Effect Of Non-covalent Interactions Research Articles

Effect of non-covalent interactions on the stability and structural properties of 2,4-dioxo-4-phenylbutanoic complex: a computational analysis.

The 2,4-dioxo-4-phenylbutanoic acid (DPBA) is a subject of interest in pharmaceutical research, particularly in developing new drugs targeting viral and bacterial infections. Complexation with metal ions can improve the stability and solubility of organic compounds. The present study uses quantum chemical calculations to explore the structural and electronic results arising from the interaction between the metal cation (Fe2+) and the π-system of DPBA in different solvents. For this purpose, the analyses of atoms in molecules (AIM) and natural bond orbital (NBO) are employed to comprehend the interaction features and the charge delocalization during the process of complexation. The results demonstrate that the strongest/weakest interactions are evident when the complex is situated in non-polar/polar solvents, respectively. In addition, the investigated complex exhibits two intramolecular hydrogen bonds (IMHBs) characterized by the O-H···O motif. The results indicate that the HBs present in the complex fall within the category of weak to medium HBs. Moreover, the O-H···O HBs are influenced by cation-π interactions, which can increase/decrease their strength in polar/non-polar solvents. To enhance understanding of the interactions above, an examination is conducted on various physical properties including the energy gap, electronic chemical potential, chemical hardness, softness, and electrophilicity power. All calculations are conducted within the density functional theory (DFT) using the ωB97XD functional and 6-311 + + G(d,p) basis set. The computations are performed using the quantum chemistry package GAMESS, and the obtained results are visualized by employing the GaussView program.

Structural, physicochemical, and digestive properties of enzymatic debranched rice starch modified by phenolic compounds with varying structures

The physicochemical properties of starch and phenolic acid (PA) complexes largely depend on the effect of non-covalent interactions on the microstructure of starch. However, whether there are differences and commonalities in the interactions between various types of PAs and starch remains unclear. The physicochemical properties and digestive characteristics of the complexes were investigated by pre-gelatinization of 16 structurally different PAs and pullulanase-modified rice starches screened. FT-IR and XRD results revealed that PA complexed with debranched rice starch (DRS) through hydrogen bonding and hydrophobic interaction. Benzoic/phenylacetic acid with polyhydroxy groups could enter the helical cavities of the starch chains to promote the formation of V-shaped crystals, and cinnamic acid with p-hydroxyl structure acted between starch chains in a bridging manner, both of which increased the relative crystallinity of DRS, with DRS-ellagic acid increasing to 20.03 %. The digestion and hydrolysis results indicated that the acidification and methoxylation of PA synergistically decreased the enzyme activity leading to a decrease in the digestibility of the complexes, and the resistant starch content of the DRS-vanillic acid complexes increased from 28.27 % to 71.67 %. Therefore, the selection of structurally appropriate PAs can be used for the targeted preparation of starch-based foods and materials.

Interactions between xanthan gum and phenolic acids

The molecular and colloidal-level interactions between two major phenolic acids, gallic and caffeic acid, with a major food polysaccharide, xanthan gum, were studied in binary systems aiming to correlate the stability of the binary systems as a function of pH and xanthan-polyphenol concentrations. Global stability diagrams were built, acting as roadmaps for examining the phase separation regimes followed by the fluorimetry-based thermodynamics of the interactions. The effects of noncovalent interactions on the macroscopic behavior of the binary systems were studied, using shear and extensional rheometry. The collected data for caffeic acid – xanthan gum mixtures showed that the main interactions were pH-independent volume exclusions, while gallic acid interacts with xanthan gum, especially at pH 7 with other mechanisms as well, improving the colloidal dispersion stability. A combination of fluorimetry, extensional rheology and stability measurements highlight the effect of gallic acid-induced aggregation of xanthan gum, both in structuring and de-structuring the binary systems. The above provide a coherent framework of the physicochemical aspect of binary systems, shedding light on the role of xanthan gum in its oral functions, such as in inducing texture, in model complex systems containing phenolic acids.

