1
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Deng YH, Sun TY, Wu YD. Understanding the Nonlinear Hammett Relationship in Osmylation of Olefins with OsO 4-Amine Ligands: Importance of Singlet-Diradical Character. J Org Chem 2024; 89:11173-11182. [PMID: 39072554 DOI: 10.1021/acs.joc.4c00693] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/30/2024]
Abstract
Although the concerted [3 + 2] mechanism of osmium-catalyzed asymmetric dihydroxylation has been generally accepted, the unusual nonlinear Hammett relationship induced by amine-type ligands remains unexplained. To understand this, we carried out a density functional theory (DFT) study for the osmylation of substituted styrenes by the following: OsO4, OsO4-pyridine, OsO4-4-cyanopyridine, OsO4-4-pyrrolidinopyridine, and OsO4-quinuclidine. Calculations using the M06 functional successfully reproduce the experimentally observed nonlinear relationships. The transition states exhibit considerable singlet-diradical character, which causes the nonlinear Hammett relationship. Regardless of the presence or absence of an amine-type ligand, an electron donation from styrene to OsO4 is observed, indicating no mechanistic change. Calculations indicate that the electronic interaction between the amine-type ligand and styrene also influences the reaction rate.
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Affiliation(s)
- Yi-Hui Deng
- Key Laboratory of Computational Chemistry and Drug Design, State Key Laboratory of Chemical Oncogenomics, Shenzhen Key Laboratory of Chemical Genomics, School of Chemical Biology and Biotechnology, Peking University Shenzhen Graduate School, Shenzhen, Guangdong 518055, PR China
| | - Tian-Yu Sun
- Key Laboratory of Computational Chemistry and Drug Design, State Key Laboratory of Chemical Oncogenomics, Shenzhen Key Laboratory of Chemical Genomics, School of Chemical Biology and Biotechnology, Peking University Shenzhen Graduate School, Shenzhen, Guangdong 518055, PR China
- Institute of Chemical Biology, Shenzhen Bay Laboratory, Shenzhen 518132, China
| | - Yun-Dong Wu
- Key Laboratory of Computational Chemistry and Drug Design, State Key Laboratory of Chemical Oncogenomics, Shenzhen Key Laboratory of Chemical Genomics, School of Chemical Biology and Biotechnology, Peking University Shenzhen Graduate School, Shenzhen, Guangdong 518055, PR China
- Institute of Chemical Biology, Shenzhen Bay Laboratory, Shenzhen 518132, China
- College of Chemistry and Molecular Engineering, Peking University, Beijing 100871, China
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2
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Todorov P, Georgieva S, Trapella C, Chakarov K, Tchekalarova J, Pechlivanova D, Cheshmedzhieva D, Fantinati A, Illuminati D. Synthesis, characterization, and biological study of new synthetic opioid hemorphin-4 peptides containing sterically restricted nonnatural amino acids. Arch Pharm (Weinheim) 2024; 357:e2400052. [PMID: 38578075 DOI: 10.1002/ardp.202400052] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2024] [Revised: 02/25/2024] [Accepted: 02/29/2024] [Indexed: 04/06/2024]
Abstract
Some new hemorphin-4 analogs with structures of Xxx-Pro-Trp-Thr-NH2 and Tyr-Yyy-Trp-Thr-NH2, where Xxx is 2-amino-3-(4-hydroxy-2,6-dimethylphenyl)propanoic acid or 2-amino-3-(4-dibenzylamino-2,6-dimethylphenyl)propanoic acid, and Yyy is (2S,4S)-4-amino-pyrrolidine-2-carboxylic acid, were synthesized and characterized by electrochemical and spectral analyses. In vivo anticonvulsant and antinociceptive activities of peptide derivatives were studied after intracerebroventricular injection in mice. The therapeutic effects of the modified peptides on seizures and pain in mice were evaluated to provide valuable insights into the potential applications of the novel compounds. Electrochemical characterization showed that the compounds behave as weak protolytes and that they are in a soluble, stable molecular form at physiological pH values. The antioxidant activity of the peptides was evaluated with voltammetric analyses, which were confirmed by applying the 2,2-Diphenyl-1-picrylhydrazyl method. The compounds showed satisfactory results regarding their structural stability, reaching the desired centers for the manifestation of biological activity without hydrolysis processes at 37°C and physiological pH. Dm-H4 and H4-P1 exhibited 100% and 83% potency to suppress the psychomotor seizures in the 6-Hz test compared to 67% activity of H4. Notably, only the H4-P1 had efficacy in blocking the tonic component in the maximal electroshock test with a potency comparable to H4. All investigated peptides containing unnatural conformationally restricted amino acids showed antinociceptive effects. The analogs Db-H4 and H4-P1 showed the most pronounced and long-lasting effect in both experimental models of pain induced by thermal and chemical stimuli. Dm-H4 produced a dose-dependent thermal antinociception and H4-P2 inhibited only formalin-induced pain behavior.
