Non-covalent Interaction Analysis Research Articles

Sulfonic acid functionalized monolithic column for high selectivity capillary electrochromatography separation.

A new nano-scale spherical vinyl-functionalized covalent organic polymer (TAPT-DVA-COP) with uniform sizes around 300nm was initially constructed using 2,5-divinyl-1,4-benzaldehyde (DVA) and 2,4,6-tris(4-aminophenyl)-1,3,5-triazine (TAPT) as monomers. Then, a sulfonic acid (-SO3H) modified COP termed COP-SO3H was developed based on post-sythesis method employing TAPT-DVA-COP as precursor. Capillary electrochromatography (CEC) monolithic columns were fabricated using the physical doping technique to exhibit the application potential of TAPT-DVA-COP and COP-SO3H. Compared to the TAPT-DVA-COP monolithic column, the COP-SO3H monolithic column achieved a highly selective separation between analytes with different properties, including monosubstituted benzenes, alkylbenzenes, hydroxybenzoates, nucleoside bases, and biogenic amines. Non-covalent interaction (NCI) analysis and experimental data show that the synergism of the sulfonic acid group and aromatic moieties on COP-SO3H endows the new stationary phase with diverse interactions, including ion exchange, hydrophobic, π-π and hydrogen bonding. In addition, the COP-SO3H monolithic column exhibited good reproducibility and excellent potential for the determination of hydroxybenzoates in compact powders and alkylbenzenes in effluent samples.

Theoretical investigation of anion perfluorocubane.

In this work, we did a theoretical exploration of C8F8 (Ib) and its anion radical analogue (IIb) in this work. By investigating the thermochemistry of electron capture, we find that the free energy associated with the conversion of C8H8 (Ia) into its anion radical analogue IIa is of the order of + 92.83 kcal.mol-1, while the conversion of Ib into IIb is - 6.42 kcal.mol-1. Therefore, species IIb is thermodynamically more stable than its neutral analogue. Natural bond orbitals (NBO) analyses revealed that compound Ib exhibits a relative electronic stability as a function of intramolecular delocalisations of the type [Formula: see text] of the order of 2.70 kcal.mol-1. Similar delocalizations for Ia are energetically lower (1.45 kcal.mol-1). Topological analyses of compounds Ib and IIb indicate that the addition of an electron to Ib enhances the covalency of the C-C bond, as can be seen by the reduction in the ellipticity of the C-C bond. The opposite is observed for Ia, whose addition of the electron (leading to IIa) reduces the covalency of the C-C bond. By comparing the free and packaged forms of the species, it is found that, in the crystalline form, the system will present greater relative stability due to the dispersive interactions involved, as evidenced by non-covalent interactions (NCI) analysis. Finally, it was possible to verify that the manifestation of the current density with a lower paratropic and less antiaromatic character in Ib and IIb point to C8F8 as a strong candidate for electron capture. Geometry optimization calculations were carried out, for all monomer structures using the hybrid functional B3LYP-D3 and the 6-31+G(d,p) basis set. To determine the formation thermochemistry of the ions, electronic energy corrections was performed using the DLPNO-CCSD(T)/aug-cc-pVTZ/C method. Starting from the optimised forms, shielding, nuclear magnetic resonance (NMR) spectra employing gauge-independent atomic orbital (GIAO), and NBO calculations were performed for these monomers, using the PBE0 functional and the pCSseg-2 atomic basis set. The magnetochemical analysis of ring currents was performed using the GIMIC formalism. For the topological analysis, it was applied the combination DLPNO-CCSD(T)/aug-cc-pVTZ/C, previously used for correcting the electronic energy.

Ab Initio Approach to the Structure, Vibrational Properties, and Electron Binding Energies of H2S∙∙∙SO2.

