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Leyva-Parra L, Pino-Rios R. Update for Isomerization Stabilization Energies: The Fulvenization Approach. ACS OMEGA 2024; 9:1436-1442. [PMID: 38222592 PMCID: PMC10785285 DOI: 10.1021/acsomega.3c07881] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/09/2023] [Revised: 11/28/2023] [Accepted: 12/04/2023] [Indexed: 01/16/2024]
Abstract
An alternative approach for calculating aromatic stabilization energies is proposed based on transforming an (anti)aromatic ring into a fulvene isomer. This fulvenization process gives a value of 34.05 kcal·mol-1 for benzene in the singlet state and a value of -17.85 kcal·mol-1 in the triplet state. Additionally, it is possible to use experimental values (as long as they exist) for the calculation as the gas-phase formation enthalpies of benzene and fulvene, whose difference is 33.72 kcal·mol-1. On the other hand, this same approach has been evaluated on several six-membered rings, including those persubstituted, biradicals, azines, and inorganic analogues, giving results in agreement with those reported in the literature using different criteria. Additionally, it is possible to differentiate the aromaticity of the rings in polycyclic aromatic hydrocarbons according to Clar's rules. Assigning the (anti)aromatic character in various nonbenzenoid rings (neutral and charged), except for five- and seven-membered rings, is also possible. The construction of the fulvene isomers in PAHs is set such that nonaromaticity-related effects are not considered. The results show that the fulvenization approach is an effective and efficient approach that can serve as an alternative or complement to existing tools.
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Affiliation(s)
- Luis Leyva-Parra
- Departamento
de Ciencias Químicas, Centro de Química Teórica
& Computacional (CQT&C), Universidad
Andrés Bello, Facultad de Ciencias Exactas, Avenida República 275, 8370146 Santiago de Chile, Chile
| | - Ricardo Pino-Rios
- Instituto
de Estudios de la Salud, Universidad Arturo
Prat, 1100000 Iquique, Chile
- Química
y Farmacia, Facultad de Ciencias de la Salud, Universidad Arturo Prat, Casilla 121, 1100000 Iquique, Chile
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2
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Coordination Chemistry of Polynitriles, Part XII—Serendipitous Synthesis of the Octacyanofulvalenediide Dianion and Study of Its Coordination Chemistry with K+ and Ag+. INORGANICS 2023. [DOI: 10.3390/inorganics11020071] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
The reaction of diazotetracyanocyclopentadiene with copper powder in the presence of NEt4Cl yields, unexpectedly, besides the known NEt4[C5H(CN)4] (3), the NEt4 salt of octacyanofulvalenediide (NEt4)2[C10(CN)8] (5), which can be transformed via reaction with AgNO3 to the corresponding Ag+ salt (4), which in turn can be reacted with KCl to yield the corresponding K+ salt 6. The molecular and crystal structures of 4–6 could be determined, and show a significantly twisted aromatic dianion which uses all its nitrile groups for coordination to the metals; 4 and 6 form three-dimensional coordination polymers with fourfold coordinated Ag+ and eightfold coordinated K+ cations.
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3
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Wang J, Kleimeier NF, Johnson RN, Gozem S, Abplanalp MJ, Turner AM, Marks JH, Kaiser RI. Photochemically triggered cheletropic formation of cyclopropenone (c-C 3H 2O) from carbon monoxide and electronically excited acetylene. Phys Chem Chem Phys 2022; 24:17449-17461. [PMID: 35713004 DOI: 10.1039/d2cp01978g] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
For more than half a century, pericyclic reactions have played an important role in advancing our fundamental understanding of cycloadditions, sigmatropic shifts, group transfer reactions, and electrocyclization reactions. However, the fundamental mechanisms of photochemically activated cheletropic reactions have remained contentious. Here we report on the simplest cheletropic reaction: the [2+1] addition of ground state 18O-carbon monoxide (C18O, X1Σ+) to D2-acetylene (C2D2) photochemically excited to the first excited triplet (T1), second excited triplet (T2), and first excited singlet state (S1) at 5 K, leading to the formation of D2-18O-cyclopropenone (c-C3D218O). Supported by quantum-chemical calculations, our investigation provides persuasive testimony on stepwise cheletropic reaction pathways to cyclopropenone via excited state dynamics involving the T2 (non-adiabatic) and S1 state (adiabatic) of acetylene at 5 K, while the T1 state energetically favors an intermediate structure that directly dissociates after relaxing to the ground state. The agreement between experiments in low temperature ices and the excited state calculations signifies how photolysis experiments coupled with theoretical calculations can untangle polyatomic reactions with relevance to fundamental physical organic chemistry at the molecular level, thus affording a versatile strategy to unravel exotic non-equilibrium chemistries in cyclic, aromatic organics. Distinct from traditional radical-radical pathways leading to organic molecules on ice-coated interstellar nanoparticles (interstellar grains) in cold molecular clouds and star-forming regions, the photolytic formation of cyclopropenone as presented changes the perception of how we explain the formation of complex organics in the interstellar medium eventually leading to the molecular precursors of biorelevant molecules.
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Affiliation(s)
- Jia Wang
- Department of Chemistry, University of Hawaii at Manoa, Honolulu, HI 96822, USA. .,W. M. Keck Research Laboratory in Astrochemistry, University of Hawaii at Manoa, Honolulu, HI 96822, USA
| | - N Fabian Kleimeier
- Department of Chemistry, University of Hawaii at Manoa, Honolulu, HI 96822, USA. .,W. M. Keck Research Laboratory in Astrochemistry, University of Hawaii at Manoa, Honolulu, HI 96822, USA
| | - Rebecca N Johnson
- Department of Chemistry, Georgia State University, Atlanta, GA 30302, USA.
| | - Samer Gozem
- Department of Chemistry, Georgia State University, Atlanta, GA 30302, USA.