Noncovalent Interactions, Structure Elucidation and Docking Studies of anti-Fungal Pyridine Carboxamide Derivatives of Co(II), Ni(II), Cu(II) & Zn(II)

Computational analysis of four antifungal transition metal complexes of Co(II), Ni(II), Cu(II) and Zn(II) with pyridine carboxamide derivates (methyl 2-amino-3- methylbenzoate isonicotinic acid amide (L1) and methyl 2-amino-3-methylbenzoate picolinic acid amide (L2)) as ligands is provided here within the DFT framework. Geometry optimization, binding energy, HOMO-LUMO energy gap, Density of States (DOS) plots, and MEP surfaces have been calculated to rationalize the molecular structure of these complexes. The effect of noncovalent interactions on the crystal structure of these complexes has been deciphered using CE-B3LYP model instigated into CrystalExplorer using experimental geometries accessed from Cambridge Crystallographic Data Center (CCDC). These complexes are docked against Enterococcus Faecalis using AutoDock Vina to quantify binding energy between the complexes and protein accessed from the protein data bank (PDB).

Study of Non-Covalent Interactions Present in the Tapinarof-Ethanol System with Special Emphasis on Hydrogen-Bonding Interactions.

In this study, the effect of non-covalent interaction in the tapinarof-EtOH systems is evaluated, particularly the hydrogen-bonding interaction using density functional theory in a gas phase. From the optimization results and the binding energy calculated thereafter, it is concluded that interaction in the employed system occurs between the O-H groups on tapinarof and the oxygen atom of EtOH molecules existing in the vicinity of the O-H group. These interactions were concluded to be those of the weak hydrogen bonds by carrying out the reduced gradient approach and QTAIM analysis, which are basically electron-density-based topological analyses. The charge localization between the donor-acceptor moieties was analyzed using the NBO analysis. Using the LED analysis, the binding energy between the tapinarof and EtOH was partitioned into different energy terms centered on a domain-based local pair natural orbital coupled cluster method. Thus, the electronic environment of the tapinarof-EtOH systems is evaluated.

Influence of non-covalent interactions on the coordination geometry of Ni(ii) in Ni(ii)–M(ii) complexes (M = Zn and Hg) with a salen-type N2O2 Schiff base ligand and thiocyanate ion as the coligand

The effect of non-covalent interactions on the coordination geometry of Ni(ii) in a Ni(ii)–Zn(ii) and a Ni(ii)–Hg(ii) complexes has been studied using DFT calculations.

Effects of non-covalent interactions between pectin and volatile compounds on the flavor release of tomato paste

Breaking methods have been shown to affect the sensory attributes of tomato paste, including volatile compounds and pectin content. This study aimed to explore the roles of interactions between pectin and aroma active compounds in the flavor release of tomato paste. Based on our results, phenethyl alcohol (PA) was one of the representative aroma active compounds and showed highly negative correlation with pectin content in tomato paste. According to ultraviolet–visible, fluorescence emission spectra and DLS analysis, PA could interact with pectin through hydrophobic and electrostatic interactions. The IGM analysis showed that van der Waals forces played a dominant role in the formation of PA-pectin complexes, which was further confirmed by 1 H NMR spectra and MD simulation. Overall, the non-covalent interaction of volatile compounds with pectin remarkably affected their release in tomato paste. These findings provide some insights into methods for improving the sensory quality of tomato paste. • Volatiles and pectin contents of tomato pastes greatly changed after processing. • PA was one of the representative aroma active compounds in tomato paste. • PA exhibited highly negative correlation with pectin content in tomato paste. • The quenching of PA fluorescence by pectin was based on a static mechanism. • Non-covalent interactions of volatile compounds with pectin affected their release.

DFT calculations, structural analysis, solvent effects, and non-covalent interaction study on the para-aminosalicylic acid complex as a tuberculosis drug: AIM, NBO, and NMR analyses.

