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Espitia Cogollo E, Echeverría GA, Piro OE, Jios JL, Ulic SE. Perhalomethyl Chromones: Spectroscopic, X‐Ray Diffraction, Hirshfeld Surface, and Density Functional Theory Studies of the Noncovalent Interactions. CRYSTAL RESEARCH AND TECHNOLOGY 2022. [DOI: 10.1002/crat.202200085] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Affiliation(s)
- Edeimis Espitia Cogollo
- CEQUINOR (CONICET‐UNLP) Facultad de Ciencias Exactas Universidad Nacional de La Plata Bv. 120 N° 1465 La Plata 1900 Argentina
| | - Gustavo A. Echeverría
- Departamento de Física Facultad de Ciencias Exactas Universidad Nacional de La Plata e IFLP (CONICET, CCT‐La Plata) C. C. 67 La Plata 1900 Argentina
| | - Oscar E. Piro
- Departamento de Física Facultad de Ciencias Exactas Universidad Nacional de La Plata e IFLP (CONICET, CCT‐La Plata) C. C. 67 La Plata 1900 Argentina
| | - Jorge L. Jios
- Laboratorio UPL (UNLP‐CIC) Campus Tecnológico Gonnet (CIC‐BA) Cno. Centenario e/505 y 508 Gonnet (1897) Argentina
- Departamento de Química Facultad de Ciencias Exactas Universidad Nacional de La Plata 47 esq. 115 La Plata (1900) Argentina
| | - Sonia E. Ulic
- CEQUINOR (CONICET‐UNLP) Facultad de Ciencias Exactas Universidad Nacional de La Plata Bv. 120 N° 1465 La Plata 1900 Argentina
- Departamento de Ciencias Básicas Universidad Nacional de Luján Rutas 5 y 7 Luján Buenos Aires 6700 Argentina
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Saleh EAM, Kotian SY, Al Dawsari AM, Hassan I, Husain K, Abishad PC, Byrappa K, Sharabi RSSAL, Rai KML. Synthesis, Antioxidant, and Antibacterial Activities of Two Novel Series of 3,5-Disubstituted Isoxazole Ether-Linked Isoxazolines and 3,5-Disubstituted Pyrazole Ether-Linked Isoxazolines Mediated by Chloramine-T. RUSSIAN JOURNAL OF BIOORGANIC CHEMISTRY 2022. [DOI: 10.1134/s1068162022050181] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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Jabłoński M, Krygowski TM. Dependence of the substituent energy on the level of theory. J Comput Chem 2021; 42:2079-2088. [PMID: 34432304 DOI: 10.1002/jcc.26738] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2021] [Revised: 06/24/2021] [Accepted: 07/22/2021] [Indexed: 01/08/2023]
Abstract
Most often, the substituent effects are described using rather troublesome Hammett constants. Quite recently, it has been proposed to use the so-called substituent energy, which is based on total energies of the X-substituted polycyclic aromatic hydrocarbon and phenyl. This article concerns the influence of the applied level of theory (i.e., both the basis set and the method) on the determined values of the substituent energies. For this purpose, the energies of the NH2 and NO2 groups in 16 unique positions of naphthalene, anthracene, tetracene, phenanthrene, and pyrene were calculated using 10 different basis sets and 23 various exchange-correlation functionals representing the entire Jacob's Ladder, from local, through gradient- and meta-gradient-corrected, to hybrid and double-hybrid ones. Additionally, using even larger 6-311++G(2df,2p) basis set, the energies of NH2 , NO2 , CN, and Cl were also computed. Both the basis set and the method used have little effect on the substituent energy if the substituent is in the benzene-like position. On the contrary, the effect of the level of theory is pronounced especially in the case of the most spatially crowded 4-substituted phenanthrene. Substituent energies have been shown to be very useful theoretical parameters describing the proximity effect in the substituted derivatives of polycyclic aromatic hydrocarbons.
