Quantum Theory Of Atoms In Molecules Research Articles

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.

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.

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.

Synthesis, structure and non-covalent interactions of trans-[2-(HCF2(CF2)3CH2OCH2)2-py-PdCl2] complex: rare C−F⋯F−C halogen bonds and blue-shifting C−H⋯X hydrogen bonds

The sp3-based C−F⋯F−C halogen bonds (XBs) and blue-shifting C−H⋯X (X= F, Cl) hydrogen bonds (HBs) are a relatively unusual phenomenon in chemistry, due to their uncommonness and the challenges associated with their direct observations. To investigate these interactions, a novel fluorinated trans-[2-(HCF2(CF2)3CH2OCH2)2-py-PdCl2], abbreviated as 2-(8FH-py)2PdCl2 complex, has been synthesized and structurally characterized. The incorporation of a fluorinated ponytail on the pyridyl ring in the 2-(8FH-py)2PdCl2 complex allows us to explore rare sp3-based type II C9−F4⋯F6−C10 and C8−F2⋯F6−C10 XBs dimers. These findings suggest, for the first time, the formation of halogen bonding dimers through C−F⋯F−C interactions, to our knowledge. Additionally, the 2-(8FH-py)2PdCl2 reveals interesting blue-shifting C−H⋯X hydrogen bonding interactions in the crystal packing. These C−H⋯F interactions connect adjacent molecules in a head-to-tail manner, resulting in the continuation of R22(9) synthons along the crystallographic a-axis. These hydrophobic interactions, which are expected to be very different from the typical hydrophilic interactions, play a crucial role in enhancing the self-assembly and stability of the crystal structure. In addition, the presence of blue-shifting C−H⋯X hydrogen bonding interactions affirmed by the FT-IR studies. Furthermore, the high positive values of electron density (ρ) and Laplacian density (∇2ρ) from quantum theory of atoms in molecule (QTAIM) analyses suggest the presence of electrostatic and weak interactions between atoms. We believe that this discovery will open up new opportunities for exploring and utilizing fluorinated complexes in various scientific fields, fluoro-pharmaceuticals and crystal engineering.

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.

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 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 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 consist 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.

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.

Theoretical Study of the Effects of Different Coordination Atoms (O/S/N) on Crystal Structure, Stability, and Protein/DNA Binding of Ni(II) Complexes with Pyridoxal-Semi, Thiosemi, and Isothiosemicarbazone Ligand Systems

Nickel transition metal complexes have shown various biological activities that depend on the ligands and geometry. In this contribution, six Ni(II) nitrate complexes with pyridoxal-semi, thiosemi, and isothiosemicarbazone ligands were examined using theoretical chemistry methods. The structures of three previously reported complexes ([Ni(PLSC)(H2O)3]∙2NO3−, [Ni(PLTSC)2] ∙2NO3−∙H2O, and [Ni(PLITSC)(H2O)3]∙2NO3−) were investigated based on Hirshfeld surface analysis, and the most important stabilization interactions in the crystal structures were outlined. These structures were optimized at the B3LYP/6-311++G(d,p)(H,C,N,O,(S))/LanL2DZ(Ni) level of theory, and the applicability was checked by comparing theoretical and experimental bond lengths and angles. The same level of theory was applied for the optimization of three additional structures, ([Ni(PLSC)2]2+, [Ni(PLTSC)(H2O)3]2+, and [Ni(PLITSC)2]2+). The interactions between selected ligands and Ni(II) were examined using the Natural Bond Orbital (NBO) and Quantum Theory of Atoms in Molecules (QTAIM) approaches. Particular emphasis was placed on interactions between oxygen, sulfur, and nitrogen donor atoms and Ni(II). Human Serum Albumin (HSA) and the DNA-binding properties of these complex cations were assessed using molecular docking simulations. The presence of water molecules and various substituents in the thermodynamics of the processes was demonstrated. The results showed significant effects of structural parameters on the stability and reactivity towards important biomolecules.

Noncovalent Interactions in Palladium (II)-Catalyzed Meta-Selective C-H Functionalization: Mechanistic Insights and Origins of Regioselectivity.