The present study employs high-level ab initio calculations to investigate the structure, vibrational frequencies, and electronic properties of H2S∙∙∙SO2. The analysis of vibrational frequencies reveals an intramolecular vibrational energy transfer phenomenon, where energy from the stretching modes of H2S is transferred to the ν1s mode of SO2. At the CCSD(T)/aug-cc-pVQZ level, the interaction energy between H2S and SO2 is predicted to be 2.78 kcal/mol. Electron propagator theory calculations yield a HOMO-LUMO gap of 8.24 eV for H2S∙∙∙SO2. Furthermore, by utilizing ab initio results for the adiabatic ionization energy and electron affinity, the electrophilicity of H2S∙∙∙SO2 is estimated to be 2.01 eV. This value is similar to the electrophilicity of SO2, suggesting comparable reactivity and chemical behavior. The non-covalent interaction (NCI) analysis of the H2S∙∙∙SO2 complex emphasizes the significant contribution of non-covalent van der Waals interactions in its energetic stabilization.

Experimental and theoretical investigation of structure activity relationship on L-Lysine Monohydrate for antioxidant efficacy

Comprehensive spectroscopic research has been undertaken to investigate the structural behaviour of the l-lysine monohydrate molecule. The spectral properties of the l-lysine monohydrate molecule in solid phase were examined using Fourier Transform Infrared (FTIR) and Fourier Transform Raman methods. The B3LYP/6–311++G (d, p) computations were used to optimize the structure of the molecule. To provide complete vibrational spectral assignments, vibration energy distribution analysis (VEDA) was used. The Natural bond orbital (NBO) analysis explains the stability and distinct forms of hydrogen bonds with in the molecule. The chemical stability of the molecule is predicted by Highest Occupied Molecular Orbital (HOMO) and Lowest Unoccupied Molecular Orbital (LUMO) analysis. Non-Covalent Interaction (NCI) analysis was done to identify weak interactions according to density of electron of the title compound. The fukui function identified the chemical reactivity sites. To predict its antioxidant efficacy, docking studies were done.

Asymmetric reductive carboxylation of N-(2-bromophenyl)-N-methylmethacrylamide with CO2 catalyzed by nickel complex: A theoretical study

To provide guiding information for developing efficient catalysts for CO2 carboxylation, we investigated the mechanism of asymmetric reductive carboxylation of N-(2-bromophenyl)-N-methylmethacrylamide with CO2 catalyzed by a nickel complex using density functional theory (DFT) calculations. The reaction was found to proceed via a multistep and elaborate mechanism. Additionally, CO2 exhibits a preference for inserting into the Ni(I) intermediate rather than Ni(II) intermediate. The noncovalent interaction (NCI) analysis reveals that the π-π stacking interactions and hydrogen bonding interactions lead to the stereoselectivity.

Functionalized boron doped graphene (BGP) as smart nanocarrier for delivery of hydroxyurea (HU) drug

The concerning toxicity associated with hydroxyurea (HU), an anticancer drug used in cancer treatment, has spurred significant attention within the research community over the years. To address this adverse effect, there is a critical need for a smart and targeted drug delivery system (Nano carrier) that can effectively deliver the drug to the tumor site while minimizing side effects for the patient. In this study, we employed density functional theory computations at (DFT)/ωB97XD/6–311++G (d, p) level of theory to evaluate the adsorption properties of functionalized boron-doped graphene (BGP) surfaces, namely COOH@BGP, NH2@BGP, and OH@BGP, for the delivery of the HU anticancer drug. The electronic properties analysis revealed that COOH@BGP/HXU (M2) exhibited the most favorable reactivity with an energy gap value of 5.3756 eV, making it the most reactive surface compared to other complexes investigated. Moreover, a comprehensive natural bond orbital analysis was conducted to investigate hyper-conjugative effects, hybridization, charge transfer, and H-bonding interactions within the systems studied. The results confirmed the following trend: HXU-COOH@BGP (M2) > HXU-OH@BGP (K2) > HXU-NH2@BGP (Q2). Additionally, topological analysis (QTAIM) and Non-covalent interaction (NCI) analysis were performed to ascertain the interaction forces at play. The results strongly support the significant electrostatic force of interaction in the M2 complex, suggesting the presence of hydrogen bond interactions that facilitate the doped surface's ability to bind with HXU and enhance the smooth delivery of the investigated drug. Furthermore, the adsorption studies revealed negative adsorption energy values, indicating favorable adsorption. Among all the analyzed complexes, M2 nanocarrier demonstrated the most suitable characteristics for the delivery of the HXU anticancer drug. These findings hold promise for the development of an efficient and targeted drug delivery system that could potentially mitigate the toxicity associated with HU and enhance cancer treatment outcomes."

