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Sturm L, Artigas A, Coquerel Y, Bechtold IH, Durola F, Bock H. Helicene Aromaticity Deviates from the Clar Rule-On the Electronic Dissimilarity of Large Isomeric Fibonacenes. Angew Chem Int Ed Engl 2024; 63:e202403170. [PMID: 38568685 DOI: 10.1002/anie.202403170] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2024] [Indexed: 04/30/2024]
Abstract
This combined experimental and theoretical study illustrates the profound consequences of non-planarity on the electronic properties of polycyclic arenes. Three isomeric [10]fibonacene tetraesters were synthesized through a robust and regiocontrolled Perkin/Mallory approach: a nearly planar [10]phenacene derivative, a moderately twisted [10]semicircle derivative, and a 3D non-planar [10]helicene derivative. The photophysical properties of the 3D [10]helicene isomer were found to be dramatically different from the comparable ones of the [10]phenacene and [10]semicircle isomers. The aromatic properties of the [10]phenacene and [10]semicircle isomers conform well with their predictive Kekulé and Clar analyses, but the [10]helicene isomer deviates from these general topological rules, which appears to be a general phenomenon for [n]fibonacenes with n≥9.
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Affiliation(s)
- Ludmilla Sturm
- Centre de Recherche Paul Pascal, Université de Bordeaux, 115 av. Schweitzer, 33600, Pessac, France
| | - Albert Artigas
- Facultat de Ciències, Universitat de Girona, Campus Montilivi, Carrer de Maria Aurèlia Capmany i Farnès 69, 17003, Girona, Catalunya, Spain
| | - Yoann Coquerel
- Aix Marseille Univ, CNRS, Centrale Méditerranée, ISM2, 13397, Marseille, France
| | - Ivan H Bechtold
- Departamento de Física, Universidade Federal de Santa Catarina, Trindade, 88040-900, Florianópolis, Brazil
| | - Fabien Durola
- Centre de Recherche Paul Pascal, CNRS, 115 av. Schweitzer, 33600, Pessac, France
| | - Harald Bock
- Centre de Recherche Paul Pascal, CNRS, 115 av. Schweitzer, 33600, Pessac, France
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2
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Wang Y, Zhou Y, Du K. Enumeration, Nomenclature, and Stability Rules of Carbon Nanobelts. J Chem Inf Model 2024; 64:1261-1276. [PMID: 38327033 DOI: 10.1021/acs.jcim.3c02051] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/09/2024]
Abstract
With recent breakthroughs and advances in synthetic chemistry, carbon nanobelts (CNBs) have become an emerging hot topic in chemistry and materials science. Owing to their unique molecular structures, CNBs have intriguing properties with applications in synthetic materials, host-guest chemistry, optoelectronics, and so on. Although a considerable number of CNBs with diverse forms have been synthesized, no systematic nomenclature is available yet for this important family of macrocycles. Moreover, little is known about the detailed isomerism of CNBs, which, in fact, exhibits greater complexity than that of carbon nanotubes. The copious variety of CNB isomers, along with the underlying structure-property relationships, bears fundamental relevance to the ongoing design and synthesis of novel nanobelts. In this paper, we propose an elegant approach to systematically enumerate, classify, and name all possible isomers of CNBs. Besides the simplest, standard CNBs defined by chiral indices (n, m), the nonstandard CNBs (n, m, l) involve an additional winding index l. Based on extensive quantum chemical calculations, we present a comprehensive study of the relative isomer stability of CNBs containing up to 30 rings. A simple Hückel-based model with a high predictive power reveals that the relative stability of standard CNBs is governed by the π stabilization and the strain destabilization induced by the cylindrical carbon framework, and the former effect prevails over the latter. For nonstandard CNBs, a third stability factor, the H···H repulsion in the benzo[c]phenanthrene-like motifs, is also shown to be important and can be incorporated into the simple quantitative model. In general, lower-energy CNB isomers have a larger HOMO-LUMO gap, suggesting that their thermodynamic stability coincides with kinetic stability. The most stable CNB isomers determined can be considered the optimal targets for future synthesis. These results lay an initial foundation and provide a useful theoretical tool for further research on CNBs and related analogues.
