Quantum Theory Of Atoms In Molecules Research Articles

Consequences of the Pb-S Bond Formation for Lead Halide Perovskites.

Lead halide perovskites are structurally not stable due to their ionic bonds. Using sulfur agents in the crystal growth improves the stability and performance of the photovoltaic and light-emitting devices. In this theoretical work, we use a small toy S-radical in place of A cation in the bulk of lead iodide perovskite, and highlight the significance of the Pb-S covalent-double-bond formation for: the charge redistribution on the neighboring bonds that also turn to be covalent, phase transformation to a stable non-perovskite structure, and superior optoelectronic properties. The chemical analysis was performed with the Quantum Theory of Atoms In Molecules (QTAIM) and Non-Covalent Interactions (NCI) index. Excitonic properties were obtained from the solution of ab initio Bethe-Salpeter equation. Presence of the spin-orbit coupling triggers an interplay between the Frenkel and charge-transfer multiexcitons, switching between the photovoltaic and laser applications. Multiexcitons obey the exciton-fission preconditions.

In-Depth Theoretical Investigations of Borazine’s Aromaticity: Tailoring Electron Delocalization through Substituent Effects

The current study investigates the influence of several R substituents (e.g., Me, SiH3, F, Cl, Br, OH, NH2, etc.) on the aromaticity of borazine, also known as the “inorganic benzene”. By performing hybrid DFT methods, blended with several computational techniques, e.g., Natural Bond Orbital (NBO), Quantum Theory of Atoms in Molecules (QTAIM), Gauge-Including Magnetically Induced Current (GIMIC), Nucleus-Independent Chemical Shift (NICS), and following a simultaneous evaluation of four different aromaticity indices (para-delocalization index (PDI), multi-centre bond order (MCBO), ring current strength (RCS), and NICS parameters), it is emphasized that the aromatic character of B-substituted (B3R3N3H3) and N-substituted (B3H3N3R3) borazine derivatives can be tailored by modulating the electronic effects of R groups. It is also highlighted that the position of R substituents on the ring structure is crucial in tuning the aromaticity. Systematic comparisons of calculated aromaticity index values (i.e., via regression analyses and correlation matrices) ensure that the reported trends in aromaticity variation are accurately described, while the influence of different R groups on electron delocalization and related aromaticity phenomena is quantitatively assessed based on NBO analyses. The most relevant interactions impacting the aromatic character of investigated systems are (i) the electron conjugations occurring between the p lone pair electrons (LP) on the F, Cl, Br, O or N atoms, of R groups, and the π*(B=N) orbitals on the borazine ring (i.e., LP(R)→π*(B=N) donations), and (ii) the steric-exchange (Pauli) interactions between the same LP and the π(B=N) bonds (i.e., LP(R)↔π(B=N) repulsions), while inductive/field effects influence the aromaticity of the investigated trisubstituted borazine systems to a much lesser extent. This work highlights that although the aromatic character of borazine can be enhanced by grafting electron-donor substituents (F, OH, NH2, O−, NH−) on the N atoms, the stabilization due to aromaticity has only a moderate impact on these systems. By replacing the H substituents on the B atoms with similar R groups, the aromatic character of borazine is decreased due to strong exocyclic LP(R)→π*(B=N) donations affecting the delocalization of π-electrons on the borazine ring.

Unusual Metal–organic Multicomponent Ni(II) and Mononuclear Zn(II) Compounds Involving Pyridine dicarboxylates: Supramolecular Assemblies and Theoretical Studies

