT), the structural optimizations were performed both under applied EEF and without EEF at the B3LYP/6-311G (d, p) level. All optimized results were converged and exhibited no imaginary frequencies. Based on the optimized structures, single-point energy calculations were further conducted at the B3LYP/def2-TZVPP level. Subsequently, analyses of molecular structure, electronic structure, decomposition mechanism, frontier molecular orbitals, and density of states were carried out.

Photovoltaic response promoted via intramolecular charge transfer in triphenylpyridine core with small acceptors: A DFT/TD-DFT study

Currently, A−π−A configured molecules (TTP1-TTP6) were designed from the reference compound (TPPR) by modifying the terminal acceptors for photovoltaic materials. Density functional theory (DFT) and time-dependent density functional theory (TD-DFT) using the M06/6-311G(d,p) functional were employed to analyze the photonic and electronic properties of the newly designed derivatives. Various analyses; frontier molecular orbitals (FMOs), density of states (DOS), absorption spectra (λmax), transition density matrix (TDM), binding energy (Eb), hole-electron and open circuit voltage (Voc) were performed to explore the photovoltaic properties of triphenylpyridine based compounds. The structural modulation with acceptor moieties significantly tuned their HOMO and LUMO levels, resulting in reduced band gaps (2.833–3.037 eV). They also exhibited broader absorption spectra (λmax) ranging from 482.560 to 514.756 nm as compared to the reference compound (486.289 nm). Notably, TPP3 showed the good photovoltaic response as it displayed the least energy gap (2.833 eV) with lower binding energy (0.415 eV) and bathochromic shift (512.798 nm) in absorption spectra as compared to all other derivatives. Beside this, a comparative study with spiro-OMeTAD and P3HT standard hole transport materials illustrated that these materials can also be utilized as effective photovoltaic materials.

Heavy Alkaline Earth Cyclic (Alkyl)(Amino)Carbene Complexes Supported by Aryl-Silyl Amides.

A series of 8 trigonal planar, heavy alkaline earth (AE = Ca-Ba) metal complexes containing cyclic (alkyl)(amino)carbene (CAAC) ligands were prepared from AE bis(amide) species. Complexation can be achieved by first generating the free carbene in situ or by direct addition of the free carbene, with the former route giving rise to unexpected mixed-amide AE complexes. The frontier molecular orbitals of the highly equatorial, 3-coordinate AE-CAAC species were also probed computationally, revealing the lowest unoccupied molecular orbital (LUMO) consisting predominantly of the π* system located on the carbene ligand.

Improving Optoelectronic Properties of Acceptor–Donor–Acceptor‐Type Non‐Fullerene Acceptors Containing Extended Fused Ring Donor Units for Efficient Organic Semiconductors

Developing efficient small molecule‐based non‐fullerene acceptors (NFAs) has gained huge attention in fabricating high‐efficiency and stable organic solar cells (OSCs). Herein, we designed and characterized eight new NFAs for OSCs. To investigate the potential of these newly designed NFAs series (IBH1–IBH8) for OSCs, various advanced quantum chemical simulation approaches are used and compared with the synthetic reference molecule IBH–R. Due to the extended donor cores, the IBH1–IBH8 molecules possess strong intramolecular and intermolecular interactions, which helps improve the thin‐film surface crystallinity. Moreover, the designed IBH1–IBH8 molecules present improved UV–visible absorption, narrower bandgaps, lower excitation, and binding energies, and improved photovoltaic characteristics. Furthermore, the impact on the intrinsic properties such as transition density matrix, density of state, electrostatic potential, distribution of frontier molecular orbitals, and reorganizational energies of holes and electrons are estimated. Additionally, the charge‐transfer phenomenon by establishing a donor:acceptor blend (PTB7–Th:IBH4) is analyzed, their geometric analyses are studied, and a good charge‐shifting process is found at the donor:acceptor interface. With these results, we demonstrated the enhancements in the optoelectronic and photovoltaic characteristics of OSCs by performing a simple end‐capped modulation. Hence, these molecules are recommended for the development of efficient and cost‐effective OSCs.

