Non-covalent Interaction Analysis Research Articles

Analyzing noncovalent interactions between notoginseng saponins and lysozyme by deposition scanning intensity fading MALDI-TOF mass spectrometry.

Analysis of noncovalent interactions between natural products and proteins is important for rapid screening of active ingredients and understanding their pharmacological activities. In this work, the intensity fading MALDI-TOF mass spectrometry (IF-MALDI-MS) method with improved reproducibility was implemented to investigate the binding interactions between saponins from Panax notoginseng and lysozyme. The benchmark IF-MALDI-MS experiment was established using N,N',N″-triacetylchitotriose-lysozyme as a model system. The reproducibility of ion intensities in IF-MALDI-MS was improved by scanning the whole sample deposition with a focused laser beam. The relative standard deviation (RSD) of deposition scanning IF-MALDI-MS is 5.7%. Similar decay trends of the relative intensities of notoginseng saponins against increasing amounts of lysozyme were observed for all six notoginseng saponins. The half-maximal fading concentration (FC50) was calculated to quantitatively characterize the binding affinity of each ligand based on the decay curve. According to the FC50 values obtained, the binding affinities of the six notoginseng saponins were evaluated in the following order: notoginsenoside S > notoginsenoside Fc > ginsenoside Rb1 > ginsenoside Rd > notoginsenoside Ft1 > ginsenoside Rg1. The binding order was in accordance with molecular docking studies, which showed hydrogen bonding might play a key role in stabilizing the binding interaction. Our results demonstrated that deposition scanning IF-MALDI-MS can provide valuable information on the noncovalent interactions between ligands and proteins.

Carbene-catalyzed and Pnictogen Bond-assisted Access to PIII-Stereogenic Compounds.

Intermolecular pnictogen bonding (PnB) catalysis has received increased interest in non-covalent organocatalysis. It has been demonstrated that organic electron-deficient pnictogen atoms can act as prospective Lewis acids. Here, we present a catalytic approach for the asymmetric synthesis of chiral PIII compounds by combining intramolecular PnB interactions and carbene catalysis. Our design features a pre-chiral phosphorus molecules bearing two electron-withdrawing benzoyl groups, resulting in the formation of a σ-hole at the P atom. X-ray and non-covalent interaction (NCI) analysis indicate that these phosphorus substrates exhibit intrinsic PnB interactions between the oxygen atom of the formyl group and the phosphorus atom. This induces a conformational locking effect, leading to the crystallization of the phosphorus substrates in a preferred conformation (P212121 chiral group). Under the catalysis of N-heterocyclic carbene, the aldehyde moiety activated by the pnictogen bond selectively reacts with an alcohol to yield the corresponding chiral monoester/phosphorus products with excellent enantioselectivity. This Lewis acidic phosphorus center, aroused by the non-polarized intramolecular pnictogen bond interaction, assists in conformational and selective regulations, providing unique opportunities for catalysis and beyond.

Frustrated Lewis pair-mediated hydro-dehalogenation: crucial role of non-covalent interactions.