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Affiliation(s)
- Mirosław Jabłoński
- Faculty of Chemistry, Nicolaus Copernicus University in Toruń, Toruń, Poland
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4
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Pretelín-Castillo G, Silva Miranda M, Espitia C, Chávez-Santos RM, Suárez-Castro A, Chacón-García L, Aguayo-Ortiz R, Martinez R. ( 2Z)-3-Hydroxy-3-(4-R-Phenyl)-Prop-2-Enedithioic Acids as New Antituberculosis Compounds. Infect Drug Resist 2021; 14:4323-4332. [PMID: 34707377 PMCID: PMC8543028 DOI: 10.2147/idr.s328132] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2021] [Accepted: 09/28/2021] [Indexed: 11/23/2022] Open
Abstract
Background Tuberculosis is an infectious disease caused by the bacillus Mycobacterium tuberculosis. Compounds including a sulfur-containing scaffold have been shown to be key scaffolds in various antituberculosis agents. Interestingly, the 3-hydroxy-3-phenyl-prop-2-enedithioic acids 11a-j have, to the best of our knowledge, not been previously described as antituberculosis agents. Purpose In the present study, we investigated the role of substituents attached to the phenyl ring of a 3-hydroxy-3-phenyl-prop-2-enedithioic acid scaffold (compounds 11a–j) in inhibiting the growth of M. tuberculosis strain H37Rv. Methods (Z)-3-hydroxy-3-(4-R-phenyl)-prop-2-enedithioic acids 11b–j, with R groups including various electron-donating or electron-withdrawing groups, were designed by structurally modifying the lead compound 11a. The syntheses of 11a–j involved each one-step procedure starting from the corresponding substituted acetophenone. Compounds 11a–j were tested against M. tuberculosis strain H37Rv to evaluate their bacterial growth inhibitory activities. ADMET profiles were predicted by employing three different methods. In addition, molecular docking studies were carried out, based on the molecular similarities of the synthesized compounds with ethionamide (5), on the active site of the M. tuberculosis H37Rv (3R)-hydroxyacyl-ACP (HadAB) dehydratase heterodimer. Results The antituberculosis activities of compounds 11a–j could be explained in terms of the presence of electron-donating or electron-withdrawing substituents on the aromatic ring of the substituted 3-hydroxy-3-phenyl)-prop-2-enedithioic acid core. The activity and selectivity index (SI) value of (Z)-3-hydroxy-3-(4-nitrophenyl)-prop-2-enedithioic acid 11e suggested that this compound could be used for the design of novel antituberculosis agents. Most of the synthesized molecules showed an acceptable ADME profile and a low probability of being toxic. Docking studies of 11d and 11e showed them forming hydrogen bonds with the ACys61 residue of the HadAB enzyme. Conclusion Our results suggested that the antituberculosis compound 11e could be used for the design of novel antituberculosis agents.
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Affiliation(s)
- Gustavo Pretelín-Castillo
- Instituto de Química, Universidad Nacional Autónoma de México, Circuito Exterior, Ciudad Universitaria, Cd. México, 04510, México
| | - Mayra Silva Miranda
- Catedrática CONACYT adscrita al Instituto de Investigaciones Biomédicas, Universidad Nacional Autónoma de México, Ciudad Universitaria, Cd. México, 04510, México.,Instituto de Investigaciones Biomédicas, Universidad Nacional Autónoma de México, Departamento de Inmunología, Ciudad Universitaria, Cd. México, 04510, México
| | - Clara Espitia
- Catedrática CONACYT adscrita al Instituto de Investigaciones Biomédicas, Universidad Nacional Autónoma de México, Ciudad Universitaria, Cd. México, 04510, México.,Instituto de Investigaciones Biomédicas, Universidad Nacional Autónoma de México, Departamento de Inmunología, Ciudad Universitaria, Cd. México, 04510, México
| | - Rosa María Chávez-Santos
