How far the substituent effects in disubstituted cyclohexa-1,3-diene derivatives differ from those in bicyclo[2.2.2]octane and benzene?

Szatyłowicz, Halina; Jezuita, Anna; Siodła, Tomasz; Varaksin, Konstantin S.; Ejsmont, Krzysztof; Shahamirian, Mozhgan; Krygowski, Tadeusz M.

doi:10.1007/s11224-018-1113-5

Cited by 10 publications

(26 citation statements)

References 38 publications

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“…[64] Knowledge of cSAR(X) and cSAR(Y) allows determining the so-called Charge Flow Index (CFI) CFI ¼ cSARðYÞÀ cSARðXÞ (4) which is a very valuable parameter describing electronic effects in XRY systems. [22,67] However, it should be emphasized that CFI should not be identified with the amount of charge flowing from a substituent X to group Y. In order to make a reliable assessment of this effect, we have proposed a novel interpretation of the charge transfer from X to Y, which can be formally used for any XRY charge-transfer system.…”

Section: Methodsmentioning

confidence: 99%

Changes in Electron Structure of the Triple Bond in Substituted Acetylene and Diacetylene Derivatives

Jabłoński

Krygowski

2020

ChemPhysChem

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The substituent effect is usually considered by means of various Hammett‐like substituent constants and is most often related to aromatic systems. Unlike this, we present results of our research on the influence of 27 substituents spanning a wide range of electronic properties, from strongly electron‐withdrawing to strongly electron‐donating, on the electron structure of X‐substituted acetylenes and diacetylenes – thus the systems which until now have practically not been subject of any deeper studies. It is shown that the interaction through triple bond(s) is associated with a significant advantage of resonance effects and that the substituent effect transmitted by the C≡C−C≡C unit is about half of that transmitted by the C≡C unit alone. Substituent X mainly affects the closest carbon atom by means of proximity effect, hence changes of charge on this atom do not follow any substituent constants. The effect on further carbon atoms is much smaller. The presence of the C≡C−C≡C unit withdraws more charge from X than a triple bond alone, and hinders communication between X and the terminal H atom. Comparison of substituent effects to those present in X‐substituted benzene derivatives shows that the electronic properties of the terminal hydrogen atom in acetylenes and diacetylenes are most similar to the electronic properties of ortho and para hydrogen atoms in X‐substituted benzene derivatives.

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Section: Methodsmentioning

confidence: 99%

Changes in Electron Structure of the Triple Bond in Substituted Acetylene and Diacetylene Derivatives

Jabłoński

Krygowski

2020

ChemPhysChem

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“…Systematic studies of the SE on π-electron delocalization estimated by HOMA and transmission properties of 3-and 4-disubstituted derivatives of benzene and cyclohexa-1,3-diene (CHD) were carried out using quantum chemistry-based descriptors: cSAR and SESE as well as traditional Hammett-like substituent constants. The results for the 4-substituted 1-nitro, and 1-hydroxy derivatives of CHD [122] are shown in Fig. 9.…”

Section: Disubstituted π-Electron Systemsmentioning

confidence: 99%

“…The transmission properties of the substituent from a given position to the reaction center can be described by the charge flow index (CFI) [122], defined as:…”

Section: Disubstituted π-Electron Systemsmentioning

confidence: 99%

“…sites^, Y = NO 2 [116,117], OH [118], COOH [119], NH 2 [120,121] as well anionic COO − [119] and O − [118] moieties, with substituents in three and four positions of R = benzene or cyclohexa-1,3-diene. In addition, the use of both traditional and quantum chemistry-based descriptors of SE allows us to answer the question of how far the substituent effect in disubstituted cyclohexa-1,3-diene derivatives differ from those in bicyclo[2,2,2]octane and benzene [122]. The use of quantum chemistry-based descriptors has allowed to study dependence of the solvent on SE [123] and also provided a physical interpretation of the inductive and resonance effects [124].…”

Section: Introductionmentioning

confidence: 99%

“…Dependences of HOMA on SESE for 4-X-CHD-NO 2 and 4-X-CHD-OH series. Reused from[122], this work is licensed under the Creative Commons Attribution 4.0 International License (http:// creativecommons.org/licenses/by/4.0/)…”

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On the relations between aromaticity and substituent effect

2019

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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 Boriginal^aromatic rings, alike the benzene. For larger systems, a long-distance substituent effect has been found.

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Imidazole and nitroimidazole derivatives as NADH‐fumarate reductase inhibitors: Density functional theory studies, homology modeling, and molecular docking

et al. 2022

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Chagas disease is caused by Trypanosoma cruzi. Benznidazole and nifurtimox are drugs used for its therapy; nevertheless, they have collateral effects. NADH‐fumarate (FUM) reductase is a potential pharmacological target since it is essential for survival of parasite and is not found in humans. The objectives are to design and characterize the electronic structure of imidazole and nitroimidazole derivatives at DFT‐M06‐2X level in aqueous solution; also, to model the NADH‐FUM reductase and analyze its intermolecular interactions by molecular docking. Quantum‐chemical descriptors allowed to select the molecules with the best physicochemical properties and lowest toxicity. A high‐quality three‐dimensional structure of NADH‐FUM reductase was obtained by homology modeling. Water molecules do not have influence in the interaction between FUM and NADH‐FUM reductase. The main hydrogen‐binding interactions for FUM were identified in NADH, Lys172, and Arg89; while hydrophobic interactions in Phe479, Thr174, Met63. The molecules S3‐8, S2‐8, and S1‐8 could be inhibitors of NADH‐FUM reductase.

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How far the substituent effects in disubstituted cyclohexa-1,3-diene derivatives differ from those in bicyclo[2.2.2]octane and benzene?

Cited by 10 publications

References 38 publications

Changes in Electron Structure of the Triple Bond in Substituted Acetylene and Diacetylene Derivatives

Changes in Electron Structure of the Triple Bond in Substituted Acetylene and Diacetylene Derivatives

On the relations between aromaticity and substituent effect

Imidazole and nitroimidazole derivatives as NADH‐fumarate reductase inhibitors: Density functional theory studies, homology modeling, and molecular docking

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