A theoretical investigation into the impact of solvents (alkanolic and non-alkanolic), structural and spectroscopic properties, donor-acceptor insights, Hirshfeld surface, and molecular docking of the anti-tumor compound (2E)-3-[4-(dimethylamino)phenyl]-1-(3-nitrophenyl)prop-2-en-1-one

In this study, computational methods were employed to analyze the molecular structure of (2E)-3-[4-(Dimethylamino)phenyl]-1-(3-nitrophenyl)prop-2-en-1-one (DMAPNP), investigating its structural and spectroscopic properties along with its biological activity. In particular, the Frontier Molecular Orbital (FMO) and Molecular Electrostatic Potential (MEP) surfaces in alkanolic solvents (ethanediol, ethanol, and methanol) and non-alkanolic solvents (DMSO, toluene, and water) were generated to analyze the solvent-solute interactions. The H→L transition shows low oscillator strengths (0.0002 in toluene to 0.0013 in ethanediol, DMSO, and water), indicating limited significance in the absorption spectrum. In contrast, the H→L+1 transition has much higher oscillator strengths, around 0.9412 for ethanediol and 0.9385 for DMSO and toluene, suggesting a greater likelihood of absorption at these wavelengths. The simulated vibrational wavenumbers revealed the presence of CH, NO2, CN, CC, CH3, and C=O groups in DMAPNP. The calculated chemical shifts confirmed the molecular structure of DMAPNP and aligned with standard values. In Hirshfeld surface analysis, the crystal packing of DMAPNP was primarily stabilized by H…H interactions, contributing 41.3%, followed by O…H / H…O interactions at 30.9%. In Natural Bond Orbital (NBO) analysis, the interaction between C20-H38 and C15-H33 shows a stabilization energy of 1102.89 kJ/mol, highlighting σ-σ* transitions. In contrast, the C12-C16 and C15-H33 interactions exhibit a stabilization energy of 2542.16 kJ/mol, indicating substantial π-σ* contributions. In the Mulliken charge distribution, the carbon atoms C18 (-1.33704e) and C13 (1.776064e), located in the para and meta positions concerning the nitro group (NO2), exhibit the highest positive and negative potentials, respectively. Molecular docking assessed DMAPNP as a potential anti-tumor agent by inhibiting the key regulatory enzyme fructose-2,6-bisphosphatase, with a binding energy of -8.13 kcal/mol.

Cubic-like A4B4 (A = Be, Mg, Ca; B = O) clusters for novel potential applications under density functional study

A density functional investigation of A4B4 (A = Be, Mg, Ca; B = O) metal-oxide clusters series is carried out in search for the stable and potential candidates. The minimum energy isomers for each of the A4B4 systems are identified, and frontier molecular orbitals (FMOs) have been generated and analyzed for the same. It is noteworthy that two nearly cubic-like stable motifs have been identified along with favorable electronic and optical properties that may be utilized for developing novel, useful nanomaterials. All the A4O4 systems revealed to be of cubic-like lowest energy structures, very interestingly, cubic Mg4O4 (λ = 418 Å) and cubic Ca4O4 (λ = 552 Å) are obtained as visible active clusters, which certainly confirms their promises in developing novel cluster-assembled nanomaterials with different dimensions with applications in optical and semiconductor arenas. Simulated infrared spectra of these identified novel cubic-like cluster-building units might help experimentalists with the possible synthesis and applications.

Computational Investigation and Antimicrobial Activity Prediction of Potential Antiviral Drug

The ethyl 2-amino-4,5,6,7-tetrahydrobenzo[b]thiophene-3-carboxylate (S1) was chosen for this investigation due to its important biological and pharmacological activities. Detailed infrared and Raman spectra have been investigated in both theoretical and experimental. Frontier molecular orbitals and the electronic properties of the S1 are explained. The titled compound S1 calculated HOMO-LUMO energy gap is 4.60 eV. In molecular electrostatic potential (MEP) map the NO2 group exhibits a blue color, indicating the presence of nucleophilic sites. The density of state (DOS), non-covalent interaction (NCI), electron localized function (ELF), localized orbital locator (LOL), Mulliken atomic charges, and reactive sites have been investigated. The anti-bacterial, antifungal, antitoxin, antiviral, and antimycobacterial studies have been investigated. The molecular docking investigations of the compound were also conducted. Using the Auto-dock program, the compound S1 molecular docking study has been conducted. The molecular docking study's lowest binding energy is -7.91, -5.62, -6.92, and -5.85 kcal/mol for 4XGK, 4ATO, 3U9G, and 2DP4 respectively.