In the present work, we reported the synthesis and characterization [single crystal X-ray diffraction technique, spectroscopic, etc.] of two new Ni(II) and Zn(II) coordination compounds, viz. [Ni(2,6-PDC)2]2[Ni(en)2(H2O)2]2[Ni(en)(H2O)4]·4H2O (1) and [Zn(2,6-PDC)(Hdmpz)2] (2) (where 2,6-PDC = 2,6-pyridinedicarboxylate, en = ethylene-1,2-diamine, and Hdmpz = 3,5-dimethyl pyrazole). Compound 1 is found to crystallize as a multicomponent Ni(II) compound with five discrete complex moieties, whereas compound 2 is isolated as a mononuclear Zn(II) compound. A deep analysis of the crystal structure of 1 unfolds unusual dual enclathration of guest complex cationic moieties within the supramolecular host cavity stabilized by anion–π, π-stacking, N–H⋯O, C–H⋯O, and O–H⋯O hydrogen bonding interactions. Again, the crystal structure of compound 2 is stabilized by the presence of unconventional C–H⋯π(chelate ring) interactions along with C–H⋯O, C–H⋯N hydrogen bonding, π-stacking, and C–H⋯π(pyridyl) interactions. These non-covalent interactions were further studied theoretically using density functional theory (DFT) calculations, molecular electrostatic potential (MEP) surfaces, non-covalent interaction (NCI) plot index, and quantum theory of atoms in molecules (QTAIM) computational tools. The computational study displays that π-stacking or H bonds greatly tune the directionality of compound 1, although non-directional electrostatic forces dominate energetically. For compound 2, a combined QTAIM/NCI plot analysis confirms the presence of unconventional C–H⋯π(chelate ring) interactions along with other weak interactions obtained from the crystal structure analysis. Further, the individual energy contributions of these weak yet significant non-covalent interactions have also been determined computationally.

Incrimination and impact on recovery times and effects of BN nanostructures on antineoplastic drug-electronic density study.

By delivering the drug to the intended cell location, the use of nanomaterials in the drug delivery system may influence how the patient receives the medication and may assist in mitigating severe side effects. Density functional theory was used to assess the use of boron carbon nitride nanocages (BNCNCs), boron nitride (BNNSs), and boron carbon nitride nanosheets (BNCNSs) as melphalan (Mln) drug carriers in both the gaseous and fluid phases. We systematically examined the dipole moment, density of states, frontier molecular orbital, and optimal adsorption energy to understand the targeted drug delivery potential of these nanostructures. Adsorption energy analysis revealed that in both gas and water media, Mln drug adsorption takes place spontaneously on all the conjugated structures. The occurrence of adsorption energy as physisorbed energy suggests that the process is reversible, and desorption can take place with a much lower energy input. This physical contact is appropriate for the unquestionable unloading of Mln medications to the intended location. The reactivity is higher in BNNSs and BNCNSs, while the stability is higher in BNCNCs. The recovery time shows a shorter time for BNNSs and BNCNSs, while BNCNC shows a potential desorption time in higher temperature. These conclusions are corroborated by the results of the quantum theory of atoms in molecules (QTAIM). After the interaction analysis, it was observed that the BNCNCs can act as potential carriers for the melphalan. From dipole moment analysis, all three nanostructures show a high hydrophilic nature but quite higher in BNCNCs after doping in both media. Overall, all the structures show the potential carrier for melphalan drug. The quantum mechanical approach, or DFT, has been used to study the fundamental structural, electrical, thermodynamic, and other aspects of proposed structures to develop an acceptable Mln drug detector. The adsorbate and all adsorbents were optimized via the hybrid B3LYP functional and the 6-311G + + (2d, p) basis set approach prior to the adsorption process. The Gaussian 09 package was used at 298K as the constant temperature and 1 atm as the constant pressure. The structures are examined using the same functional models for solvation analysis-6-311 G + + (2d, p) and B3LYP-as well as the polarized continuum model (PCM) model as the foundation set. Density of states was studied using GaussSum 3.0 software. The interaction studies QTAIM and RDG were studied using VMD and Multiwfn software.

Role of Intermolecular Interactions in Deep Eutectic Solvents for CO2 Capture: Vibrational Spectroscopy and Quantum Chemical Studies.

