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Carboxylic Acids, Carboxylic Acid Derivatives, and Acyl Substitution Reactions
Published in Michael B. Smith, A Q&A Approach to Organic Chemistry, 2020
Bond polarization of σ-bonds leads to a so-called inductive effect, an electronic effect that is typically due to a difference in electronegativity between the atoms of that bond. What are through-bond inductive effects?
A DFT investigation of the influence of α,β unsaturation in chemical reactivity of coumarin and some hydroxy coumarins
Published in Tanmoy Chakraborty, Prabhat Ranjan, Anand Pandey, Computational Chemistry Methodology in Structural Biology and Materials Sciences, 2017
M. A. Jaseela, T. M. Suhara, K. Muraleedharan
It is generally accepted that during the interaction between a substituent and its parent ring, the manifestation of two main electronic effects is possible. One is inductive effect, also known as polar effect; arise from the covalent single bond between unlike atoms. The electron pair forming the σ bond between unlike atoms is never shared absolutely equally for the two atoms, but always tends to be attracted towards the more electronegative atoms among the two [50]. It attenuates in proportion to the distance from a carbon atom bonded to the substituent. All inductive effects are permanent polarizations in the ground state of a molecule, and are therefore manifested in its physical properties, such as dipole moment and their polarisability. In addition, inductive effects operating through the bonds of a chemical system, an essentially analogous effect can operate either through the space surrounding to the molecule or in solution, via molecules of solvent surround it. As all the computational calculations of these considering structures are performed in gas phase, the solvent effect on reactivity can’t be predicted from the results.
Effect of chain length and donor–acceptor substitution on the electrical responsive properties of conjugated biphenyls: a DFT-based computational study
Published in Molecular Physics, 2019
Debkumar Mandal, Rakesh Maity, Sudipto Dey, Ajay Misra
The dipole moments of the titled compounds at DFT CAM-B3LYP with 6-311G(2d,2p) level of theory are presented in Table S1. The dipole moment, μ, is obtained from the ground state response of the electron density and hence does not require a density response calculation. A distinct variation of dipole moment from unsubstituted cis and trans to substituted cis and trans are shown in Table S1. Both the cis and trans unsubstituted biphenyl (n = 0) have zero dipole moment and thus have no polarity. But dipole moment launched on cis and trans substituted biphenyl compound (n = 0) by the same amount (µ = 8.1544) after the addition of donor–acceptor groups. Substitution of the donor dimethyl amino (NMe2) group and the acceptor cyano (CN) group on the respective biphenyl ring and the orientation of the molecular skeleton are responsible for commence of the dipole moment. Substitution of the dimethyl amino group on one ring and the cyano group on another ring of biphenyl results in loss of symmetry in terms of the delocalised π-electron cloud. Thus, the electron-donating inductive effect of the dimethyl amino group and electron withdrawing inductive effect of the CN group leads to high polarity of the molecules. The inductive effects arise due to the non-equal sharing of the bonding electrons in the σ bond [57]. All inductive effects are due to permanent polarisations in the ground state of molecules and are therefore reflected in the physical properties, like the dipole moment.
Synthesis and characterization of tailor-made o-hydroxysubstituted anils through 1H NMR, 13C NMR, SC-XRD and DFT studies for possible optoelectronic applications
Published in Molecular Physics, 2023
Supriya Priyambada Biswal, Prabhudatta Hota, Manas Ranjan Dash, Amitabh Mahapatra, Pramila Kumari Misra
In the current work, two simple tailor-made derivatives of N-benzylideneaniline, o-hydroxybenzylidene-orthochloroaniline and o-hydroxynaphthalidene-orthochloroaniline[47], have been synthesized, and characterized by 1H & 13C Nuclear magnetic resonance(NMR) and Single crystal X-ray diffraction spectroscopic analyses(SC-XRD). The introduction of substituents in aniline leads to the variation of charge distribution in the molecule, and consequently, this substitution greatly affects the structural, electronic and spectral characteristics parameters of the anil[48]. The substitutions of chlorine and oxygen would offer singular chemical reactivity profiles and excitation energies in the phenyl rings of the candidate anils due to the high electronegativity of these two elements [49]. Any functional group like –OH and Cl with a lone pair of electrons, when connected to a phenyl ring, tend to push electron density over the ring due to the mesomeric effect (resonance), increasing its electron density [50]. Nevertheless, due to the high electronegative effect, the Cl atom also withdraws electrons towards itself, which occurs because of differences in electronegativity caused by two atoms connected with an σ-bond. The unequal sharing of the bonding electrons develops a permanent dipole in a given molecule, known as the Inductive effect. However, since the strong resonance effect dominates over the inductive effect, it becomes an electron-donating group when connected with a phenyl ring [51]. The position of the substituent also plays an imperative role in deciding the electron-donating/accepting capabilities of these anils[52]. Moreover, the additional interest in –Cl substituted anils molecules stems largely from the fact that these anils inhibit the corrosion of various metals and alloys in acid media [53]. The information on the structural modification of inserting –Cl and O atoms as the substituents in phenyl rings have been accrued from the optimized data and compared with the experimental findings. A good correlation between the SC-XRD data with optimized structural parameters established the structure and purity of the molecules. The molecular electrostatic potential surface was plotted for both anils and Mullikan charges on different atoms were determined to elucidate the electron population and charge sites of the molecules.