Organic halides stand as invaluable reagents with diverse applications in synthetic chemistry and various industrial processes. Despite their utility, concerns arise due to their inherent toxicity. Addressing these apprehensions, hydro-dehalogenation has emerged as a promising strategy involving the replacement of halogen atoms with hydrogen atoms to transform toxic organic halides into hydrocarbons. This study delves into the computational exploration of hydro-dehalogenation reactions of benzyl halide, mediated by frustrated Lewis pairs (FLPs), using density functional theory (DFT). The reactions entail the formation of FLP1 or FLP2 in the presence of TMP or lutidine with B(C6F5)3, respectively. This is followed by heterolytic cleavage of dihydrogen and subsequent reaction with benzyl halides. Non-covalent interaction analysis underscores the significance of π-π stacking and CH-π interactions in stabilizing transition states. Additionally, the activation strain model (ASM) dissects activation energies, revealing the substantial impact of strain energy on reaction barriers. Energy decomposition analysis (EDA) offers insights into the contributions of electrostatic, orbital, and dispersion energies to the overall attractive interaction energy. The investigation extends to hydro-dehalogenation reactions of ethyl halides, uncovering distinct mechanisms and activation barriers. This comprehensive analysis illuminates the intricacies of hydro-dehalogenation reactions, providing valuable insights into their mechanisms and paving the way for future studies in this field. Geometry optimizations were carried out at the M06-2X/def2-SVP level of theory, which was performed using the Gaussian 16 program. Solvent-corrected single-point energies were also calculated using the polarizable continuum model (PCM) at the PCM(chloroform)-M06-2X/def2-TZVP//M06-2X/def2-SVP level of theory. The Gibbs free energy correction was determined from computations performed at the M06-2X/def2-SVP level of theory. Principal interacting orbital (PIO) analysis was conducted using the NBO 6.0 software. The nature of bonding in the respective transition state (TS) structures was analyzed using atoms-in-molecules (AIM) analyses. Additionally, the presence of non-covalent interactions (NCI) was exemplified using Multiwfn software.

Carborane-Cluster-Wrapped Copper Cluster with Cyclodextrin-like Cavities for Chiral Recognition.

Chiral atomically precise metal clusters, known for their remarkable chiroptical properties, hold great potential for applications in chirality recognition. However, advancements in this field have been constrained by the limited exploration of host-guest chemistry, involving metal clusters. This study reports the synthesis of a chiral Cu16(C2B10H10S2)8 (denoted as Cu16@CB8, where C2B10H12S2H2 = 9,12-(HS)2-1,2-closo-carborane) cluster by an achiral carboranylthiolate ligand. The chiral R-/S-Cu16@CB8 cluster features chiral cavities reminiscent of cyclodextrins, which are surrounded by carborane clusters, yet they crystallize in a racemate. These cyclodextrin-like cavities demonstrated the specific recognition of amino acids, as indicated by the responsive output of circular dichroism and circularly polarized luminescence signals of Cu16 moieties of the Cu16@CB8 cluster. Notably, a quantitative chiroptical analysis of amino acids in a short time and a concomitant deracemization of Cu16@CB8 were achieved. Density functional tight-binding molecular dynamics simulation and noncovalent interaction analysis further unraveled the great importance of the cavities and binding sites for chiral recognition. Dipeptide, tripeptide, and polypeptide containing the corresponding amino acids (Cys, Arg, or His residues) display the same chiral recognition, showing the generality of this approach. The functional synergy of dual clusters, comprising carborane and metal clusters, is for the first time demonstrated in the Cu16@CB8 cluster, resulting in the valuable quantification of the enantiomeric excess (ee) value of amino acids. This work opens a new avenue for chirality sensors based on chiral metal clusters with unique chiroptical properties and inspires the development of carborane clusters in host-guest chemistry.

Unveiling the Intermolecular Interactions between Drug 5-Fluorouracil and Watson-Crick/Hoogsteen Base Pairs: A Computational Analysis.

The adsorption of 5-fluorouracil (5FU) on Watson-Crick (WC) base pairs and Hoogsteen (HT) base pairs has been studied using the dispersion-corrected density functional theory (DFT). The adsorption, binding energy, and thermochemistry for the drug 5FU on the WC and HT base pairs were determined. The most stable geometries were near planar geometry, and 5FU has a higher preference for WC than HT base pairs. The adsorption energies of 5FU on nucleobase pairs are consistently higher than pristine nucleobase pairs, indicating that nucleobase pair cleavage is less likely during the adsorption of the 5FU drug. The enthalpy change for the formation of 5FU-DNA base pairs is higher than that for the formation of 5FU-nucleobases and is enthalpy-driven. The E gap of AT base pairs is higher, suggesting that their chemical reactivity toward further reaction would be less than that of GC base pairs. The electron density difference (EDD) analysis shows a significant decrease in electron density in aromatic regions on the purine bases (adenine/guanine) compared to the pyrimidine bases. The MESP diagram of the stable 5FU-nucleobase pair complexes shows a directional interaction, with the positive regions in a molecule interacting with the negative region of other molecules. The atoms in molecule analysis show that the ρ(r) values of C=O···H-N are higher than those of N···H/N-H···O. The N···H intermolecular bonds between the base pair/drug and nucleobases are weak, closed shell interactions and are electrostatic in nature. The noncovalent interaction analysis shows that several new spikes are engendered along with an increase in their strength, which indicates that the H-bonding interactions are stronger and play a dominant role in stabilizing the complexes. Energy decomposition analysis shows that the drug-nucleobase pair complex has a marginal increase in the electrostatic contributions compared to nucleobase pair complexes.