Tetrabromidocuprate(II) complexes with diprotonated 1-hydroxy-4methyl-2-(pyridin-2-yl)-5-phenylimidazole and 1-hydroxy-2-(pyridin-2-yl)-4,5,6,7-tetrahydrobenzimidazole ligands: Relationship between the structure and magnetic properties

Two new tetrabromidocuprate(II) complexes with diprotonated 1-hydroxy-2-(pyridin-2-yl)-4,5,6,7-tetrahydrobenzimidazole (1) and 1-hydroxy-4methyl-2-(pyridin-2-yl)-5-phenylimidazole (2) were synthesized and their structure established from single-crystal X-ray data. Compounds crystallized in the monoclinic space groups P21/n and P21/c, respectively, where tetrabromidocuprate anions formed magnetic chains as inferred from the distances between the halide ions of different [CuBr4]2− units. Magnetization measurements showed that both compounds behave as well-isolated uniform S = 1/2 antiferromagnetic chains described by the one-dimensional Heisenberg antiferromagnetic model with intra-chain exchange interaction 2 J = 23 K (1) and 2 J = 33 K (2) (the Hamiltonian Hˆ=2J∑SˆiSˆi+1). Electron paramagnetic resonance, optical absorption, and density functional theory investigations provided complementary results for 1 and 2. A calculation of exchange coupling constants gave values of 2 J = 24 K (1) and 2 J = 39 K (2), in good agreement with the experiment. The quantum theory of atoms in molecules and non-covalent interaction analyses showed that halogen bonding determined the exchange interaction between [CuBr4]2− units in magnetic chains of these cation–anion compounds.

Metals (B, Ni) encapsulation of graphene/PEDOT hybrid materials for gas sensing applications: A computational study

Recent attention has been directed towards the role of greenhouse gases, including methane (CH4), carbon dioxide (CO2), and ammonia (NH3), in driving climate change and global warming by trapping heat within the Earth's atmosphere. This has ignited an escalating interest amongst researchers to devise sensor materials capable of efficiently detecting and monitoring these gases. Herein, a novel interface material composed of boron (B) and nickel (Ni) encapsulated within a graphene/PEDOT matrix (B_Ni@GP_PEDOT) was subjected to comprehensive simulations employing density functional theory (DFT) at the B3LYP-GD3(BJ)/Def2-SVP level of theory. The primary objective of these simulations was to assess the potential of B_Ni@GP_PEDOT in detecting and capturing targeted ruminant gases. The outcomes of molecular dynamics simulations unveiled a favourable interaction between B_Ni@GP_PEDOT and all three gases, with CO2 displaying the strongest attractive interaction. Interestingly, these simulations also revealed a substantial rise in system temperature during the interaction, indicative of significant energy transfer from the gases to the solid structure. Furthermore, an insightful evolution in the band gap of the system was observed, signifying increased stability. Specifically, the sequence B_Ni@GP_PEDOT_NH3 < B_Ni@GP_PEDOT_CH4 < B_Ni@GP_PEDOT < B_Ni@GP_PEDOT_CO2 was established, corresponding to ascending energies of 1.30 < 1.49 < 1.72 < 1.78 eV, respectively. Intriguingly, a comprehensive analysis of the mechanistic adsorption behaviour of the studied gases indicated varying degrees of energy for adsorption: B_Ni@GP_PEDOT_CH4 < B_Ni@GP_PEDOT_CO2 < B_Ni@GP_PEDOT_NH3, corresponding to energies of -0.273, -0.191, and -0.047 eV, respectively. The nature of the interaction between the adsorbent and adsorbates was meticulously explored using Quantum Theory of Atoms in Molecules (QTAIM) and Non-Covalent Interaction (NCI) analysis, yielding outcomes that perfectly aligned. Interestingly, B_Ni@GP_PEDOT_CO2 system was observed to have a more stable configuration with

A DFT investigation of the catalytic oxidation of benzyl alcohol using graphene oxide.