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Affiliation(s)
- Petar Todorov
- Department of Organic Chemistry, University of Chemical Technology and Metallurgy, Sofia, Bulgaria
| | - Stela Georgieva
- Department of Analytical Chemistry, University of Chemical Technology and Metallurgy, Sofia, Bulgaria
| | - Claudio Trapella
- Department of Chemical, Pharmaceutical and Agricultural Sciences, University of Ferrara, Ferrara, Italy
| | - Kalin Chakarov
- Department of Organic Chemistry, University of Chemical Technology and Metallurgy, Sofia, Bulgaria
- Department of Analytical Chemistry, University of Chemical Technology and Metallurgy, Sofia, Bulgaria
| | - Jana Tchekalarova
- Institute of Neurobiology, Bulgarian Academy of Sciences, Sofia, Bulgaria
| | - Daniela Pechlivanova
- Institute of Neurobiology, Bulgarian Academy of Sciences, Sofia, Bulgaria
- Faculty of Medicine, Sofia University "St. Kliment Ohridski" 1, Sofia, Bulgaria
| | - Diana Cheshmedzhieva
- Faculty of Chemistry and Pharmacy, Sofia University "St. Kliment Ohridski", Sofia, Bulgaria
| | - Anna Fantinati
- Department of Environmental and Prevention Sciences, University of Ferrara, Ferrara, Italy
| | - Davide Illuminati
- Department of Life Science, University of Modena and Reggio Emilia, Modena, Italy
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3
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Lohithakshamenon R, Prasanthkumar KP, Femina C, Sajith PK. Bond Strength and Interaction Energies in Togni Reagents: Insights from Molecular Electrostatic Potential-Based Parameters. J Phys Chem A 2024; 128:727-737. [PMID: 38253016 DOI: 10.1021/acs.jpca.3c06378] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2024]
Abstract
Togni reagents and their analogs, classified as hypervalent iodine(III) complexes, serve as potent trifluoromethylation agents. The interplay of cis and trans factors plays a pivotal role in shaping their performance, affecting aspects such as bond strength, interaction energies, stability, and subsequent nucleophilic reactions. In this context, we propose the utilization of the molecular electrostatic potential (MESP) at the carbon atom (VC) of the I-CF3 moiety as a sensitive parameter to quantify the cis and trans influences in Togni-type reagents. Our study has shown that VC serves as a convenient probe for determining the heterolytic bond dissociation energy (BDE) and, consequently, assessing the reactivity of these reagents. Moreover, these parameters have been successfully applied to evaluate the strength of the σ-hole interactions with nucleophiles (Cl- and NMe3). Additionally, we provide insights into interactions of Togni reagents with Brønsted acids such as HCl and HSO3F, elucidating them in terms of MESP topological parameters. These findings yield valuable information about the electronic properties of hypervalent iodine reagents, particularly Togni-type reagents, offering the potential for optimizing structurally modified reagents with enhanced activity and stability.
