Theoretical study of inclusion complexes of dopamine with β-cyclodextrin based on PM6, ONIOM, and natural bonding orbital analysis

2011 ◽  
Vol 89 (12) ◽  
pp. 1519-1524 ◽  
Author(s):  
Rayenne Djemil ◽  
Djameleddine Khatmi
Keyword(s):  
Intermolecular Hydrogen Bond ◽  
Inclusion Process ◽  
Hydrogen Bond Interactions ◽  
Complex Orientation ◽  
Optimum Position ◽  
Natural Bonding Orbital ◽  
Donor Acceptor ◽  
The Stability ◽  
Cpcm Model ◽  
Orbital Analysis

The inclusion process involving β-cyclodextrin (β-CD) with dopamine (DA) was investigated by using PM6, HF, and ONIOM methods. The most stable structure was obtained at the optimum position and angle. The complex orientation in which the catechol ring of dopamine penetrates into the β-CD cavity near primary hydroxyls is preferred in energy. The structures show the presence of several intermolecular hydrogen bond interactions that were studied on the basis of natural bonding orbital analysis, employed to quantify the donor–acceptor interactions between dopamine and β-CD. A study of these complexes in solution was carried out using the CPCM model to examine the influence of solvation on the stability of the dopamine β-CD complex.

COMPUTER SIMULATIONS TO INVESTIGATE STABILITY AND STRUCTURAL PROPERTIES OF PEPTIDE AMPHIPHILE NANOFIBERS

2007 ◽  
Vol 06 (03) ◽  
pp. 621-630
Author(s):  
RUO-YU CHEN ◽  
LING-YING WU ◽  
JUN-MIN LIAO ◽  
CHENG-LUNG CHEN
Keyword(s):  
Molecular Dynamics ◽  
Disulfide Bonds ◽  
Md Simulation ◽  
Intermolecular Hydrogen Bond ◽  
Intermolecular Distance ◽  
Peptide Amphiphile ◽  
Hydrogen Bond Interactions ◽  
Self Assembling ◽  
Polar Groups ◽  
The Stability

Molecular mechanics (MM) method followed by molecular dynamics (MD) simulation was carried out to investigate the stability of an aggregate formed by self-assembling of peptide amphiphile (PA) molecules. The MM + MD simulation confirms that the cylindrical shaped aggregate is very stable. The analysis showed that the remarkable stability of the aggregate was partly due to various intermolecular hydrogen-bond interactions between polar groups of PA molecules. The hydrophobic alkyl tails of PA molecules are packed loosely inside the interior of the aggregates. The packing of alkyl tails contribute further stability of the PA aggregate. Our simulations reproduce qualitatively experimental observations and support the fact that PA molecules are self-assembled within closed intermolecular distance to favor the forming of disulfide bonds.

Synthesis, Photophysics and Theoretical Calculation of (E)-2-(benzo[d] thiazol-2-yl)-3-(3-methoxyphenyl)acrylonitrile

2020 ◽  
Vol 17 (9) ◽  
pp. 688-693
Author(s):  
Pei-Chieh Wu ◽  
Chih-Hsien Chen
Keyword(s):  
Crystal Structure ◽  
Hydrogen Bond ◽  
Emission Intensity ◽  
Intermolecular Hydrogen Bond ◽  
Aromatic Rings ◽  
Organic Nanoparticles ◽  
X Ray ◽  
Hydrogen Bond Interactions ◽  
New Type ◽  
The Stability

In this study, a new type of luminogen with aggregation-induced-emission (AIE) behavior was designed and synthesized. The result of single-crystal X-ray structure showed a planar structure in which the dihedral angle between two aromatic rings is less than 30o. Moreover, two different intermolecular hydrogen bond interactions supported the stability of the crystal structure. After the formation of organic nanoparticles in poor solubility solvent, the emission intensity of the desired product was increased and the enhancement achieved was 14-fold. This new design of luminogen provided further understanding of the AIE mechanism.

scholarly journals Structural and Vibrational Spectroscopic Elucidation of Nitrogen Rich Energetic Salt: 2,4-Diamino-6-methyl-1,3,5-triazinium Levulinate Dihydrate

2021 ◽  
Vol 33 (8) ◽  
pp. 1891-1904
Author(s):  
K. Ayisha Begam ◽  
N. Kanagathara ◽  
V. Ragavendran ◽  
R. Gowri Shankar Rao ◽  
M.K. Marchewka
Keyword(s):  
Crystal Packing ◽  
Structural Parameters ◽  
Intermolecular Hydrogen Bond ◽  
Three Dimensional ◽  
Basis Set ◽  
Frontier Molecular Orbital ◽  
Monoclinic System ◽  
The Stability ◽  
Molecular Orbital Analysis ◽  
Orbital Analysis