| | - Matthew J Abplanalp
- Department of Chemistry, University of Hawaii at Manoa, Honolulu, HI 96822, USA. .,W. M. Keck Research Laboratory in Astrochemistry, University of Hawaii at Manoa, Honolulu, HI 96822, USA
| | - Andrew M Turner
- Department of Chemistry, University of Hawaii at Manoa, Honolulu, HI 96822, USA. .,W. M. Keck Research Laboratory in Astrochemistry, University of Hawaii at Manoa, Honolulu, HI 96822, USA
| | - Joshua H Marks
- Department of Chemistry, University of Hawaii at Manoa, Honolulu, HI 96822, USA. .,W. M. Keck Research Laboratory in Astrochemistry, University of Hawaii at Manoa, Honolulu, HI 96822, USA
| | - Ralf I Kaiser
- Department of Chemistry, University of Hawaii at Manoa, Honolulu, HI 96822, USA. .,W. M. Keck Research Laboratory in Astrochemistry, University of Hawaii at Manoa, Honolulu, HI 96822, USA
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4
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Mayr H, Hartnagel M, Ofial AR. Elucidation of the Nucleophilic Potential of Diazocyclopentadiene. SYNTHESIS-STUTTGART 2022. [DOI: 10.1055/s-0041-1737327] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
Abstract
AbstractDiazocyclopentadiene reacts with benzhydrylium ions (Ar2CH+) to give 2,5-dibenzhydryl-substituted diazocyclopentadienes. The kinetics have been determined photometrically in dichloromethane under pseudo-first-order conditions using diazocyclopentadiene in excess. Plots of the second-order rate constants (log k
2) versus the electrophilicity parameters E of the benzhydrylium ions gave the nucleophilicity parameter N = 4.84 and susceptibility s
N = 1.06 for diazocyclopentadiene according to the correlation log k(20 °C) = s
N(E + N). Diazocyclopentadiene thus has a similar nucleophilic reactivity as pyrrole. Previously reported electrophilic substitutions of diazocyclopentadiene are rationalized by these parameters and new reaction possibilities are predicted.
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5
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Berlicka A, Foryś-Martowłos P, Hassa K, Białek MJ, Ślepokura K, Latos-Grażyński L. 21-Carba-23-oxaporphyrinoids and 21-oxo-21-carba-23-oxaporphyrinoids: macrocyclic π-conjugation involving the carbonyl moiety. Org Chem Front 2022. [DOI: 10.1039/d2qo00960a] [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
Aromaticity of 21-oxo-21-carba-23-oxachlorin resulted from a predominant dipolar contributor. Nonaromaticity of 21-oxo-21-carba-23-oxaporphyrin reflects a participation of canonical aromatic and antiaromatic forms engaged in a peculiar “tug of war”.
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Affiliation(s)
- Anna Berlicka
- Department of Chemistry, University of Wrocław, 14 F. Joliot-Curie, 50-383 Wrocław, Poland
| | | | - Karolina Hassa
- Department of Chemistry, University of Wrocław, 14 F. Joliot-Curie, 50-383 Wrocław, Poland
| | - Michał J. Białek
- Department of Chemistry, University of Wrocław, 14 F. Joliot-Curie, 50-383 Wrocław, Poland
| | - Katarzyna Ślepokura
- Department of Chemistry, University of Wrocław, 14 F. Joliot-Curie, 50-383 Wrocław, Poland
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6
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Kodama T, Kawashima Y, Uchida K, Deng Z, Tobisu M. Synthesis and Characterization of 1-Hydroxy-4,5-arene-Fused Tropylium Derivatives. J Org Chem 2021; 86:13800-13807. [PMID: 34519215 DOI: 10.1021/acs.joc.1c01818] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The properties of 1-hydroxy-4,5-arene-fused tropyliums were assessed based on experimental and theoretical investigations. An X-ray crystallographic analysis revealed a decrease of bond alternation in the seven-membered ring of 1-hydroxy-4,5-benzotropylium derivatives compared with that of the parent 4,5-benzotropones, which is indicative of an increase in aromaticity upon protonation. NICS and AICD calculations also supported the increased aromaticity of 1-hydroxy-4,5-arene-fused tropylium. The pKa values for a series of 1-hydroxy-4,5-arene-fused tropylium derivatives were also determined.
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Affiliation(s)
- Takuya Kodama
- Department of Applied Chemistry, Graduate School of Engineering, Osaka University, Suita, Osaka 565-0871, Japan.,Innovative Catalysis Science Division, Institute for Open and Transdisciplinary Research Initiatives (ICS-OTRI), Osaka University, Suita, Osaka 565-0871, Japan
| | - Yuki Kawashima
- Department of Applied Chemistry, Graduate School of Engineering, Osaka University, Suita, Osaka 565-0871, Japan
| | - Kenta Uchida
- Department of Applied Chemistry, Graduate School of Engineering, Osaka University, Suita, Osaka 565-0871, Japan
| | - Zhirong Deng
- Department of Applied Chemistry, Graduate School of Engineering, Osaka University, Suita, Osaka 565-0871, Japan
| | - Mamoru Tobisu
- Department of Applied Chemistry, Graduate School of Engineering, Osaka University, Suita, Osaka 565-0871, Japan.,Innovative Catalysis Science Division, Institute for Open and Transdisciplinary Research Initiatives (ICS-OTRI), Osaka University, Suita, Osaka 565-0871, Japan
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7
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Pandey SK, Arunan E. Effects of Multiple OH/SH Substitution on the H‐Bonding/Stability versus Aromaticity of Benzene Rings: From Computational Insights. ChemistrySelect 2021. [DOI: 10.1002/slct.202100689] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Affiliation(s)
- Sarvesh Kumar Pandey
- Department of Inorganic and Physical Chemistry Indian Institute of Science Bangalore Bangalore 560 012 India
- Department of Chemistry Indian Institute of Technology Kanpur Kanpur 208 016 India
| | - Elangannan Arunan
- Department of Inorganic and Physical Chemistry Indian Institute of Science Bangalore Bangalore 560 012 India
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8
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O'Driscoll LJ, Bryce MR. Extended curly arrow rules to rationalise and predict structural effects on quantum interference in molecular junctions. NANOSCALE 2021; 13:1103-1123. [PMID: 33393950 DOI: 10.1039/d0nr07819k] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/02/2023]
Abstract
The ability to easily and reliably predict quantum interference (QI) behaviour would facilitate the design of functional molecular wires with potential applications in switches, transistors and thermoelectric devices. A variety of predictive methods exist, but with the exception of computationally-expensive DFT-based charge transport simulations, these often fail to account for the experimentally observed behaviour of molecules that differ significantly in structure from alternant polycyclic aromatic hydrocarbons. By considering a range of prior studies we have developed an extension to predictive "curly arrow rules". We show that, in most cases, these extended curly arrow rules (ECARs) can rationalise the type of QI exhibited by conjugated molecular wires containing heteroatoms, cross-conjugation and/or non-alternant structures. ECARs provide a straightforward "pen-and-paper" method to predict whether a molecular wire will display constructive, destructive or "shifted destructive" QI, i.e. whether or not its transmission function would be expected to show an antiresonance, and if this antiresonance would occur close to the Fermi energy or be shifted elsewhere.