Recent research and reviews on CO2 capture methods, along with advancements in industry, have highlighted high costs and energy-intensive nature as the primary limitations of conventional direct air capture and storage (DACS) methods. In response to these challenges, deep eutectic solvents (DESs) have emerged as promising absorbents due to their scalability, selectivity, and lower environmental impact compared to other absorbents. However, the molecular origins of their enhanced thermal stability and selectivity for DAC applications have not been explored before. Therefore, the current study focuses on a comprehensive investigation into the molecular interactions within an alkaline DES composed of potassium hydroxide (KOH) and ethylene glycol (EG). Combining Fourier transform infrared (FT-IR) and quantum chemical calculations, the study reports structural changes and intermolecular interactions induced in EG upon addition of KOH and its implications on CO2 capture. Experimental and computational spectroscopic studies confirm the presence of noncovalent interactions (hydrogen bonds) within both EG and the KOH-EG system and point to the aggregation of ions at higher KOH concentrations. Additionally, molecular electrostatic potential (MESP) surface analysis, natural bond orbital (NBO) analysis, quantum theory of atoms-in-molecules (QTAIM) analysis, and reduced density gradient-noncovalent interaction (RDG-NCI) plot analysis elucidate changes in polarizability, charge distribution, hydrogen bond types, noncovalent interactions, and interaction strengths, respectively. Evaluation of explicit and hybrid models assesses their effectiveness in representing intermolecular interactions. This research enhances our understanding of molecular interactions in the KOH-EG system, which are essential for both the absorption and desorption of CO2. The study also aids in predicting and selecting DES components, optimizing their ratios with salts, and fine-tuning the properties of similar solvents and salts for enhanced CO2 capture efficiency.

Charge-Assisted Anion-π Interaction and Hydrogen Bonding Involving Alkylpyridinium Cations.

Competition and cooperation of charge-assisted anion-π interactions and hydrogen bonding were explored in the solid state and in solutions of 1-ethyl-4-carbomethoxypyridinium iodide, the compound utilized by Kosower to calculate solvent polarity Z-indices. X-ray structural analysis of this salt revealed multiple short contacts of iodide anions with hydrogen atoms and aromatic rings of pyridinium cations. Geometric characteristics, quantum theory of atoms in molecules (QTAIM), and noncovalent interaction (NCI) analysis of these contacts indicated comparable interaction energies of the anion-π and hydrogen bonding between iodide and pyridinium cation. 1H NMR (indicating the presence of the hydrogen-bonded complexes) and UV-vis measurements (which were consistent with the formation of anion-π associations) pointed out that both these supramolecular interactions also coexist in solutions. The comparable interaction energies (ΔE) of these modes were confirmed by the DFT computations. Also, while the variations of ΔE with the dielectric constant of the solvents for the complexes of iodide with the neutral π-acceptors were related to the increase of the effective radii of hydrogen- or anion-π bonded iodides, the changes in ΔE for the complexes with pyridinium followed interaction energies between two unit charges. However, the distinction of the bonding in hydrogen-bonded and anion-π complexes of iodide with pyridinium led to a switch of their relative energies with an increase of the polarity of the medium.

Adsorption mechanism of CO, CO2, NO, NO2, and SO2 gases onto AlNNT(m,n)_k, (m = 5, 7; n = 0, 5, 7; k = 3–9)

This study provides valuable insights into two key areas. First, we conduct a detailed examination of aluminum nitride nanotubes (AlNNT (m,n)_k), where m = 5,7; n = 0,5,7; and k = 3−9, focusing on their electronic properties across different lengths and diameters. We then investigate how these nanotubes interact with various gases, including CO, CO2, NO, NO2, and SO2. To determine the most energetically favorable configurations, we use the bee colony algorithm for global optimization. Our computational approach employs several Density Functional Theory (DFT) methods, such as PBE0, B3LYP(GD3BJ), CAM-B3LYP, HSE06, M06–2X, TPSSh, and ωB97XD functionals, in combination with the Def2svpp basis set. We prioritize the optimization of structural configurations and analyze the changes in energy band gaps within the nanotubes using conceptual DFT analysis. Additionally, we examine charge transfer mechanisms during gas/nanotube interactions through Natural Bond Orbital (NBO) analysis and assess the nature of these interactions with the Quantum Theory of Atoms in Molecules (QTAIM) framework. Our findings reveal that the interaction with SO2 tends to be slightly stronger compared to the other gases, as evidenced by various analytical techniques. This comprehensive analysis enhances our understanding of gas interactions with aluminum nitride nanotubes and provides insights into their practical applications.