Unveiling the Selectivity of Ru(II)-Catalyzed C-H Activation for Defluorinative Cyclization of 2-Arylbenzimidazole and Trifluoromethyl Diazo: A DFT Study.

The synthesis of monofluorinated heterocyclic compounds by C-H activation combined with defluorination is useful. Studies on the reaction mechanism and selectivity have shown that these processes play a positive role in promoting the development of monofluorinated reactions. Density functional theory (DFT) calculations were performed to investigate the mechanism and selectivity of Ru(II)-catalyzed 2-arylbenzimidazole with trifluoromethyl diazo. DFT calculations showed that C-H activation occurs through a concerted metalation/deprotonation (CMD) mechanism. After that, deprotonation and defluorinative cyclization are assisted by acetate and trifluoroethanol (TFE). Further mechanistic insights through noncovalent interaction (NCI) analysis were also obtained to elucidate the origin of the selectivity in the defluorination process.

Disentangling the Conformational Space and Structural Preferences of Tetrahydrofurfuryl Alcohol Using Rotational Spectroscopy and Computational Chemistry.

The influence of the hydroxymethyl (CH2OH) group on the tetrahydrofuran (THF) ring structure was investigated by disentangling the gas phase conformational landscape of the sugar analogue tetrahydrofurfuryl alcohol (THFA). By combining rotational spectroscopy (6-20 GHz) and quantum chemical calculations, transitions corresponding to two stable conformers of THFA and their 13C isotopologues were observed and assigned in the rotational spectrum. The positions of the C atoms were precisely determined to unambiguously distinguish between nearly isoenergetic pairs of conformers that differ in their ring configurations: envelope (E) versus twist (T). The rotational spectrum confirms that the E ring geometry is favoured when the CH2OH fragment lies gauche (-) to the THF backbone (OCCO ~-60°) whereas the T form is more stable for the gauche (+) alignment of the substituent (OCCO ~+60°). The observed spectral intensities suggest that conformational relaxation of the THF geometry (E↔T) to the more stable form readily occurs within the pairs of g- and g+ conformers which is consistent with the low barriers (1.5-1.7 kJ mol-1) for conversion determined via transition state calculations. Insights into the intramolecular hydrogen bonding and other weak interactions stabilizing the lowest energy structures of THFA were derived and rationalized using non-covalent interaction analyses.

The future of drug Monitoring: Highly selective ratiometric sensing of mefenamic acid by simple AIEE active probe supported through Extensive fluorometric and DFT studies

Over intake of mefenamic acid (MA) cause morbidity, mortality, liver damage, and hepatic necrosis. For this reason, it is of great importance to discover novel methodologies that provide sharp detection timing, improved sensing efficiency, and profound reproducibility in MA detection. In our current research, we synthesized a naphthalic anhydride based probe PPN which revealed excellent sensing potential towards MA. Probe PPN exhibited ratiometric fluorescence against MA based on complex formation and photoinduced electron transfer (PET) process. Detection mechanism was verified through Density functional theory (DFT) calculations and 1H NMR titration experiments. The type of interaction between probe PPN and MA was investigated through quantum theory of atoms in molecules (QTAIM) analysis and noncovalent interaction (NCI) analysis and was further evaluated via spectroscopic analysis. Moreover, the probe PPN was practically employed to the sensing of MA in artificial urine, pharmaceutical wastewater, and blood samples. Probe PPN is the most streamlined probe designed ever for the sensing of MFA in complex environments with extreme selectivity and sensitivity.