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Affiliation(s)
- Luke J O'Driscoll
- Department of Chemistry, Durham University, Lower Mountjoy, Stockton Road, Durham, DH1 3LE, UK.
| | - Martin R Bryce
- Department of Chemistry, Durham University, Lower Mountjoy, Stockton Road, Durham, DH1 3LE, UK.
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9
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Orozco AJ, Joachim K, Ruiz HD, Fronczek FR, Isovitsch R. Investigating the change in the photophysical properties of a trio of tetraphenylcyclopentadienone derivatives with varied groups on the aromatic rings in the 3- and 4-positions. LUMINESCENCE 2020; 36:247-255. [PMID: 32860639 DOI: 10.1002/bio.3944] [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: 05/11/2020] [Revised: 08/14/2020] [Accepted: 08/27/2020] [Indexed: 11/08/2022]
Abstract
Organic compounds with electronic properties, such as a small band gap, are useful in areas ranging from organic field effect transistors to solar cells. Such organic compounds can possess conjugation and/or aromatic systems, with one example being tetraphenylcyclopentadienone and its derivatives. A trio of dramatically coloured tetraphenylcyclopentadienone derivatives with varied substituents on the aromatic rings in the 3- and 4-positions were prepared. Their identities were confirmed using the usual methods, for example 1 H nuclear magnetic resonance (NMR) spectroscopy, and their purity quantified using elemental analysis. The X-ray crystal structure of compound 2 was determined. Its notable structural features involved the cyclopentadienone core with its distinct C-C and C=C bond lengths and its overall nonplanarity, both of which served to mitigate its antiaromatic nature. Chloroform solutions of compounds 2-4 exhibited absorption spectra with three absorption bands at approximately 250, 350, and 500 nm that were assigned to (π)→(π*) transitions. Computational chemistry methods assisted in assigning the observed transitions to a specific molecular orbital combination in the structures of 2-4. Emission in the red end of the visible spectrum (550-625 nm) was observed from chloroform solutions of all three of the prepared compounds.
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Affiliation(s)
| | - Kole Joachim
- Department of Chemistry, Whittier College, Whittier, CA, USA
| | - Henry D Ruiz
- Department of Chemistry, Whittier College, Whittier, CA, USA
| | - Frank R Fronczek
- Department of Chemistry, Louisiana State University, Baton Rouge, LA, USA
| | - Ralph Isovitsch
- Department of Chemistry, Whittier College, Whittier, CA, USA
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10
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Jena S, Tulsiyan KD, Rana A, Choudhury SS, Biswal HS. Non-conventional Hydrogen Bonding and Aromaticity: A Systematic Study on Model Nucleobases and Their Solvated Clusters. Chemphyschem 2020; 21:1826-1835. [PMID: 32506748 DOI: 10.1002/cphc.202000386] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2020] [Revised: 06/02/2020] [Indexed: 12/25/2022]
Abstract
The conceptual development of aromaticity is essential to rationalize and understand the structure and behavior of aromatic heterocycles. This work addresses for the first time, the interconnection between aromaticity and sulfur/selenium centered hydrogen bonds (S/SeCHBs) involved in representative heterocycle models of canonical nucleobases (2-Pyridone; 2PY) and its sulfur (2-Thiopyridone; 2TPY) and selenium (2-Selenopyridone; 2SePY) analogs. The nucleus-independent chemical shift (NICS) and gauge induced magnetic current density (GIMIC) values suggested significant reduction of aromaticity upon replacement of exocyclic carbonyl oxygen with sulfur and selenium. However, we observed two-fold (57 %) and three-fold (80 %) enhancement in the aromaticity for 2TPY dimer, and 2SePY dimer, respectively which are connected through S/SeCHBs. Aromaticity enhancement was also noticed in 1 : 1 H-bonded complexes (heterodimers), micro hydrated clusters and for bulk hydration. It is expected that exocyclic S and Se incorporation into heterocycles without compromising aromatic loss would definitely reinforce to design new supramolecular building blocks via S/SeCH-bonded complexes.
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Affiliation(s)
- Subhrakant Jena
- School of Chemical Sciences, National Institute of Science Education and Research (NISER), PO-Bhimpur-Padanpur, Via-Jatni, District-Khurda, PIN-752050, Bhubaneswar, INDIA.,Homi Bhaba National Institute, Training School Complex, Anushakti Nagar, Mumbai, 400094, INDIA
| | - Kiran Devi Tulsiyan
- School of Chemical Sciences, National Institute of Science Education and Research (NISER), PO-Bhimpur-Padanpur, Via-Jatni, District-Khurda, PIN-752050, Bhubaneswar, INDIA.,Homi Bhaba National Institute, Training School Complex, Anushakti Nagar, Mumbai, 400094, INDIA
| | - Abhijit Rana
- School of Chemical Sciences, National Institute of Science Education and Research (NISER), PO-Bhimpur-Padanpur, Via-Jatni, District-Khurda, PIN-752050, Bhubaneswar, INDIA.,Homi Bhaba National Institute, Training School Complex, Anushakti Nagar, Mumbai, 400094, INDIA
| | - Shubhranshu S Choudhury
- School of Chemical Sciences, National Institute of Science Education and Research (NISER), PO-Bhimpur-Padanpur, Via-Jatni, District-Khurda, PIN-752050, Bhubaneswar, INDIA.,Homi Bhaba National Institute, Training School Complex, Anushakti Nagar, Mumbai, 400094, INDIA
| | - Himansu S Biswal
- School of Chemical Sciences, National Institute of Science Education and Research (NISER), PO-Bhimpur-Padanpur, Via-Jatni, District-Khurda, PIN-752050, Bhubaneswar, INDIA.,Homi Bhaba National Institute, Training School Complex, Anushakti Nagar, Mumbai, 400094, INDIA
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11
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Paudel HR, Karas LJ, Wu JIC. On the reciprocal relationship between σ-hole bonding and (anti)aromaticity gain in ketocyclopolyenes. Org Biomol Chem 2020; 18:5125-5129. [PMID: 32601633 DOI: 10.1039/d0ob01076f] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
σ-Hole bonding interactions (e.g., tetrel, pnictogen, chalcogen, and halogen bonding) can polarize π-electrons to enhance cyclic [4n] π-electron delocalization (i.e., antiaromaticity gain) or cyclic [4n + 2] π-electron delocalization (i.e., aromaticity gain). Examples based on the ketocyclopolyenes: cyclopentadienone, tropone, and planar cyclononatetraenone are presented. Recognizing this relationship has implications, for example, for tuning the electronic properties of fulvene-based π-conjugated systems such as 9-fluorenone.