Aluminum fluorides as noncovalent Lewis acids in proteins: The case of phosphoryl transfer enzymes.

The Protein Data Bank (PDB) was scrutinized for the presence of noncovalent O···Al Triel Bonding (TrB) interactions, involving protein residues (e.g. GLU and GLN), adenosine/guanine diphosphate moieties (ADP and GDP), water molecules and two aluminum fluorides (AlF3 and AlF4-). The results were statistically analyzed, revealing a vast number of O···Al contacts in the active sites of phosphoryl transfer enzymes, with a marked directionality towards the Al σ-/π-hole. The physical nature of the TrBs studied herein was analyzed using Molecular Electrostatic Potential (MEP) maps, the Quantum Theory of Atoms in Molecules (QTAIM), the Non Covalent Interaction plot (NCIplot) visual index and Natural Bonding Orbital (NBO) studies. As far as our knowledge extends, it is the first time that O···Al TrBs are analyzed within a biological context, participating in protein trapping mechanisms related to phosphoryl transfer enzymes. Moreover, since they are involved in the stabilization of aluminum fluorides inside the protein's active site, we believe the results reported herein will be valuable for those scientists working in supramolecular chemistry, catalysis and rational drug design.

Acetic acid-benzaldehyde solutions: FTIR studies, DFT, isosurface, NBO and QTAIM analyses

Fourier Transform Infrared (FTIR) spectra of pure Acetic acid (AcOH), Benzaldehyde (PhCHO) and their binary solutions at various concentration have been recorded. Density functional theory (DFT) calculations using the functional B3LYP/6-311++G (d, p), isosurface, natural bond orbital analysis (NBO) and quantum theory of atoms in molecules (QTAIM) analyses have been performed on dimers of AcOH, PhCHO and their complexes in gas phase. The results of FTIR and DFT calculations have been analysed to identify the dimers present in liquid AcOH/PhCHO and the PhCHO-AcOH complexes present in the binary solutions. The liquid AcOH consists of closed nine dimers with the different interaction schemes. The frequency shift suffered by vibrational bands of AcOH or PhCHO suggest the formation of 1:1 (PhCHO:AcOH) and 1:2 complexes in the binary solutions. The 1:2 complex exist even in 1:3/3:1 binary solution and this indicates that the AcOH dimers remains stable in the diluted solutions.

Investigation of synthesis, spectroscopic characterization, crystal structure, and computational studies of 3-(4-(dimethylamino)phenyl)-1,5-di(thiophen-2- yl)pentane-1,5-dione as potent against Cathepsin S

The chief purpose of this work was to synthesize and characterize 3-(4-(dimethylamino)phenyl)-1,5-di(thiophen-2-yl)pentane-1,5-dione (4) whose structure was subsequently confirmed by single-crystal X-ray analysis. This molecule adopts a conformation approximating a three-bladed fan. In the crystal, C–H···O and C–H···S hydrogen bonds, together with C–H···π(ring) interactions form corrugated layers parallel to the bc plane. Electronic structure calculations were performed at the ωB97xd/def2tzvp level to explore the reactivity and topology of the molecule. Quantum theory of atoms in molecule (QTAIM) and NBO studies provide bonding characteristics and the extent of charge transfer with orbital energies computed from FMO theory together with optical and nonlinear optical (NLO) properties. A Hirschfeld surface analysis was performed to explore the nature of interactions in the crystal packing and the dispersion interactions were found to have a significant role in stabilizing the crystal structure. The H···H interactions are the most significant among the intermolecular interactions. Compound 4 was subjected to structural activity relationship analysis and exhibited potency against Cathepsin S. Molecular docking and molecular dynamics analysis were carried out to understand the binding interaction mechanism and stability of 4 in its complex with Cathepsin S.