Metal-free heterogeneous materials have attracted great interest due to their potential to facilitate various organic transformations in line with circular economy and green chemistry principles. Among various 2D materials, graphene oxide (GO) is considered an attractive material for numerous applications in physics, chemistry, biology, material sciences, and catalysis. Furthermore, graphene-based catalysts exhibit good catalytic activity toward the selective oxidation of benzyl alcohol to benzaldehyde or benzoic acid under eco-friendly conditions. In this regard, a theoretical investigation was carried out to study both catalytic oxidation reaction pathways (i.e., benzyl alcohols to aldehyde and to benzoic acid) using GO as an eco-friendly and metal-free catalyst. In this study, we report a theoretical investigation at the B3LYP/6-31G level to better understand the oxidation of benzyl alcohol using GO as a metal-free catalyst. The possible bond formation was investigated using the global and local reactivity indexes derived from Fukui functions. Furthermore, we performed a non-covalent interaction (NCI) analysis to unveil the stability and the interaction nature between both reagents and GO surface. The effect of the solvent on the oxidation efficiency was also performed and the results indicate that the solvent significantly affects the decrease of reactivity by increasing the activation barriers through oxidation reactions of benzyl alcohol. Additionally, the electron localization function (ELF) analysis was performed for all intermediates showing the ionic nature of the studied epoxide structure of GO and rules out any type of covalent interaction during the oxidation reaction of benzyl alcohol. All these obtained results are in good agreement with experimental observations and reveal that the epoxide functions on the graphene surface promote an excellent catalyst turnover.

Enhanced Thermal Decomposition and Safety of Spherical CL-20@MOF-199 Composites via Micro-Nanostructured Self-Assembly Regulation.

The characteristics of high burning rate, high energy output, and low pressure exponent have always been the focus of development in the field of composite solid rocket propellants. In this paper, a metal-organic framework (MOF-199) compound is introduced to prepare micro-nanospherical CL-20@MOF-199 composites via the spray-drying self-assembly technique to reach the above goals. MOF-199, which acts as an attractive combustion catalyst and a safety regulator, is uniformly coated on the surface of CL-20 with close interface contact between particles, effectively accelerating the thermal decomposition of CL-20 and ensuring safety performance. The average noncovalent interaction (aNCI) analysis illustrates that there are strong C-H···O hydrogen bonds and van der Waals interaction between CL-20 and MOF-199 molecules, greatly enhancing the effect of interparticle assembly. The effects of different contents of MOF-199 on the thermal, safety, and energy properties of CL-20 were discussed. The thermal analysis demonstrates that MOF-199 has a significant thermal catalytic effect on CL-20, with an advanced peak temperature of thermal decomposition of 14.2 °C and a reduced activation energy barrier of 34.2 kJ·mol-1, mainly benefitting from more exposed catalytic active sites and close interface contact. In addition, CL-20@MOF-199 composites exhibit decreased mechanical sensitivity (IS: 21-40 cm, FS: 80-240 N) and excellent energy performance. This work clearly demonstrates that MOF-199 is both a superior combustion catalyst and a good safety buffer for CL-20, and it opens new potential for further applications of CL-20 in composite solid propellants.

Analysis of non-covalent interactions in proteins

Analysis of non-covalent interactions in proteins

Theoretical investigation on the structural properties, scavenging mechanism and toxicological profile of Nymphaeol C, a flavanone in Macaranga Tanarius

The quantum chemical calculations of Nymphaeol C (C30H36O6) have been carried out using the density functional theory method, M06-2X in the 6-311+G (d, p) basis set. The HOMO, LUMO, molecular electrostatic potential, and physicochemical descriptors of the optimized structure have been evaluated at the same level of theory. Further, this study was designed to evaluate and compare the radical scavenging activity of Nymphaeol C in different solvent media using three potential working mechanisms. The results showed that Nymphaeol C can act as a good antioxidant molecule and it can be better understood by high-ELF localization domain population analysis, atoms in molecules analysis, non-covalent interaction analysis, Fukui analysis, and aromaticity indices evaluated by using the Multiwfn software package. Bond energy is an important concept to evaluate the potency of chemical bonds. The active antioxidant site in the title compound can be predicted more accurately. The molecule displays good drug-like characteristics, as expected by the examination of absorption, distribution, metabolism, excretion, and toxicity.