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Affiliation(s)
- Yang Wang
- School of Chemistry and Chemical Engineering, Yangzhou University, Yangzhou, Jiangsu 225002, China
| | - Yi Zhou
- School of Chemistry and Chemical Engineering, Yangzhou University, Yangzhou, Jiangsu 225002, China
| | - Ke Du
- School of Chemistry and Chemical Engineering, Yangzhou University, Yangzhou, Jiangsu 225002, China
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Joice SL, Raja SMJ. Minimum Number of Kekulé Structures of Certain Benzenoid Graphs and Pr[m,n]-Polyacenic Nanotubes. Polycycl Aromat Compd 2022. [DOI: 10.1080/10406638.2022.2156557] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
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Abstract
Despite its great explanatory power in understanding the chemistry of polycyclic aromatic hydrocarbons (PAHs) and related systems, the Clar sextet rule still remains an intuitive and qualitative model with notable exceptions in some cases. Here we develop a quantitative theory of chemical resonance based on semilocalized Clar-type resonance structures (named the Clar resonators) consisting of variable numbers of Clar sextets and C═C bonds. The constructed wave functions of the Clar resonators are used to expand the actual wave function of the π-conjugated system obtained from a DFT or Hartree-Fock calculation. The resultant weights and one-electron energies of the Clar resonators can serve as a quantitative measure of the importance of these resonators. Implementing the theory in our open-source python code EzReson and applying it to over a thousand PAH molecules of different sizes and shapes, we show that the weight of the Clar resonators increases exponentially with increasing number of sextets and that their energy decreases linearly with the latter, thus confirming the general validity of the Clar rule. On the basis of such a large-scale resonance analysis, we propose three extended Clar rules, along with a unified quantitative model, that are able to evaluate the importance of all Clar resonators and the ring aromaticity for PAHs. Using the present theories, we uncover the essential role that the minor Clar resonators may play in correctly understanding the resonance stabilization and local aromaticity of rings, which was totally overlooked in the original Clar model.
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Affiliation(s)
- Yang Wang
- School of Chemistry and Chemical Engineering, Yangzhou University, Yangzhou, Jiangsu 225002, China
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Wang Y. Extension and Quantification of the Fries Rule and Its Connection to Aromaticity: Large-Scale Validation by Wave-Function-Based Resonance Analysis. J Chem Inf Model 2021; 62:5136-5148. [PMID: 34428367 DOI: 10.1021/acs.jcim.1c00735] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The Fries rule is a simple, intuitive tool to predict the most dominant Kekulé structures of polycyclic aromatic hydrocarbons (PAHs), which is valuable for understanding the structure, stability, reactivity, and aromaticity of these conjugated compounds. However, it still remains an empirical hypothesis, with limited qualitative applications. Herein, we verify, generalize, and quantify the Fries rule based on the recently developed resonance analysis of the DFT wave functions of over 1500 PAH and fullerene molecules with over a billion Kekulé structures. The extended rules, counting the numbers of electrons within all rings (not just sextets), are able to rank the relative importance of all Kekulé structures for all considered systems. The statistically meaningful quantification also opens a way to evaluate ring aromaticity based on the resonance theory, which generally agrees well with conventional aromaticity descriptors. Furthermore, we propose a purely graph-based aromaticity indicator nicely applicable to PAHs and fullerenes, with no need of any quantum chemistry calculations, so that it can make valuable predictions for molecular properties that are related to local aromaticity.
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Affiliation(s)
- Yang Wang
- School of Chemistry and Chemical Engineering, Yangzhou University, Yangzhou, Jiangsu 225002, China
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6
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Wang Y. Response to comment on "Superposition of waves or densities: Which is the nature of chemical resonance?". J Comput Chem 2021; 42:1341-1343. [PMID: 34046913 DOI: 10.1002/jcc.26523] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2021] [Revised: 03/02/2021] [Accepted: 03/12/2021] [Indexed: 12/14/2022]
Abstract
I reply to the comment by Weinhold and Glendening on the article (J. Comput. Chem. 2021, 42, 412). I provide further explanation and an additional numerical example to support my previous assertion that the present form of natural resonance theory is fundamentally flawed, at least within the DFT framework.