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Affiliation(s)
- Hari Ram Paudel
- Department of Chemistry, University of Houston, Houston, TX 77204, USA.
| | - Lucas José Karas
- Department of Chemistry, University of Houston, Houston, TX 77204, USA.
| | - Judy I-Chia Wu
- Department of Chemistry, University of Houston, Houston, TX 77204, USA.
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12
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Coluccini C, Anusha PT, Chen HYT, Liao SL, Ko YK, Yabushita A, Luo CW, Ng YM, Khung YL. Tuning of the Electro-Optical Properties of Tetraphenylcyclopentadienone via Substitution of Oxygen with Sterically-Hindered Electron Withdrawing Groups. Sci Rep 2019; 9:12762. [PMID: 31484973 PMCID: PMC6726659 DOI: 10.1038/s41598-019-49303-w] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2019] [Accepted: 08/19/2019] [Indexed: 01/09/2023] Open
Abstract
In this report, the substitution of the oxygen group (=O) of Tetraphenylcyclopentadienone with =CR2 group (R = methyl ester or nitrile) was found to have tuned the electro-optical properties of the molecule. Although both groups are electrons withdrawing in nature, their absorption from UV-vis spectra analysis was observed to have been blue-shifted by methyl ester substitution and red-shifted by nitrile substitution. Interestingly, these substitutions helped to enhance the overall intensity of emission, especially in the context of methyl ester substitution whereby the emission was significantly boosted at higher concentrations due to hypothesized restrictions of intramolecular motions. These observations were explained through detailed descriptions of the electron withdrawing capability and steric properties of the substituents on the basis of density functional theory calculations.
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Affiliation(s)
- Carmine Coluccini
- Institute of New Drug Development, China Medical University, No.91 Hsueh-Shih Road, Taichung, 40402, Taiwan
| | - Puliparambil Thilakan Anusha
- Department of Electrophysics, National Chiao Tung University, 1001 University Road, Hsinchu, 30010, Taiwan
- Department of Physics, School of Advanced Sciences, Vellore Institute of Technology, Vellore, 632 014, India
| | - Hsin-Yi Tiffany Chen
- Department of Engineering and System Science, National Tsing Hua University, Hsinchu, 30013, Taiwan
| | - Sheng-Lun Liao
- Molecular Science Center, GGA Corp, Taipei, 11493, Taiwan
| | - Ying Kuan Ko
- Department of Electrophysics, National Chiao Tung University, 1001 University Road, Hsinchu, 30010, Taiwan
| | - Atsushi Yabushita
- Department of Electrophysics, National Chiao Tung University, 1001 University Road, Hsinchu, 30010, Taiwan
| | - Chih Wei Luo
- Department of Electrophysics, National Chiao Tung University, 1001 University Road, Hsinchu, 30010, Taiwan
- Taiwan Consortium of Emergent Crystalline Materials (TCECM), Ministry of Science and Technology, Taipei, Taiwan
| | - Yoke Mooi Ng
- Institute of New Drug Development, China Medical University, No.91 Hsueh-Shih Road, Taichung, 40402, Taiwan
| | - Yit Lung Khung
- Department of Biological Science and Technology, China Medical University, No.91 Hsueh-Shih Road, Taichung, 40402, Taiwan.
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13
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Anjali BA, Suresh CH. Predicting reduction potentials of 1,3,6-triphenyl fulvenes using molecular electrostatic potential analysis of substituent effects. J Comput Chem 2018; 39:881-888. [PMID: 29322538 DOI: 10.1002/jcc.25164] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2017] [Revised: 12/20/2017] [Accepted: 12/22/2017] [Indexed: 11/06/2022]
Abstract
The influence of mono- and multiple substituent effect on the reduction potential (E0 ) of 1,3,6-triphenyl fulvenes is investigated using B3LYP-SMD/6-311+G(d,p) level density functional theory. The molecular electrostatic potential (MESP) minimum at the fulvene π-system (Vmin ) and the change in MESP at any of the fulvene carbon atoms (ΔVC ) for both neutral and reduced forms are used as excellent measures of substituent effect from the para and meta positions of the 1,3 and 6-phenyl moieties. Substitution at 6-phenyl para position has led to significant change in E0 than any other positions. By applying the additivity rule of substituent effects, an equation in ΔVC is derived to predict E0 for multiply substituted fulvenes. Further, E0 is predicted for a set of 2000 hexa-substituted fulvene derivatives where the substituents and their positions in the system are chosen in a random way. The calculated E0 agreed very well with the experimental E0 reported by Godman et al. Predicting E0 solely by substituent effect offers a simple and powerful way to select suitable combinations of substituents on fulvene system for light harvesting applications. © 2018 Wiley Periodicals, Inc.