The use of noncovalent interactions to control the regioselectivity of transition metal-catalyzed C-H functionalization of arenes has received significant attention in recent years. Herein, we present a mechanistic study based on Density Functional Theory (DFT) of palladium(II)-catalyzed meta-selective C-H olefination employing a noncovalent directing template. We analyze the key steps of the mechanism and discuss the origins of reaction selectivity. The role of the directing template was elucidated, demonstrating its essential function in lowering reaction barriers and controlling selectivity. Our results reveal a competition in activation between ortho- and meta-C-H bonds. Contrary to the previous proposal in the literature, hydrogen bonds between the N-H bonds of the urea moiety and the carbonyl oxygen of the substrate predominantly favor ortho-selectivity over meta-selectivity. DFT results, alongside Quantum Theory of Atoms in Molecules (QTAIM) and Non-Covalent Interaction Index analysis, suggest that secondary interactions between the R group linked to the urea moiety and the catalyst exert a more pronounced influence compared to the aforementioned hydrogen bonds, directing the selectivity towards the meta C-H bond.

The Counterion (SO42− and NO3−) Effect on Crystallographic, Quantum-Chemical, Protein-, and DNA-Binding Properties of Two Novel Copper(II)–Pyridoxal-Aminoguanidine Complexes

New Cu(II) complexes with pyridoxal-aminoguanidine (PLAG) ligands and different counterions (SO42− and NO3−) were prepared and their crystal structures were solved by the X-ray crystallography. The geometries of the obtained complexes significantly depended on the counterions, leading to the square-pyramidal structure of [Cu(PLAG)NO3H2O]NO3 (complex 1) and square-planar structure of [Cu(PLAG)H2O]SO4 (complex 2). The intermolecular interactions were examined using the Hirshfeld surface analysis. The theoretical structures of these complexes were obtained by optimization at the B3LYP/6-311++G(d,p)(H,C,N,O,S)/LanL2DZ(Cu) level of theory. The Quantum Theory of Atoms in Molecules (QTAIM) was applied to assess the strength and type of the intramolecular interactions and the overall stability of the structures. The interactions between the complexes and transport proteins (human serum albumin (HSA)) and calf thymus DNA (CT-DNA) were examined by spectrofluorometric/spectrophotometric titration and molecular docking. The binding mechanism to DNA was assessed by potassium iodide quenching experiments. The importance of counterions for binding was shown by comparing the experimental and theoretical results and the examination of binding at the molecular level.

Cuprophilic Interactions in Polymeric [Cu10O2(Mes)6]n.

The properties of cuprophilic compounds and the underlying fundamental principles responsible for the Cu(I)···Cu(I) interactions have been the subject of intense research as their diverse structural and physical attributes are being explored. In this light, we performed a new study of the compound [Cu10O2(Mes)6] reported by Haakansson et al. using state of the art experimental and theoretical analysis techniques. Doing this, we found the compound to be a polymer in the solid state, best written as [Cu10O2(Mes)6]n, with unsupported Cu(I)···Cu(I) contacts linking the monomers (2.776 Å). The monomeric unit also exhibits various cuprophilic contacts bridged by mesityl and/or oxo ligands. The compound was analyzed in its solid state, revealing luminescent properties resulting from two distinct fluorescent emissions, as well as in solution, in which its polymeric structure reversibly decomposes. A quantum theory of atoms in molecules (QTAIM) analysis based on density functional theory (DFT) calculations allows to characterize the various Cu(I)···Cu(I) contacts, in which only a few, and not necessarily the shortest, are associated with a bond critical point. Additionally, an energy decomposition analysis of the bonding between monomers indicates that it is dominated by dispersion forces in which the ligands play a dominant role, resulting in bonding energies significantly larger than found in previous DFT investigations based on less bulky models.

Mechanism of ammonium adsorption onto the surface of heteroatom doped graphene quantum dots

The adsorption mechanism of ammonium (NH4+) ion onto graphene quantum dots (GQDs) surface, modified with vacancy and heteroatom (nitrogen (N) and oxygen (O)), has been studied using a combination of dispersion-corrected density functional theory (DFT) and quantum theory of atoms in molecules (QTAIM) approaches in aqueous media. The potential of GQD-NX and GQD-OX surfaces as highly effective adsorbents for NH4+ ions has been explored by detailed analysis of adsorption energies, molecular electrostatic potential, charge transfer, density-of-states, non-covalent interaction, and desorption time. It has been observed that the adsorption of NH4+ ions on the GQD-NX surfaces is primarily chemisorption, governed by electrostatic interactions and hydrogen bonds. However, adsorption of NH4+ over the surface of GQD-OX predominantly ranges from strong physisorption to weak chemisorption arising from van der Waals interactions and hydrogen bonds. These findings present compelling new approach utilizing modified GQDs as highly efficient adsorbents for removing NH4+ ions from water.