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Affiliation(s)
- Yang Wang
- School of Chemistry and Chemical Engineering, Yangzhou University, Yangzhou, Jiangsu, China
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Klein DJ, Ferrer M, Elguero J, Bytautas L, Oliva-Enrich JM. Hückeloid model for planar boranes. Theor Chem Acc 2021. [DOI: 10.1007/s00214-021-02752-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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8
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Lozynski M, Rusinska-Roszak D. Finding the direct energy-structure correlations in intramolecular aromaticity assisted hydrogen bonding (AAHB). J Mol Graph Model 2021; 105:107884. [PMID: 33725643 DOI: 10.1016/j.jmgm.2021.107884] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2020] [Revised: 02/25/2021] [Accepted: 02/25/2021] [Indexed: 11/25/2022]
Abstract
A predictive model for intramolecular hydrogen bond energy (EHB) calculation of polyaromatic ortho-hydroxyaldehydes based on a set of small, functionalized hydrocarbons is developed. The complete data set of 18 compounds was used for this study. The model is based on one of four optional categories of molecular descriptors: geometric, spectroscopic, bond order and topological indices. The model of Wiberg bond indices (WBIs) as descriptors of the CC involved bond based on stepwise regression has acceptable prediction abilities for 14 structures of ortho-hydroxyformylobenzo[a]pyrene derivatives already at the semiempirical level. The presented correlation enables a significantly more rapid and quantitative description of the hydrogen bonding strength than the much more time-consuming MTA method. Thus, WBIs are shown to provide a reliable means for fast prescreening of the energy of chelate hydrogen bonds potentially for any polyaromatic derivatives.
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Affiliation(s)
- Marek Lozynski
- Faculty of Chemical Technology, Poznan University of Technology, Berdychowo 4, 60-965, Poznan, Poland
| | - Danuta Rusinska-Roszak
- Faculty of Chemical Technology, Poznan University of Technology, Berdychowo 4, 60-965, Poznan, Poland.
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Naulet G, Huet-Exiga S, Bock H, Durola F. Synthesis of a [20]phenacene dodeca-ester by controlled condensation of seven naphthalene-based building blocks. Org Chem Front 2019. [DOI: 10.1039/c9qo00125e] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
A soluble [20]phenacene dodeca-ester has been synthesized by Perkin strategy from naphthalene-based building blocks using complementary protecting techniques.
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Affiliation(s)
- Guillaume Naulet
- Centre de Recherche Paul Pascal
- CNRS & Université de Bordeaux
- 33600 Pessac
- France
| | | | - Harald Bock
- Centre de Recherche Paul Pascal
- CNRS & Université de Bordeaux
- 33600 Pessac
- France
| | - Fabien Durola
- Centre de Recherche Paul Pascal
- CNRS & Université de Bordeaux
- 33600 Pessac
- France
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10
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An extension of the Fries rule to non-benzenoid hydrocarbons having four-atomic rings. MONATSHEFTE FUR CHEMIE 2018. [DOI: 10.1007/s00706-017-2133-3] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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11
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Moreira TS, Ferreira M, Dall'armellina A, Cristiano R, Gallardo H, Hillard EA, Bock H, Durola F. Tetracarboxy-Functionalized [8]-, [10]-, [12]-, and [14]Phenacenes. European J Org Chem 2017. [DOI: 10.1002/ejoc.201700893] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Thamires S. Moreira
- Centre de Recherche Paul Pascal; CNRS; 115, av. Schweitzer 33600 Pessac France
- Departamento de Química; Universidade Federal da Paraíba; CEP 58051-900 João Pessoa Paraíba Brazil
| | - Marli Ferreira