Theoretical Investigation of Substitution Effect on the First Position of Coumarin Derivatives

AbstractDensity functional theory (DFT) and time‐dependent DFT (TD‐DFT) were used to investigate the linear and nonlinear optical properties of 1‐substituted coumarins. The molecular electrostatic potential plot, frontier molecular orbitals, and natural bond order analysis were used to study charge transfer properties. The bandgap exhibited an inverse relationship with the chemical potential (µ) and electrophilicity index (ω), while the chemical hardness (η) and hyperhardness (Γ) showed a direct relationship. First‐order hyperpolarizability (β0) and second‐order hyperpolarizability (γ) were directly correlated with the global reactivity descriptors μ and ω and inversely correlated with η and Γ.

Substitution effect and charge transport properties in organic field-effect transistors (OFETs) of simply functionalized carbazole derivatives

Development of low cost, easy-preparation and good performance organic semiconductors is in high demand for the practical application of organic field-effect transistors (OFETs). Even though the π-extended carbazole derivatives have been intensively studied in OFETs, the application potential of simple carbazole derivatives, i.e., owning simple substituents directly at carbazole backbone, remains unclear. In this work, we designed and synthesized a series of carbazole derivatives with simple phenyl or thienyl functionalization directly at 2,7- or 2,6-positions, respectively. The photophysical and electrochemical properties, together with their theoretical frontier molecular orbitals and energy levels were investigated. The molecular conformations and packing structures in the solid state of these molecules were understood by single-crystal structure analysis. In addition, single-crystal based OFETs were fabricated to explore their intrinsic charge transporting properties, in which the 2,7-diphenyl modified carbazole derivative showed hole-transporting mobilities up to 0.16 cm2 V-1 s-1. Our study not only proves that simply functionalized carbazoles have great potentials to act as easy-preparation high-performance p-type semiconducting materials, but also illustrates that 2,7-positon functionalization is more advantageous for balancing the molecular conformations and packing structures of carbazole derivatives to achieve good charge transport performance.

Investigation into the Quantitative Structure-Biotoxicity Relationship of Antibiotics and their Estrogenic Receptor Disruption Effects.

In light of antibiotics being classified as environmental hormone-like compounds, their interference with the endocrine system has significantly impacted human health and ecological environments. This study employed Gaussian09 software's Density Functional Theory (DFT) to structurally optimize and perform frequency calculations on 23 representative antibiotic molecules, aiming to obtain microscopic quantum mechanical structural parameters.Physicochemical property parameters were acquired through the RDKit database in the ChemDes platform. Through multiple linear regression analysis, the primary factors affecting antibiotic biotoxicity (pLD50) were identified, leading to the establishment of a QSAR model. The predictive capability of the model was analyzed using leave-one-out cross-validation, and molecular docking was used to investigate the binding mode and mechanism of action between estrogen receptors (ER) and antibiotics. Research outcomes indicate that the established QSAR model C has regression coefficients R2and leave-one-out cross-validation coefficients Q2of 0.92474 and 0.74913, respectively, demonstrating good stability and predictive power. Analysis through molecular surface electrostatic potential, frontier molecular orbitals,molecular docking, and molecular dynamicsrevealed that the potential estrogenic disrupting effects are primarily due to hydrogen bonds and hydrophobic interactions between antibiotics and estrogen receptors. This provides a valuable exploration for identifying and screening PPCPs with potential estrogenic disrupting effects.