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Affiliation(s)
| | - Kavanal P Prasanthkumar
- Post Graduate and Research Department of Chemistry, Maharaja's College, Ernakulam 682011, India
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4
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Cai Y, Luo YH, Long X, Roldan MA, Yang S, Zhou C, Zhou D, Rittmann BE. Reductive Dehalogenation of Herbicides Catalyzed by Pd 0NPs in a H 2-Based Membrane Catalyst-Film Reactor. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2022; 56:18030-18040. [PMID: 36383359 DOI: 10.1021/acs.est.2c07317] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/16/2023]
Abstract
More food production required to feed humans will require intensive use of herbicides to protect against weeds. The widespread application and persistence of herbicides pose environmental risks for nontarget species. Elemental-palladium nanoparticles (Pd0NPs) are known to catalyze reductive dehalogenation of halogenated organic pollutants. In this study, the reductive conversion of 2,4-dichlorophenoxyacetic acid (2,4-D) was evaluated in a H2-based membrane catalyst-film reactor (H2-MCfR), in which Pd0NPs were in situ-synthesized as the catalyst film and used to activate H2 on the surface of H2-delivery membranes. Batch kinetic experiments showed that 99% of 2,4-D was removed and converted to phenoxyacetic acid (POA) within 90 min with a Pd0 surface loading of 20 mg Pd/m2, achieving a catalyst specific activity of 6.6 ± 0.5 L/g-Pd-min. Continuous operation of the H2-MCfR loaded with 20 mg Pd/m2 sustained >99% removal of 50 μM 2,4-D for 20 days. A higher Pd0 surface loading, 1030 mg Pd/m2, also enabled hydrosaturation and hydrolysis of POA to cyclohexanone and glycolic acid. Density functional theory identified the reaction mechanisms and pathways, which involved reductive hydrodechlorination, hydrosaturation, and hydrolysis. Molecular electrostatic potential calculations and Fukui indices suggested that reductive dehalogenation could increase the bioavailability of herbicides. Furthermore, three other halogenated herbicides─atrazine, dicamba, and bromoxynil─were reductively dehalogenated in the H2-MCfR. This study documents a promising method for the removal and detoxification of halogenated herbicides in aqueous environments.
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Affiliation(s)
- Yuhang Cai
- Engineering Lab for Water Pollution Control and Resources Recovery of Jilin Province, School of Environment, Northeast Normal University, Changchun130117, China
- Biodesign Swette Center for Environmental Biotechnology, Arizona State University, Tempe, Arizona85287-5701, United States
| | - Yi-Hao Luo
- Biodesign Swette Center for Environmental Biotechnology, Arizona State University, Tempe, Arizona85287-5701, United States
- Nanosystems Engineering Research Center for Nanotechnology-Enabled Water Treatment, School of Sustainable Engineering and the Built Environment, Arizona State University, Tempe, Arizona85287-3005, United States
| | - Xiangxing Long
- Biodesign Swette Center for Environmental Biotechnology, Arizona State University, Tempe, Arizona85287-5701, United States
- Nanosystems Engineering Research Center for Nanotechnology-Enabled Water Treatment, School of Sustainable Engineering and the Built Environment, Arizona State University, Tempe, Arizona85287-3005, United States
| | - Manuel A Roldan
- Eyring Materials Center, Arizona State University, Tempe,Arizona85287-3005, United States
| | - Shize Yang
- Eyring Materials Center, Arizona State University, Tempe,Arizona85287-3005, United States
| | - Chen Zhou
- Biodesign Swette Center for Environmental Biotechnology, Arizona State University, Tempe, Arizona85287-5701, United States
| | - Dandan Zhou
- Engineering Lab for Water Pollution Control and Resources Recovery of Jilin Province, School of Environment, Northeast Normal University, Changchun130117, China
- Biodesign Swette Center for Environmental Biotechnology, Arizona State University, Tempe, Arizona85287-5701, United States
| | - Bruce E Rittmann
- Biodesign Swette Center for Environmental Biotechnology, Arizona State University, Tempe, Arizona85287-5701, United States
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5
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Suresh CH, Remya GS, Anjalikrishna PK. Molecular electrostatic potential analysis: A powerful tool to interpret and predict chemical reactivity. WIRES COMPUTATIONAL MOLECULAR SCIENCE 2022. [DOI: 10.1002/wcms.1601] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Affiliation(s)
- Cherumuttathu H. Suresh
- Chemical Sciences and Technology Division CSIR‐National Institute for Interdisciplinary Science and Technology Thiruvananthapuram Kerala India
- Academy of Scientific and Innovative Research (AcSIR) Ghaziabad India
| | - Geetha S. Remya
- Chemical Sciences and Technology Division CSIR‐National Institute for Interdisciplinary Science and Technology Thiruvananthapuram Kerala India
- Academy of Scientific and Innovative Research (AcSIR) Ghaziabad India
| | - Puthannur K. Anjalikrishna
- Chemical Sciences and Technology Division CSIR‐National Institute for Interdisciplinary Science and Technology Thiruvananthapuram Kerala India
- Academy of Scientific and Innovative Research (AcSIR) Ghaziabad India