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Affiliation(s)
- Bai Amutha Anjali
- Chemical Sciences and Technology Division, Academy of Scientific & Innovative Research (AcSIR), CSIR-National Institute for Interdisciplinary Science and Technology, Trivandrum, 695019, India
| | - Cherumuttathu H Suresh
- Chemical Sciences and Technology Division, Academy of Scientific & Innovative Research (AcSIR), CSIR-National Institute for Interdisciplinary Science and Technology, Trivandrum, 695019, India
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14
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Electronic properties and aromaticity of substituted diphenylfulvenes in the ground (S0) and excited (T1) states. Struct Chem 2017. [DOI: 10.1007/s11224-017-0995-y] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
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15
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Preethalayam P, Krishnan KS, Thulasi S, Chand SS, Joseph J, Nair V, Jaroschik F, Radhakrishnan KV. Recent Advances in the Chemistry of Pentafulvenes. Chem Rev 2017; 117:3930-3989. [DOI: 10.1021/acs.chemrev.6b00210] [Citation(s) in RCA: 87] [Impact Index Per Article: 12.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Preethanuj Preethalayam
- Organic
Chemistry Section, National Institute for Interdisciplinary Science and Technology (CSIR-NIIST), Trivandrum 695 019, Kerala, India
| | - K. Syam Krishnan
- Organic
Chemistry Section, National Institute for Interdisciplinary Science and Technology (CSIR-NIIST), Trivandrum 695 019, Kerala, India
| | - Sreeja Thulasi
- Organic
Chemistry Section, National Institute for Interdisciplinary Science and Technology (CSIR-NIIST), Trivandrum 695 019, Kerala, India
| | - S. Sarath Chand
- Organic
Chemistry Section, National Institute for Interdisciplinary Science and Technology (CSIR-NIIST), Trivandrum 695 019, Kerala, India
| | - Jomy Joseph
- Institut de Chimie Moléculaire de Reims CNRS (UMR 7312) and Université de Reims Champagne-Ardenne, Reims 51687 Cedex 2, France
| | - Vijay Nair
- Organic
Chemistry Section, National Institute for Interdisciplinary Science and Technology (CSIR-NIIST), Trivandrum 695 019, Kerala, India
| | - Florian Jaroschik
- Institut de Chimie Moléculaire de Reims CNRS (UMR 7312) and Université de Reims Champagne-Ardenne, Reims 51687 Cedex 2, France
| | - K. V. Radhakrishnan
- Organic
Chemistry Section, National Institute for Interdisciplinary Science and Technology (CSIR-NIIST), Trivandrum 695 019, Kerala, India
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16
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Methylenecyclopropene: local vision of the first 1B 2 excited state. J Mol Model 2017; 23:22. [PMID: 28064374 DOI: 10.1007/s00894-016-3191-x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2016] [Accepted: 12/15/2016] [Indexed: 10/20/2022]
Abstract
The 1A1 ground and the first 1B2 excited states of the methylenecyclopropene (triafulvene) are described by localized wave functions, based on 20 structures valence bond structures. The results are compared to CASSCF(4,4) calculations for both the energetics and the dipole moment. Additional calculations with partial electronic delocalization are presented, and it is shown that the dipole moment modification does not correspond to a situation where the antiaromatic situation prevails (with 4n electrons in the cycle). Part of the analysis uses a "trust factor" that helps to decide if a wave function is appropriate to describe a given state. The trust factor compares the VB wave function to the CASSCF's with their overlap. Finally, the valence bond density is used to produce density maps that illustrate the electron transfer upon excitation. Graphical Abstract A projector-based method compares CASSCF wave functions to local wave functions, including Lewis structures as shown in the picture. A "trust factor" (τ) is obtained. Both the ground state and the first excited state of the methylenecyclopropene are discussed.
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17
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Yu D, Rong C, Lu T, Chattaraj PK, De Proft F, Liu S. Aromaticity and antiaromaticity of substituted fulvene derivatives: perspectives from the information-theoretic approach in density functional reactivity theory. Phys Chem Chem Phys 2017; 19:18635-18645. [DOI: 10.1039/c7cp03544f] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Strong correlations among aromaticity descriptors and information-theoretic quantities are unveiled, providing novel insights about aromaticity and antiaromaticity from different perspectives.
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Affiliation(s)
- Donghai Yu
- Key Laboratory of Chemical Biology and Traditional Chinese Medicine Research (Ministry of Education of China)
- College of Chemistry and Chemical Engineering
- Hunan Normal University
- Changsha
- P. R. China
| | - Chunying Rong
- Key Laboratory of Chemical Biology and Traditional Chinese Medicine Research (Ministry of Education of China)
- College of Chemistry and Chemical Engineering
- Hunan Normal University
- Changsha
- P. R. China
| | - Tian Lu
- Beijing Kein Research Center for Natural Sciences
- Beijing 100022
- P. R. China
| | - Pratim K. Chattaraj
- Department of Chemistry and Center for Theoretical Studies
- Indian Institute of Technology
- Kharagpur 721302
- India
| | - Frank De Proft
- Research Group of General Chemistry (ALGC)
- Vrije Universiteit Brussel (VUB)
- 1050 Brussels
- Belgium
| | - Shubin Liu
- Key Laboratory of Chemical Biology and Traditional Chinese Medicine Research (Ministry of Education of China)
- College of Chemistry and Chemical Engineering
- Hunan Normal University
- Changsha
- P. R. China
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18
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Mauksch M, Tsogoeva SB. 4N electron aromatic cycles in polycyclic hydrocarbons. Phys Chem Chem Phys 2017; 19:14066-14072. [DOI: 10.1039/c7cp02288c] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Antiaromatic frameworks become aromatic in polycyclics through fusion, resulting in 4N electron hydrocarbons that possess aromatic properties by energetic, magnetic and geometric criteria.