- Instituto de Química, Universidad Nacional Autónoma de México, Circuito Exterior, Ciudad Universitaria, Cd. México, 04510, México
| | - Abel Suárez-Castro
- Instituto de Investigaciones Químico-Biológicas, Universidad Michoacana de San Nicolás de Hidalgo, Edificio B-1, Ciudad Universitaria, Morelia Michoacán, 58030, México
| | - Luis Chacón-García
- Instituto de Investigaciones Químico-Biológicas, Universidad Michoacana de San Nicolás de Hidalgo, Edificio B-1, Ciudad Universitaria, Morelia Michoacán, 58030, México
| | - Rodrigo Aguayo-Ortiz
- Departamento de Farmacia, Facultad de Química, Universidad Nacional Autónoma de México, Circuito Exterior, Ciudad Universitaria, Cd. México, 04510, México
| | - Roberto Martinez
- Instituto de Química, Universidad Nacional Autónoma de México, Circuito Exterior, Ciudad Universitaria, Cd. México, 04510, México
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5
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Ramos-Orea A, Ramírez-Apan T, Chávez-Santos RM, Aguayo-Ortiz R, Espitia C, Silva Miranda M, Torres-Ochoa RO, Martínez R. Total syntheses and antiproliferative activities of prenostodione and its analogues. Org Biomol Chem 2021; 19:8272-8280. [PMID: 34518856 DOI: 10.1039/d1ob00897h] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
A high-yielding total synthesis of the indole alkaloid prenostodione was completed in 4 steps and 44% overall yield from 1H-indole-3-carboxylic acid. The expedient syntheses of prenostodiones containing distinct substituents at the para position of the phenyl frame underscored the scope of this methodology. The cytotoxic activities of the tert-butyl esters of prenostodione analogues were tested using six tumor cell lines. Preliminary structure-activity studies revealed the importance of the identity of the aromatic substituent at the C-4 position for cytotoxic activity. The IC50 values of these compounds were found to compare satisfactorily with those of the commercially available drugs etoposide and cisplatin. Furthermore, the compounds with, respectively, -OMe (14d) and -NO2 (14f) groups at C-4 were more selective than these control compounds in PC-3, K-562, and MCF-7 cells. Also, computational studies were carried out to determine the ADMET profiles and passive membrane permeabilities of the compounds. The results suggested the promise of 14d and 14f as hit compounds for the development of new anticancer agents.
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Affiliation(s)
- Aldahir Ramos-Orea
- Instituto de Química, Universidad Nacional Autónoma de México, Circuito Exterior, Ciudad Universitaria, Coyoacán, Ciudad de México, 04510, Mexico.
| | - Teresa Ramírez-Apan
- Instituto de Química, Universidad Nacional Autónoma de México, Circuito Exterior, Ciudad Universitaria, Coyoacán, Ciudad de México, 04510, Mexico.
| | - Rosa María Chávez-Santos
- Instituto de Química, Universidad Nacional Autónoma de México, Circuito Exterior, Ciudad Universitaria, Coyoacán, Ciudad de México, 04510, Mexico.
| | - Rodrigo Aguayo-Ortiz
- Departamento de Farmacia, Facultad de Química, Universidad Nacional Autónoma de México, Circuito Escolar, Ciudad Universitaria, Coyoacán, Ciudad de México, 04510, Mexico
| | - Clara Espitia
- Instituto de Investigaciones Biomédicas, Universidad Nacional Autónoma de México, Ciudad Universitaria, Coyoacán, Ciudad de México, 04510, Mexico
| | - Mayra Silva Miranda
- Instituto de Investigaciones Biomédicas, Universidad Nacional Autónoma de México, Ciudad Universitaria, Coyoacán, Ciudad de México, 04510, Mexico
| | - Rubén O Torres-Ochoa
- Instituto de Química, Universidad Nacional Autónoma de México, Circuito Exterior, Ciudad Universitaria, Coyoacán, Ciudad de México, 04510, Mexico.
| | - Roberto Martínez
- Instituto de Química, Universidad Nacional Autónoma de México, Circuito Exterior, Ciudad Universitaria, Coyoacán, Ciudad de México, 04510, Mexico.
