Substituent Effect

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Tadeusz M. Krygowski - One of the best experts on this subject based on the ideXlab platform.

  • Most of the field/inductive Substituent Effect works through the bonds.
    Journal of molecular modeling, 2019
    Co-Authors: Halina Szatylowicz, Anna Jezuita, Krzysztof Ejsmont, Tadeusz M. Krygowski
    Abstract:

    An application of the quantum chemical modeling allowed to investigate the nature of the field/inductive Substituent Effect (SE). For this purpose, series of X-tert-butyl···tert-butane (TTX) complexes (where X = NMe2, NH2, OH, OMe, Me, H, F, Cl, CF3, CN, CHO, COMe, CONH2, COOH, NO2, NO) were studied. A starting distance between central carbon atoms in substituted and unsubstituted fragments of TTX, dC1-C4, was the same as the distance C1-C4 in X-substituted bicyclo[2.2.2]octane (BCO), where the SE acts both via bonds and via space. A strength of interaction between substituted and unsubstituted components of TTX was described by deformation and interaction energies. The Substituent Effect on electronic structure through the bonds and the space was characterized using charge of the Substituent active region (cSAR) approach. The comparison of the SE characteristics obtained for alicyclic BCO and for TTX complexes document a significantly stronger field/inductive Effect through bonds than through space.

  • On the relations between aromaticity and Substituent Effect
    Structural Chemistry, 2019
    Co-Authors: Halina Szatylowicz, Anna Jezuita, Tadeusz M. Krygowski
    Abstract:

    Aromaticity/aromatic and Substituent/Substituent Effects belong to the most commonly used terms in organic chemistry and related fields. The quantitative description of aromaticity is based on energetic, geometric (e.g., HOMA), magnetic (e.g., NICS) and reactivity criteria, as well as the properties of the electronic structure (e.g., FLU). The Substituent Effect can be described using either traditional Hammett-type Substituent constants or characteristics based on quantum-chemistry. For this purpose, the energies of properly designed homodesmotic reactions and electron density distribution are used. In the first case, a descriptor named SESE (energy stabilizing the Substituent Effect) is obtained, while in the second case cSAR (charge of the Substituent active region), which is the sum of the charge of the ipso carbon atom and the charge of the Substituent. The use of the above-mentioned characteristics of aromaticity and the Substituent Effect allows revealing the relationship between them for mono-, di-, and polysubstituted π-electron systems, including substituted heterocyclic rings as well as quasi-aromatic ones. It has been shown that the less aromatic the system, the stronger the Substituent influence on its π-electron structure. In all cases, when the Substituent changes number of π-electrons in the ring in the direction of 4N+2, its aromaticity increases. Intramolecular charge transfer (a resonance Effect) is privileged in cases where the number of bonds between the electron-attracting and electron-donating atoms is even. Quasi-aromatic rings, when attached to a truly aromatic hydrocarbon, simulate well the “original” aromatic rings, alike the benzene. For larger systems, a long-distance Substituent Effect has been found.

  • Dependence of the Substituent Effect on Solvent Properties.
    The journal of physical chemistry. A, 2018
    Co-Authors: Halina Szatylowicz, Anna Jezuita, Tomasz Siodła, Konstantin S. Varaksin, Krzysztof Ejsmont, Izabela D. Madura, Tadeusz M. Krygowski
    Abstract:

    The influence of a solvent on the Substituent Effect (SE) in 1,4-disubstituted derivatives of benzene (BEN), cyclohexa-1,3-diene (CHD), and bicyclo[2.2.2]octane (BCO) is studied by the use of polarizable continuum model method. In all X–R–Y systems for the functional group Y (NO2, COOH, OH, and NH2), the following Substituents X have been chosen: NO2, CHO, H, OH, and NH2. The Substituent Effect is characterized by the charge of the Substituent active region (cSAR(X)), Substituent Effect stabilization energy (SESE), and Substituent constants σ or F descriptors, the functional groups by cSAR(Y), whereas π-electron delocalization of transmitting moieties (BEN and CHD) is characterized by a geometry-based index, harmonic oscillator model of aromaticity. All computations were carried out by means of B3LYP/6-311++G(d,p) method. An application of quantum chemistry SE models (cSAR and SESE) allows to compare the SE in water solutions and in the gas phase. Results of performed analyses indicate an enhancement of t...