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Affiliation(s)
- Michael Mauksch
- Department of Chemistry and Pharmacy
- Institute of Theoretical Chemistry
- Computer Chemistry Center
- 91052 Erlangen
- Germany
| | - Svetlana B. Tsogoeva
- Department of Chemistry and Pharmacy
- Organic Chemistry Chair I and Interdisciplinary Center for Molecular Materials (ICMM)
- Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU)
- Henkestrasse 42, 91054 Erlangen
- Germany
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19
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Wu JI, Jackson JE, Schleyer PVR. Reciprocal Hydrogen Bonding–Aromaticity Relationships. J Am Chem Soc 2014; 136:13526-9. [DOI: 10.1021/ja507202f] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Judy I. Wu
- Center
for Computational Quantum Chemistry, University of Georgia, Athens, Georgia 30602, United States
| | - James E. Jackson
- Department
of Chemistry, Michigan State University, East Lansing, Michigan 48824, United States
| | - Paul von Ragué Schleyer
- Center
for Computational Quantum Chemistry, University of Georgia, Athens, Georgia 30602, United States
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20
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Jorner K, Emanuelsson R, Dahlstrand C, Tong H, Denisova AV, Ottosson H. Impact of Ground- and Excited-State Aromaticity on Cyclopentadiene and Silole Excitation Energies and Excited-State Polarities. Chemistry 2014; 20:9295-303. [DOI: 10.1002/chem.201402577] [Citation(s) in RCA: 52] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2014] [Indexed: 11/09/2022]
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21
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Pal R, Mukherjee S, Chandrasekhar S, Guru Row TN. Exploring Cyclopentadienone Antiaromaticity: Charge Density Studies of Various Tetracyclones. J Phys Chem A 2014; 118:3479-89. [DOI: 10.1021/jp5010924] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Rumpa Pal
- Solid State and Structural
Chemistry Unit and ‡Organic Chemistry, Indian Institute of Science, Bangalore-560012, India
| | - Somnath Mukherjee
- Solid State and Structural
Chemistry Unit and ‡Organic Chemistry, Indian Institute of Science, Bangalore-560012, India
| | - S. Chandrasekhar
- Solid State and Structural
Chemistry Unit and ‡Organic Chemistry, Indian Institute of Science, Bangalore-560012, India
| | - T. N. Guru Row
- Solid State and Structural
Chemistry Unit and ‡Organic Chemistry, Indian Institute of Science, Bangalore-560012, India
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22
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Shakerzadeh E, Tahmasebi E, Oftadeh M. The impact of intramolecular H-bonding on the aromatic character of substituted penta-fulvenes. COMPUT THEOR CHEM 2013. [DOI: 10.1016/j.comptc.2013.05.003] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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23
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Tadić JM, Xu L. Ab initio and density functional theory study of keto-enol equilibria of deltic acid in gas and aqueous solution phase: a bimolecular proton transfer mechanism. J Org Chem 2012; 77:8621-6. [PMID: 22954314 DOI: 10.1021/jo301575c] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Keto-enol tautomerism in deltic acid (2,3-dihydroxycycloprop-2-en-1-one) has been studied using ab initio methods and the B3LYP functional of density functional theory, as well as complete basis set (CBS-QB3 and CBS-APNO) and G4 methods. Relative and absolute energies were calculated with each of the methods, whereas computations of geometries and harmonic frequencies for dihydroxycyclopropenone and hydroxycyclopropanedione were computed in the gas phase but were limited to HF, MP2, and the B3LYP functional, in combination with the 6-31++G(3df,3pd) basis set. Using the MP2/6-31++G(3df,3pd) gas phase optimized structure, each species was then optimized fully in aqueous solution by using the polarizable continuum model (PCM) self-consistent reaction field approach, in which HF, MP2, and B3LYP levels of theory were utilized, with the same 6-31++G(3df,3pd) basis set. In both gas and aqueous solution phases, the keto form is higher in energy for all of the model chemistries considered. From the B3LYP/6-31++G(3df,3pd) Gibbs free energy, the keto-enol tautomeric equilibrium constant for 2,3-dihydroxycycloprop-2-en-1-one/3-hydroxy-1,2-cyclopropanedione is computed to be K(T)(gas) = 2.768 × 10(-12) and K(T)(aq) = 5.469 × 10(-14). It is concluded that the enol form is overwhelmingly predominant in both environments.
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Affiliation(s)
- Jovan M Tadić
- NASA Ames Research Center, Moffett Field, California 94035, United States.
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24
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Williams RV, Edwards WD, Zhang P, Berg DJ, Mitchell RH. Experimental Verification of the Homoaromaticity of 1,3,5-Cycloheptatriene and Evaluation of the Aromaticity of Tropone and the Tropylium Cation by Use of the Dimethyldihydropyrene Probe. J Am Chem Soc 2012; 134:16742-52. [DOI: 10.1021/ja306868r] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Affiliation(s)
- Richard Vaughan Williams
- Department of Chemistry, University of Idaho, Post Office Box 442343, Moscow,
Idaho 83844-2343, United States
| | - W. Daniel Edwards
- Department of Chemistry, University of Idaho, Post Office Box 442343, Moscow,
Idaho 83844-2343, United States
| | - Pengrong Zhang
- Department of Chemistry, University of Victoria, Post Office Box 3065, Victoria,
British Columbia V8W 3V6, Canada
| | - David J. Berg
- Department of Chemistry, University of Victoria, Post Office Box 3065, Victoria,
British Columbia V8W 3V6, Canada
| | - Reginald H. Mitchell
- Department of Chemistry, University of Victoria, Post Office Box 3065, Victoria,
British Columbia V8W 3V6, Canada
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25
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Amiralaei S, Gauld J, Green JR. Dehydrotropylium-Co2(CO)6 ion: generation, reactivity and evaluation of cation stability. Chemistry 2011; 17:4157-65. [PMID: 21387422 DOI: 10.1002/chem.201002685] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2010] [Revised: 10/18/2010] [Indexed: 11/11/2022]
Abstract
The dehydrotropylium-Co(2)(CO)(6) ion was generated by the action of HBF(4) or BF(3)⋅OEt(2) on the corresponding cycloheptadienynol complex, which in turn has been prepared in four steps from a known diacetoxycycloheptenyne complex. The reaction of the cycloheptadienynol complex via the dehydrotropylium-Co(2)(CO)(6) ion with several nucleophiles results in substitution reactions with reactive nucleophiles (N>1) under normal conditions, and a radical dimerisation reaction in the presence of less reactive nucleophiles. Competitive reactions of the cycloheptadienynol complex with an acyclic trienynol complex show no preference for generation of the dehydrotropylium-Co(2)(CO)(6) ion over an acyclic cation. DFT studies on the dehydrotropylium-Co(2)(CO)(6) ion, specifically evaluation of its harmonic oscillator model of aromaticity (HOMA) value (+0.95), its homodesmotic-reaction-based stabilisation energy (≈2.8 kcal mol(-1)) and its NICS(1) value (-2.9), taken together with the experimental studies suggest that the dehydrotropylium-Co(2)(CO)(6) ion is weakly aromatic.