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Albu RM, Stoica I, Barzic AI, Postolache M, Angheluta M, Dorohoi DO. Effect of mechanical treatments on orientation behavior and spectral properties of azoderivative dyes incorporated in poly(vinyl alcohol) films. POLYM ENG SCI 2021. [DOI: 10.1002/pen.25771] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Raluca Marinica Albu
- Department of Physical Chemistry of Polymers “Petru Poni” Institute of Macromolecular Chemistry Iasi Romania
| | - Iuliana Stoica
- Department of Physical Chemistry of Polymers “Petru Poni” Institute of Macromolecular Chemistry Iasi Romania
| | - Andreea Irina Barzic
- Department of Physical Chemistry of Polymers “Petru Poni” Institute of Macromolecular Chemistry Iasi Romania
| | - Mihai Postolache
- Automatic Control and Computer Engineering “Gheorghe Asachi” Technical University Iasi Romania
| | - Mihai‐Daniel Angheluta
- Faculty of Medicine “Iuliu Hatieganu” University of Medicine and Pharmacy Cluj‐Napoca Romania
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7
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Solvent Effect on the Stability and Reverse Substituent Effect in Nitropurine Tautomers. Symmetry (Basel) 2021. [DOI: 10.3390/sym13071223] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
The solvent effect on the stability and electron-accepting properties (EA) of the nitro group attached to the C2, C6, or C8 position of nitropurine NH tautomers is investigated. For this purpose, the density functional theory (DFT) and the polarizable continuum model (PCM) of solvation in a wide range of solvents (1 < ε < 109) are used. We show that the EA properties of the NO2 group, described by the charge of the substituent active region (cSAR) model, are linearly dependent on the reciprocal of the solvent dielectric constant; in all cases, solvation enhances the EA properties of this group. Furthermore, the sensitivity of EA properties of the nitro group to the solvent effect depends on the proximity effects. It has been shown that the proximity of two endocyclic N atoms (two repulsive interactions) results in higher sensitivity than the asymmetric proximity of the endocyclic N atom and NH group (one repulsive and one attractive interaction). To explain this phenomenon, the geometry of the nitro group in coplanar form and after forcing its rotation around the CN bond is discussed. Relative stabilities of nitropurine tautomers in different solvents are also presented. Differences in the stabilities and solvation energies are explained by aromaticity, electronic structure, and intramolecular interactions of the nitropurine tautomers.
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Jabłoński M, Krygowski TM. Energetic characteristics of the substituents in para- and meta-substituted derivatives of benzoic acids. Chem Phys Lett 2021. [DOI: 10.1016/j.cplett.2021.138464] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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Abstract
AbstractNumerous studies on nitro group properties are associated with its high electron-withdrawing ability, by means of both resonance and inductive effect. The substituent effect of the nitro group may be well described using either traditional substituent constants or characteristics based on quantum chemistry, i.e., cSAR, SESE, and pEDA/sEDA models. Interestingly, the cSAR descriptor allows to describe the electron-attracting properties of the nitro group regardless of the position and the type of system. Analysis of classical and reverse substituent effects of the nitro group in various systems indicates strong pi-electron interactions with electron-donating substituents due to the resonance effect. This significantly affects the pi-electron delocalization of the aromatic ring decreasing the aromatic character, evidenced clearly by HOMA values. Use of the pEDA/sEDA model allows to measure the population of electrons transferred from the ring to the nitro group.
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Jabłoński M, Krygowski TM. Changes in Electron Structure of the Triple Bond in Substituted Acetylene and Diacetylene Derivatives. Chemphyschem 2020; 21:1847-1857. [PMID: 32511830 DOI: 10.1002/cphc.202000378] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2020] [Revised: 06/05/2020] [Indexed: 11/06/2022]
Abstract
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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Affiliation(s)
- Mirosław Jabłoński
- Faculty of Chemistry, Nicolaus Copernicus University in Toruń, Gagarina 7, 87-100, Toruń, Poland
| | - Tadeusz M Krygowski
- Department of Chemistry, Warsaw University, Pasteura 1, 02-093, Warsaw, Poland
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Medviediev V, Shishkina S, Ribalka AO, Zaręba JK, Drozd M, Daszkiewicz M. Revisiting 2-chloro-4-nitroaniline: analysis of intricate supramolecular ordering of a triclinic polymorph featuring a high Z value and strong second harmonic generation. CrystEngComm 2020. [DOI: 10.1039/d0ce00582g] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
A new polymorph of 2-chloro-4-nitroaniline is more stable than its 55 year-old antecedent.