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6
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Cheshmedzhieva D, Ilieva S, Hadjieva B, Galabov B. Hydrogen bonding probes electron density variations at the basic center in substituted alkyl benzoates: Theory and experiment. J PHYS ORG CHEM 2021. [DOI: 10.1002/poc.4258] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Affiliation(s)
| | - Sonia Ilieva
- Department of Chemistry and Pharmacy University of Sofia Sofia Bulgaria
| | - Boriana Hadjieva
- Department of Chemistry and Pharmacy University of Sofia Sofia Bulgaria
| | - Boris Galabov
- Department of Chemistry and Pharmacy University of Sofia Sofia Bulgaria
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7
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Anjali BA, Suresh CH. Absorption and emission properties of 5-phenyl tris(8-hydroxyquinolinato) M(III) complexes (M = Al, Ga, In) and correlations with molecular electrostatic potential. J Comput Chem 2020; 41:1497-1508. [PMID: 32289191 DOI: 10.1002/jcc.26193] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2020] [Accepted: 03/09/2020] [Indexed: 11/07/2022]
Abstract
Substituent effect for a series of 5-phenyl tris(8-hydroxyquinolinato) M(III) complexes (Mq3) of aluminum, gallium, and indium are investigated using density functional theory (DFT) for the ground state properties and the time-dependent version of DFT (TDDFT) for their absorption and emission properties. A comparison between the ground state energy of mer and fac isomers of all the complexes revealed that the mer configuration is always more stable than fac. The substituent effect is significantly reflected at the fluorescence maximum (λF ) values whereas the effect is moderate at the absorption maximum (λabs ) values. The molecular electrostatic potential (MESP) at the metal center (VM ) and the most electron rich region indicated by MESP minimum (Vmin ), located at the oxygen of phenoxide ring exhibit excellent correlations with the λF and Stokes shift (λF -λabs ) values. The study suggests the use of Stokes shift as an experimental quantity to measure the excited state substituent effect while the Vmin or VM emerge as theoretical quantities to measure the same.
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Affiliation(s)
- Bai A Anjali
- Chemical Sciences and Technology Division, CSIR-National Institute for Interdisciplinary Science and Technology, Trivandrum, India.,Academy of Scientific & Innovative Research (AcSIR), CSIR-NIIST Campus, Trivandrum, India
| | - Cherumuttathu H Suresh
- Chemical Sciences and Technology Division, CSIR-National Institute for Interdisciplinary Science and Technology, Trivandrum, India.,Academy of Scientific & Innovative Research (AcSIR), CSIR-NIIST Campus, Trivandrum, India
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8
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Chen XL, Shen YJ, Gao C, Yang J, Sun X, Zhang X, Yang YD, Wei GP, Xiang JF, Sessler JL, Gong HY. Regulating the Structures of Self-Assembled Mechanically Interlocked Moleculecular Constructs via Dianion Precursor Substituent Effects. J Am Chem Soc 2020; 142:7443-7455. [PMID: 32216311 DOI: 10.1021/jacs.9b13473] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Substituent effects play critical roles in both modulating reaction chemistry and supramolecular self-assembly processes. Using substituted terephthalate dianions (p-phthalic acid dianions; PTADAs), the effect of varying the type, number, and position of the substituents was explored in terms of their ability to regulate the inherent anion complexation features of a tetracationic macrocycle, cyclo[2](2,6-di(1H-imidazol-1-yl)pyridine)[2](1,4-dimethylenebenzene) (referred to as the Texas-sized molecular box; 14+), in the form of its tetrakis-PF6- salt in DMSO. Several of the tested substituents, including 2-OH, 2,5-di(OH), 2,5-di(NH2), 2,5-di(Me), 2,5-di(Cl), 2,5-di(Br), and 2,5-di(I), were found to promote pseudorotaxane formation in contrast to what was seen for the parent PTADA system. Other derivatives of PTADA, including those with 2,3-di(OH), 2,6-di(OH), 2,5-di(OMe), 2,3,5,6-tetra(Cl), and 2,3,5,6-tetra(F) substituents, led only to so-called outside binding, where the anion interacts with 14+ on the outside of the macrocyclic cavity. The differing binding modes produced by the choice of PTADA derivative were found to regulate further supramolecular self-assembly when the reaction components included additional metal cations (M). Depending on the specific choice of PTADA derivatives and metal cations (M = Co2+, Ni2+, Zn2+, Cd2+, Gd3+, Nd3+, Eu3+, Sm3+, Tb3+), constructs involving one-dimensional polyrotaxanes, outside-type rotaxanated supramolecular organic frameworks (RSOFs), or two-dimensional metal-organic rotaxane frameworks (MORFs) could be stabilized. The presence and nature of the substituent were found to dictate which specific higher order self-assembled structure was obtained using a given cation. In the specific case of the 2,5-di(OH), 2,5-di(Cl), and 2,5-di(Br) PTADA derivatives and Eu3+, so-called MORFs with distinct fluorescence emission properties could be produced. The present work serves to illustrate how small changes in guest substitution patterns may be used to control structure well beyond the first interaction sphere.