- Centre de Recherche Paul Pascal; CNRS; 115, av. Schweitzer 33600 Pessac France
| | - Alice Dall'armellina
- Centre de Recherche Paul Pascal; Université de Bordeaux; 115, av. Schweitzer 33600 Pessac France
| | - Rodrigo Cristiano
- Departamento de Química; Universidade Federal da Paraíba; CEP 58051-900 João Pessoa Paraíba Brazil
| | - Hugo Gallardo
- Departamento de Química; Universidade Federal de Santa Catarina; CEP 88040-900 Florianópolis Santa Catarina Brazil
| | | | - Harald Bock
- Centre de Recherche Paul Pascal; CNRS; 115, av. Schweitzer 33600 Pessac France
| | - Fabien Durola
- Centre de Recherche Paul Pascal; CNRS; 115, av. Schweitzer 33600 Pessac France
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12
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Randić M, Vukičević D, Balaban AT, Vračko M, Plavšić D. Conjugated circuits currents in hexabenzocoronene and its derivatives formed by joining proximal carbons. J Comput Chem 2012; 33:1111-22. [PMID: 22344894 DOI: 10.1002/jcc.22941] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2012] [Accepted: 01/08/2012] [Indexed: 01/31/2023]
Abstract
We report on calculated CC bond currents for a dozen derivatives of hexabenzocoroenene in which one or more proximal carbon atoms at the molecular periphery have been bridged. The approach that we use is graph-theoretical in nature, following our outline of this method in 2003, which is based on finding all conjugated circuits in all Kekulé valence structures of these molecules. To the π-electrons having 4n + 2 π-electrons are assigned anticlockwise π-electron currents and to conjugated circuits having 4n π-electrons are assigned π-electron currents. One may summarize the results reported in this work by stating that CC bond currents in the compounds considered decrease on going from peripheral rings to the central ring of the molecule, and also that CC bond currents decrease by insertion of bridges to proximal peripheral benzenoid rings.
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Affiliation(s)
- Milan Randić
- Department of Mathematics, Faculty of Natural Sciences and Mathematics, University of Split, Nikole Tesle 12, HR-21000 Split, Croatia
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13
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Ciesielski A, Stepień DK, Dobrowolski MA, Dobrzycki Ł, Cyrański MK. On the aromatic stabilization of benzenoid hydrocarbons. Chem Commun (Camb) 2012; 48:10129-31. [DOI: 10.1039/c2cc33974a] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
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14
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15
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Ciesielski A, Krygowski TM, Cyrański MK, Balaban AT. Defining rules of aromaticity: a unified approach to the Hückel, Clar and Randić concepts. Phys Chem Chem Phys 2011; 13:3737-47. [DOI: 10.1039/c0cp01446j] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Randić M, Kroto HW, Vukicević D. Numerical Kekulé structures of fullerenes and partitioning of pi-electrons to pentagonal and hexagonal rings. J Chem Inf Model 2007; 47:897-904. [PMID: 17474734 DOI: 10.1021/ci600484u] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
We calculated the partitioning of pi-electrons within individual pentagonal and hexagonal rings of fullerenes for a collection of fullerenes from C20 to C72 by constructing their Kekulé valence structures and averaging the pi-electron content of individual rings over all Kekulé valence structures. The resulting information is collected in Table 2, which when combined with the Schlegel diagram of fullerenes (illustrated in Figure 7) uniquely characterizes each of the 19 fullerenes considered. The results are interpreted as the basic information on the distributions (variation) of the local (ring) pi-electron density.
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Affiliation(s)
- Milan Randić
- National Institute of Chemistry, Hajdrihova 19, SI-1000 Ljubljana, Slovenia.