Unlocking the power of Dryopteris filix mas extract: A green solution for corrosion inhibition in A210Gr carbon steel in acidified 3% wt. NaCl environment

This study investigates the corrosion inhibition effectiveness of Dryopteris filix-mas L. (DFM) extract for A210Gr carbon steel in a 3 % NaCl solution. The DFM ethanolic extract was successfully prepared and comprehensively characterized using a combination of spectroscopic and physicochemical techniques, including HPLC, FTIR, and NMR (1H and 13C). These analyses confirmed the presence of key phenolic compounds, with Quercetin-3-O-diglucoside (Q3ODG) being the major component, comprising 82.14 % peak area as identified by HPLC. The extract, obtained via an economical ethanol extraction method, exhibited a maximum inhibition efficiency up to 88 % at a concentration of 400 ppm, as determined through electrochemical impedance spectroscopy (EIS), open circuit potential (OCP), potentiodynamic polarization (PDP), and weight loss measurements. Temperature studies revealed a drop in efficiency to 70.14 % at 323 K, indicating a temperature-sensitive inhibition mechanism. Extended immersion times led to a slight decrease in efficiency due to partial desorption, though significant protection remained after 72 h. The primary corrosion inhibition mechanism was determined to be physisorption, following the Langmuir isotherm model, with a ΔGads0 value of − 24.02 kJ/mol, indicating a spontaneous adsorption process. Thermodynamic analysis revealed an increase in Ea from 22.11 kJ/mol (blank) to 56.61 kJ/mol (400 ppm), confirming the formation of a strong protective barrier. Surface characterization techniques, including FTIR, XRD, SEM, and AFM, further confirmed the presence of a protective film rich in polar organic compounds. Complementary Density Functional Theory (DFT) and Quantum Theory of Atoms in Molecules (QTAIM) studies provided detailed insights into the molecular interactions, highlighting the key role of hydrogen bonding and van der Waals forces in the adsorption of Q3ODG onto the steel surface. These findings underscore the potential of DFM extract as an effective and sustainable corrosion inhibitor, advancing the application of biocompounds in corrosion control and encouraging further exploration of their industrial applications and environmental benefits.

Finely tuned energy gaps in host-guest complexes: Insights from belt[14]pyridine and fullerene-based nano-Saturn systems

Over the past few decades, doping, physisorption and chemisorption remained some of the commonly utilized methods to modify the energy gaps and electronic properties of materials. Yet, achieving precise control over tuning the highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) levels within these systems persisted as a remarkable challenge. Therefore, there is a growing need for systems that facilitate exact adjustments of energy gaps and HOMO/LUMO levels. Here, in this research work, the nano-Saturn host-guest complex systems are designed based on belt[14]pyridine as a host and fullerene nanocages (C20, C32, C34 and C36) as guests. The greater thermodynamic stability of the complexes is revealed by the higher values of interaction energies (Eint) for these complexes, ranging from −45.50 to −56.81 kcal/mol. The frontier molecular orbital (FMO) analysis revealed the contribution of HOMO of fullerenes and LUMO of belt[14]pyridine towards the HOMO and LUMO of the designed complexes, respectively. The energy gaps of the complexes also decrease compared to the constituents, with the least Egap of 0.52 eV observed for C20@N-belt. Moreover, the charge transfer from the host towards the guests is predicted and confirmed via natural bond orbital (NBO) and electron density difference (EDD) analyses. The non-covalent interaction index (NCI) and quantum theory of atoms in molecules (QTAIM) analyses determine the nature and strength of interactions in the host-guest complexes. Moreover, it is noticed through the UV–vis analysis that the bare fullerenes show the maximum absorption in ultraviolet (UV) region, but after complexation, maximum absorption is observed in visible and near infrared (NIR) regions, with highest λmax of 927 nm for C36@N-belt. These findings highlight the successful development of nano-Saturn host-guest complexes with precise control over HOMO-LUMO levels and energy gaps. This work aims to address the challenges in fine-tuning the electronic properties and demonstrates potential applications in optoelectronics, photovoltaics, and NIR-based sensors. Moreover, the ability to tune the electronic properties can guide future material design strategies for advanced energy storage and photonic devices.