  • Towards a physical interpretation of Substituent Effect: Quantum chemical interpretation of Hammett Substituent constants
    Journal of Molecular Structure, 2017
    Co-Authors: Konstantin S. Varaksin, Halina Szatylowicz, Tadeusz M. Krygowski
    Abstract:

    Abstract Quantitative description of Substituent Effects is of a great importance especially in organic chemistry and QSAR-type treatments. The proposed approaches: Substituent Effect stabilization energy (SESE) and charge of the Substituent active region (cSAR) provide Substituent Effect characteristics, physically independent of the Hammett's Substituent constants, σ. To document abilities of these descriptors the B3LYP/6-311++G(d,p) method is employed to examine changes in properties of a reaction center Y (Y = COOH or COO− groups) and a transmitting moiety (benzene ring) due to Substituent Effects in a series of meta- and para-X-substituted benzoic acid and benzoate anion derivatives (X = NMe2, NH2, OH, OMe, CH3, H, F, Cl, CF3, CN, CHO, COMe, CONH2, COOH, NO2, NO). The transmitting moiety is described by aromaticity indices HOMA and NICS(1). Furthermore, an advantage of the cSAR characteristic is the ability to use it to describe both electron donating/accepting properties of a Substituent as well as a reaction center. It allows demonstration of the reverse Substituent Effects of COOH and COO− groups on Substituent X.

  • inductive or field Substituent Effect quantum chemical modeling of interactions in 1 monosubstituted bicyclooctane derivatives
    ACS omega, 2017
    Co-Authors: Halina Szatylowicz, Tomasz Siodla, Tadeusz M. Krygowski
    Abstract:

    Inductive Substituent constants were obtained for systems lacking the resonance Effect. The application of the charge of the Substituent active region concept to study the Substituent Effect in 1-X-substituted bicyclooctane derivatives (B3LYP/6-311++G** calculations, X = NMe2, NH2, OH, OMe, CH3, H, F, Cl, CF3, CN, CHO, COMe, CONH2, COOH, NO2, NO) has revealed inductive interactions, which are through bonds.

Jan Cz. Dobrowolski - One of the best experts on this subject based on the ideXlab platform.

  • On the nonadditivity of the Substituent Effect in homo‐disubstituted pyridines
    Journal of Physical Organic Chemistry, 2016
    Co-Authors: Karol Hęclik, Jan Cz. Dobrowolski
    Abstract:

    The Substituent Effect in mono- and disubstituted pyridines was studied by means of the sEDA and pEDA Substituent Effect descriptors expressing the Substituent Effect on the σ- and π-electron systems of the ring, respectively. The sEDA descriptors calculated for mono- or disubstituted pyridines can be presented as perfectly linear functions of either benzene or monosubstituted pyridine sEDA descriptors, respectively. For the pEDA descriptors, there are substantial deviations from linearity observed for both mono- and disubstituted systems. For the disubstituted systems, the nonadditivity of the pEDA descriptors is strongly pronounced for the Substituents in the ortho- and para-positions to each other while it is only weak for the meta-located groups. For both mono- and disubstituted systems, there are correlations between charge at the nitrogen lone electron pair and the σ- and π-electron withdrawing and donating properties of the Substituent. In general, the electron charge increases with the increase of the σ-electron donating ability but decreases with the increase of π-electron donating ability of Substituents. Again, the Effects are more significant for Substituents in the ortho- and para-positions than in the meta-position. The influence of the π-electron properties of the Substituent on the lone pair, belonging to σ-electron system of pyridines, shows the presence of hyperconjugation Effects in the substituted pyridines. The hyperconjugation can be also clearly observed in cross-dependencies of the sEDA and pEDA descriptors.

  • Substituent Effect in theoretical ROA spectra
    RSC Advances, 2016
    Co-Authors: Piotr F. J. Lipiński, Jan Cz. Dobrowolski
    Abstract:

    The first systematic study on Substituent Effect in theoretical VCD spectral parameters is reported. The VCD spectra of 5-substituted indenes revealed strong correlations of ν(C*H) and ν(CN) VCD intensities with σp or pEDA(I) descriptors. We also report correlations of VCD intensity factors as well as VCD sign-change with Substituent.

  • Substituent Effect in theoretical VCD spectra
    RSC Adv., 2014
    Co-Authors: Piotr F. J. Lipiński, Jan Cz. Dobrowolski
    Abstract:

    A correlational study shows for the first time a quantitative Substituent Effect on Vibrational Circular Dichroism intensity.