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20
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Lawson AJ. THERMAL FISSION OF HYDROXYLAMINE DERIVATIVES WITH NEIGHBOURING-GROUP-PARTICIPATION BY THIOETHER FUNCTIONS: PREPARATION OF 1,2-BENZISOTHIAZOLES. ACTA ACUST UNITED AC 2007. [DOI: 10.1080/03086648208078969] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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21
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Isothiazolium Salts and Their Use as Components for the Synthesis of S,N-Heterocycles. ADVANCES IN HETEROCYCLIC CHEMISTRY 2007. [DOI: 10.1016/s0065-2725(06)94004-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register]
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22
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23
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Sedlar J, Anđelić I, Gutman I, Vukičević D, Graovac A. Vindicating the Pauling-bond-order concept. Chem Phys Lett 2006. [DOI: 10.1016/j.cplett.2006.06.026] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
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24
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Pellegrin V, Fruchier A, Elguero J. Synthese de l'indazole-1-15N, de l'indazole-2-15N et de leurs derives n-methyles. J Labelled Comp Radiopharm 2006. [DOI: 10.1002/jlcr.2580180710] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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Affiliation(s)
- Eiji Ochiai
- Pharmazeut. Institut d. Kaiserl. Universität Tokio
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Weidenhagen R, Weeden U. Über neue Imidazoloverbindungen der heterocyclischen Reihe (VII. Mitteil. über Imidazole). ACTA ACUST UNITED AC 2006. [DOI: 10.1002/cber.19380711123] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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29
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Kohlrausch KWF, Seka R. Raman-Effekt und Konstitutions-Probleme, XII. Mitteil.: Naphthalinartig kondensierte bicyclische Kohlenwasserstoffe. ACTA ACUST UNITED AC 2006. [DOI: 10.1002/cber.19380710802] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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30
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Böshagen H, Geiger W. Über die Umsetzung von 3‐Chlor‐1,2‐benzisothiazolium‐chloriden mit
N
‐Mono‐ und
N
,
N
‐Dialkylanilinen. ACTA ACUST UNITED AC 2006. [DOI: 10.1002/cber.19791120924] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Affiliation(s)
- Horst Böshagen
- Wissenschaftliche Laboratorien der Bayer AG, Werk Wuppertal‐Elberfeld, Postfach 101709, D‐5600 Wuppertal 1
| | - Walter Geiger
- Wissenschaftliche Laboratorien der Bayer AG, Werk Wuppertal‐Elberfeld, Postfach 101709, D‐5600 Wuppertal 1
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31
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Randić M, Balaban AT. Partitioning of π-Electrons in Rings for Clar Structures of Benzenoid Hydrocarbons. J Chem Inf Model 2005; 46:57-64. [PMID: 16426040 DOI: 10.1021/ci050196s] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Resonance structures of polycyclic aromatic hydrocarbons can be associated with numerical formulas by assigning pi-electrons of C=C double bonds to individual benzenoid rings. Each C=C double bond in a resonance structure assigns two pi-electrons to a ring in a fused-benzenoid system if it is not shared by adjacent rings and one pi-electron when it is common to two rings, obtaining thus a "local" characterization of rings in polycyclic conjugated hydrocarbons. In the present contribution we extend this approach to the aromatic pi-sextet model of Clar, which offers an alternative description of benzenoid hydrocarbons. In this model local characteristics of individual benzenoid rings are based on partitioning of pi-electrons but only for those resonance structures (fewer in number) that contribute to Clar's formula of benzenoid hydrocarbons.
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Affiliation(s)
- Milan Randić
- National Institute of Chemistry, Ljubljana, Slovenia, and Texas A&M University Galveston, 77551, USA
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Havenith RWA, van Lenthe JH, Jenneskens LW. An ab Initio Valence Bond Study on Cyclopenta-Fused Naphthalenes and Fluoranthenes. J Org Chem 2005; 70:4484-9. [PMID: 15903329 DOI: 10.1021/jo050296x] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
To probe the effect of external cyclopenta-fusion on a naphthalene core, ab initio valence bond (VB) calculations have been performed, using strictly atomic benzene p-orbitals and p-orbitals that are allowed to delocalize, on naphthalene (1), acenaphthylene (2), pyracylene (3), cyclopenta[b,c]acenaphthylene (4), fluoranthene (5), and cyclopenta[c,d]fluoranthene (6). For the related compounds 1-4 and 5,6 the total resonance energies (according to Pauling's definition) are similar. Partitioning of the total resonance energy in contributions from the possible 4n + 2 and 4n pi-electron conjugated circuits shows that only the 6pi-electron conjugated circuits (benzene-like) contribute to the resonance energy. The results show that cyclopenta-fusion does not extend the pi system in the ground state; the five-membered rings act as peri-substituents. As a consequence, the differences in (total) resonance energy do not coincide with the differences in thermodynamic stability. Notwithstanding, the relative energies of the Kekule structures can be estimated using Randic's conjugated circuits model.