Theoretical Perspective on the Sensing Mechanism of a Pyrazinium‐Based Fluorescent Probe Towards 2,4,6‐Trinitrophenol

ABSTRACTRapid detection of chemical explosives plays a critical role in national security and public safety. An in‐depth study of the sensing mechanism is particularly urgent for the development of highly efficient, sensitive, and selective chemical sensors for the precise detection of chemical explosives. Density functional theory (DFT) and time‐dependent DFT approaches were used in this work to examine the sensing mechanism of a novel fluorescent probe 1‐benzyl‐3,5‐di (thiophen‐2‐yl)pyrazin‐1‐ium bromide (BTPyz) for the detection of 2,4,6‐trinitrophenol (TNP). A comprehensive theoretical exploration was carried out, and a different interaction mode between the probe and TNP from that in the original experiment was proposed. The π–π stacking was established to be the recognition interaction between BTPyz and TNP anion, and the active site was determined from the three potential sizes according to the Gibbs free energy analysis results. The rationality of the reaction mode and the π–π stacking product between the BTPyz and TNP (BTN) was further confirmed by the fluorescence properties (absorption and emission spectra). According to the findings of frontier molecular orbitals (FMOs), photoinduced electron transfer (PET) is the intrinsic mechanism through which TNP quenches the probe's fluorescence.

DFT Computation, Spectroscopic, Hirshfeld Surface, Docking and Topological Analysis on 2,2,5‐Trimethyl‐1,3‐Dioxane‐5‐Carboxylic Acid as Potent Anti‐Cancer Agent

ABSTRACTThe 2,2,5‐trimethyl‐1,3‐dioxane‐5‐carboxylic acid (TDCA) using both theoretical and experimental methods have been studied. The sample has been subjected to XRD, FTIR, FT‐Raman, (C13 and H1) NMR, and UV–vis spectrum analysis. Then, theoretical calculations have been performed at the DFT/B3LYP/6‐311++G(d,p) higher based scale. The theoretical and experimental geometrical parameters and frequencies have been compared well. Theoretical and experimental NMR chemical shifts have been determined. Absorption wavelengths of UV–Vis spectrum were experimentally measured and compared with TD‐DFT predictions. Detailed explanations have been given for frontier molecular orbitals, low density gradient, distribution of Mulliken charges, molecular electrostatic potential (MEP), RDG, localized orbital location, and electron localized activities. Based on the studied 2D image of the Hirschfield surfaces, H···H (65.6%) and O···H/H···O (33.6%) are found as the controlling interactions. A high binding affinity of −6.5 Kcal/mol has been calculated against 4OAR protein. These theoretical findings of the molecule may be used as an anticancer drug candidate, which helps to explain the structural stability, reactivity and anticancer potential of TDCA. High drug affinity for the TDCA has been detected by in silico ADMET prediction.

Design, synthesis and antibacterial activity of new Isatin-based Schiff base derivatives: Molecular docking, POM analysis, in silico pharmacokinetics and identification of antitumor pharmacophore sites

In this study,we have reported a series of Isatin-based Schiff base derivatives G(1–5), the formation of the synthesized compounds was confirmed by Spectro analytical techniques. The synthesized compounds were screened for antimicrobial activity against Pseudomonas aeruginosa, Salmonella typhie,andStaphylococcus aureusbacterial strainsandantifungalscreening againstCandida albicansusing disc diffusion and broth microdilution with ciprofloxacin and fluconazole as reference standards, which indicated that the studied compounds exhibited exceptional antibacterial properties. The density functional theory (DFT) studies were used to study atomic structure and reactivity, including absolute electronegativity (χ), electrophilicity (ω), electron acceptor (ω+), donor capabilities (ω–), electron affinity (EA), energy gap (∆E), global hardness (η), global softness (S), and ionization potential (IP) and frontier molecular orbitals (FMOs), molecular electrostatic potential (MEP), and Mulliken Charge analysis. The Petra, Osiris, and Molinspiration(POM) tests found three integrated pharmacophore sites with antibacterial, antiviral, and anticancer activities. Molecular docking studies are also used to determine theaffinity and mode of action of the synthesized compounds with the targeted receptor, Staphylococcus aureus nucleoside diphosphate kinase receptor, which supported the experimental results. In silico analysis of thermodynamic and therapeutic effectiveness properties, including Lipinski's 'rule of five', Veber's rule, boiled egg model, and ADME properties, forecastthetoxicity-free, non-carcinogenic, and risk-free oral administration of the synthesized complexes.

Topological Band Engineering of One-Dimensional π-d Conjugated Metal-Organic Frameworks.