Synergistic Spectroscopic and Computational Characterization Evidencing the Preservation or Flipping of the Hydroxyl Group of 2-Phenylethyl Alcohol upon Single and Double Hydration.

Even apparently simple, obtaining and analyzing observations on molecules and clusters and unambiguously assigning their structures is challenging. We report here the first ionization-loss Raman spectra compared to quantum chemical predictions for establishing the structural preferences of hydrates of the neurotransmitters hydroxy analogue, 2-phenylethyl alcohol (PEAL). The spectra encode two monohydrates and two previously unnoticed dihydrates, consequences of water insertion and sidewise attachment to the O-H group of gauche PEALs, in PEAL-H2O and PEAL-(H2O)2, or the higher-energy gauche-trans PEAL in the latter. The electronic structures retain the stable PEAL or flip its O-H to convert the gauche-trans PEAL conformer to the global minimum-energy dihydrate. We disclose conventional and bifurcated hydrogen bonds and electron steric repulsions by noncovalent interaction analysis and correlations between the experimental O-H stretching vibrational frequencies and the O-H and H···X bond lengths and electron densities, pointing to implications on hydrate forms and our approach virtue.

Theoretical insights on the development of a 55–77 graphene sheet by embedding Agn=1-4 and Pdn=1-4 metal nanoclusters for efficient CO2 capture

Recent advancements in two-dimensional (2D) allotropes of carbon materials and their usage as superior CO2 adsorbents can decrease the detrimental impact of CO2 on climate change. With the use of quantum chemical calculations, the effect of metal clusters (Agn = 1-4 and Pdn = 1-4) on the structural and electrical characteristics of 55–77 2D graphene sheet is examined in the current work with an aim towards enhancing CO2 capture capacity. The findings revealed that the binding energy (Eb) of the 55–77 sheet decoration with Pdn = 1-4 metal clusters are greater owing to chemisorption by 1.17 eV, 1.69 eV, 0.27 eV, and 1.58 eV than the decoration with Agn = 1-4 clusters. Moreover, CO2 molecules adsorb on the Pdn = 1-4 cluster decorated systems having −0.35 eV, 0.83 eV, 1.53 eV, and −0.98 eV greater adsorption energies than on the Agn = 1-4 decorated 55–77 sheet due to a stronger charge transfer. Further, the findings of an atoms in molecules (AIM) study show that the interaction between CO2 and Pdn = 1-4 decorated 55–77 sheet is partially covalent and non-covalent, confirming the greater charge transfer between the CO2 molecule and Pdn = 1-4 decorated 55–77 systems. Moreover, the CO2 adsorption on Pdn = 1-4 decorated 55–77 systems is clearly demonstrated by non-covalent interaction (NCI) analysis to be a strong electrostatic interaction at sign(λ2)ρ = −0.05 a.u, and this is further supported by an electron localization function (ELF) map. The highest CO2 adsorption capacity is obtained for 55–77/Pd1+CO2 with the value of 6.27 wt % which concludes 55–77 sheet with Pdn decoration is a more suitable structure for CO2 adsorption than the Agn decorated system.