Density functional theory investigation of the contributions of π-π stacking and hydrogen bonding with water to the supramolecular aggregation interactions of model asphaltene heterocyclic compounds

ContextA complex supramolecular process involving electrostatic and dispersion interactions and asphaltene aggregation is associated with detrimental petroleum deposition and scaling that pose challenges to petroleum recovery, transportation, and upgrading. The homodimers of seven heterocyclic model compounds, representative of moieties commonly found in asphaltene structures, were studied: pyridine, thiophene, furan, isoquinoline, pyrazine, thiazole, and 1,3-oxazole. The contributions of hydrogen bonding involving water bridges spanning between dimers and π-π stacking to the total interaction energy were calculated and analyzed. The distance between the planes of the aromatic rings is correlated with the π-π stacking interaction strength. All the dimerization reactions were exothermic, although not spontaneous. This was mostly modulated by the strength of the hydrogen bond of the water bridge and the π-π stacking interaction. Dimers bridged by two water molecules were more stable than those with additional water molecules or without any water molecule in the bridge. Energy decomposition analysis showed that the electrostatic and polarization components were the main stabilizing terms for the hydrogen bond interaction in the bridge, contributing at least 80% of the interaction energy in all dimers. The non-covalent interaction analysis confirmed the molecular sites that had the strongest (hydrogen bond) and weak (π-π stacking) attractive interactions. They were concentrated in the water bridge and in the plane between the aromatic rings, respectively.MethodsThe density functional ωB97X-D with a dispersion correction and the Def2-SVP basis set were employed to investigate supramolecular aggregates incorporating heterocycles dimers with 0, 1, 2, and 3 water molecules forming a stabilizing bridge connecting the monomers. The non-covalent interactions were analyzed using the NCIplot software and plotted as isosurface maps using Visual Molecular Dynamics.

Substituent effect on the electronic and optical properties of newly designed pyrrole derivatives using density functional theory

Abstract This work explores six newly designed compounds obtained by several substitutions in 2,5-di(2-thienyl) pyrrole molecule. For this series of compounds, the electronic and optical properties were investigated using density functional theory and time-dependent density functional theory (TD-DFT). The new compounds were characterized by calculating the chemical parameters that correlated with their optical and electrical properties. The lowest unoccupied molecular orbital (LUMO) and the highest occupied molecular orbital (HOMO) energies are calculated using the B3LYP functional with the 6-311G (d, p) basis set. The most low-lying energy level of the LUMO was found for Perr-NO2, indicating its effective electron injection capabilities and oxidation resistance. The HOMO and LUMO distributions of Perr-Cl and Perr-NO2 displayed a remarkable complementarity throughout each component of the two compounds, indicating an effective intermolecular charge transfer. The molecular electrostatic potential analysis demonstrated that the proposed compounds have a broad distribution of electrophilic and nucleophilic sites, which predict a high degree of chemical reactivity. The electron density analysis at the bonding and anti-bonding sites of the title compounds was performed using the electron localization function and local orbital locator techniques. Non-covalent interaction analysis using the reduced density gradient approach classified all types of interaction: repulsive, weak, and attractive interactions within compound fragments. All compounds exhibited a robust repulsive interaction, as proved by the red spikes at 0.038 a.u. The ultraviolet/visible (UV/vis) spectrum was obtained by TD-DFT using CAM-B3LYP models in conjunction with 6-311G (d, p) basis set and methanol as a solvent, the absorption bands were found within the UV range, and the maximum wavelength showed red-shifted increases. These compounds could serve as a base material for developing selective gas sensors with considerable UV/vis absorption (180–400 nm). According to the research results, the designed compounds are good candidates for use as precursors in polymer designs for optoelectronic and sensor applications due to their high electrical conductivity and photochemical properties.

