scholarly journals Structure-Property Relationships in Benzofurazan Derivatives: A Combined Experimental and DFT/TD-DFT Investigation

2021 ◽  
Author(s):  
Hanen Raissi ◽  
Imen Chérif ◽  
Hajer Ayachi ◽  
Ayoub Haj Said ◽  
Fredj Hassen ◽  
...  
Keyword(s):  
Energy Levels ◽  
Electrophilic Aromatic Substitution ◽  
Aromatic Substitution ◽  
Structure Property ◽  
Electrophilicity Index ◽  
Cyclic Amines ◽  
Structure Property Relationships ◽  
Physico Chemical ◽  
Homo And Lumo ◽  
The Relationship

In this work we seek to understand and to quantify the reactivity of benzofurazan derivatives toward secondary cyclic amines, like pyrrolidine, piperidine and morpholine, acting as nucleophile groups in SNAr reactions. For this aim, physico-chemical and structural descriptors were determined experimentally and theoretically using the DFT/B3LYP/6-31+ g (d,p) methodology. Thus, different 4-X-7-nitrobenzofurazans (X = OCH3, OC6H5 and Cl) and products corresponding to the electrophilic aromatic substitution by pyrrolidine, piperidine and morpholine, were investigated. Particularly, the HOMO and LUMO energy levels of the studied compounds, determined by Cyclic Voltammetry (CV) and DFT calculations, were used to evaluate the electrophilicity index (ω). The latter was exploited, according to Parr’s approach, to develop a relationship which rationalizes the kinetic data previously reported for the reactions of the 4-X-7-nitrobenzofurazans with nucleophiles cited above. Moreover, the Parr’s electrophilicity index (ω) of these benzofurazans determined in this work were combined with their electrophilicity parameters (E), reported in preceding papers, was found to predict the unknown electrophilicity parameters E of 4-piperidino, 4-morpholino and 4-pyrrolidino-7-nitrobenzofurazan. In addition, the relationship between the Parr’s electrophilicity index (ω) and Hammett constants σ, has been used as a good model to predict the electronic effect of the nucleophile groups. Finally, we will subsequently compare the electrophilicity index (ω) and the electrophilicity parameters (E) of these series of 7-X-4-nitrobenzofurazans with the calculated dipole moment (μ) in order to elucidate general relationships between E, ω and μ.

Structure – Property Relationships for Dyes of Different Nature

2013 ◽  
Vol 821-822 ◽  
pp. 488-492
Author(s):  
Felix Telegin ◽  
Irina Shushina ◽  
Jian Hua Ran ◽  
Yulia Biba ◽  
Aleksandr Mikhaylov ◽  
...  
Keyword(s):  
Practical Importance ◽  
Structure Property ◽  
Light Fastness ◽  
Theoretical Evaluation ◽  
Fixation Rate ◽  
Systematic Analysis ◽  
Structure Property Relationships ◽  
Physico Chemical ◽  
Quantitative Structure Property Relationships ◽  
Homo And Lumo

Systematic analysis of quantitative structure – property relationships for dyes of different nature has been reviewed. On the basis of the experimental results published in the literature and theoretical evaluation of amphiphilic and electrophilic properties of dyes of different nature several basic conclusions of scientific and practical importance are proposed. It was found that water/octanol partition coefficients exhibit correlation with dye partition between hydrophobic synthetic fibres and dyebath as well as dye affinity. Hydrophobicity of dyes controls several technical properties of dyes and dyeings, such as wash fastness and light fastness, migration factor, rate of dyeing and fixation rate. Energy of frontier electronic orbitals (HOMO and LUMO energies) correlates with different properties characterizing redox properties of dyes: oxidative and reductive destruction in chemical reactions, photochemical and biochemical destruction of dyes, wash and light fastness of dyeings. The results of this study are useful for physico-chemical analysis of dye sorption by textile fibres, destruction of dyes in polymers and solutions as well as for design of new dyes of high quality.

scholarly journals Modeling of Structure-Property Relationships of Polymerizable Surfactants with Antimicrobial Activity

2018 ◽  
Vol 8 (10) ◽  
pp. 1972 ◽  
Author(s):  
Giorgio De Luca ◽  
Roberta Amuso ◽  
Alberto Figoli ◽  
Raffaella Mancuso ◽  
Lucio Lucadamo ◽  
...  
Keyword(s):  
Aspect Ratio ◽  
Molecular Structures ◽  
Maximum Length ◽  
Aliphatic Chain ◽  
Structure Property ◽  
Net Charge ◽  
Structure Property Relationships ◽  
Electrostatic Charges ◽  
Partial Charges ◽  
The Relationship

Polymerizable quaternary ammonium salts (PQASs) were synthesized in a previous work and some of them were used as surfactants in the antimicrobial coating of commercial membranes. Herein, the electrostatic charges, maximum length, and aspect ratio of these antibacterial surfactants were calculated with the aim of investigating the relationship between the properties, recognized to control the biocidal activity of these molecules, and the molecular structures. The effect of the water molecules was considered through a quantum and molecular mechanics approach. The correlation between the number of carbons in the main aliphatic chain of PQAS and the above properties was investigated, by finding that the net charge on the ammonium group does not increase as the number of carbons in the aliphatic chain increase. Thus, although this number influences the antibacterial activity of the surfactants, this influence is not correlated with an increase of the ammonium positive charge. Unlike the partial charges, a different trend was obtained for the surfactants’ maximum length and aspect ratio in agreement with the experimental behavior. As this modeling does not use empirical or adjustable parameters, it can assist the synthetic plan of new structures for surface functionalization, in order to improve the biofouling resistance of the membranes.