The van der Waals interaction and absorption and electron circular dichroism spectra of two-dimensional bilayer stacked structures

van der Waals (vdW) heterojunctions based on two-dimensional (2D) materials, graphene and transition metal dichalcogenides (TMDs), are a research hotspot for future optoelectronic and exciton devices. Bond-free vdW interactions are key to 2D material heterojunction device reliability and stability. However, most of the current research on 2D stacked materials heterostructures mainly focuses on optical properties and electronic structure. Furthermore, vdW interaction in 2D heterostructures is studied and understood on the basis of qualitative description and energy ranges from the literature. There are few studies on the nature of vdW interaction based on practical calculations of the quantitative strength and microscopic mechanism of vdW interaction between 2D stacked materials. Therefore, this paper explores the vdW interaction between 2D material stacked bilayer structures, including bilayer graphene, graphene/MoS2 and graphene/WS2 heterostructures, focusing on quantitative analysis of the energy components of the vdW interaction. We first visually observed the weak interactions in the three stacked bilayer structures through noncovalent interaction (NCI) analysis, and found that the interactions are concentrated in the binding region between the two-layer structures. We mainly decomposed the weak interaction energy in the three 2D material bilayer heterostructures through energy decomposition analysis based on the force field (EDA-FF) method and obtained the energy values and proportions of the three components-electrostatic energy, exchange repulsion energy and dispersion energy of the total binding energy between the 2D stacked bilayer structures. The vdW interaction energy is the sum of the exchange repulsion energy and dispersion energy, and the dispersion energy of the vdW interaction accounts for more than 60% of the binding energy of the weak interaction between the 2D bilayer stacked structures. The vdW strengths in the bilayer structures are on the order of 177.07, 123.85, and 133.93 kJ/mol, approxmately 1–2 orders of magnitude larger than the classically defined vdW energies of 0.1–10 kJ/mol. Furthermore, we calculate the density of states of the three 2D stacked structures, and further obtained HOMO-LOMO information; to further understand the electronic structures of the graphene/MoS2 and graphene/WS2 heterostructures, we calculated their optical absorption spectra and electron circular dichroism (ECD) spectra. According to the calculation results, the two heterostructures have strong absorption peaks in the visible region, and the charge transfer forms at the strong absorption peak can be determined according to the charge transfer diagram. The ECD spectra indicate that the configurations of the graphene/MoS2 and graphene/WS2 heterostructures have large chirality. Our work contributes to a deeper understanding of the nature of the weak interactions and optical properties in 2D stacked materials, which plays a fundamental role in promoting the construction of stable 2D heterostructure configurations and the development of multifunctional 2D devices. The research is conducive to further promoting the basic research and practical development of strong optoelectronic and excitonic 2D heterojunctions devices.

Dispersion-Corrected DFT-D4 Study of the Adsorption of Halobenzenes and 1,3,5-Trihalobenzenes on the Cu(111) Surface─Effect of Sigma Hole Properties.

Halogen bonds, characterized by directionality, tunability, hydrophobicity, and variable sizes, are ideal noncovalent interactions to design and control the formation of self-assembled nanostructures. The specific self-assembly cases formed by the halogen-bonding interaction have been well studied by scanning tunneling microscopy (STM) experiments and density functional theory (DFT) calculations. However, there is a lack of systematic theoretical adsorption studies on halogenated molecules. In this work, the adsorption of halobenzenes and 1,3,5-trihalobenzenes on the Cu(111) surface was examined by dispersion-corrected DFT methods. The adsorption geometries, noncovalent molecule-surface interactions, electronic densities, and electrostatic potential maps were examined for their most stable adsorption sites using the DFT-D4 method. Our calculations revealed that the iodo compounds favor a different adsorption geometry from aryl chlorides and bromides. Down the halogen group (Cl to I), the adsorption energy increases and the distance between the halogen atom and Cu surface decreases, which indicates stronger molecule-surface interactions. This is supported by the changes in the density of states upon adsorption. Noncovalent interaction analysis was also employed to further understand the nature and relative strength of the molecule-surface interactions. Electrostatic potential maps revealed that the positive character of the halogen sigma hole becomes stronger upon adsorption. Thus, surface adsorption of the halogenated molecule will enhance the formation of intermolecular halogen bonds. The present theoretical findings are expected to contribute toward a more comprehensive understanding of halogen bonding on the Cu(111) surface.