GeSe nanoclusters as potential drug delivery agent for anti-cancer drugs: First-principles study

For effective drug delivery, a drug carrier that is biocompatible, antitoxic, and appropriate for drug loading/release is required. Here, GeSe nanoclusters are investigated as potential drug delivery for anti-cancer drugs using density functional theory (DFT) calculations. They are dynamically and energetically stable with abundant active sites that facilitate binding with drugs. The anti-cancer drugs, adrucil and hydroxyurea, are successfully loaded on the nanoclusters with adsorption energy ∼ -0.7 eV. Interestingly, no chemical bonds were formed between the drug and the nanocluster highlighting the robust non-covalent interactions (NCI). These slight changes in the electronic properties after drug adsorption are confirmed by the partial density of states, natural bond orbital (NBO) and NCI analysis, and UV–vis spectra. This moderate adsorption without notable changes in the electronic structure facilitates the drug release at the infected tissue. Therefore, GeSe nanoclusters with appropriate electronic and drug adsorption/release properties represent a viable drug delivery agent.

Structural, spectral analysis, reactivity, topological and pharmacological investigations on an antihistamine agent

In this work, quantum computational techniques have been applied to the title compound (Methyl [2-(pyridin-3-yl) ethyl] amine) for insights into structural, vibrational, and electronic spectral features and chemical reactivity. The observed vibrational spectra in solid-phase have been compared with the theoretical one (DFT together with B3LYP /6–311++G (d, p). For the understanding of intra-molecular hyper conjugative interactions, a natural bond orbital (NBO) study was carried out. Nonlinear optical (polarizabilities) calculations have been performed. The molecule's bioactivity is confirmed by the frontier molecular orbital energy gap, and information regarding intra- and inter-non-covalent interactions is provided by non-covalent bond interaction (NCI) analysis. Molecular electrostatic potential (MEP) can identify a molecule's electrophilic and nucleophilic areas, and it can explain a molecule's chemical implications using electron localization function (ELF). The compound's reactive sites were examined using the Fukui function computations, and the molecule's reactivity is defined by its chemical descriptors. The bioactivity of a molecule is supported by molecular docking using the Histamine 1 receptors 3RZE and 7DFL protein, and drug likeness factors were computed to understand the biological properties of MP3EA.

Theoretical study on the capture of toxic gases by ionic liquids encapsulated in assembled belt[14[pyridine

In the current study, self-assembled belt[14]pyridine (BP) encapsulated IL (tetramethylammonium chloride (TMACl)) is theoretically explored to capture greenhouse gases (GHGs) at B3LYP-D3/6-311G(d,p) level of theory. The encapsulation of TMACl in assembled belt[14]pyridine is thermodynamically feasible as revealed through high interaction energy value of −50.7 kcal/mol. Moreover, the results of capturing of gas molecules (SO2, CO2, CO and CH4) show that attractive forces involved in capturing of gases are strong van der Waals forces i.e., London dispersion forces and electrostatic interactions. The synergic effect of self-assembled belts and ionic liquid results in significantly high interaction energy values ranging from −7.88 to −25.92 kcal/mol for capturing of gas molecules. Furthermore, the interaction between BP-TMACl and gas molecules is studied in detail through natural bond orbital (NBO) analysis. NBO results show the charge transfer between the fragments (BP-TMACl and gases) which is further validated through EDD analysis. The charge shifts towards all of the captured gas molecules but the most prominent change in NBO charges is shown by captured SO2. The successful charge transfer indicates better interaction in the designed systems. Additionally, the type and strength of interactions involved in the process of encapsulation is studied through quantum theory of atoms in molecules (QTAIM) and noncovalent interactions (NCI) analysis. NCI analysis clearly shows that gases are captured by BP-TMACl complex through strong van der Waals forces. However, in capturing of SO2, strong electrostatic attractive forces are also involved. The nature of attractive forces is confirmed through QTAIM analysis. Furthermore, the relation between recovery time and desorption energy of captured gas molecules has been studied. The strongest absorption for SO2 results in prolonged recovery time for it (as compared to the other gas molecules). AIMD analysis is performed to find the dynamical stability of assembled-belts before and after loading ionic liquids along with gases to be captured. These results reveal that assembled-belts are suitable for encapsulation of ionic liquids along with capturing of gases. Overall, the best results are shown for SO2 capture. The study intends to deliver valuable information on the important progress in the environmental-remediation field and we hope our work is going to inspire more investigators to provide novel research on such challenging tasks.

