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Si MK, Shigeta Y. Rational Design of Cyclopentadiene-Based Super- and Hyperacids Based on Aromaticity. J Phys Chem A 2024; 128:7384-7395. [PMID: 39172702 DOI: 10.1021/acs.jpca.4c03786] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/24/2024]
Abstract
The design and synthesis of neutral organic superacids have been of interest recently due to their vast applications in chemistry and material sciences, for example, olefinic polymerization, isolation of highly reactive short-lived cations, etc. Cyclopentadiene behaves as a mild organic acid, producing a stable conjugate base by gaining aromaticity and conjugation after deprotonation. To stabilize conjugate bases of organic acids to show superacidities and hyperacidities, we considered aromatic phenyl substituents with cyclopentadiene (mono-, di-, and triphenyl-substituted cyclopentadiene and their cyano derivatives). The MP2, DFT (B3LYP, M06-2X), and CBS-QB3 methods were used to calculate the gas-phase proton affinities of the parent cyclopentadiene, and the DFT methods were chosen for the substituted cyclopentadiene as they yield an experimental proton affinity of cyclopentadiene of 253.66 kcal/mol (Expt. 253.6 ± 1.3 kcal/mol). The stable trisubstituted cyclopentadiene derivative shows gas-phase enthalpies of deprotonation (ΔHacid) of 245 and 239 kcal/mol with DFT B3LYP and M06-2X methods, respectively, with values in the range of hyperacidity. Some of the tautomers of cyclopentadiene derivatives show hyperacidity, with proton affinity values of 205-240 kcal/mol. Triphenyl-substituted cyclopentadiene behaves as a moderate acid but transforms into a superacid after replacing the phenyl group with nitrobenzene, which is a stronger acid than H2SO4 (ΔHacid = 298 kcal/mol). The nucleus-independent chemical shift (NICS) shows the extent of conjugation in the derivatives of cyclopentadienyl anions after deprotonation, which affects the stabilities of conjugate bases, i.e., the acidities of the protonated species. The calculated harmonic oscillator model of aromaticity and NICS indices reveal that the stability of conjugate bases as well as their acidities increase with increasing aromaticity of cyclopentadiene rings after deprotonation in all molecules.
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Affiliation(s)
- Mrinal Kanti Si
- Center for Computational Sciences, University of Tsukuba, Tsukuba 305-8577, Japan
| | - Yasuteru Shigeta
- Center for Computational Sciences, University of Tsukuba, Tsukuba 305-8577, Japan
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Salikov RF, Belyy AY, Ilyushchenko MK, Platonov DN, Sokolova AD, Tomilov YV. Antiaromaticity of Cycloheptatrienyl Anions: Structure, Acidity, and Magnetic Properties. Chemistry 2024; 30:e202401041. [PMID: 38785416 DOI: 10.1002/chem.202401041] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2024] [Revised: 05/23/2024] [Accepted: 05/24/2024] [Indexed: 05/25/2024]
Abstract
Investigations of the nature and degree of antiaromaticity of cycloheptatrienyl anion derivatives using both experimental and computational tools are presented. The ground state of cycloheptatrienyl anion in the gas phase is triplet, planar and Baird-aromatic. In DMSO, it assumes a singlet distorted allylic form with a paratropic ring current. The other derivatives in both phases assume either allylic or diallylic conformations depending on the substituent pattern. A combination of experimental and computational methods was used to determine the pKa values of 16 derivatives in DMSO, which ranged from 36 to -10.7. We revealed that the stronger stabilization of the anionic system, which correlates with acidity, does not necessarily imply a lower degree of antiaromaticity in terms of magnetic properties. Conversely, the substitution pattern first affects the geometry of the ring through the bulkiness of the substituents and their better conjugation with a more distorted system. Consequently, the distortion reduces the cyclic conjugation in the π-system and thereby decreases the paratropic current in a magnetic field, which manifests itself as a decrease in the NICS. The triplet-state geometries and magnetic properties are nearly independent on the substitution pattern, which is typical for simple aromatic systems.