One-dimensional (1D) π-d conjugated metal-organic frameworks (c-MOFs) have garnered widespread research interest in chemical energy storage and conversion. In this work, we introduce a universal principle to engineer the topological bands of 1D c-MOFs. Connected by d orbitals of transition metals, two equivalent hidden molecular π orbitals in 1D c-MOFs can generate a staggered hopping within and between the organic ligands, forming Su-Schrieffer-Heeger-shaped 1D topological bands. Guided by this discovery, we investigate the electronic structures of the typical 1D c-MOF assembled from Ni atoms and 2HQDI (QDI = 2,5-diamino-1,4-benzoquinonediimine) precursors (NiQDI) by first-principles calculations, revealing 1D topological bands around the Fermi level. Due to local bonding variations at the QDI terminations, these two hidden molecular π orbitals become atomically bonded but electronically separated at the edge QDI, creating spatially localized in-gap topological edge states at the end of the NiQDI chain. This definitive signature for 1D topological bands is identified through differential conductance spectra in scanning tunneling microscopy measurements. Our results provide conclusive experimental evidence for topological bands in 1D c-MOFs, paving the way for exploring the topological physics in organic materials through frontier molecular orbitals.

Experimental and computational analysis of poly(4-vinyl pyridine) and polyvinylpyrrolidone as effective corrosion inhibitors for low carbon steel in sulfuric acid

This study investigates the inhibitory effects of poly(4-vinyl pyridine) (P4VP) and polyvinylpyrrolidone (PVP) on the corrosion of low carbon steel (LCSt) in 1 M H2SO4. Protection efficacy (%PE) was measured using mass loss, potentiodynamic polarization, and electrochemical impedance spectroscopy (EIS). Results showed %PE values increased with higher polymer concentration and lower temperature. At 450 mg/L, %PE reached 93.13% and 94.19% for P4VP and PVP, respectively. These polymers function as mixed inhibitors, adsorbing onto the LCSt surface per Langmuir’s model as a mode of physical adsorption. EIS indicated that higher polymer concentration increased charge transfer resistance and decreased effective double-layer capacitance. Both P4VP and PVP also reduced pitting corrosion in chloride-containing solutions. Density Functional Theory (DFT) and Time-Dependent DFT (TD-DFT) optimized the molecular structures of the inhibitors, evaluating electronic parameters such as frontier molecular orbital (FMO) energies, energy gap, softness, hardness, electron transfer fraction, dipole moment, and hyperpolarizability ( β ° ). Monte Carlo (MC) and molecular dynamics (MD) simulations provided insights into adsorption mechanisms, corroborating experimental findings and highlighting the effect of protonation. This comprehensive study enhances our understanding of the relationship between molecular structure and function in polymer inhibitors, improving their application in corrosion protection.

Synthesis of novel isostere analogues of naphthyridines using CuI catalyst: DFT computations (FMO, MEP), molecular docking and ADME analysis

An approach towards the synthesis of novel isosteres of benzonaphthyridines and benzonaphthonaphthyridines from the condensation reaction between 4-chloro-2-methylquinolines/4-chloro-2-methylbenzo[h]quinoline and appropriate o-amino aromatic and heteroaromatic carboxylic acids by using solvent (ethanol)/solvent free (neat) condition to yield the intermediate followed by the cyclization with PPA. The intermediate yield has been slightly increased in neat (solvent-free) conditions compared to solvent conditions. Further, the target isosteres of benzonaphthyridines and benzonaphthonaphthyridines were achieved in the one-pot synthesis using a CuI catalyst with a higher yield than the stepwise method. Quantum chemical calculations of synthesized compounds are performed by using M06-2X with 6-311+G(d,p) basis set in water, DFT calculations of the molecular electrostatic potential (MEP), frontier molecular orbitals (FMOs), and the optimized geometry of the XRD values are compared with experimental values. All the synthesized novel isosteres molecules are investigated under molecular docking studies using MMP1 and MMP2 proteins, which showed all the molecules have the potential to heal pancreatic cancer. The most potent molecules among them are 3i and 3h due to their better docking scores. Furthermore, the molecules' pharmacokinetic (ADME) parameters have been observed to be effective in future biological evaluations of these compounds to be active.