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Affiliation(s)
- Xu-Lang Chen
- College of Chemistry, Beijing Normal University, No. 19, Xinwai street, Beijing 100875, People's Republic of China
| | - Yun-Jia Shen
- College of Chemistry, Beijing Normal University, No. 19, Xinwai street, Beijing 100875, People's Republic of China
| | - Chao Gao
- College of Chemistry, Beijing Normal University, No. 19, Xinwai street, Beijing 100875, People's Republic of China
| | - Jian Yang
- College of Chemistry, Beijing Normal University, No. 19, Xinwai street, Beijing 100875, People's Republic of China
| | - Xin Sun
- College of Chemistry, Beijing Normal University, No. 19, Xinwai street, Beijing 100875, People's Republic of China
| | - Xin Zhang
- College of Chemistry, Beijing Normal University, No. 19, Xinwai street, Beijing 100875, People's Republic of China
| | - Yu-Dong Yang
- College of Chemistry, Beijing Normal University, No. 19, Xinwai street, Beijing 100875, People's Republic of China
| | - Gong-Ping Wei
- Institute of Chemistry, Chinese Academy of Sciences, Zhongguancunbeiyijie 2, Beijing 100190, People's Republic of China.,University of Chinese Academy of Sciences, Beijing 100049, People's Republic of China
| | - Jun-Feng Xiang
- Institute of Chemistry, Chinese Academy of Sciences, Zhongguancunbeiyijie 2, Beijing 100190, People's Republic of China.,University of Chinese Academy of Sciences, Beijing 100049, People's Republic of China
| | - Jonathan L Sessler
- Department of Chemistry, Shanghai University, Shanghai 200444, People's Republic of China.,Department of Chemistry, The University of Texas at Austin, 105 East 24th Street, Stop A5300, Austin, Texas 78712-1224, United States
| | - Han-Yuan Gong
- College of Chemistry, Beijing Normal University, No. 19, Xinwai street, Beijing 100875, People's Republic of China
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9
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Vik EC, Li P, Pellechia PJ, Shimizu KD. Transition-State Stabilization by n→π* Interactions Measured Using Molecular Rotors. J Am Chem Soc 2019; 141:16579-16583. [DOI: 10.1021/jacs.9b08542] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Affiliation(s)
- Erik C. Vik
- Department of Chemistry and Biochemistry, University of South Carolina, Columbia, South Carolina 29208, United States
| | - Ping Li
- Department of Chemistry and Biochemistry, University of South Carolina, Columbia, South Carolina 29208, United States
| | - Perry J. Pellechia
- Department of Chemistry and Biochemistry, University of South Carolina, Columbia, South Carolina 29208, United States
| | - Ken D. Shimizu
- Department of Chemistry and Biochemistry, University of South Carolina, Columbia, South Carolina 29208, United States
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10
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Galabov B, Nikolova V, Cheshmedzhieva D, Hadjieva B, Schaefer HF. Hyperconjugative effects in π-hydrogen bonding: Theory and experiment. J Comput Chem 2017; 39:527-534. [DOI: 10.1002/jcc.25088] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2017] [Revised: 09/26/2017] [Accepted: 09/29/2017] [Indexed: 11/08/2022]
Affiliation(s)
- Boris Galabov
- Department of Chemistry and Pharmacy; University of Sofia; Sofia 1164 Bulgaria
- Center for Computational Quantum Chemistry, University of Georgia; Athens Georgia 30602
| | - Valia Nikolova
- Department of Chemistry and Pharmacy; University of Sofia; Sofia 1164 Bulgaria
| | | | - Boriana Hadjieva
- Department of Chemistry and Pharmacy; University of Sofia; Sofia 1164 Bulgaria
| | - Henry F. Schaefer
- Center for Computational Quantum Chemistry, University of Georgia; Athens Georgia 30602
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11
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Charry J, Pedraza-González L, Reyes A. On the physical interpretation of the nuclear molecular orbital energy. J Chem Phys 2017; 146:214103. [PMID: 28576090 PMCID: PMC5453789 DOI: 10.1063/1.4984098] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2017] [Accepted: 05/11/2017] [Indexed: 11/14/2022] Open
Abstract
Recently, several groups have extended and implemented molecular orbital (MO) schemes to simultaneously obtain wave functions for electrons and selected nuclei. Many of these schemes employ an extended Hartree-Fock approach as a first step to find approximate electron-nuclear wave functions and energies. Numerous studies conducted with these extended MO methodologies have explored various effects of quantum nuclei on physical and chemical properties. However, to the best of our knowledge no physical interpretation has been assigned to the nuclear molecular orbital energy (NMOE) resulting after solving extended Hartree-Fock equations. This study confirms that the NMOE is directly related to the molecular electrostatic potential at the position of the nucleus.