  • The sEDA(=) and pEDA(=) descriptors of the double bonded Substituent Effect.
    Organic & biomolecular chemistry, 2013
    Co-Authors: A.p Mazurek, Jan Cz. Dobrowolski
    Abstract:

    New descriptors of the double bonded Substituent Effect, sEDA() and pEDA(), were constructed based on quantum chemical calculations and NBO methodology. They show to what extent the σ and π electrons are donated to or withdrawn from the substituted system by a double bonded Substituent. The new descriptors differ from descriptors of the classical Substituent Effect for which the pz orbital of the ipso carbon atom is engaged in the π-electron system of the two neighboring atoms in the ring. For double bonded Substituents, the pz orbital participates in double bond formation with only one external atom. Moreover, the external double bond forces localization of the double bond system of the ring, significantly changing the core molecule. We demonstrated good agreement between our descriptors and the Weinhold and Landis’ “natural σ and π-electronegativities”: so far only descriptors allowing for evaluation of the substitution Effect by a double bonded atom. The equivalency between descriptors constructed for 5- and 6-membered model structures as well as linear dependence/independence of the constructed parameters was discussed. Some interrelations between sEDA() and pEDA() and the other descriptors of (hetero)cyclic systems such as aromaticity and electron density in the ring and bond critical points were also examined.

  • On Substituent Effect on the benzodiazepinone system
    Computational and Theoretical Chemistry, 2012
    Co-Authors: Grażyna Karpińska, Aleksander P. Mazurek, Jan Cz. Dobrowolski
    Abstract:

    Abstract Tautomerism, aromaticity, and electron density at ring critical points of substituted benzodiazepinones, composed of condensed 6- and 7-membered rings (7-substituted 1,3-dihydro-benzo[e][1,4]diazepin-2-ones), were studied at the B3LYP/6-31G ∗∗ level. We found that in the gas phase and in water, the N1H tautomers are more stable than the N4H ones by at least 8 kcal/mol. We have demonstrated that the greater the π-electron donation of the Substituent, the more stable the N1H tautomer. Analysis of the HOMA index of the two rings shows that in the N1H tautomers, the benzo ring is aromatic and the diazepinone ring is antiaromatic. In the N4H tautomers the former ring loses aromaticity and the latter one gains a more antiaromatic character. This is the main reason for the relative instability of the N4H tautomers. The AIM analysis combined with the Substituent Effect analysis by use of the sEDA and pEDA descriptors reveal that the π-electron properties of the Substituents attached to the 6-membered benzo ring linearly correlate with the electron density and Laplacian at ring critical point of the 7-membered diazepinone one. Surprisingly, the analogous correlation for the substituted at the 6-membered ring is far less significant, if it is significant at all. This strongly suggests that modification in pharmaceutical activity of benzodiazepinones can be partially controlled just by attaching a Substituent of the proper π-electron donor–acceptor properties in the C7-position of the benzo ring.

Yuho Tsuno - One of the best experts on this subject based on the ideXlab platform.

Halina Szatylowicz - One of the best experts on this subject based on the ideXlab platform.

  • Most of the field/inductive Substituent Effect works through the bonds.
    Journal of molecular modeling, 2019
    Co-Authors: Halina Szatylowicz, Anna Jezuita, Krzysztof Ejsmont, Tadeusz M. Krygowski
    Abstract:

    An application of the quantum chemical modeling allowed to investigate the nature of the field/inductive Substituent Effect (SE). For this purpose, series of X-tert-butyl···tert-butane (TTX) complexes (where X = NMe2, NH2, OH, OMe, Me, H, F, Cl, CF3, CN, CHO, COMe, CONH2, COOH, NO2, NO) were studied. A starting distance between central carbon atoms in substituted and unsubstituted fragments of TTX, dC1-C4, was the same as the distance C1-C4 in X-substituted bicyclo[2.2.2]octane (BCO), where the SE acts both via bonds and via space. A strength of interaction between substituted and unsubstituted components of TTX was described by deformation and interaction energies. The Substituent Effect on electronic structure through the bonds and the space was characterized using charge of the Substituent active region (cSAR) approach. The comparison of the SE characteristics obtained for alicyclic BCO and for TTX complexes document a significantly stronger field/inductive Effect through bonds than through space.

