FREQUENCY-DEPENDENT HYPERPOLARIZABILITY OF BENZENE DERIVATIVES: AB-INITIO CALCULATIONS

2007 ◽  
Vol 16 (03) ◽  
pp. 367-380
Author(s):  
DIKSHA MAKWANI ◽  
R. VIJAYA
Keyword(s):  
Ab Initio Calculations ◽  
Ab Initio ◽  
Energy Gap ◽  
Lone Pair ◽  
Benzene Derivatives ◽  
Structure Property ◽  
Disubstituted Benzene ◽  
Structure Property Relationship ◽  
Donor Acceptor ◽  
Acceptor Capacity

Structure–property relationship and dispersion effects for disubstituted benzene molecules have been investigated. Ab-initio calculations of the first hyperpolarizabilities (β) of donor–acceptor benzene derivatives show that the magnitude of β depends upon the availability of the lone pair of electrons on the nitrogen atom to conjugate with the benzene ring. The HOMO–LUMO energy gap and β have an inverse relationship. From the dispersion studies, it is observed that the first resonance peak shifts towards lower frequencies as the donor/acceptor capacity increases.

ab initio MO Optimization of Molecular Structures of Fluoro- and Chloro-Substituted Dibenzo-p-dioxines and the Effect of Halogen Substitution at the 2,3,7,8-Positions on Metabolic Attack

1997 ◽  
Vol 52 (11) ◽  
pp. 1418-1431 ◽  
Author(s):  
Roland Weber ◽  
Till Kühn ◽  
Hanspaul Hagenmaier ◽  
Günter Häfelinger
Keyword(s):  
Ab Initio Calculations ◽  
Ab Initio ◽  
Energy Gap ◽  
Substituent Effects ◽  
Molecular Structures ◽  
X Ray ◽  
Degree Pattern ◽  
Chlorine Substituent ◽  
Homo Lumo ◽  
Good Agreement

Full ab initio optimizations were performed on the molecular structures of 24 fluorinated and chlorinated dibenzodioxines (PFDD/PCDD ) and dibenzofurans (PFDF/PCDF). Reasonable agreement was found by comparing the geometries of four calculated structures with known X-ray data from the literature. For the fluorine substituent, calculated electron densities (Mulliken total charges and π-electron charges) clearly demonstrate the opposite influence of the inductive (I) and mesomeric (M) effect. The changes in π-densities at carbons in ortho-, meta- and para-position are constant for each fluorine substituent (independent of degree, pattern, and position of substitution). It is thus possible to calculate the π-densities of the substituted dioxines by increments starting from dibenzodioxine. π-Charges from quantum mechanical calculations and the increment system show good agreement even for OctaFDD (O8FDD ), where eight substituent effects are acting additively. Compared with fluorine, the chlorine substituent exercises a smaller -I-effect and a clearly weaker +M-effect. The HOMO coefficients of the unsubstituted dibenzodioxine and dibenzofuran, extracted from ab initio calculations, yield a good explanation for the observed regioselective metabolic attack at the 2,3,7,8-positions. The squares of the HOMO-coefficients of the 2,3,7,8-positions in dibenzodioxine (DD ) are about ten times greater than those of the 1,4,6,9-positions. These HOMO coefficients are practically unaffected by halide substitution. But halogen substitution reduces strongly the electron density at the halogen-bound carbon, which, however, is a necessary prerequisite for the electrophilic oxygen transfer during metabolism. One would therefore expect halogen substitution of dibenzodioxine and dibenzofuran (DF) at the 2,3,7,8-position to hinder metabolism, as is indeed found. This provides a plausible explanation for the highly selective tissue retention of 2,3,7,8-substituted PCDDs and PCDFs. Our ab initio calculations of five tetra CDDs (T4CDDs) confirm the postulate of Kobayashi et al. [1 ] who, using semiempirical calculations, found a correlation between the toxicity of a dioxine congener and its absolute molecular hardness. The 2,3,7,8-T4CDD also exhibits the smallest absolute hardness (derived from the HOMO-LUMO energy gap) in our calculations.

Donor–acceptor substituted 1,8-naphthalimides: design, synthesis, and structure–property relationship

2019 ◽  
Vol 7 (47) ◽  
pp. 14798-14815 ◽  
Author(s):  
Madhurima Poddar ◽  
Gangala Sivakumar ◽  
Rajneesh Misra
Keyword(s):  
Structure Property ◽  
Design Synthesis ◽  
Molecular Systems ◽  
Property Relationship ◽  
Structure Property Relationship ◽  
Donor Acceptor ◽  
Organic Photonics

Research on developing new donor–acceptor (D–A) substituted 1,8-naphthalimide (NI) based molecular systems is a rapidly growing research are due to their wide-ranging applications in the field of organic photonics and electronics.