Exploration of crystal structure, supramolecular organization, and computational studies of a novel pyrazole derivative: A structural and theoretical perspectives

An eminent challenge in contemporary medicine and pharmacy is the identification of powerful, biologically active, and benign anti-COVID drugs. The objective of this work is to synthesize 3-chloro-1-(3-chloropyridin-2-yl)-1H-pyrazole-5-carboxylic acid to investigate its properties using different spectroscopic methods. The crystal structure of the compound is determined using single-crystal X-ray diffraction methodology. Hirshfeld surface analysis was employed to evaluate the impact of intermolecular interactions on crystal packing. The interactions were visually depicted using 2D fingerprint plots, which highlighted the specific surface area associated with each interactant. Indications suggest that the crystal packing is mostly governed by C-H...O and N-H...O interactions, resulting in the formation of S(7) self-motif and R44(24) synthon, which greatly improve crystal stability. Density functional theory (DFT) was employed to better examine the structural and electrical characteristics. Computations were conducted at the 6–311+G(d,p) level to determine the optimal geometry, total energy, HOMO-LUMO gap, and vibrational spectra. The results showed a HOMO-LUMO gap of 3.092 eV, suggesting a moderate amount of stability. Bader et al. employed reduced density gradient (RDG) techniques and topological analysis, taking into account the quantum theory of atoms in molecules (QTAIM), to examine noncovalent interactions. Additionally, the molecule satisfies Lipinski's rule of five and exhibits encouraging pharmacokinetic activities. Additional in-silico investigations, including molecular docking, were conducted on the SARS-CoV-2 spike protein variation to assist in the advancement of enhanced vaccines and therapeutics.

Fluxional halogen bonds in linear complexes of tetrafluorodiiodobenzene with dinitrobenzene.

The fluxional nature of halogen bonds (XBs) in small molecular clusters, supramolecules, and molecular crystals has received considerable attention in recent years. In this work, based on extensive density-functional theory calculations and detailed electrostatic potential (ESP), natural bonding orbital (NBO), non-covalent interactions-reduced density gradient (NCI-RDG), and quantum theory of atoms in molecules (QTAIM) analyses, we unveil the existence of fluxional halogen bonds (FXBs) in a series of linear (IC6F4I)m(OONC6H4NOO)n (m + n = 2-5) complexes of tetrafluorodiiodobenzene with dinitrobenzene which appear to be similar to the previously reported fluxional hydrogen bonds (FHBs) in small water clusters (H2O)n (n = 2-6). The obtained fluxional mechanisms involve one FXB in the systems which fluctuates reversibly between two linear CI···O XBs in the ground states (GS and GS') via a bifurcated CI O2N van der Waals interaction in the transition state (TS). The cohesive energies (Ecoh) of these complexes with up to four XBs exhibit an almost perfect linear relationship with the numbers of XBs in the systems, with the average calculated halogen bond energy of Ecoh/XB = 3.48 kcal·mol-1 in the ground states which appears to be about 55% of the average calculated hydrogen bond energy (Ecoh/HB = 6.28 kcal·mol-1) in small water clusters.

Chalcogenides encapsulated Pt-doped carbon quantum dot (Pt@CQD) as a carrier for the controlled release of lapachone: Outlook from theoretical calculations

While cancer remains a significant health concern for humans, and is a serious and life-threatening disease, this research introduces an innovative drug delivery strategy employing platinum-doped carbon quantum dots (Pt@CQD) decorated with chalcogenide (O, S, Te) atoms for targeted delivery of the anti-inflammatory drug lapachone (LPC), which was analysed through density functional theory (DFT) at the ωB97XD/def2svp level of theory. Adsorption studies indicated exothermic behaviour, with negative energies for LPC_Pt@CQD, LPC_OdecPt@CQD, LPC_SdecPt@CQD, and LPC_TedecPt@CQD with corresponding values of −25.549 kcal/mol, −24.583 kcal/mol, −24.629 kcal/mol and − 24.419 kcal/mol respectively, indicating their chemisorption strengths. The quantum theory of atoms in molecules (QTAIM) and non-covalent interaction (NCI) analyses highlight weak and partial interactions among the complexes. Significantly, the engineered systems exhibit notable drug-release properties, especially LPC_OdecPt@CQD, where we observed a considerably slight physisorption and an adsorption energy of 10.277 kcal/mol and a protonation energy gap (ΔE) of 2.648 eV which balances effective adsorption and the ability to release the drug when needed. Furthermore, molecular dynamics and reactivity analysis revealed high stability and biological activity respectively among the designed systems, making them promising candidates for therapeutic delivery and holding potential for further in vivo and clinical investigations.