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Affiliation(s)
- Remco W A Havenith
- Debye Institute, Theoretical Chemistry Group and Organic Chemistry and Catalysis, Utrecht University, Padualaan 8, 3584 CH Utrecht, The Netherlands
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Abstract
Tiling modification in nanostructure modeling can be achieved by map operations, as well as the well-known Stone-Wales bond rotation. In this respect, sequences of classical operations, or single generalized operations, were used to obtain corannulenic flowers and corannulene-like azulenic patterns. The first "corazulenic" tessellation is reported. The aromaticity of some cages tessellated by the above supra-faces is discussed in terms of several different criteria. The covering was given as a pi-electron partition within some Kekulé valence structures.The well-known geometric index of aromaticity HOMA (harmonic oscillator model of aromaticity) enabled the evaluation of local aromaticity of the discussed supra-faces and brought evidence for several dominant Kekulé valence structures. The most intriguing is the "Kekulé-Dewar" valence structure of the cage C(192) having a disjoint corazulenic tessellation.
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Affiliation(s)
- Mircea V Diudea
- Faculty of Chemistry and Chemical Engineering, "Babes-Bolyai" University, 400028 Cluj, Romania
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Ruiz-Morales Y. The Agreement between Clar Structures and Nucleus-Independent Chemical Shift Values in Pericondensed Benzenoid Polycyclic Aromatic Hydrocarbons: An Application of the Y-Rule. J Phys Chem A 2004. [DOI: 10.1021/jp040179q] [Citation(s) in RCA: 66] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Yosadara Ruiz-Morales
- Programa de Ingeniería Molecular, Instituto Mexicano del Petróleo, Eje Lázaro Cárdenas 152, Mexico City 07730, Mexico
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37
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Randić M, Balaban AT. PARTITIONING OF π-ELECTRONS IN RINGS OF POLYCYCLIC conjugated HYDROCARBONS. PART 1: CATACONDENSED BENZENOIDS. Polycycl Aromat Compd 2004. [DOI: 10.1080/10406630490432792] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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38
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Abstract
By assigning two pi-electrons of CC double bonds in a Kekulé valence structure to a benzene ring if not shared by adjacent rings and one pi-electron if CC double bond is shared by two rings we arrived at numerical valence formulas for benzenoid hydrocarbons. We refer to numerical Kekulé formulas as algebraic Kekulé valence formulas to contrast them to the traditional geometrical Kekulé valences formulas. The average over all numerical Kekulé valence structures results in a single numerical structure when a benzenoid hydrocarbon molecule is considered. By ignoring numerical values the novel quantitative formula transforms into a qualitative one which can replace incorrectly used notation of pi-electron sextets to indicate aromatic benzenoids by placing inscribed circles in adjacent rings-which contradicts Clar's characterization of benzenoid hydrocarbons.
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Affiliation(s)
- Milan Randić
- National Institute of Chemistry, P.O.B. 3430, 1001 Ljubljana, Slovenia.