Structure–property relationship of D–A type copolymers based on phenanthrene and naphthalene units for organic electronics

2017 ◽  
Vol 5 (39) ◽  
pp. 10332-10342 ◽  
Author(s):  
Yeong-A Kim ◽  
Minji Kang ◽  
Ye-Jin Jeon ◽  
Kyeongil Hwang ◽  
Yeon-Ju Kim ◽  
...  
Keyword(s):  
Conjugated Polymers ◽  
Organic Electronics ◽  
Organic Photovoltaics ◽  
Field Effect ◽  
Field Effect Transistors ◽  
Organic Field Effect Transistors ◽  
Structure Property ◽  
Structure Property Relationship ◽  
Donor Acceptor ◽  
Relationship Of

Four donor–acceptor (D–A) type conjugated polymers were synthesized for organic photovoltaics and organic field effect transistors.

Structure−Property Relationship inpy-Hexahydrocinchonidine Diastereomers: Ab Initio and NMR Study

2005 ◽  
Vol 109 (5) ◽  
pp. 860-868 ◽  
Author(s):  
György Szöllösi ◽  
Abhijit Chatterjee ◽  
Péter Forgó ◽  
Mihály Bartók ◽  
Fujio Mizukami
Keyword(s):  
Ab Initio ◽  
Structure Property ◽  
Property Relationship ◽  
Nmr Study ◽  
Structure Property Relationship

Quantitative Relationship between Organic Molecular Structure and Infinite Dilution Activity Coefficients in 1-Ethyl-3-Methylimidazolium Tetrafluoroborate

2012 ◽  
Vol 524-527 ◽  
pp. 1848-1851
Author(s):  
Jie Ming Xiong ◽  
Chen Chen ◽  
Ming Lan Ge
Keyword(s):  
Molecular Structure ◽  
Activity Coefficients ◽  
Infinite Dilution ◽  
Energy Gap ◽  
Dipole Moments ◽  
Quantitative Relationship ◽  
Structure Property ◽  
Qspr Model ◽  
Structure Property Relationship ◽  
Correlation Parameters

Base on structural descriptors including dipole moments (μ), Energy gap (∆ε), hydration energy (∆H), and hydrophobic parameter lg P of 25 organic solutes, the quantitative structure-property relationship (QSPR) method was used to correlate the values of activity coefficients at infinite dilution, , for the solutes in ionic liquid 1-ethyl-3-methylimidazolium tetrafluoroborate ([EMIM][BF4]) at 323.15 K. The result showed that the QSPR model had a good correlation and could successfully describe . The quantitative relationship between organic molecular structure and in [EMIM][BF4] was obtained and the correlation parameters were analyzed to understand the interactions that affect activity coefficients at infinite dilution.

PYRAMIDALITY AND AROMATICITY IN POLYPHOSPHAPHOSPHOLES

2008 ◽  
Vol 07 (06) ◽  
pp. 1203-1214 ◽  
Author(s):  
WEI-QI LI ◽  
LI-LI LIU ◽  
JI-KANG FENG ◽  
ZI-ZHONG LIU ◽  
AI-MIN REN ◽  
...  
Keyword(s):  
Ab Initio Calculations ◽  
Ab Initio ◽  
Electron Correlation ◽  
Phosphorus Atom ◽  
Lone Pair ◽  
Ring Strain ◽  
Aromatic Molecules ◽  
Lone Pair Electron

Ab initio calculations show that, for the P n( CH )4-n PH with n = 0 - 4, the fully optimized structures have decreasing pyramidality at the tri-coordinated phosphorus atom with n. The interaction between the tri-coordinated phosphorus [Formula: see text] and the carbons–phosphorus π-system [Formula: see text] with different n, the differences of the structure, electron properties and energy among the phospholes indicate that the ring strain and the delocalization of the lone pair electron of tri-coordinated phosphorus should be responsible for this phenomena. Various aromatic criteria such as geometry, magnetism, and energy show that these molecules are aromatic, and their aromaticities increase with the number of phosphorus atoms in the nonplanar pentagons. The electron circulation in the aromatic molecules can promote the delocalization of the lone pair. In contrast to the B3LYP prediction, we draw some similar conclusions, but the planarity and aromaticity of molecules increase largely at the MP2 lever due to the consideration of electron correlation.

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