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Affiliation(s)
- Rinat F Salikov
- N. D. Zelinsky Institute of Organic Chemistry, Russian Academy of Sciences, 47 Leninsky prosp., Moscow, 119991, Russian Federation
- Department of Chemistry, Higher School of Economics National Research University, Moscow, 101000, Russian Federation
| | - Alexander Y Belyy
- N. D. Zelinsky Institute of Organic Chemistry, Russian Academy of Sciences, 47 Leninsky prosp., Moscow, 119991, Russian Federation
| | - Matvey K Ilyushchenko
- N. D. Zelinsky Institute of Organic Chemistry, Russian Academy of Sciences, 47 Leninsky prosp., Moscow, 119991, Russian Federation
| | - Dmitry N Platonov
- N. D. Zelinsky Institute of Organic Chemistry, Russian Academy of Sciences, 47 Leninsky prosp., Moscow, 119991, Russian Federation
| | - Alena D Sokolova
- N. D. Zelinsky Institute of Organic Chemistry, Russian Academy of Sciences, 47 Leninsky prosp., Moscow, 119991, Russian Federation
| | - Yury V Tomilov
- N. D. Zelinsky Institute of Organic Chemistry, Russian Academy of Sciences, 47 Leninsky prosp., Moscow, 119991, Russian Federation
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In silico designing of Si- and Ge-doped imidazolium: a new heterocyclic aromatic superacid. Theor Chem Acc 2022. [DOI: 10.1007/s00214-022-02934-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/31/2022]
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Spectroscopic and Computational Study of the Protonation Equilibria of Amino-Substituted benzo[b]thieno[2,3-b]pyrido[1,2-a]benzimidazoles as Novel pH-Sensing Materials. CHEMOSENSORS 2022. [DOI: 10.3390/chemosensors10010021] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
We present the synthesis and analytical, spectroscopic and computational characterization of three amino-substituted benzo[b]thieno[2,3-b]pyrido[1,2-a]benzimidazoles as novel pH probes with a potential application in pH-sensing materials. The designed systems differ in the number and position of the introduced isobutylamine groups on the pentacyclic aromatic core, which affects their photophysical and acid-base properties. The latter were investigated by UV-Vis absorption and fluorescence spectroscopies and interpreted by DFT calculations. An excellent agreement in experimentally measured and computationally determined pKa values and electronic excitations suggests that all systems are unionized at neutral pH, while their transition to monocationic forms occurs at pH values between 3 and 5, accompanied by substantial changes in spectroscopic responses that make them suitable for detecting acidic conditions in solutions. Computations identified imidazole imino nitrogen as the most favorable protonation site, further confirmed by analysis of perturbations in the chemical shifts of 1H and 13C NMR, and showed that the resulting basicity emerges as a compromise between the basicity-reducing effect of a nearby nitrile and a favorable contribution from the attached secondary amines. With this in mind, we designed a system with three amino substituents for which calculations predict pKa = 7.0 that we suggest as an excellent starting point for a potential pH sensor able to capture solution changes during the transition from neutral towards acidic media.