Probing the influence of defects and Si-doping in graphene sheet as an efficacious carrier for drug delivery system in gas and aqua phases - Combined DFT and classical MD simulation

In this study, for the bioavailability and distribution of the drug on the tumor cells we have chosen targeted drug delivery system and for the delivery system, pristine, defected, and doped graphene sheets are chosen with the anticancer drugs as lapachol and β – lapachone which are studied using density functional theory (DFT) for efficacious drug delivery. The defect formation and doping are shown to alter the properties of pristine sheets, which results in the enhanced adsorption of anticancer drugs. The cohesive energy found for all the sheets are in the 7 eV range which shows their high stability. This study revealed that the adsorption of lapachol and β – lapachone in pristine graphene sheet is poor with low adsorption energy of about −1.49 (−1.39) eV and −1.52 (−1.43) eV in gas (water) medium respectively and the adsorption energy is enhanced about 30–70% by introducing defects and about 55% by doping of silicon in the pristine graphene sheet. The highest adsorption energy for both lapachol and β – lapachone are found to be about −2.69 (−2.59) eV and −2.55 (−2.41) eV in mono vacant graphene sheet in gas (water) medium respectively. The major interaction within the complexes is studied using quantum theory of atoms in molecule (QTAIM) analysis and it is further studied via non-covalent interaction (NCI) analysis with the help of reduced density gradient (RDG) map. The ρ values at bond critical points (BCP) lie between 0.007 and 0.01 a. u. With ∇2ρ and H(r) > 0, −G/V > 1 for all the complexes showing that non-covalent interaction plays a major role in the adsorption of active drugs. Furthermore, NCI analysis shows that the van der Waals interaction and hydrogen bonding play a major influence on the interaction between the anticancer drug and the carrier sheets. The molecular dynamic (MD) study shows that all the drug-loaded complexes are stable with minimal variation in the van der Waals energy during the production run. Thus, the results obtained from DFT and MD shows that the defected and Si-doped graphene sheets are much more suitable as a carrier for drug delivery than the pristine sheet. This study paves the way for the future research on the defected and doped graphene sheets as a suitable drug carrier for numerous drugs in the targeted drug delivery system.

Exploring the Potential of Chemically Modified Graphyne Nanodots as an Efficient Adsorbent and Sensitive Detector of Environmental Contaminants: A First Principles Study.

In this study, we investigated the reactivity of γ-graphyne (Gp) and its derivatives, Gp-CH3, Gp-COOH, Gp-CN, Gp-NO2, and Gp-SOH, for the removal of toxic heavy metal ions (Hg+ 2, Pb+ 2, and Cd+ 2) from wastewater. From the analysis of the optimized structures, it was observed that all the compounds exhibited planar geometry. The dihedral angles (C9-C2-C1-C6 and C9-C2-C1-C6) were approximately 180.00°, indicating planarity in all molecular arrangements. To understand the electronic properties of the compounds, the HOMO (EH) and LUMO (EL) energies were calculated, and their energy gaps (Eg) were determined. The EH and EL values ranged between - 6.502 and - 8.192eV and - 1.864 and - 3.773eV, respectively, for all the compounds. Comparing the EH values, Gp-NO2 exhibited the most stable HOMO, while Gp-CH3 had the least stable structure. In terms of EL values, Gp-NO2 had the most stable LUMO, while Gp-CH3 was the least stable. The Eg values followed the order: Gp-NO2 < Gp-COOH < Gp-CN < Gp-SOH < Gp-CH3 < Gp, with Gp-NO2 (4.41eV) having the smallest energy gap. The density of states (DOS) analysis showed that the shape and functional group modifications affected the energy levels. Functionalization with electron-withdrawing (CN, NO2, COOH, SOH) or electron-donating (CH3) groups reduced the energy gap. To specifically target the removal of heavy metal ions, the Gp-NO2 ligand was selected for its high binding energy. Complexes of Gp-NO2-Cd, Gp-NO2-Hg, and Gp-NO2-Pb were optimized, and their properties were analyzed. The complexes were found to be planar, with metal-ligand bond distances within the range of 2.092→3.442 Å. The Gp-NO2-Pb complex exhibited the shortest bond length, indicating a stronger interaction due to the smaller size of Pb+ 2. The computed adsorption energy values (Eads) indicated the stability of the complexes, with values ranging from - 0.035 to -4.199eV. Non-covalent interaction (NCI) analysis was employed to investigate intermolecular interactions in Gp-NO2 complexes. The analysis revealed distinct patterns of attractive and repulsive interactions, providing valuable insights into the binding preferences and steric effects of heavy metals.