Spiro[fluorene-9,9′-xanthene]-based universal hosts for understanding structure–property relationships in RGB and white PhOLEDs

RSC Advances ◽  
2015 ◽  
Vol 5 (38) ◽  
pp. 29828-29836 ◽  
Author(s):  
Yan Qian ◽  
Yeren Ni ◽  
Shouzhen Yue ◽  
Wenwen Li ◽  
Shufen Chen ◽  
...  
Keyword(s):  
Energy Level ◽  
Molecular Orbital ◽  
Energy Levels ◽  
Frontier Molecular Orbital ◽  
Orbital Energy ◽  
Structure Property ◽  
Triplet Energy ◽  
Structure Property Relationships ◽  
Molecular Orbital Energy

Independent and accumulative modification of frontier molecular orbital energy levels without affecting the triplet energy level can be realized.

scholarly journals Theoretical Studies of Electronic Structure and Photophysical Properties of a Series of Indoline Dyes with Triphenylamine Ligand

2015 ◽  
Vol 2015 ◽  
pp. 1-9 ◽  
Author(s):  
Xue-Feng Ren ◽  
Jun Zhang ◽  
Guo-Jun Kang
Keyword(s):  
Density Functional ◽  
Energy Gap ◽  
Photophysical Properties ◽  
Energy Levels ◽  
Dye Sensitized Solar Cells ◽  
Dft Method ◽  
Structure Property ◽  
Lumo Energy ◽  
Semiconductor Interface ◽  
Homo And Lumo

To design efficient organic sensitizer, a series of D-π-A indoline dyes with different donor parts have been investigated by density functional theory (DFT) and time-dependent DFT (TD-DFT) approach. The molecular geometries, frontier molecular orbitals, and absorption spectra of these dyes have been systematically investigated to provide comprehensive understanding of the structure-property relationships. Compared with D149, our designed dyes have proper HOMO and LUMO energy level, narrowed HOMO-LUMO energy gap, and broadened absorption band by introducing the N(CH3)2and N(phenyl)2groups at the donor part. Furthermore, the dimeric dyes and dye-(TiO2)6systems have been optimized by DFT method to simulate the intermolecular interactions, as well as interaction between the dyes dimmers and semiconductor interface, respectively. Through the analyses of absorption energies (Eads), energy levels of the HOMO and LUMO, light harvesting efficiency (LHE), and the driving force of electrons injections (ΔGinject), it is found that the designed dyes should have improved optical properties by importing the N(CH3)2group. This work is hoped to provide a theoretical guiding role in design of new dyes for dye-sensitized solar cells.

Petrofabric study using electron channeling patterns of quartzes and hematites in dual-phase banded iron formations

1995 ◽  
Vol 53 ◽  
pp. 388-389
Author(s):  
K. Y. Lee ◽  
B. W. Robertson
Keyword(s):  
Spatial Arrangement ◽  
Structure Property ◽  
Banded Iron Formations ◽  
Thin Sections ◽  
Electron Channeling ◽  
Structure Property Relationships ◽  
Structure Property Relationship ◽  
The Individual ◽  
The Relationship ◽  
Iron Formations

Research in deformation of rocks requires the understanding of structure-property relationship. The study of structure-property relationships requires knowledge of the crystallographic texture on a local scale. Electron Channeling in scanning microscope has been used to analyze textures of local features in a microstructure, misorientations between grains and the spatial arrangement of grains of individual crystallographic orientations can be determined. This information is critical for a mechanical understanding of microstructure evolution during the deformation of rocks. Petrofabric analysis using Electron Channeling Patterns can use normal geological thin sections and mounted sections, which allows relatively fast and easy interpretation and allows one to determine the relationship between a microstructural feature and the individual orientations of its grains. The most efficient and satisfactory way of accomplishing this task is by direct electronic detection and indexing of Kikuchi patterns, which requires modification of the microscope, at considerable cost. This study, however, has been undertaken using only an unmodified SEM with electron channeling capability.

Predictions and constructing explanations: an investigation into introductory chemistry students’ understanding of structure–property relationships

2019 ◽  
Vol 20 (1) ◽  
pp. 316-328 ◽  
Author(s):  
Alex T. Kararo ◽  
Rachel A. Colvin ◽  
Melanie M. Cooper ◽  
Sonia M. Underwood
Keyword(s):  
Boiling Point ◽  
Explicit Instruction ◽  
Chemical Properties ◽  
Relevant Information ◽  
Structure Property ◽  
Multiple Choice Questions ◽  
Chemistry Students ◽  
Structure Property Relationships ◽  
Physical And Chemical ◽  
The Relationship

The relationship between chemical structure and physical and chemical properties is essential to chemistry. Studies have shown that students have difficulty using structural representations to predict properties, which is not surprising because of the sequence of inferences that are required for sense-making. However, obtaining a nuanced model of students’ understanding depends on how information is elicited. This study investigated how the phrasing of the question prompt may elicit students’ understanding of structure–property relationships. Students were given a two-part assessment: (1) four multiple-choice questions assessing students’ self-reported abilities to predict structure–property relationships, and (2) three questions requiring students to predict, argue, and explain a boiling point trend. Two groups of students were selected to determine the sensitivity of the instrument (one with less explicit instruction of structure–property relationships and one with more explicit instruction). We found that Part I of the assessment was able to differentiate between these two groups of students. The group with more explicit instruction was further analyzed to determine how their prediction on a boiling point task connected to their arguments and explanations of the phenomenon. Even though 64% of students answered the boiling point ranking task correctly, the students typically provided less complete arguments as to why that structure had a higher boiling point. However, after scaffolding (i.e., providing relevant information for the phenomenon) and asking for an explanation, students’ responses began to include a much more mechanistic understanding, suggesting that having students provide explanations instead of constructing an argument would display their reasoning at a deeper level.

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