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Saeidian H, Malekian H, Vessally E. Density functional estimation of hydride and proton affinities of substituted allenes and heteroallenes. J PHYS ORG CHEM 2021. [DOI: 10.1002/poc.4251] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Affiliation(s)
- Hamid Saeidian
- Department of Science Payame Noor University (PNU) Tehran Iran
| | - Hadi Malekian
- Department of Science Payame Noor University (PNU) Tehran Iran
| | - Esmail Vessally
- Department of Science Payame Noor University (PNU) Tehran Iran
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Saeidian H. Design of organic superacids based on triflic and perchloric acid by using DFT-B3LYP calculations. Struct Chem 2019. [DOI: 10.1007/s11224-019-01444-4] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
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Valadbeigi Y, Vianello R. A density functional theory study on the superacidity of sulfuric, fluorosulfuric, and triflic acid derivatives with two cyclopentadiene rings: ion pairs formation in the gas phase. J PHYS ORG CHEM 2019. [DOI: 10.1002/poc.3995] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Affiliation(s)
- Younes Valadbeigi
- Department of Chemistry, Faculty of ScienceImam Khomeini International University Qazvin Iran
| | - Robert Vianello
- Computational Organic Chemistry and Biochemistry Group, Division of Organic Chemistry and BiochemistryRuđer Bošković Institute Zagreb Croatia
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Saeidian H, Shams B, Mirjafary Z. Comprehensive DFT calculations on organic sulfuric acid derivatives to design of powerful neutral organic superacids. Struct Chem 2018. [DOI: 10.1007/s11224-018-1222-1] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Shams B, Saeidian H. Design of the novel neutral organic superacids by comprehensive DFT study on organic fluorosulfuric acids. COMPUT THEOR CHEM 2018. [DOI: 10.1016/j.comptc.2018.05.011] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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Radtke MA, Lambert TH. Silylated cyclopentadienes as competent silicon Lewis acid catalysts. Chem Sci 2018; 9:6406-6410. [PMID: 30310569 PMCID: PMC6115689 DOI: 10.1039/c8sc02279h] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2018] [Accepted: 06/23/2018] [Indexed: 11/21/2022] Open
Abstract
The synthesis and characterization of silicon Lewis acid complexes that incorporate highly electron-deficient cyclopentadienes is reported. Several pentacarboxycyclopentadienyl and monocarboxytetracyanocyclopentadienyl complexes were prepared. A comparison of their reactivities for catalysis of the allylation of an electron-deficient benzaldehyde was established. The use of a monocarboxytetracyano silylium donor was shown to be effective for the allylation or arylation of a variety of electrophiles via an anion abstraction pathway.
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Affiliation(s)
- M Alex Radtke
- Department of Chemistry , Columbia University , New York , NY 10027 , USA
| | - Tristan H Lambert
- Department of Chemistry , Columbia University , New York , NY 10027 , USA.,Department of Chemistry and Chemical Biology , Cornell University , Ithaca , NY 14853 , USA .
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Horak E, Vianello R, Hranjec M, Murković Steinberg I. Colourimetric and fluorimetric metal ion chemosensor based on a benzimidazole functionalised Schiff base. Supramol Chem 2018. [DOI: 10.1080/10610278.2018.1436708] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Affiliation(s)
- Ema Horak
- Department of General and Inorganic Chemistry, Faculty of Chemical Engineering and Technology, University of Zagreb, Zagreb, Croatia
| | - Robert Vianello
- Computational Organic Chemistry and Biochemistry Group, Ruđer Bošković Institute, Zagreb, Croatia
| | - Marijana Hranjec
- Department of Organic Chemistry, Faculty of Chemical Engineering and Technology, University of Zagreb, Zagreb, Croatia
| | - Ivana Murković Steinberg
- Department of General and Inorganic Chemistry, Faculty of Chemical Engineering and Technology, University of Zagreb, Zagreb, Croatia
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O'Connor GD, Chan B, Sanelli JA, Cergol KM, Dryza V, Payne RJ, Bieske EJ, Radom L, Schmidt TW. Hydrogen-adduction to open-shell graphene fragments: spectroscopy, thermochemistry and astrochemistry. Chem Sci 2017; 8:1186-1194. [PMID: 28451259 PMCID: PMC5369534 DOI: 10.1039/c6sc03787a] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2016] [Accepted: 09/24/2016] [Indexed: 11/25/2022] Open
Abstract
We apply a combination of state-of-the-art experimental and quantum-chemical methods to elucidate the electronic and chemical energetics of hydrogen adduction to a model open-shell graphene fragment. The lowest-energy adduct, 1H-phenalene, is determined to have a bond dissociation energy of 258.1 kJ mol-1, while other isomers exhibit reduced or in some cases negative bond dissociation energies, the metastable species being bound by the emergence of a conical intersection along the high-symmetry dissociation coordinate. The gas-phase excitation spectrum of 1H-phenalene and its radical cation are recorded using laser spectroscopy coupled to mass-spectrometry. Several electronically excited states of both species are observed, allowing the determination of the excited-state bond dissociation energy. The ionization energy of 1H-phenalene is determined to be 7.449(17) eV, consistent with high-level W1X-2 calculations.