In this study, the effect of non-covalent interactions on the para-aminosalicylic acid complex is explored using density functional theory (DFT) in the gas phase and the solution. Our findings exhibit that the achieved binding energies considerably change on going from the gas phase to the solution. Based on the obtained results, the absolute value of the binding energy of the complex in the polar solvents is lower than the non-polar ones while in the gas phase it is higher than the solution. The atoms in molecules (AIM) and the natural bond orbital (NBO) analyses are applied to estimate the topological properties and the charge transfer during complexation, respectively. The results indicate that the presence of the cation-π interaction increases the strength of the intramolecular hydrogen bond in the studied complex. Finally, the various electronic descriptors such as energy gap, hardness, softness, and electronic chemical potential are investigated to gain further insight into these interactions. According to the achieved results, the high energy gap of the complex in the water solvent indicates high chemical stability and low reactivity compared to the others. On the other hand, the most reactive as well as the softest complex belongs to the gas phase.

Effect of Non-Covalent Interactions on the 2,4- and 3,5-Dinitrobenzoate Eu-Cd Complex Structures

Heterometallic {Eu2Cd2} complexes [Eu2(NO3)2Cd2(Phen)2(2,4-Nbz)8]n·2nMeCN (I) and [Eu2(MeCN)2Cd2(Phen)2(3,5-Nbz)10] (II) with the 2,4-dinitrobenzoate (2,4-Nbz) and 3,5-dinitrobenzoate (3,5-Nbz) anions and 1,10-phenanthroline were synthesized. The compounds obtained were characterized by X-ray single-crystal analysis, powder X-ray diffraction analysis, IR spectroscopy, and elemental analysis. Moreover, the thermal stability of the complexes was also studied. Analysis of the crystal packing showed that where 1,10-phenanthroline is combined with various isomers of dinitrobenzoate anions, different arrangements of non-covalent interactions are observed in the complex structures. In the case of the compound with the 2,4-dinitrobenzoate anion, these interactions lead to a significant distortion of the metal core geometry and formation of a polymeric structure, while the complex with the 3,5-dinitrobenzoate anion has a structure that is typical of similar systems. The absence of europium metal-centered luminescence at 270 nm wavelength was shown. For all the reported compounds, a thermal stability study was carried out that showed that the compounds decomposed with a significant thermal effect.

Recent advances in studying the nonnegligible role of noncovalent interactions in various types of energetic molecular crystals

This highlight summarizes the research progress on the considerable effects of noncovalent interactions on diverse types of energetic materials and enlighten us to explore new factors that affect the key performance of explosives.

Effects of the non-covalent interactions between polyphenols and proteins on the formations of the heterocyclic amines in dry heated soybean protein isolate

Soybean proteins are the main component of plant‐based meat alternatives in the Chinese market. The effects of non-covalent interactions between polyphenols and proteins on the protein structures, the rest physicochemical properties, and formations of heterocyclic amines (HAs) were examined using a polyphenols-containing soybean protein isolate (SPI) complex as a model to dry heating at 170℃ for 10 min. The results showed that tetrahydro-curcumin had extensive inhibitory effects on the HA formation. In addition, tea polyphenols, grapeseed procyanidins, and dihydromyricetin were also found to have inhibitory effects only on some HAs. Correlation analysis showed that polyphenols altered the secondary structure and steric structure of the protein by interacting with the protein, which affects the HA formation. The results provided theoretical references and a basis for the formation mechanisms of HAs in polyphenol-inhibiting protein foods.

Beyond Conformational Control: Effects of Noncovalent Interactions on Molecular Electronic Properties of Conjugated Polymers.