A novel nitrogen rich energetic salt 2,4-diamino-6-methyl-1,3,5-triazinium levulinate dihydrate (DMTLDH) has been grown by slow evaporation method at room temperature. The grown synthesized salt crystallizes in the centrosymmetric space group P21/n of monoclinic system. The intermolecular hydrogen bond N–H···N, N–H···O, C–H···O, O–H···O type interactions stabilizes the structure and leads to three dimensional network. In addition to that the crystal structure also possesses C–O···Cg interactions. Also, quantum chemical computational studies using DFT-B3LYP/6-311++G(d,p) and PBEPBE/6-31G(d,p) basis set is used to analyze the structural parameters and vibrational frequencies of grown crystal. Frontier molecular orbital analysis describes the charge transfer within the molecule and also other electronics parameters were calculated. The natural bonding orbital analysis has also been performed to study the stability of the molecule. Further, the crystal packing behaviour of DMTLDH was studied quantitatively with the aid of Hirshfeld surface analysis.

Characterization of Novel Solid Dispersions of Moringa oleifera Leaf Powder Using Thermo-Analytical Techniques

Processes ◽  
2021 ◽  
Vol 9 (12) ◽  
pp. 2230
Author(s):  
Nontsikelelo Noxolo Tafu ◽  
Victoria A. Jideani
Keyword(s):  
Solid Dispersion ◽  
Moringa Oleifera ◽  
Solid Dispersions ◽  
Intermolecular Hydrogen Bond ◽  
Thermo Gravimetric Analysis ◽  
Analytical Techniques ◽  
Gravimetric Analysis ◽  
Scanning Calorimetry ◽  
Hydrogen Bond Interactions ◽  
Leaf Powder

Moringa oleifera leaf powder (MOLP) has been identified as the most important functional ingredient owing to its rich nutritional profile and healthy effects. The solubility and functional properties of this ingredient can be enhanced through solid dispersion technology. This study aimed to investigate the effects of polyethylene glycols (PEGs) 4000 and 6000 as hydrophilic carriers and solid dispersion techniques (freeze-drying, melting, solvent evaporation, and microwave irradiation) on the crystallinity and thermal stability of solid-dispersed Moringa oleifera leaf powders (SDMOLPs). SDMOLPs were dully characterized using powder X-ray diffraction (PXRD), differential scanning calorimetry (DSC), thermo-gravimetric analysis (TGA), and Fourier transform infrared spectroscopy (FTIR). The PXRD results revealed that the solid dispersions were partially amorphous with strong diffraction peaks at 2θ values of 19° and 23°. The calorimetric and thermogravimetric curves showed that PEGs conferred greater stability on the dispersions. The FTIR studyrevealed the existence of strong intermolecular hydrogen bond interactions between MOLP and PEG functional groups. MOLP solid dispersions may be useful in functional foods and beverages and nutraceutical formulations.

scholarly journals Phosphorene–Fullerene Nanostructures: A First-Principles Study

2021 ◽  
Author(s):  
Diego Cortes-Arriagada ◽  
Daniela E. Ortega
Keyword(s):  
Active Sites ◽  
Short Range ◽  
Density Functional ◽  
Dipole Moments ◽  
Molecular Size ◽  
Bandgap Engineering ◽  
Donor Acceptor ◽  
The Stability ◽  
Strong Repulsion ◽  
Intermolecular Distances

Hybrid materials formed by carbon fullerenes and layered materials have emerged due to their advantages for several technological applications, and phosphorene arises as a promising two-dimensional semiconductor for C60 adsorption. However, the properties of phosphorenefullerene hybrids remain mainly unexplored. In this work, we employed density functional theory to obtain structures, adsorption energies, electronic/optical properties, binding (AIM, NBO), and energy decomposition analyses (ALMO-EDA) of nanostructures formed by phosphorene and fullerenes (C24 to C70). We find fullerenes form covalent and non-covalent complexes with phosphorene depending on the molecular size, showing remarkable stability even in solution. Two classes of covalent complexes arise by cycloaddition-like reactions: the first class, where short-range effects (charge-transfer and polarization) determines the stability; and the second one, where short-range effects decay to avoid steric repulsion, and balanced longrange forces (electrostatics and dispersion) favors the stability. Otherwise, high-size fullerenes (C50 to C70) only form non-covalent complexes due to strong repulsion at shorter intermolecular distances and lack of dissociation barriers. In terms of electronic properties, fullerenes act as mild p-dopants for phosphorene, increasing its polar character and ability to acquire induced dipole moments (polarizability). Also, small energy-bandgap fullerenes (<0.8 eV) largely increase the phosphorene metallic character. We also note fullerenes retain their donor/acceptor properties upon adsorption, acting as active sites for orbital-controlled interactions and maximizing the phosphorene light absorbance at the UV-Vis region. Finally, we strongly believe our study will inspire future experimental/theoretical studies focused on phosphorene-fullerene uses for storage, anode materials, sensing, phosphorene bandgap engineering, and optoelectronics.<br>

scholarly journals Certain Inclusion Problems in Autism Spectrum Disorders

2020 ◽  
Vol 18 (1) ◽  
pp. 51-61
Author(s):  
S.A. Morozov ◽  
S.S. Morozova ◽  
T.I. Morozova
Keyword(s):  
Autism Spectrum Disorders ◽  
Inclusive Education ◽  
Autism Spectrum ◽  
Ceteris Paribus ◽  
Inclusion Process ◽  
Great Achievement ◽  
Patterns Of Behavior ◽  
Spectrum Disorders ◽  
The Stability ◽  
Autistic Disorders