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Affiliation(s)
- Sheida Amiralaei
- Department of Chemistry and Biochemistry, University of Windsor, Windsor, ON, N9B 3P4, Canada
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26
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Balaban AT. Monocyclic Hetarenes with π-Electron Aromatic Sextet. ADVANCES IN HETEROCYCLIC CHEMISTRY 2010. [DOI: 10.1016/s0065-2725(10)09903-4] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
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27
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Havenith RW, Meijer AJ, Irving BJ, Fowler PW. Comparison of ring currents evaluated consistently at density functional and Hartree–Fock levels. Mol Phys 2009. [DOI: 10.1080/00268970903449396] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
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28
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Aumüller IB, Yli-Kauhaluoma J. Computational methods for analysis of an unsaturated carbocycle: heptafulvene. Theor Chem Acc 2009. [DOI: 10.1007/s00214-009-0675-0] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
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29
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Kudoh M, Satoh T, Ikeda H, Nakazawa T, Miyashi T, Katagiri S, Sudoh S. Experimental and Computational Studies on the Dipole Moments of Annulated-Tropones and 1,4-Polyacenequinones. BULLETIN OF THE CHEMICAL SOCIETY OF JAPAN 2009. [DOI: 10.1246/bcsj.82.70] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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30
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Alonso M, Herradón B. A universal scale of aromaticity for π-organic compounds. J Comput Chem 2009; 31:917-28. [DOI: 10.1002/jcc.21377] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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31
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Mitchell RH, Zhang R, Berg DJ, Twamley B, Williams RV. Measuring Aromaticity with the Dimethyldihydropyrene Ring Current Probe. Experimental and Computational Studies of the Fulvenes and the Strongly Antiaromatic Cyclopentadienone Reveal Large Mills−Nixon-Type Bond Localization Effects. Synthesis of Fulvene-Fused Dihydropyrenes. J Am Chem Soc 2008; 131:189-99. [DOI: 10.1021/ja806427n] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Reginald H. Mitchell
- Department of Chemistry, University of Victoria, P.O. Box 3065, Victoria, BC, Canada V8W 3V6, and Department of Chemistry, University of Idaho, P.O. Box 442343, Moscow, Idaho 83844-2343
| | - Rui Zhang
- Department of Chemistry, University of Victoria, P.O. Box 3065, Victoria, BC, Canada V8W 3V6, and Department of Chemistry, University of Idaho, P.O. Box 442343, Moscow, Idaho 83844-2343
| | - David J. Berg
- Department of Chemistry, University of Victoria, P.O. Box 3065, Victoria, BC, Canada V8W 3V6, and Department of Chemistry, University of Idaho, P.O. Box 442343, Moscow, Idaho 83844-2343
| | - Brendan Twamley
- Department of Chemistry, University of Victoria, P.O. Box 3065, Victoria, BC, Canada V8W 3V6, and Department of Chemistry, University of Idaho, P.O. Box 442343, Moscow, Idaho 83844-2343
| | - Richard Vaughan Williams
- Department of Chemistry, University of Victoria, P.O. Box 3065, Victoria, BC, Canada V8W 3V6, and Department of Chemistry, University of Idaho, P.O. Box 442343, Moscow, Idaho 83844-2343
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32
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33
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Potter RG, Hughes TS. Predicting the UV−Vis Spectra of Tetraarylcyclopentadienones: Using DFT Molecular Orbital Energies to Model Electronic Transitions of Organic Materials. J Org Chem 2008; 73:2995-3004. [DOI: 10.1021/jo701676x] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Robert G. Potter
- Department of Chemistry, Cook Physical Sciences Building, 82 University Place, University of Vermont, Burlington, Vermont 05405
| | - Thomas S. Hughes
- Department of Chemistry, Cook Physical Sciences Building, 82 University Place, University of Vermont, Burlington, Vermont 05405
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34
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Höltzl T, Nguyen MT, Veszprémi T. Mono-, di-, tri- and tetraphosphatriafulvenes: Electronic structure and aromaticity. ACTA ACUST UNITED AC 2007. [DOI: 10.1016/j.theochem.2007.02.045] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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35
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Harmata M, Zheng P, Schreiner PR, Navarro-Vázquez A. Deantiaromatization as a Driving Force in an Electrocyclic Reaction. Angew Chem Int Ed Engl 2006. [DOI: 10.1002/ange.200503812] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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36
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Harmata M, Zheng P, Schreiner PR, Navarro-Vázquez A. Deantiaromatization as a Driving Force in an Electrocyclic Reaction. Angew Chem Int Ed Engl 2006; 45:1966-71. [PMID: 16496272 DOI: 10.1002/anie.200503812] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Affiliation(s)
- Michael Harmata
- Department of Chemistry, University of Missouri--Columbia, MO 65211, USA.