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Affiliation(s)
- Jorge Charry
- Department of Chemistry, Universidad Nacional de Colombia, Ave. Cra. 30 #45-03, Bogotá, Colombia
| | - Laura Pedraza-González
- Department of Chemistry, Universidad Nacional de Colombia, Ave. Cra. 30 #45-03, Bogotá, Colombia
| | - Andrés Reyes
- Department of Chemistry, Universidad Nacional de Colombia, Ave. Cra. 30 #45-03, Bogotá, Colombia
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12
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Galabov B, Koleva G, Schaefer HF. Positional selectivity in the interaction of toluene with nitronium ion. Mol Phys 2017. [DOI: 10.1080/00268976.2017.1318225] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
Affiliation(s)
- Boris Galabov
- Department of Chemistry and Pharmacy, University of Sofia, Sofia, Bulgaria
- Center for Computational Quantum Chemistry, University of Georgia, Athens, GA, USA
| | - Gergana Koleva
- Department of Chemistry and Pharmacy, University of Sofia, Sofia, Bulgaria
| | - Henry F. Schaefer
- Center for Computational Quantum Chemistry, University of Georgia, Athens, GA, USA
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13
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Vijayalakshmi KP, Suresh CH. Ammonia Borane Clusters: Energetics of Dihydrogen Bonding, Cooperativity, and the Role of Electrostatics. J Phys Chem A 2017; 121:2704-2714. [DOI: 10.1021/acs.jpca.7b01527] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Kunduchi P. Vijayalakshmi
- Analytical and Spectroscopy
Division, Analytical, Spectroscopy and Ceramics Group, Propellants,
Polymers, Chemicals and Materials Entity, Vikram Sarabhai Space Centre, Thiruvananthapuram- 695022, India
| | - Cherumuttathu H. Suresh
- Chemical Sciences and Technology Division, CSIR- National Institute for Interdisciplinary Science and Technology, Thiruvananthapuram, 695 019, India
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14
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Hao Z, Xu J, Huang J, Peng X. Highly competitive and selective electrophilic catalytic bromination of polynitro stilbenes with molecular bromine in the presence of ZnO/H-beta-25. CATAL COMMUN 2017. [DOI: 10.1016/j.catcom.2016.12.005] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
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15
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Wiberg KB, Frisch MJ. Effect of Conjugation on Electron Distributions. Separation of σ and π Terms. J Chem Theory Comput 2016; 12:1220-7. [DOI: 10.1021/acs.jctc.5b01149] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Kenneth B. Wiberg
- Department of Chemistry, Yale University, New Haven, Connecticut 06520, United States
| | - Michael J. Frisch
- Gaussian, Inc., 340 Quinnipiac Street, Wallingford, Connecticut 06492, United States
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16
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Robiette R, Trieu-Van T, Aggarwal VK, Harvey JN. Activation of the SN2 Reaction by Adjacent π Systems: The Critical Role of Electrostatic Interactions and of Dissociative Character. J Am Chem Soc 2016; 138:734-7. [PMID: 26725828 DOI: 10.1021/jacs.5b11402] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The activation of the SN2 reaction by π systems is well documented in textbooks. It has been shown previously that this is not primarily due to classical (hyper)conjugative effects. Instead, π-conjugated substituents enhance favorable substrate-nucleophile electrostatic interactions, with electron-withdrawing groups (EWG) on the sp(2) system leading to even stronger activation. Herein we report computational and experimental results which show that this activation by sp(2) EWG-substitution only occurs in a fairly limited number of cases, when the nucleophile involves strong electrostatic interactions (usually strongly basic negatively charged nucleophiles). In other cases, where bond breaking is more advanced than bond making at the transition state, electrophile-nucleophile electrostatic interactions are less important. In such cases, (hyper)conjugative electronic effects determine the reactivity, and EWG-substitution leads to decreased reactivity. The basicity of the nucleophile as well as solvent effects can help to determine which of these two regimes occurs for a given electrophile.