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Affiliation(s)
- Volodymyr Medviediev
- Institute of Low Temperature and Structure Research
- Polish Academy of Sciences
- 50-422 Wrocław
- Poland
| | - Svitlana Shishkina
- SSI “Institute for Single Crystals”
- National Academy of Science of Ukraine
- Kharkiv 61001
- Ukraine
- V. N. Karazin Kharkiv National University
| | - A. O. Ribalka
- V. N. Karazin Kharkiv National University
- Kharkiv 61077
- Ukraine
| | - Jan K. Zaręba
- Advanced Materials Engineering and Modelling Group
- Faculty of Chemistry
- Wroclaw University of Science and Technology
- 50-370 Wrocław
- Poland
| | - Marek Drozd
- Institute of Low Temperature and Structure Research
- Polish Academy of Sciences
- 50-422 Wrocław
- Poland
| | - Marek Daszkiewicz
- Institute of Low Temperature and Structure Research
- Polish Academy of Sciences
- 50-422 Wrocław
- Poland
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13
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Martínez R, Zamudio GJN, Pretelin-Castillo G, Torres-Ochoa RO, Medina-Franco JL, Espitia Pinzón CI, Miranda MS, Hernández E, Alanís-Garza B. Synthesis and antitubercular activity of new N-[5-(4-chlorophenyl)-1,3,4-oxadiazol-2-yl]-(nitroheteroaryl)carboxamides. HETEROCYCL COMMUN 2019. [DOI: 10.1515/hc-2019-0007] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
AbstractNitro-substituted heteroaromatic carboxamides 1a-e were synthesized and tested against three Mycobacterium tuberculosis cell lines. The activities can be explained in terms of the distribution of the electronic density across the nitro-substituted heteroaromatic ring attached to the amide group. 1,3,5-Oxadiazole derivatives 1c-e are candidates for the development of novel antitubercular agents. Ongoing studies are focused on exploring the mechanism by which these compounds inhibit M. tuberculosis cell growth.
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Affiliation(s)
- Roberto Martínez
- Instituto de Química, Universidad Nacional Autónoma de México, Circuito Exterior, Ciudad Universitaria, 04510, Cd. México, México
| | - Gladys J. Nieves Zamudio
- Instituto de Química, Universidad Nacional Autónoma de México, Circuito Exterior, Ciudad Universitaria, 04510, Cd. México, México
| | - Gustavo Pretelin-Castillo
- Instituto de Química, Universidad Nacional Autónoma de México, Circuito Exterior, Ciudad Universitaria, 04510, Cd. México, México
| | - Rubén O. Torres-Ochoa
- Instituto de Química, Universidad Nacional Autónoma de México, Circuito Exterior, Ciudad Universitaria, 04510, Cd. México, México
| | - José L. Medina-Franco
- Departamento de Farmacia, Facultad de Química, Universidad Nacional Autónoma de México, Avenida Universidad3000, 04510Cd. México, México
| | - Clara I. Espitia Pinzón
- Instituto de Investigaciones Biomédicas, Universidad Nacional Autónoma de México, Ciudad Universitaria, 04510, Cd. México, México
| | - Mayra Silva Miranda
- Catedrática CONACYT adscrita al Insituto de Investigaciones Biomédicas, Universidad Nacional Autónoma de México, Ciudad Universitaria, 04510, Cd. México, México
| | - Eugenio Hernández
- Facultad de Ciencias Químicas, Universidad Autónoma de Nuevo León, Pedro de Alba s/n, Ciudad Universitaria, 66400 San Nicolás de los Garza, Nuevo León, México
| | - Blanca Alanís-Garza
- Departamento de Química Analítica, Facultad de Medicina, Universidad Autónoma de Nuevo León, Madero s/n Col. Mitras Centro. Monterrey, N. L. MéxicoC. P. 64460
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Majerz I, Dziembowska T. Aromaticity of benzene derivatives: an exploration of the Cambridge Structural Database. ACTA CRYSTALLOGRAPHICA SECTION B-STRUCTURAL SCIENCE CRYSTAL ENGINEERING AND MATERIALS 2018; 74:148-151. [DOI: 10.1107/s2052520618000987] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/16/2017] [Accepted: 01/16/2018] [Indexed: 11/11/2022]
Abstract
The harmonic oscillator model of aromaticity (HOMA) index, one of the most popular aromaticity indices for solid-state benzene rings in the Cambridge Structural Database (CSD), has been analyzed. The histograms of HOMA for benzene, for benzene derivatives with one formyl, nitro, amino or hydroxy group as well as the histograms for the derivatives with two formyl, nitro, amino or hydroxy groups inortho,metaandparapositions were investigated. The majority of the substituted benzene derivatives in the CSD are characterized by a high value of HOMA, indicating fully aromatic character; however, the distribution of the HOMA value from 1 to about 0 indicates decreasing aromaticity down to non-aromatic character. Among the benzene derivatives investigated, a significant decrease in aromaticity can be related to compounds with diamino and dinitro groups in themetaposition.