Tuning the electronic properties of polymers is of great importance in designing highly efficient organic solar cells. Noncovalent intramolecular interactions have been often used for conformational control to enhance the planarity of polymers or molecules, which may reduce band gaps and promote charge transfer. However, it is not known if noncovalent interactions may alter the electronic properties of conjugated polymers through some mechanism other than the conformational control. Here, we studied the effects of various noncovalent interactions, including sulfur–nitrogen, sulfur–oxygen, sulfur–fluorine, oxygen–nitrogen, oxygen–fluorine, and nitrogen–fluorine, on the electronic properties of polymers with planar geometry using unconstrained and constrained density functional theory. We found that the sulfur–nitrogen intramolecular interaction may reduce the band gaps of polymers and enhance the charge transfer more obviously than other noncovalent interactions. Our findings are also consistent with the experimental data. For the first time, our study shows that the sulfur–nitrogen noncovalent interaction may further affect the electronic structure of coplanar conjugated polymers, which cannot be only explained by the enhancement of molecular planarity. Our work suggests a new mechanism to manipulate the electronic properties of polymers to design high-performance small-molecule-polymer and all-polymer solar cells.

Effect of Noncovalent Interactions on the Intersystem Crossing Behavior in Charge-Transfer Cocrystals of 3,5-Dinitrobromobenzene

The strength of the noncovalent interactions between donor and acceptor in charge-transfer (CT) cocrystals plays a significant role in controlling their optical behavior. Herein, we demonstrate the...

Stability of spherical molecular complexes: a theoretical study of self-assembled M12L24 nanoballs

Supramolecular coordination complexes have become of great interest due to their broad spectrum of applicability, mainly in the area of biomedicine. Understanding the role played by the metal center and the weak interactions in the formation and stabilization of these compounds allow us to have a better design of these molecules and therefore a better guide for the examination of novel applications. In this work, we investigate the effect of noncovalent interactions and the presence of metal centers in the stabilization of Tominaga’s M12L24 nanoballs. We considered bis(4-pyridyl)-substituted bent frameworks involving two acetylenes spacers as the ligand (L), using –H, –CH3, and a cyanophenyl group as substituents, and two different metal cations: Pd2+ and Ni2+. We found that the bond distance between the metal and the ligand was smaller for the nickel complexes than for the palladium compounds. This is related to the dissociation energies (Ni2+ systems are more stable than Pd2+ compounds). Furthermore, nanoballs with the largest ligand’s substituent are significantly more stable than those with the smallest ligand’s substituents. Analyzing the frontier states and the Independent Gradient Model isosurfaces, we found that noncovalent interactions contribute to the stabilization of the complexes. Through the charge distribution, we observed that the metal also polarizes the density of the coordination bond. With these results we can conclude that metal centers and noncovalent interactions play an important role in the stabilization of nanoballs.

Improving photovoltaic performance of benzothiadiazole-based small molecules: A synergistic effect of non-covalent interaction and aryl terminal group

Abstract

Effects of non-covalent interactions on the properties of 3D printed flexible piezoresistive strain sensors of conductive polymer composites

ABSTRACT In this work, flexible piezoresistive strain sensors of carbon nanotubes (CNT)/thermoplastic polyurethane (TPU) conductive polymer composites were prepared using fused filament fabrication (FFF) 3D printing. The constructed porous structure and highly elastic TPU matrix allow the sensors to experience strains up to 30% with great recoverability. The printed sensors exhibited a typical negative piezoresistive effect under compressive strain. The effects of non-covalent modification and loading of CNTs on the mechanical and piezoresistive behavior of sensors were investigated. The introduction of 1-pyrenecarboxylic acid (PCA) increased the dispersibility of CNTs and nanofiller-polymer interfacial interactions, resulting in the excellent sensing performance. A sensor with higher CNT content showed greater sensitivity due to generation of more conductive paths during compression. The gauge factor () of the 3 wt% CNT/PCA/TPU sensor increased by 43 and 35 times compared with the 3 wt% CNT/TPU and the 1.5 wt% CNT/PCA/TPU sensors, respectively, when strained at 26% to 30%. In addition, the printed sensor of 3 wt% CNT/PCA/TPU showed great reproducibility over 1500 loading cycles. Some applications in monitoring external loads and motion of the human body were demonstrated. This work provides important information for the property optimization and customizable fabrication of flexible piezoresistive strain sensors.