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Affiliation(s)
- Gerard D O'Connor
- School of Chemistry , UNSW Sydney , NSW 2052 , Australia . ; Tel: +61 439 386 109
| | - Bun Chan
- School of Chemistry , The University of Sydney , Sydney , New South Wales 2006 , Australia
- Graduate School of Engineering , Nagasaki University , Bunkyo 1-14 , Nagasaki 852-8521 , Japan
| | - Julian A Sanelli
- School of Chemistry , The University of Melbourne , Victoria 3010 , Australia
| | - Katie M Cergol
- School of Chemistry , The University of Sydney , Sydney , New South Wales 2006 , Australia
| | - Viktoras Dryza
- School of Chemistry , The University of Melbourne , Victoria 3010 , Australia
| | - Richard J Payne
- School of Chemistry , The University of Sydney , Sydney , New South Wales 2006 , Australia
| | - Evan J Bieske
- School of Chemistry , The University of Melbourne , Victoria 3010 , Australia
| | - Leo Radom
- School of Chemistry , The University of Sydney , Sydney , New South Wales 2006 , Australia
| | - Timothy W Schmidt
- School of Chemistry , UNSW Sydney , NSW 2052 , Australia . ; Tel: +61 439 386 109
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Mó O, Yáñez M, Alkorta I, Elguero J. Enhancing and modulating the intrinsic acidity of imidazole and pyrazole through beryllium bonds. J Mol Model 2013; 19:4139-45. [PMID: 23292320 DOI: 10.1007/s00894-012-1682-y] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2012] [Accepted: 11/06/2012] [Indexed: 11/30/2022]
Abstract
The structure and electronic properties of the complexes formed by the interaction of imidazole and pyrazole with different BeXH(BeX2) (X = H, Me, F, Cl) derivatives have been investigated via B3LYP/6-311+G(3df,2p)//B3LYP/6-31+G(d,p) calculations. The formation of these azole:BeXH(BeX2) complexes is accompanied by a dramatic enhancement of the intrinsic acidity of the azole, as the deprotonated azole is much more stable after the aforementioned interaction. Most importantly, the increase in acidity is so large that the azole:BeXH or azole:BeX2 complexes behave as NH acids, which are stronger than typical oxyacids such as phosphoric acid and oxalic acid. Interestingly, the increase in acidity can be tuned through appropriate selection of the substituents attached to the Be atom, permitting us to modulate the electron-accepting ability of the BeXH or BeX2 molecule.
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Affiliation(s)
- Otilia Mó
- Departamento de Química, Módulo 13, Universidad Autónoma de Madrid, Campus de Excelencia UAM-CSIC, Cantoblanco, 28049, Madrid, Spain
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Vianello R, Maksić ZB. Polycyano Derivatives of some Organic Tri- and Hexacyclic Molecules Are Powerful Super- and Hyperacids in the Gas Phase and DMSO: Computational Study by DFT Approach. J Org Chem 2010; 75:7670-81. [DOI: 10.1021/jo101581a] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Robert Vianello
- Quantum Organic Chemistry Group, Ruđer, Bošković Institute, Bijenička 54, HR-10000 Zagreb, Croatia
- Laboratory for Biocomputing and Bioinformatics, National Institute of Chemistry, Hajdrihova 19, SI-1000 Ljubljana, Slovenia
| | - Zvonimir B. Maksić
- Quantum Organic Chemistry Group, Ruđer, Bošković Institute, Bijenička 54, HR-10000 Zagreb, Croatia
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Glodde M, Liu S, Varanasi PR. Fluorine-free Photoacid Generators for 193nm Lithography Based on Non-Sulfonate Organic Superacids. J PHOTOPOLYM SCI TEC 2010. [DOI: 10.2494/photopolymer.23.173] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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17