Structure-Activity relationship of 5‑butyl‑4,6-dimethyl-2-{[4-(o-fluorophenyl)-1-piperazinyl]-2-oxoethyl}-pyrrolo[3,4-c]pyrrole-1,3(2H,5H)‑dione: An experimental and theoretical study

Synthesis of 5‑butyl‑4,6-dimethyl-2-{[4-(o-fluorophenyl)-1-piperazinyl]-2-oxoethyl}-pyrrolo[3,4-c]pyrrole-1,3(2H,5H)‑dione 3 is reported. The compound was obtained by direct alkylation of 3,4-pyrrolodicarboximide 1 with (1-chloroacetyl-4-(o-fluorophenyl)piperazine) 2 in DMF. Its physico-chemical features were characterized by 1H NMR, 13C NMR, FT-IR, MS spectra, and elemental analysis. Single-crystal X-ray diffraction was also recorded. A colorimetric inhibitor screening assay was used to determine its inhibitory potency towards COX-1 and COX-2. It was found that the compound exhibits anti-inflammatory activity higher than the reference structure – Meloxicam (MXM). According to the experimental results, the tested compound inhibited the activity of COX-1 and COX-2 respectively. In the next step, molecular docking was performed to estimate the binding affinity of compound 3 and commercially available reference compounds for COX-1/COX-2 enzymes. It was found that the binding affinity of 3 is higher than for the reference compounds. Quantum Theory of Atoms In Molecules (QTAIM) and Reduced Density Gradient (RDG) methods were used to reveal non-covalent interactions present in the COX-1/COX-2 binding pocket. Finally, Born-Oppenheimer molecular dynamics (BOMD) based on semiempirical forces was carried out to gain insight into the dynamic features of the studied complexes and confirmed the fact that the weak hydrogen bonds play the most important role in stabilizing the ligand conformation for the studied COX-2 complexes with compound 3 and Rofecoxib.

Reactions of Ru3(CO)12 with 1,5-bis(diphenylphosphino)pentane: Synthesis, characterization, crystal structure, Hirshfeld surface and QTAIM Analysis of Ru3(CO)10(µ-dpppe)

Reactions of Ru3(CO)12 with 1,5-bis(diphenylphosphino)pentane (dpppe) in THF induced by sodium benzophenone ketyl radical anion, resulted in the expected metal cluster [Ru3(CO)11]2(µ-dpppe) (1) and Ru3(CO)10(µ-dpppe) (2) as the main products. Clusters 1 and 2 were characterized by spectroscopic methods, including Fourier-transform infrared spectroscopy (FTIR) and nuclear magnetic resonance spectroscopy (1H and 31P{1H} NMR).The structural features were determined using single crystal X-ray diffraction analysis. In cluster 1 and 2, the (dpppe) links two trinuclear cluster units via phosphine moieties and bridges to Ru–Ru bond, respectively. Both clusters were stabilized by the presence of C–H⋯O interactions and were further analyzed by Hirshfeld surface analysis. The bonding interactions within cluster 2 were studied using the Quantum Theory of Atoms in Molecules (QTAIM). Various local and integral topological properties of the electron density were calculated, along with the source function (SF) calculations and electron localization function (ELF) analysis.

Investigating the electronic properties of edge glycine/biopolymer/graphene quantum dots