Application of statistical physical, DFT computation and molecular dynamics simulation for enhanced removal of crystal violet and basic fuchsin dyes utilizing biosorbent derived from residual watermelon seeds (Citrullus lanatus)

This study investigates the use of watermelon seeds (Citrullus lanatus), a plentiful and cost-effective biosorbent, for the removal of basic fuchsin (BF) and crystal violet (CV) dyes from aqueous solutions. Characterization of the biosorbent was conducted using Fourier Transform Infrared Spectroscopy (FT-IR), X-Ray Diffraction (XRD), and Scanning Electron Microscopy (SEM), while Brunauer–Emmett–Teller (BET) analysis revealed a specific surface area (SBET) of 54.50 m² g−1, highlighting its mesoporous structure advantageous for adsorption. Adsorption isotherms were best described by the Langmuir model, indicating monolayer adsorption with high correlation coefficients (R² values of 0.9959 for CV and 0.9978 for BF) and notable adsorption capacities of 139.2493 mg g−1 for CV and 238.80501 mg g−1 for BF. Thermodynamic analysis confirmed the spontaneous and exothermic nature of the adsorption, driven by molecular interactions. To elucidate the adsorption mechanism at the molecular level, we employed Density Functional Theory (DFT) calculations, Molecular Dynamics (MD) simulations, and Non-Covalent Interaction (NCI) analysis. These computational methods provided insights that closely aligned with experimental data, establishing a robust theoretical-experimental framework for understanding dye adsorption by watermelon seed biosorbent. The practical implications of our findings are significant, suggesting that watermelon seed biosorbent can be effectively scaled up for industrial effluent treatment in continuous systems. The study underscores the potential of utilizing this sustainable and economically viable biosorbent for environmental remediation, offering a promising alternative to conventional adsorbents with its high efficiency and lower sensitivity to environmental conditions such as pH and temperature.

A combined experimental and theoretical approach for doxycycline sensing using simple fluorescent probe with distinct fluorescence change in wide range of interferences

Overuse of doxycycline (DOXY) can cause serious problems to human health, environment and food quality. So, it is essential to develop a new sensing methodology that is both sensitive and selective for the quantitative detection of DOXY. In our current research, we synthesized a simple fluorescent probe 4,4′-bis(benzyloxy)-1,1′-biphenyl (BBP) for the highly selective detection of doxycycline by through fluorescence spectroscopy. The probe BBP displayed ultra-sensitivity towards doxycycline due to Forster resonance energy transfer (FRET). Fluorescence spectroscopy, density functional theory (DFT), 1H NMR titration, UV–Vis, and Job's plot were used to confirm the sensing mechanism. The charge transfer between the probe and analyte was further examined qualitatively by electron density differences (EDD) and quantitively by natural bond orbital (NBO) analyses. Whereas the non-covalent nature of probe BBP towards DOXY was verified by theoretical non-covalent interaction (NCI) analysis as along with Bader's quantum theory of atoms in molecules (QTAIM) analysis. Furthermore, probe BBP was also practically employed for the detection of doxycycline in fish samples, pharmaceutical wastewater and blood samples.