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37
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Suresh CH, Koga N. An isodesmic reaction based approach to aromaticity of a large spectrum of molecules. Chem Phys Lett 2006. [DOI: 10.1016/j.cplett.2005.12.028] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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38
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Thanh NC, Miyatake R, Kainuma H, Kuroda S, Oda M. Synthesis, properties and molecular structure of a novel dicyanoheptafulvene derivative, 4′-dicyanomethylidenedispiro[cyclohexane-1, 1′-(1′,4′,7′-trihydrocyclopenta[f]azulene)-7′,1″-cyclohexane]. Tetrahedron 2006. [DOI: 10.1016/j.tet.2005.10.015] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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39
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Cyrański MK. Energetic aspects of cyclic pi-electron delocalization: evaluation of the methods of estimating aromatic stabilization energies. Chem Rev 2005; 105:3773-811. [PMID: 16218567 DOI: 10.1021/cr0300845] [Citation(s) in RCA: 468] [Impact Index Per Article: 24.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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40
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Pincock JA, Speed AWH. The aromatic character and resonance stabilization energies of substituted cyclopentadienyl and indenyl cations. CAN J CHEM 2005. [DOI: 10.1139/v05-137] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Calculations (B3LYP/6-31G(d)) have been used to assess the aromaticity of 5-X substituted indenyl (4) and cyclopentadienyl (5) cations with X = O, NH2, OCH3, CH3, F, H, CN, and N2+. Two criteria were used, the aromatic stabilization energy (ASE), as determined by isodesmic reactions, and bond alternation, as determined from the Julg index (A) on the basis of carboncarbon bond lengths. Substituent effects on the singlet state of the cyclopentadienyl cations resulted in significant decreases in antiaromatic character for electron-donating groups as indicated by larger A values (A = 0.25 for X = H and +0.26 for X = NH2). These decreases paralleled increases in the C-2C-3 bond length and good linear correlations were obtained between A vs. the C-2C-3 bond length and A vs. the ASE. These effects were rationalized by the stabilization by the electron-donating groups of the positive charge at C-5 generated as a consequence of a JahnTeller distortion leading to a lowest energy singlet state with a HOMO of a2 symmetry. In contrast, the lowest energy triplet state for each of the substituted cyclopentadienyl cations has little bond alternation (A > 0.9) and, by this criterion, is not significantly antiaromatic. The triplet state is more stable than the singlet state for the unsubstituted case and those with electron-withdrawing groups (ΔEST = 11.3 and 9.3 kcal/mol for X = H and CN, respectively) (1 cal = 4.184 J), but less stable for electron-donating groups (ΔEST = +15.0 kcal/mol for X = NH2). For the indenyl cations 4, the ASE values were almost independent of the substituent and the A values only decreased slightly for electron-donating groups. The A values also indicated that the indenyl cations could be divided into two moieties, an X-substituted pentadienyl cation with considerable delocalization and little bond alternation, and a 2,3-butadiene one with considerable bond alternation. This separation also placed the major portion of the positive charge on the pentadienyl part. The lack of symmetry in the substituted indenyl cations rationalizes the selective reactivity of the 5-methoxy-substituted cation at C-1. Finally, the resonance stabilization energies (RSE) of the substituted cations gave a linear correlation with the RSEs of 4-substituted benzylic cations.Key words: indenyl cations, cyclopentadienyl cations, substituent effects, stabilization energies.
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41
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Paine SW, Kresge AJ, Salam A. An Ab Initio and Density Functional Theory Study of Keto−Enol Equilibria of Hydroxycyclopropenone in Gas and Aqueous Solution Phase. J Phys Chem A 2005; 109:4149-53. [PMID: 16833739 DOI: 10.1021/jp040513i] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Keto-enol tautomerism in hydroxycyclopropenone (2-hydroxy-2-cyclopropen-1-one) has been studied using ab initio methods, the B3LYP functional of density functional theory, as well as complete basis set (CBS-QB3 and CBS-APNO) and G3 methods. Absolute and relative energies were calculated with each of the methods, whereas computations of geometries and harmonic frequencies for hydroxycyclopropenone and 1,2-cyclopropanedione were computed in the gas phase but were limited to HF, MP2 and CCSD levels of theory, and the B3LYP functional, in combination with the 6-31++G** basis set. Using the MP2/6-31++G** gas phase optimized structure, each species was then optimized fully in aqueous solution by employing the polarizable continuum model (PCM) self-consistent reaction field approach, in which HF, MP2 and B3LYP levels of theory were utilized, with the same 6-31++G** basis set. In both gas and aqueous solution phases, the keto form is higher in energy for all of the model chemistries considered. The presence of the solvent, however, is found to have very little effect on the bond lengths, angles and harmonic frequencies. From the B3LYP/6-31++G** Gibbs free energy, the keto-enol tautomeric equilibrium constant for 2-hydroxy-2-cyclopropen-1-one <==> 1,2-cyclopropanedione is computed to be K(T)(gas) = 2.35 x 10(-6), K(T)(aq) = 5.61 x 10(-14). It is concluded that the enol form is overwhelmingly predominant in both environments, with the effect of the solvent shifting the direction of equilibrium even more strongly in the favor of hydroxycyclopropenone. The almost exclusive nature of this species is attributed to stabilization resulting from aromaticity. Confirmation is provided by comparison of the simulated vibrational spectra of hydroxycyclopropenone with the measured infrared spectrum in an argon matrix.
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Affiliation(s)
- S W Paine
- Department of Chemistry, University of Toronto, 80 St. George Street, Toronto, Ontario M5S 3H6, Canada
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42
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Möllerstedt H, Piqueras MC, Crespo R, Ottosson H. Fulvenes, Fulvalenes, and Azulene: Are They Aromatic Chameleons? J Am Chem Soc 2004; 126:13938-9. [PMID: 15506751 DOI: 10.1021/ja045729c] [Citation(s) in RCA: 115] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
On the basis of the theory of Baird on reversal of Hückel's rule for aromaticity and antiaromaticity of annulenes when going from the electronic ground state (S0) to the lowest pipi* triplet state (T1) (J. Am. Chem. Soc. 1972, 94, 4941), we argue that fulvenes, fulvalenes, and azulene are "aromatic chameleons". The dipole moments of fulvenes in T1 should be of comparable magnitude to those of S0, but due to the reversal of Hückel's aromaticity rule in T1, their dipole should be in the opposite direction. Thereby, they are capable of adopting some aromaticity in both the T1 and S0 states as they adapt their dipolar resonance structures. The same applies to fulvalenes and azulene in their lowest quintet states (Q1) when compared to S0. Our hypothesis on chameleon behavior is supported by quantum chemical OLYP, CASSCF, and CASPT2 calculations of dipole moments, pi-orbital populations, and energies.
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Affiliation(s)
- Helene Möllerstedt
- Department of Chemistry and Bioscience, Kemigården 3, Chalmers University of Technology, SE- 412 96 Göteborg, Sweden
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