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Affiliation(s)
- Raphaël Robiette
- Institute of Condensed Matter and Nanosciences, Université Catholique de Louvain , Place Louis Pasteur 1 box L4.01.02, B-1348 Louvain-la-Neuve, Belgium
| | - Tran Trieu-Van
- Institute of Condensed Matter and Nanosciences, Université Catholique de Louvain , Place Louis Pasteur 1 box L4.01.02, B-1348 Louvain-la-Neuve, Belgium
| | - Varinder K Aggarwal
- School of Chemistry, University of Bristol , Cantock's Close, Bristol BS8 1TS, United Kingdom
| | - Jeremy N Harvey
- School of Chemistry, University of Bristol , Cantock's Close, Bristol BS8 1TS, United Kingdom.,Department of Chemistry, Katholieke Universiteit Leuven , Celestijnenlaan 200F, B-3001 Heverlee, Belgium
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Yadav A, Mishra P. Functionalisation of graphene by edge-halogenation and radical addition using polycyclic aromatic hydrocarbon models: edge electron density-binding energy relationship. Mol Phys 2014. [DOI: 10.1080/00268976.2014.974700] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
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18
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Gautam P, Prakash O, Dani RK, Singh NK, Singh RK. Vibrational and quantum chemical investigation of cyclization of thiosemicarbazide group in 1-benzoyl-4-phenyl-3-thiosemicarbazide. SPECTROCHIMICA ACTA. PART A, MOLECULAR AND BIOMOLECULAR SPECTROSCOPY 2014; 132:278-287. [PMID: 24873893 DOI: 10.1016/j.saa.2014.03.095] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/25/2013] [Revised: 02/28/2014] [Accepted: 03/18/2014] [Indexed: 06/03/2023]
Abstract
1-Benzoyl-4-phenyl-3-thiosemicarbazide (H3bpt) was treated with acid - base in one sequence and base - acid in other sequence, both of which lead to ring formation of thiosemicarbazide group, giving N-phenyl-5-phenyl-1,3,4-thiadiazol-2-amine (Hppta) in the first case and 4,5-diphenyl-2,4-dihydro-1,2,4-triazole-3-thione (Hdptt) in the second case. The primary (H3bpt) as well as the resulting compounds (Hppta & Hdptt) has been characterized by elemental analyses, NMR, FTIR and Raman spectroscopic techniques. The quantum chemical calculations of the compounds are performed using DFT/B3LYP/6311G(d,p) method for geometry optimizations and also for prediction of the molecular properties. The cyclization is confirmed by disappearance of many bands belonging to the open chain subgroups of H3bpt such as; NH stretching, NH bending, CN stretching, NH puckering, CO stretching etc. The ring formation of 1-benzoyl-4-phenyl-3-thiosemicarbazide (H3bpt) has been further confirmed by the appearance of many bands belonging to the closed ring of thiosemicarbazide in the resulting compounds Hppta and Hdptt.
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Affiliation(s)
- Priyanka Gautam
- Department of Physics, Banaras Hindu University, Varanasi 221005, India
| | - Om Prakash
- Department of Physics, Banaras Hindu University, Varanasi 221005, India
| | - R K Dani
- Department of Chemistry, Banaras Hindu University, Varanasi 221005, India
| | - N K Singh
- Department of Chemistry, Banaras Hindu University, Varanasi 221005, India
| | - Ranjan K Singh
- Department of Physics, Banaras Hindu University, Varanasi 221005, India.