Qualitative as well as quantitative analysis of interactions present in chlorine and bromine substituted aromatic organic crystals: A DFT linked Crystal Explorer study

The effect of noncovalent interactions in shaping a crystal structure is explored qualitatively as well as quantitatively in a DFT linked Crystal Explorer (CE) study of nine different Chlorine and Bromine substituted benzene derivatives. The qualitative approach to analyze interactions is based on Hirshfeld surface that locates electronic charge distribution on the surface, quantitative estimation is obtained by linking DFT computations withCE.In the halogen substituted benzene derivatives considered here, in addition to conventional hydrogen and halogen bonding other interactions such as those between Chlorine–Hydrogen, Bromine–Hydrogen, Bromine-Oxygen have been deciphered. The molecular crystal structure of a variety of halogen substituted aromatic molecules has been rationalized and attributed to specific interactions.

Mixed ligand coordination complexes by using multicomponent ligand: Syntheses, characterization and effect of non-covalent interactions on their framework structures

Abstract Three new coordination complexes [Mn(L1)(μ-azide)(azide)]2⋅4H2O (1), [Mn(L1)(fum)]n (2) [L1 = 2methyl-N1,N2-bis(pyridin-2yl)propane-1,2-diamine, fum = Fumaric acid] and [Co(L2)(azide)] (3) [L2 = 6 phenyl-1,3,5-triazine 2,4-diyl amino(pyridine-2yl)methanol] have been synthesized and X-ray crystallographically characterized. Complex 1, a dinuclear Mn(II) complex is formed by bridging azide ligand and other coordination sites are satisfied by tetradentate ligand L1 and terminal azide ligand. The overall structure is an incomplete supramolecular 3D cage structure, formed by intermolecular π … π interaction of pyridyl ligand and hydrogen bonding. Complex 2 comprised of eight coordinated Mn(II) centre where ligand L1 and fumarate is bridged between the metal centers that leads to a one dimensional chain structure which further extended to a 3D structure by π … π and C–H … π interactions. The overall structure is further stabilized by hydrogen bonding with the guest water molecules. Complex 3, a six coordinated mononuclear Co(II) discrete complex is consist of pentadentate ligand L2 and azide act as a terminal ligand. This Mononuclear complex is connected by π … π, C–H … π interactions and hydrogen bonding which ultimately leads to a supramolecular 2D architecture. All the complexes have been further characterized by elemental analysis, infrared spectroscopy (IR) and powder X-ray diffraction (PXRD) studies.

Conformational analysis of ticagrelor: effect of noncovalent interaction on conformational population

In order to track the source of duplicated peaks in the 1H-NMR spectrum of Ticagrelor, variable-temperature NMR (VT-NMR) experiment was carried out with temperature increasing from 300 to 343 K. The result showed that the phenomenon was brought forth by coexistence of conformational isomers. Subsequently, conformational search was carried out by molecular mechanics (MM) stimulations associating with quantum mechanics (QM) calculations. The results revealed that the isomers resulting in duplicated proton peaks were introduced by the rotation of 2,4-diflurophenyl group on C3’position of cyclopropyl. Finally, noncovalent interaction (NCI) topological analysis of the conformers exhibited that CH-π interactions and H-bonds play important roles in controlling the population of conformers of ticagrelor.

Effect of non-covalent interactions on molecular stacking and photovoltaic properties in organic photovoltaics

The conjugated structures of donor–acceptor (D–A) type with sulfur (S), nitrogen (N) and oxygen (O) atoms aid to close packing each other in the backbone by non-covalent interactions. Furthermore, non-covalent interactions are exerted three dimensionally and affect various properties. To know this effects, we introduced different S, N and O contents as benzothiadiazole (BT) and dithienophenazine (DTPz, up or down direction of S) units on each polymer backbone. Among the three polymers, P2 with up direction of S showed an open-circuit voltage (Voc) of 0.90V, fill factor (FF) of 54.7% and reached best power conversion efficiency (PCE) of 4.8%.