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39
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Affiliation(s)
- Milan Randić
- National Institute of Chemistry, Ljubljana, Slovenia
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Guarda VLDM, Perrissin M, Thomasson F, Ximenes EA, Galdino SL, Pitta IR, Luu-Duc C, Barbe J. Synthesis of 4-octyl-2H-1,4-benzo-thiazin-3-ones. Eur J Med Chem 2003; 38:769-73. [PMID: 12932908 DOI: 10.1016/s0223-5234(03)00127-2] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Synthesis, physical and analytical properties of 6-alkylacylamino-4-octyl-2H-1,4-benzo-thiazin-3-ones derivatives are described. These new compounds were prepared by acylation and/or alkylation of the amino group under phase transfer catalysis conditions. Acid hydrolysis of the alkylacylamino-2H-1,4-benzo-thiazin-3-ones afforded N-alkylamino-benzothiazin-3-ones. Some of these compounds were evaluated in vitro for possible bacteriostatic activity.
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Affiliation(s)
- Vera L de M Guarda
- Laboratoire de chimie pharmacie, UPRESA CNRS 5077, Université Joseph-Fourier, Grenoble I, 38706, La Tronche, Cedex, France
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Resonating Valence-Bond theories for carbon π-networks and classical/quantum connections. ACTA ACUST UNITED AC 2002. [DOI: 10.1016/s1380-7323(02)80016-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register]
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Clar’s π-aromatic sextet revisited***This paper is honoring Professor Ivan Gutman, a dedicated warrior for a better recognition of Clar’s insights into the nature of benzenoids dominate properties of benzenoid systems. ACTA ACUST UNITED AC 2002. [DOI: 10.1016/s1380-7323(02)80017-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register]
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Klavzar S, Vesel A, Zigert P, Gutman I. Binary coding of Kekulé structures of catacondensed benzenoid hydrocarbons. COMPUTERS & CHEMISTRY 2001; 25:569-75. [PMID: 11817050 DOI: 10.1016/s0097-8485(01)00068-7] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
An algorithm is described by means of which the Kekulé structures of a catacondensed benzenoid molecule (with h hexagons) are transformed into binary codes (of length h). By this, computer-aided manipulations with, and memory-storage of Kekulé structures are much facilitated. Any Kekulé structure can easily be recovered from its binary code.
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Affiliation(s)
- S Klavzar
- Department of Mathematics, PEF, University of Maribor, Pedagoska Fukultela Maribor, Slovenia.
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Affiliation(s)
- M Bühl
- Max-Planck-Institut für Kohlenforschung, Kaiser-Wilhelm-Platz 1, D-45470 Mülheim an der Ruhr, Germany.
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Randić M, Guo X. Giant Benzenoid Hydrocarbons. Superphenalene Resonance Energy. Polycycl Aromat Compd 2000. [DOI: 10.1080/10406630008233861] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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Randić M, El-Basil S, Nikolić S, Trinajstić N. Clar Polynomials of Large Benzenoid Systems. ACTA ACUST UNITED AC 1998. [DOI: 10.1021/ci970035r] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Milan Randić
- Department of Mathematics and Computer Science, Drake University, Des Moines, Iowa 50311, Faculty of Pharmacy, Kasr El-Aini Street, Cairo 11562, Egypt, and The Rugjer Bošković Institute, P.O. Box 1016, HR-10001 Zagreb, Croatia
| | - Sherif El-Basil
- Department of Mathematics and Computer Science, Drake University, Des Moines, Iowa 50311, Faculty of Pharmacy, Kasr El-Aini Street, Cairo 11562, Egypt, and The Rugjer Bošković Institute, P.O. Box 1016, HR-10001 Zagreb, Croatia
| | - Sonja Nikolić
- Department of Mathematics and Computer Science, Drake University, Des Moines, Iowa 50311, Faculty of Pharmacy, Kasr El-Aini Street, Cairo 11562, Egypt, and The Rugjer Bošković Institute, P.O. Box 1016, HR-10001 Zagreb, Croatia
| | - Nenad Trinajstić
- Department of Mathematics and Computer Science, Drake University, Des Moines, Iowa 50311, Faculty of Pharmacy, Kasr El-Aini Street, Cairo 11562, Egypt, and The Rugjer Bošković Institute, P.O. Box 1016, HR-10001 Zagreb, Croatia
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