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Fisher EL, Lambert TH. Leaving Group Potential of a Substituted Cyclopentadienyl Anion Toward Oxidative Addition. Org Lett 2009; 11:4108-10. [DOI: 10.1021/ol901598n] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Ethan L. Fisher
- Department of Chemistry, Columbia University, New York, New York 10027
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Ding F, Smith JM, Wang H. First-Principles Calculation of pKa Values for Organic Acids in Nonaqueous Solution. J Org Chem 2009; 74:2679-91. [DOI: 10.1021/jo802641r] [Citation(s) in RCA: 116] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Feizhi Ding
- Department of Chemistry and Biochemistry, New Mexico State University, Las Cruces, New Mexico 88003
| | - Jeremy M. Smith
- Department of Chemistry and Biochemistry, New Mexico State University, Las Cruces, New Mexico 88003
| | - Haobin Wang
- Department of Chemistry and Biochemistry, New Mexico State University, Las Cruces, New Mexico 88003
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Vianello R, Maksić ZB. The engineering of powerful non-ionic superacids in silico—a DFT-B3LYP study of open chain polycyanopolyenes. NEW J CHEM 2009. [DOI: 10.1039/b816922e] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Brand H, Liebman JF, Schulz A. Cyano-, Nitro- and Nitrosomethane Derivatives: Structures and Gas-Phase Acidities. European J Org Chem 2008. [DOI: 10.1002/ejoc.200800583] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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Vianello R, Maksić ZB. Rees polycyanated hydrocarbons and related compounds are extremely powerful Brønsted superacids in the gas-phase and DMSO—a density functional B3LYP study. NEW J CHEM 2008. [DOI: 10.1039/b713173a] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Leito I, Kütt A, Rõõm EI, Koppel I. Anions and and the superacidic properties of their conjugate acids. ACTA ACUST UNITED AC 2007. [DOI: 10.1016/j.theochem.2007.03.017] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Gupta K, Roy D, Subramanian V, Chattaraj P. Are strong Brønsted acids necessarily strong Lewis acids? ACTA ACUST UNITED AC 2007. [DOI: 10.1016/j.theochem.2007.02.013] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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Maksić ZB, Vianello R. Physical origin of chemical phenomena: Interpretation of acidity, basicity, and hydride affinity by trichotomy paradigm. PURE APPL CHEM 2007. [DOI: 10.1351/pac200779061003] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Some of the most important aspects of modeling in chemistry are discussed in detail. It is argued that the interpretive side of (quantum) chemistry is indispensable, since it gives sense to a myriad of experimental and computational results. The usefulness of some physical modeling is illustrated by the trichotomy approach in rationalizing acidity, basicity, and hydride affinities of neutral organic compounds. According to trichotomy paradigm, the simple chemical reaction of protonation and H- attachment can be decomposed into three separate sequential steps, which in turn mirror the initial-, intermediate-, and final-state effects. Ample evidence is given, which convincingly shows that the trichotomy approach has some distinct advantages in interpreting aforementioned properties that belong to the most important ones in chemistry and biochemistry.