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Fong CW. Statins in therapy: Understanding their hydrophilicity, lipophilicity, binding to 3-hydroxy-3-methylglutaryl-CoA reductase, ability to cross the blood brain barrier and metabolic stability based on electrostatic molecular orbital studies. Eur J Med Chem 2014; 85:661-74. [DOI: 10.1016/j.ejmech.2014.08.037] [Citation(s) in RCA: 74] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2014] [Revised: 08/09/2014] [Accepted: 08/09/2014] [Indexed: 01/09/2023]
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20
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Nikolova V, Ilieva S, Galabov B, Schaefer HF. Experimental measurement and theory of substituent effects in π-hydrogen bonding: complexes of substituted phenols with benzene. J Org Chem 2014; 79:6823-31. [PMID: 25004256 DOI: 10.1021/jo500732m] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
IR spectroscopic experiments and theoretical DFT computations reveal the effects of aromatic substituents on π-hydrogen bonding between monosubstituted phenol derivatives and benzene. Simultaneous formation of two π-hydrogen bonds (red-shifting O-H···π and blue-shifting ortho-C-H···π) contribute to the stability of these complexes. The interaction of the acidic phenol O-H proton-donating group with the benzene π-system dominates the complex formation. The experimental shifts of O-H stretching frequencies for the different phenol complexes vary in the range 45-74 cm(-1). Strong effects on hydrogen-bonding energies and frequency shifts of electron-withdrawing aromatic substituents and very weak influence of electron-donating groups have been established. Experimental quantities and theoretical parameters are employed in rationalizing the properties of these complexes. The acidities of the proton-donating phenols describe quantitatively the hydrogen-bonding process. The results obtained provide clear evidence that, when the structural variations are in the proton-donating species, the substituent effects on π-hydrogen bonding follow classic mechanisms, comprising both resonance and direct through-space influences. The performance of three alternative DFT functionals (B3LYP, B97-D, and PBE0 combined with the 6-311++G(2df,2p) basis set) in predicting the O-H frequency shifts upon complexation is examined. For comparison, O-H frequency shifts for several complexes were also determined at MP2/6-31++G(d,p).
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Affiliation(s)
- Valia Nikolova
- Department of Chemistry, University of Sofia , 1 James Bourchier Avenue, Sofia 1164, Bulgaria
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21
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Wu CH, Galabov B, Wu JIC, Ilieva S, Schleyer PVR, Allen WD. Do π-conjugative effects facilitate SN2 reactions? J Am Chem Soc 2014; 136:3118-26. [PMID: 24450965 DOI: 10.1021/ja4111946] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Rigorous quantum chemical investigations of the SN2 identity exchange reactions of methyl, ethyl, propyl, allyl, benzyl, propargyl, and acetonitrile halides (X = F(-), Cl(-)) refute the traditional view that the acceleration of SN2 reactions for substrates with a multiple bond at Cβ (carbon adjacent to the reacting Cα center) is primarily due to π-conjugation in the SN2 transition state (TS). Instead, substrate-nucleophile electrostatic interactions dictate SN2 reaction rate trends. Regardless of the presence or absence of a Cβ multiple bond in the SN2 reactant in a series of analogues, attractive Cβ(δ(+))···X(δ(-)) interactions in the SN2 TS lower net activation barriers (E(b)) and enhance reaction rates, whereas repulsive Cβ(δ(-))···X(δ(-)) interactions increase E(b) barriers and retard SN2 rates. Block-localized wave function (BLW) computations confirm that π-conjugation lowers the net activation barriers of SN2 allyl (1t, coplanar), benzyl, propargyl, and acetonitrile halide identity exchange reactions, but does so to nearly the same extent. Therefore, such orbital interactions cannot account for the large range of E(b) values in these systems.
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Affiliation(s)
- Chia-Hua Wu
- Center for Computational Chemistry and Department of Chemistry, University of Georgia , Athens, Georgia 30602, United States
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22
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Santos CBR, Lobato CC, Braga FS, Morais SSS, Santos CF, Fernandes CP, Brasil DSB, Hage-Melim LIS, Macêdo WJC, Carvalho JCT. Application of Hartree-Fock Method for Modeling of Bioactive Molecules Using SAR and QSPR. ACTA ACUST UNITED AC 2014. [DOI: 10.4236/cmb.2014.41001] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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23
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Mosley JD, Ricks AM, Schleyer PVR, Wu JI, Duncan MA. IR Spectroscopy of α- and β-Protonated Pyrrole via Argon Complex Photodissociation. J Phys Chem A 2012; 116:9689-95. [DOI: 10.1021/jp307631n] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- J. D. Mosley
- Department of Chemistry, University of Georgia, Athens, Georgia 30602-2556,
United States
| | - A. M. Ricks
- Department of Chemistry, University of Georgia, Athens, Georgia 30602-2556,
United States
| | - P. v. R. Schleyer
- Department of Chemistry, University of Georgia, Athens, Georgia 30602-2556,
United States
| | - J. I. Wu
- Department of Chemistry, University of Georgia, Athens, Georgia 30602-2556,
United States
| | - M. A. Duncan
- Department of Chemistry, University of Georgia, Athens, Georgia 30602-2556,
United States
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