The Persistence of Hydrogen Bonds in Pyrimidinones: From Solution to Crystal.

Pyrimidinone scaffolds are present in a wide array of molecules with synthetic and pharmacological utility. The inherent properties of these compounds may be attributed to intermolecular interactions analogous to the interactions that molecules tend to establish with active sites. Pyrimidinones and their fused derivatives have garnered significant interest due to their structural features, which resemble nitrogenous bases, the foundational building blocks of DNA and RNA. Similarly, pyrimidinones are predisposed to forming N-H···O hydrogen bonds akin to nitrogenous bases. Given this context, this study explored the supramolecular features and the predisposition to form hydrogen bonds in a series of 18 substituted 4-(trihalomethyl)-2(1H)-pyrimidinones. The formation of hydrogen bonds was observed in solution via nuclear magnetic resonance (NMR) spectroscopy experiments, and subsequently confirmed in the crystalline solid state. Hence, the 18 compounds were crystallized through crystallization assays by slow solvent evaporation, followed by single-crystal X-ray diffraction (SC-XRD). The supramolecular cluster demarcation was employed to evaluate all intermolecular interactions, and all crystalline structures exhibited robust hydrogen bonds, with an average energy of approximately -21.64 kcal mol-1 (∼19% of the total stabilization energy of the supramolecular clusters), irrespective of the substituents at positions 4, 5, or 6 of the pyrimidinone core. To elucidate the nature of these hydrogen bonds, an analysis based on the quantum theory of atoms in molecules (QTAIM) revealed that the predominant intermolecular interactions are N-H···O (average of -16.55 kcal mol-1) and C-H···O (average of -6.48 kcal mol-1). Through proposing crystallization mechanisms based on molecular stabilization energy data and contact areas between molecules and employing the supramolecular cluster and retrocrystallization concepts, it was determined that altering the halogen (F/Cl) at position 4 of the pyrimidinone nucleus modifies the crystallization mechanism pathway. Notably, the hydrogen bonds present in the initial proposed steps were confirmed by 1H NMR experiments using concentration-dependent techniques.

Single crystal XRD, Hirshfeld surface analysis and computational approach for exploration of novel xanthene derivative

In order to study the structure-activity relationship of xanthene compound, hexahydro xanthene derivative was synthesized and characterized by single crystal X-rays diffraction. The molecular geometry was described in terms of dihedral angles between various rings present in structure. The stability of the supramolecular assembly was reinforced by multiple intermolecular interactions, which were inspected comprehensively via Hirshfeld surface analysis. DFT study revealed the excellent electronic properties and reactivity of synthesized compound. FMO is employed to uncover the orbitals energies and charge transfer within compound. The contribution of van der Waals forces is minor, while covalent nature of bonding is evidenced by the quantum theory of atoms in molecules (QTAIM) study. The electron transition from nonbonding orbitals (LP) to antibonding (LP*) are most prominent donor-acceptor interactions with significant stabilization energy. Ab-initio molecular dynamics reveals the kinetic and thermodynamic stability of present compound at room temperature. The excellent nonlinear optical properties and reactivity is revealed by its remarkable hyperpolarizability value.

A comparative study of the carbon-based nanostructures for the delivery and detection of drug metronidazole

The interactions between the metronidazole molecule and three different carbon-based nanostructures, fullerene (C60), carbon nanotube (CNT), and carbon nanosheet (CNS), were examined using density functional theory (DFT) calculations. The results indicate that C60 attaches metronidazole more stronger than CNT and CNS, and the adsorption energies of metronidazole with C60, CNT, and CNS are decreased after considering the solvent effects. The variation in energy gaps follows the order of CNS > C60 > CNT, indicating that CNS has better sensing performance for metronidazole compared to fullerene and CNT. Both CNT and CNS show a reasonable recovery time at an achievable operating temperature. According to the quantum theory of atoms in molecules (QTAIM) and symmetry-adapted perturbation theory (SAPT), the dispersion component is the primary factor in stabilization, followed by electrostatic interaction. Simulated infrared (IR) and ultraviolet-visible (UV–Vis) spectra provide a basis reference for further structural characterization. This work indicates that carbon-based nanomaterials have potential applications in the delivery and detection of metronidazole.

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.