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Affiliation(s)
- Zvonimir B. Maksić
- 1Faculty of Science, The University of Zagreb, Horvatovac 102a, 10002 Zagreb, Croatia
| | - Robert Vianello
- 2Quantum Organic Chemistry Group, Division of Organic Chemistry and Biochemistry, Ruđer Bošković Institute, POB 180, 10002 Zagreb, Croatia
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da Silva RR, Ramalho TC, Santos JM, Figueroa-Villar JD. Reply to “Comment on the Paper ‘On the Limits of Highest-Occupied Molecular Orbital Driven Reactions: The Frontier Effective-for-Reaction Molecular Orbital Concept'”. J Phys Chem A 2006. [DOI: 10.1021/jp068065x] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Rodrigo R. da Silva
- Departamento de Química, Instituto Militar de Engenharia, Praça General Tibúrcio, 80, 22290-070, Rio de Janeiro-RJ, Brazil, Departamento de Química Geral e Inorgânica, Instituto de Química, Universidade do Estado do Rio de Janeiro, Rua São Francisco Xavier, 524, 20550-013 Rio de Janeiro-RJ, Brazil, and Departamento de Química, Universidade Federal de Lavras, Campus Universitário, CP 3037, 37200-000 Lavras-MG, Brazil
| | - Teodorico C. Ramalho
- Departamento de Química, Instituto Militar de Engenharia, Praça General Tibúrcio, 80, 22290-070, Rio de Janeiro-RJ, Brazil, Departamento de Química Geral e Inorgânica, Instituto de Química, Universidade do Estado do Rio de Janeiro, Rua São Francisco Xavier, 524, 20550-013 Rio de Janeiro-RJ, Brazil, and Departamento de Química, Universidade Federal de Lavras, Campus Universitário, CP 3037, 37200-000 Lavras-MG, Brazil
| | - Joana M. Santos
- Departamento de Química, Instituto Militar de Engenharia, Praça General Tibúrcio, 80, 22290-070, Rio de Janeiro-RJ, Brazil, Departamento de Química Geral e Inorgânica, Instituto de Química, Universidade do Estado do Rio de Janeiro, Rua São Francisco Xavier, 524, 20550-013 Rio de Janeiro-RJ, Brazil, and Departamento de Química, Universidade Federal de Lavras, Campus Universitário, CP 3037, 37200-000 Lavras-MG, Brazil
| | - J. Daniel Figueroa-Villar
- Departamento de Química, Instituto Militar de Engenharia, Praça General Tibúrcio, 80, 22290-070, Rio de Janeiro-RJ, Brazil, Departamento de Química Geral e Inorgânica, Instituto de Química, Universidade do Estado do Rio de Janeiro, Rua São Francisco Xavier, 524, 20550-013 Rio de Janeiro-RJ, Brazil, and Departamento de Química, Universidade Federal de Lavras, Campus Universitário, CP 3037, 37200-000 Lavras-MG, Brazil
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Vianello R, Maksić ZB. Triadic analysis of substituent effects—gas-phase acidity of para-substituted phenols. Tetrahedron 2006. [DOI: 10.1016/j.tet.2006.01.049] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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Kütt A, Leito I, Kaljurand I, Sooväli L, Vlasov VM, Yagupolskii LM, Koppel IA. A Comprehensive Self-Consistent Spectrophotometric Acidity Scale of Neutral Brønsted Acids in Acetonitrile. J Org Chem 2006; 71:2829-38. [PMID: 16555839 DOI: 10.1021/jo060031y] [Citation(s) in RCA: 259] [Impact Index Per Article: 14.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
For the first time, the self-consistent spectrophotometric acidity scale of neutral Brønsted acids in acetonitrile (AN) spanning 24 orders of magnitude of acidities is reported. The scale ranges from pK(a) 3.7 to 28.1 in AN. The scale includes 93 acids that are interconnected by 203 relative acidity measurements (DeltapK(a) measurements) and contains compounds with gradually changing acidities, including representatives from all of the conventional families of OH (alcohols, phenols, carboxylic acids, sulfonic acids), NH (anilines, diphenylamines, disulfonimides), and CH acids (fluorenes, diphenylacetonitriles, phenylmalononitriles). The CH acids were particularly useful in constructing the scale because they do not undergo homo- or heteroconjugation processes and their acidities are rather insensitive to traces of water in the medium. The scale has been fully cross-validated: the relative acidity of any two acids on the scale can be found by combining at least two independent sets of DeltapK(a) measurements. The consistency standard deviation of the scale is 0.03 pK(a) units. Comparison of acidities in many different media has been carried out, and the structure-acidity relations are discussed. The large variety of the acids on the scale, its wide span, and the quality of the data make the scale a useful tool for further acidity studies in acetonitrile.
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Affiliation(s)
- Agnes Kütt
- Institute of Chemical Physics, Department of Chemistry, University of Tartu, Jakobi 2 Str., 51014 Tartu, Estonia
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