  • On the relations between aromaticity and Substituent Effect
    Structural Chemistry, 2019
    Co-Authors: Halina Szatylowicz, Anna Jezuita, Tadeusz M. Krygowski
    Abstract:

    Aromaticity/aromatic and Substituent/Substituent Effects belong to the most commonly used terms in organic chemistry and related fields. The quantitative description of aromaticity is based on energetic, geometric (e.g., HOMA), magnetic (e.g., NICS) and reactivity criteria, as well as the properties of the electronic structure (e.g., FLU). The Substituent Effect can be described using either traditional Hammett-type Substituent constants or characteristics based on quantum-chemistry. For this purpose, the energies of properly designed homodesmotic reactions and electron density distribution are used. In the first case, a descriptor named SESE (energy stabilizing the Substituent Effect) is obtained, while in the second case cSAR (charge of the Substituent active region), which is the sum of the charge of the ipso carbon atom and the charge of the Substituent. The use of the above-mentioned characteristics of aromaticity and the Substituent Effect allows revealing the relationship between them for mono-, di-, and polysubstituted π-electron systems, including substituted heterocyclic rings as well as quasi-aromatic ones. It has been shown that the less aromatic the system, the stronger the Substituent influence on its π-electron structure. In all cases, when the Substituent changes number of π-electrons in the ring in the direction of 4N+2, its aromaticity increases. Intramolecular charge transfer (a resonance Effect) is privileged in cases where the number of bonds between the electron-attracting and electron-donating atoms is even. Quasi-aromatic rings, when attached to a truly aromatic hydrocarbon, simulate well the “original” aromatic rings, alike the benzene. For larger systems, a long-distance Substituent Effect has been found.

  • Dependence of the Substituent Effect on Solvent Properties.
    The journal of physical chemistry. A, 2018
    Co-Authors: Halina Szatylowicz, Anna Jezuita, Tomasz Siodła, Konstantin S. Varaksin, Krzysztof Ejsmont, Izabela D. Madura, Tadeusz M. Krygowski
    Abstract:

    The influence of a solvent on the Substituent Effect (SE) in 1,4-disubstituted derivatives of benzene (BEN), cyclohexa-1,3-diene (CHD), and bicyclo[2.2.2]octane (BCO) is studied by the use of polarizable continuum model method. In all X–R–Y systems for the functional group Y (NO2, COOH, OH, and NH2), the following Substituents X have been chosen: NO2, CHO, H, OH, and NH2. The Substituent Effect is characterized by the charge of the Substituent active region (cSAR(X)), Substituent Effect stabilization energy (SESE), and Substituent constants σ or F descriptors, the functional groups by cSAR(Y), whereas π-electron delocalization of transmitting moieties (BEN and CHD) is characterized by a geometry-based index, harmonic oscillator model of aromaticity. All computations were carried out by means of B3LYP/6-311++G(d,p) method. An application of quantum chemistry SE models (cSAR and SESE) allows to compare the SE in water solutions and in the gas phase. Results of performed analyses indicate an enhancement of t...

  • Towards a physical interpretation of Substituent Effect: Quantum chemical interpretation of Hammett Substituent constants
    Journal of Molecular Structure, 2017
    Co-Authors: Konstantin S. Varaksin, Halina Szatylowicz, Tadeusz M. Krygowski
    Abstract:

    Abstract Quantitative description of Substituent Effects is of a great importance especially in organic chemistry and QSAR-type treatments. The proposed approaches: Substituent Effect stabilization energy (SESE) and charge of the Substituent active region (cSAR) provide Substituent Effect characteristics, physically independent of the Hammett's Substituent constants, σ. To document abilities of these descriptors the B3LYP/6-311++G(d,p) method is employed to examine changes in properties of a reaction center Y (Y = COOH or COO− groups) and a transmitting moiety (benzene ring) due to Substituent Effects in a series of meta- and para-X-substituted benzoic acid and benzoate anion derivatives (X = NMe2, NH2, OH, OMe, CH3, H, F, Cl, CF3, CN, CHO, COMe, CONH2, COOH, NO2, NO). The transmitting moiety is described by aromaticity indices HOMA and NICS(1). Furthermore, an advantage of the cSAR characteristic is the ability to use it to describe both electron donating/accepting properties of a Substituent as well as a reaction center. It allows demonstration of the reverse Substituent Effects of COOH and COO− groups on Substituent X.

  • inductive or field Substituent Effect quantum chemical modeling of interactions in 1 monosubstituted bicyclooctane derivatives
    ACS omega, 2017
    Co-Authors: Halina Szatylowicz, Tomasz Siodla, Tadeusz M. Krygowski
    Abstract:

    Inductive Substituent constants were obtained for systems lacking the resonance Effect. The application of the charge of the Substituent active region concept to study the Substituent Effect in 1-X-substituted bicyclooctane derivatives (B3LYP/6-311++G** calculations, X = NMe2, NH2, OH, OMe, CH3, H, F, Cl, CF3, CN, CHO, COMe, CONH2, COOH, NO2, NO) has revealed inductive interactions, which are through bonds.

Mizue Fujio - One of the best experts on this subject based on the ideXlab platform.