Enhanced reactivity and selective adsorption: Unveiling the potential of metal-decorated graphene membranes for biosensing

This study investigates the structural, stability, electronic, and optical properties of finite graphene membranes through a comprehensive computational analysis. The 2D membranes are constructed from hexagonal graphene quantum dots and are decorated with Co, Mn, and Ni. Stability assessments, based on binding energies, affirm the stable formation of the 2D membrane and its derivatives. Electronic investigations reveal a reduction in the energy gap upon metal decoration, indicating enhanced reactivity. Membrane studies demonstrate effective adsorption of creatinine and uric acid on both edge and surface sites, supported by negative adsorption energies. Electronic transitions and absorption spectra shifts indicate dynamic interactions, emphasizing the materials' potential for selective molecular separation. Non-covalent interaction analysis confirmed the role of van der Waals interactions in creatinine and uric acid adsorption. Overall, the findings suggest that the graphene membrane and its decorated derivatives hold promise for selective adsorption applications, especially in the context of biosensing.

Bistriazolotriazole-tetramine: commendable energetic moiety and cation.

Various 7H,7'H-[6,6'-bi[1,2,4]triazolo[4,3-b][1,2,4]triazole]-3,3',7,7'-tetramine (A) based nitrogen-rich energetic salts were designed and their properties explored. All energetic salts possess relatively high nitrogen content (> 48%), positive heats of formation (> 429kJ/mol) and stability owing to a significant contribution from fused backbone. The cationic component shows a very high heat of formation (2516kJ/mol); therefore, it is highly suitable for enthalpy enhancement in new energetic salts. The cation was paired with the energetic anions nitrate (NO3-), perchlorate (ClO4-), dinitromethanide (CH(NO2)2-), trinitromethanide (C(NO2)3-), nitroamide (NHNO2-), and dinitroamide (N(NO2)2-) to improve oxygen balance and detonation performance. Designed salts show moderate detonation velocities (7.9-8.7 km/s) and pressures (23.8 - 33.1 GPa). The distribution of frontier molecular orbitals, molecular electrostatic surface potentials, QTAIM topological properties, and noncovalent interactions of designed salts were simulated to understand the electronic structures, charge distribution in molecules, hydrogen bonding, and other nonbond interactions. The predicted safety factor (SF) and impact sensitivity (H50) of designed salts suggest their insensitivity to mechanical stimuli. This work explored the 7H,7'H-[6,6'-bi[1,2,4]triazolo[4,3-b][1,2,4]triazole]-3,3',7,7'-tetramine as a suitable cationic component which could be promising and serve exemplarily in energetic materials. The optimization and energy calculations of all the designed compounds were carried out at the B3LYP/6-311 + + G(d,p) and M06-2X/def2-TZVPP levels, utilizing the Gaussian software package. The molecular surface electrostatic potential, quantum theory of atoms in molecules (QTAIM), reduced density gradient (RDG), and noncovalent interaction (NCI) analysis were performed by employing Multiwfn software. The EXPLO5 (v 7.01) thermochemical code and PILEM web application were used to predict the detonation properties.

The first-principles study of pure and doped g-CN nanosheet as a drug delivery system

Nanomaterials are increasingly being studied for their potential to serve as drug delivery systems that can transport anticancer drugs directly to tumor cells, thereby minimizing side effects and enhancing treatment effectiveness. This innovative application of nanotechnology holds significant promise in the field of biomedicine. Within the current piece of research, pure graphitic carbon nitride nanosheet (PC3NNS) and Si-doped C3NNS (C3NNS) were selected as a drug delivery system (DDS) for examining the distribution and bioavailability of 6-Mercaptopurine (6-MP) on cancerous cells through the DFT. After doping the Si atom, the attributes of PC3NNS changed, thereby increasing the adhesion process of 6-MP. The adhesion energy of the Si@C3NNS was in the range of 5.5 eV, which demonstrated that it was highly stable. The current work demonstrated the poor adhesion of 6-MP on the PC3NNS with the adhesion energy of approximately −1.72 eV and −2.83 eV in water and gaseous phases respectively. The adhesion energy increased by around 96.21 % after the Si atom was doped on the PC3NNS. The non-covalent interaction (NCI) analysis and the reduced density gradient (RDG) map analysis were performed to examination the main interactions between nanosheet and drug. It was demonstrated that NCIs played a key role in the adhesion of 6-MP in the complex of 6-MP@Si-C3N. Moreover, the NCI analysis demonstrated the significant impact of van der Waals interactions upon the interactions between 6-MP and the nanosheets. The current work can provide insights into the application of C3NNSs as promising drug carriers for many drugs in targeted DDSs.