Solvent influence on the crystal structures of new cadmium tri-tert-butoxysilanethiolate complexes with 1,4-bis(3-aminopropyl)piperazine: luminescence and antifungal activity.

Monocrystals of dinuclear μ-1,4-bis(3-aminopropyl)piperazine-κ4N1,N1':N4,N4'-bis[bis(tri-tert-butoxysilanethiolato-κS)cadmium(II)], [Cd2(C12H27O3SSi)4(C10H24N4)] or [Cd2{SSi(OtBu)3}4(μ-BAPP)], 1, and polynuclear catena-poly[[bis(tri-tert-butoxysilanethiolato-κS)cadmium(II)]-μ-1,4-bis(3-aminopropyl)piperazine-κ2N1':N4'], [Cd(C12H27O3SSi)2(C10H24N4)]n or [Cd{SSi(OtBu)3}2(μ-BAPP)]n, 2, with 1,4-bis(3-aminopropyl)piperazine (BAPP) and tri-tert-butoxysilanethiolate ligands, were obtained from the same ratio of reactants, but with different solvents used for the crystallization processes. The structures and properties of both complexes were characterized using elemental analysis, X-ray diffraction and FT-IR, 1H NMR and luminescence spectroscopy. Applied density functional theory (DFT) computational methods and noncovalent interaction (NCI) analysis were used for geometry optimization and visualization of the interactions between the metallic centres and their surroundings. The X-ray analysis revealed four-coordinate CdII centres bound to two S atoms of the silanethiolate groups and two N atoms of the BAPP ligand; however, it chelates to tertiary and primary N atoms in 1, whilst in 2 it does not chelate and bonds only to RNH2. The photoluminescence properties of complexes 1 and 2 result from free-ligand emission and differ significantly from each other with respect to emission intensity. Additionally, antifungal activity was investigated against 18 isolates of fungi. Compound 1 strongly inhibited the growth of three dermatophytes: Epidermophyton floccosum, Microsporum canis and Trichophyton rubrum.

Dispersion-corrected DFT calculations and umbrella sampling simulations to investigate stability of Chrysin-cyclodextrin inclusion complexes

The study of inclusion complexes of Chrysin (ChR) with three forms of cyclodextrins (CDs) α-, β-, and γ-CD was accomplished to examine the stability of ChR inside the central cavities of CDs. The aim of study was to identify the most suitable form of CD to improve the hydro-solubility of poorly soluble ChR bioactive molecule. Microsecond timescale molecular dynamics (MD) simulations were performed on four inclusion complexes (α-CD/ChR, β-CD/ChR, and two conformations of γ-CD/ChR) to examine the dynamics of ChR inside the cavity of CDs. The first conformation of γ-CD/ChR inclusion complex (γ-CD1/ChR) was identified to possess the highest affinity between host and guest molecule on the basis of binding energy calculated by employing Molecular Mechanics Poisson-Boltzmann Surface Area (MM-PBSA) and umbrella sampling simulations. To further strengthen the claims of classical and biased MD studies, Our own N-layered Integrated molecular Orbital and Molecular mechanics (ONIOM) (wB97XD/6–311+g(d,p):pm7) calculations were performed on the selected inclusion complexes. The ONIOM based complexation energy reaffirmed that ChR had highest affinity for the γ-CD1 host molecule. Further, the non-covalent interaction analysis was conducted using Multiwfn software on QM-optimized inclusion complexes with wB97XD/6–311+G(d,p) model chemistry, revealing non-covalent interactions between ChR and CDs. This atomic level information helped us to gain better insights into critical atoms of ChR and CD that participated in intermolecular interactions and identify γ-CD as a suitable host molecule for improving the hydro-solubulity of ChR. The structural insights would help to derive new derivatives of γ-CD with better host capacity.