This study systematically investigated four types of graphene quantum dots (GQDs) AHEX, ZTRI, ZHEX, and ATRI, and their interactions with glycine to form GQD-glycine complexes. Utilizing density functional theory (DFT) and the PM6 semiempirical method, the study analyzed electronic properties and structure-activity relationships. Global reactivity indices were calculated using Koopmans’ theorem, and quantitative structure-activity relationship (QSAR) parameters were assessed via SCIGRESS 0.3. The study further explored interactions using density of states (DOS) and quantum theory of atoms in molecules (QTAIM) analyses. Key findings revealed that glycine interaction significantly increased the total dipole moment (TDM) and decreased the HOMO/LUMO energy gap (ΔE) for the GQD-glycine complexes. Notably, ZTRI/glycine showed a TDM of 4.535 Debye and a reduced ΔE of 0.323 eV, indicating enhanced reactivity. Further interactions with cellulose, chitosan, and sodium alginate identified the ZTRI/glycine/sodium alginate composite as the most reactive, with a TDM of 8.020 Debye and the lowest ΔE of 0.200 eV. This composite also exhibited the highest electrophilicity index (56.421) and lowest chemical hardness (0.145 eV), underscoring its superior reactivity and stability. DOS analysis revealed that biomolecules contributed the most to molecular orbitals, with carbon atoms contributing the least. QTAIM analysis confirmed the greater stability of the ZTRI/glycine/sodium alginate complex compared to other studied composites. These results highlight the enhanced reactivity and stability of GQDs when interacting with glycine and sodium alginate.

Molecular Aspects of the Interactions between Selected Benzodiazepines and Common Adulterants/Diluents: Forensic Application of Theoretical Chemistry Methods.

Benzodiazepines are frequently encountered in crime scenes, often mixed with adulterants and diluents, complicating their analysis. This study investigates the interactions between two benzodiazepines, lorazepam (LOR) and alprazolam (ALP), with common adulterants/diluents (paracetamol, caffeine, glucose, and lactose) using infrared (IR) spectroscopy and quantum chemical methods. The crystallographic structures of LOR and ALP were optimized using several functionals (B3LYP, B3LYP-D3BJ, B3PW91, CAM-B3LYP, M05-2X, and M06-2X) combined with the 6-311++G(d,p) basis set. M05-2X was the most accurate when comparing experimental and theoretical bond lengths and angles. Vibrational and 13C NMR spectra were calculated to validate the functional's applicability. The differences between LOR's experimental and theoretical IR spectra were attributed to intramolecular interactions between LOR monomers, examined through density functional theory (DFT) optimization and quantum theory of atoms in molecules (QTAIM) analysis. Molecular dynamics simulations modeled benzodiazepine-adulterant/diluent systems, predicting the most stable structures, which were further analyzed using QTAIM. The strongest interactions and their effects on IR spectra were identified. Comparisons between experimental and theoretical spectra confirmed spectral changes due to interactions. This study demonstrates the potential of quantum chemical methods in analyzing complex mixtures, elucidating spectral changes, and assessing the structural stability of benzodiazepines in forensic samples.

Novel AIE and solvatochromism exhibiting TPE based organic fluorophore with excellent emission properties in solid and solution phase for latent fingerprint and metronidazole sensing in real samples

Organic molecules with extended aromaticity are important when designing probes with optical properties. Herein, we designed and synthesized a novel tetraphenylethylene (TPE) based organic molecule TC exhibiting excellent photophysical characteristics. A thorough and in-depth study of the optical properties of probe TC was performed including solvatochromism, aggregation and solid-state studies using ultraviolet–visible (UV Vis) and fluorescence spectroscopy. Also, its optical properties under a UV 365 nm laser were investigated. The compound exhibited aggregation induced emission (AIE) which was thoroughly investigated in a H2O/DMF system and later utilized in formulation of invisible ink and latent fingerprint sensing. Moreover, the excellent emission properties of probe TC were utilized for the highly selective detection of the antibiotic metronidazole (MET) in real samples including human serum and artificial urine. Furthermore, portable TLC and paper-based strips were designed for the on-site detection of MET. Additionally, the mechanism of selective sensing of MET was thoroughly investigated through spectroscopic studies including titration NMR, fluorescence, UV Vis studies and DFT studies. Photoinduced electron transfer (PET) was attributed as the plausible sensing mechanism for the detection of MET. Scanning electron microscopy (SEM) also supported the sensing of MET through change in morphology. DFT calculations involved the measurement of thermodynamic stability, reduced density gradient (RDG) analysis, molecular orbital, and charge transfer studies as well as analysis of quantum theory of atoms in molecules (QTAIM). All the studies supported the presence of non-covalent interactions between probe TC and MET.