Investigating structural dynamics and sensing capabilities: Spectroscopic and DFT analysis of novel AIEE active deferasirox based organic sensor

A deferasirox based sensor DPA was rationally designed through single step amidation reaction. Sensor DPA exhibited aggregation induced emission enhancement (AIEE) property that was attributed to restriction in intramolecular rotation (RIR). Moreover, the sensor DPA displayed remarkable bathochromic shift (red-shift) of 110 nm in wavelength, ascribed to formation of J-aggregates. Furthermore, sensor DPA was employed for the selective and sensitive fluorescence based sensing of hazardous and carcinogenic nitrobenzene (NB). The sensor DPA successfully detected NB in solution through the quenching of emission intensity. The quenching of sensor fluorescence intensity was ascribed to photoinduced electron transfer (PET) mechanism. The sensing mechanism was investigated by 1H NMR titration experiment, Job's plot and density functional theory (DFT) calculations. Additionally, the existence of non-covalent interactions between sensor DPA and NB were examined by Bader's Quantum theory of atoms in molecules (QTAIM) and non-covalent interaction (NCI) analysis. Finally, sensor DPA was employed for the detection of volatile nitrobenzene in vapor phase.

Solvent efficiency and role of dispersion and electrostatic forces for chiral discrimination of sulfur-containing amino acids by tetra-protonated CBPQT macrocycle

Two enantiomeric forms of amino acids in a chiral medium behave quite differently because of the different orientation of their functional groups in space. Thus, the phenomenon of chiral recognition is crucial with the focus on applications in molecular sensing and enantioselective separations. The present research work is focused on the illustration of the potential chiral recognition of a porous CBPQT4+ macrocycle for sulfur-containing amino acids, which is elucidated by the conformational energies landscape with quantitative non-covalent analysis and their electronic behaviour. Herein, we report the chiral recognition of sulfur-containing amino acids e.g., cysteine (CY), homocysteine (HCY), and methionine (MT), by tetra-protonated (4+) CBPQT macrocycle via density functional theory (DFT) calculations. Geometry optimization, thermodynamic stability, noncovalent interaction analysis, symmetry-adapted perturbation (SAPT), and electronic properties analyses are employed to characterize the chiral response of the complexes formed by CBPQT4+ with D- and L-isomers of selected amino acids. The interactive conformations of complexes indicate physisorption of amino acids through the central cavity of the macrocycle. The maximum chiral discrimination is observed in the case of D- and L-cysteine isomers, which is 3.56 kcal/mol. It is revealed that the complex; D-CY@CBPQT4+ is energetically more stable than the L-CY analogue, whereas, L-HCY and L-MT show higher stability as compared to D-type counterparts, probably due to the interaction of the thiol groups with π-electrons of macrocycle in respective stable complexes. Non-covalent interaction (NCI) analyses including, reduced density gradient-based NCI index and SAPT reveal that the methionine-based complexes show the highest attractive components e.g., electrostatic, dispersion, and induction with the lowest repulsive exchange contribution, which is followed by homocysteine and cysteine. Overall, results show that the CBPQT4+ macrocycle has an excellent ability to differentiate between L- and D-amino acids, the difference is more pronounced when the structure of amino acid is small and rigid.