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Viesser RV, Ducati LC, Tormena CF, Autschbach J. The unexpected roles of σ and π orbitals in electron donor and acceptor group effects on the 13C NMR chemical shifts in substituted benzenes. Chem Sci 2017; 8:6570-6576. [PMID: 28989684 PMCID: PMC5627350 DOI: 10.1039/c7sc02163a] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2017] [Accepted: 07/20/2017] [Indexed: 11/30/2022] Open
Abstract
NH2 and NO2 group effects on 13C NMR chemical shifts in substituted benzenes are explained by σ- instead of π-orbitals.
Effects of electron-donating (R = NH2) and electron-withdrawing (R = NO2) groups on 13C NMR chemical shifts in R-substituted benzene are investigated by molecular orbital analyses. The 13C shift substituent effect in ortho, meta, and para position is determined by the σ bonding orbitals in the aryl ring. The π orbitals do not explain the substituent effects in the NMR spectrum as conventionally suggested in textbooks. The familiar electron donating and withdrawing effects on the π system by NH2 and NO2 substituents induce changes in the σ orbital framework, and the 13C chemical shifts follow the trends induced in the σ orbitals. There is an implicit dependence of the σ orbital NMR shift contributions on the π framework, via unoccupied π* orbitals, due to the fact that the nuclear shielding is a response property.
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Affiliation(s)
- Renan V Viesser
- Institute of Chemistry , University of Campinas - UNICAMP , P. O. Box 6154 , 13083-970 , Campinas , SP , Brazil .
| | - Lucas C Ducati
- Department of Fundamental Chemistry , Institute of Chemistry , University of São Paulo , Av. Prof. Lineu Prestes, 748 , 05508-000 , São Paulo , SP , Brazil .
| | - Cláudio F Tormena
- Institute of Chemistry , University of Campinas - UNICAMP , P. O. Box 6154 , 13083-970 , Campinas , SP , Brazil .
| | - Jochen Autschbach
- Department of Chemistry , University at Buffalo , State University of New York , Buffalo , NY 14260-3000 , USA .
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Szatylowicz H, Jezuita A, Ejsmont K, Krygowski TM. Substituent Effect on the σ- and π-Electron Structure of the Nitro Group and the Ring in Meta- and Para-Substituted Nitrobenzenes. J Phys Chem A 2017. [DOI: 10.1021/acs.jpca.7b03418] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Halina Szatylowicz
- Faculty
of Chemistry, Warsaw University of Technology, Noakowskiego 3, 00-664 Warsaw, Poland
| | - Anna Jezuita
- Faculty
of Chemistry, Opole University, Oleska 48, 45-052 Opole, Poland
| | - Krzysztof Ejsmont
- Faculty
of Chemistry, Opole University, Oleska 48, 45-052 Opole, Poland
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Majerz I, Dziembowska T. Aromaticity of peri- and para-Substituted Naphthalene-1-carbaldehyde. Comparison with 1-Nitronaphthalene. J Phys Chem A 2017; 121:2627-2635. [PMID: 28281756 DOI: 10.1021/acs.jpca.6b11926] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Aromaticity of the naphthalene ring substituted by formyl or nitro and secondary amine groups in peri and para positions has been investigated. HOMA (harmonic oscillator model of aromaticity) index of the naphthalene rings has been used to characterize the aromaticity of the investigated molecules. Ellipticity of C2-C3 (C6-C7) bonds, obtained by means of topological analysis of the electron density, has been used as a measure of the through-resonance effect between the para substituents. Dependence of the HOMA values on the rotation angle of formyl and nitro groups to the aromatic plane for naphthalene-1-carbaldehyde and their derivatives with dimethylamino group in para position has been analyzed. It has been shown that the nitro group has a stronger resonance effect and causes greater decrease of aromaticity than the formyl group only for planar or close to planar conformation. The attractive and repulsive peri interactions have been analyzed by using the QTAIM and NCI methods. Interrelation between the peri and para interactions has been discussed.
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Affiliation(s)
- Irena Majerz
- Faculty of Pharmacy, Wroclaw Medical University , Borowska 211a, 50-556 Wroclaw, Poland
| | - Teresa Dziembowska
- Department of Organic and Physical Chemistry, West Pomeranian University of Technology , 70-061, Szczecin, Poland
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Classical and reverse substituent effects in meta- and para-substituted nitrobenzene derivatives. Struct Chem 2017. [DOI: 10.1007/s11224-017-0922-2] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
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