The term “Inclusion” is not identical to the concepts of “Inclusive education”, which is much wider. The educational system of children with autism spectrum disorders (ASD) in Russia is only developing and the focus on inclusion is a great achievement. Inclusive education in autistic disorders is a special case. The most difficulties in organizing of inclusion of children with ASD caused by main symptoms — communication and social interaction disorders, repeated stereotypical patterns of behavior, interests and activities. After all, these symptoms create a special development situation that makes necessary to solve the following problems: improving the organization of the inclusive process, feasibility and possibility of inclusion process. Typical difficulties faced by domestic and foreign experts reviewed, for example: increased social anxiety in children, lack of trained personnel, and lack of diagnostic in children. Emphasized that the success of inclusion process depends on several things: the readiness for inclusion of the child with autism, the readiness of the environment where inclusion carried out, the level of its tolerance and, finally, the competence of psychological and pedagogical staff. The age of the child and the environment plays a large role: ceteris paribus, the early onset of inclusion contributes to the stability of inclusive readiness of the environment.

THEORETICAL STUDY OF SANDWICH COMPLEXES [Fe(η4 - E4)2]2- (E = N, P, As, Sb, AND Bi)

2007 ◽  
Vol 06 (02) ◽  
pp. 363-376 ◽  
Author(s):  
ZHIWEI LI ◽  
CUNYUAN ZHAO ◽  
LIUPING CHEN
Keyword(s):  
Density Functional ◽  
Theoretical Study ◽  
Sandwich Complexes ◽  
Functional Theory ◽  
Atomic Orbitals ◽  
Orbital Interactions ◽  
The Stability ◽  
Equilibrium Geometries ◽  
Orbital Analysis ◽  
Iron Center

The equilibrium geometries, energies, harmonic vibrational frequencies, stability, and aromaticities for the [Formula: see text], E 4 Fe , and [ Fe (η4 - E 4)2]2- ( E = N, P, As, Sb, and Bi ) species are studied using density functional theory (DFT). The ground states of the E 4 Fe and [ Fe (η4 - E 4)2]2- systems are predicted to be Cs and D4d structures, respectively. Orbital analysis indicates that the orbital interactions between the π orbitals of the ligands and the atomic orbitals of the d 6 iron center are the main bonding scheme for these [ Fe (η4 - E 4)2]2- (D4d) complexes. The stability of the [ Fe (η4 - E 4)2]2- complexes exhibits the order P > As > Sb > Bi > N for E. On the basis of comparison with the known ferrocene, the NICS analysis confirms that the [ Fe (η4 - E 4)2]2- (D4d) as well as ferrocene are aromatic. The dissected NICS reveals that the aromaticities of the [ Fe (η4 - E 4)2]2- (D4d) are primarily attributed to the effects of their E–E π bonds and Fe lone pairs.

Fabrication of Boron Compensated Hydrogenated Amorphous Silicon Films with Significantly Improved Stability Using Plasma Enhanced Chemical Vapor Deposition Technique

1995 ◽  
Vol 377 ◽  
Author(s):  
Mohan K. Bhan
Keyword(s):  
Chemical Vapor ◽  
Short Term ◽  
Term Stability ◽  
Long Term Stability ◽  
Vapor Deposition Technique ◽  
Improved Stability ◽  
Donor Acceptor ◽  
B Doping ◽  
The Stability

ABSTRACTWe have systematically investigated the effects of addition of sub-ppm levels of boron on the stability of a-Si:H films and p-i-n devices, deposited by PE-CVD technique. The films thus produced with appropriate amounts of boron, show a significant improvement in stability, when soaked under both AM 1.5 (short-term) as well as 10×sun (long-term) illumination conditions. The opto-electronic properties of the films are quite respectable It is concluded that boron compensates the native impurities by forming donor-acceptor pairs, which reduces the “fast” defects and hence the initial degradation of the films. It is also speculated that boron may also be improving the short-term stability, by reducing the recombination of light generated electrons and holes, by converting D° into D+ states. The long-term stability appears to get affected by hydrogen dilution which seems to reduce the amount of “slow” defects. As a result of B doping of i-layer, the initial conversion efficiency of the devices decreases. It is presumed that our devices may contain an enhanced level of boron impurity, than expected, making them as worse material and to degrade less.

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