1
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Argibay-Otero S, Carballo R, Vázquez-López EM. Coordination Chemistry of Potentially S,N,N py-Tridentate Thiosemicarbazones with the {Re(CO) 3} + Fragment and Formation of Hemiaminal Derivatives. Inorg Chem 2023; 62:224-237. [PMID: 36546528 PMCID: PMC9832478 DOI: 10.1021/acs.inorgchem.2c03259] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Nine potentially S,N,Npy-tridentate thiosemicarbazones (HL) derived from pyridine-2-carbaldehyde or 1-(2-pyridyl)ethanone have been prepared and fully characterized. The X-ray crystal structures of six of them and two hydrochlorides were determined and analyzed. The reaction of the [ReX(CH3CN)2(CO)3]/[ReX(CO)5] (X = Cl and Br) precursors with these ligands yielded different kinds of compounds: the adducts [ReX(HL)(CO)3], in which the ligands were S,N-bidentate; the trinuclear species [Re3Cl2(L23)(HL23)(CO)9]; and the thiosemicarbazonate compounds [Re(L)(CO)3], where the ligand is S,N,Npy-tridentate. Besides, the reaction in methanol or ethanol of the thiosemicarbazones derived from aldehydes yielded S,N,Npy-tridentate hemiaminal cationic [Re(HLOR)(CO)3]X and neutral [Re(LOMe)(CO)3] complexes after the coordinated ligand underwent addition of the alcohol group to the imine bond. The reactivity of the complex [ReX(HL)(CO)3] in MeOH and NEt3 led to the formation of dinuclear [Re2(L)2(CO)6], where the thiosemicarbazonate is again S,N-bidentate. The influence that the substituents on the thiosemicarbazone ligands have on the stability of the complexes and the effect of the reaction medium on the resulting compounds have been analyzed.
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Affiliation(s)
- Saray Argibay-Otero
- Departamento
de Química Inorgánica, Facultade de Química,
Instituto de Investigación Sanitaria Galicia Sur, Universidade de Vigo, Campus Universitario, E-36310 Vigo, Galicia, Spain,Metallosupramolecular
Chemistry Group, Galicia South Health Research
Institute (IIS Galicia Sur), SERGAS-UVIGO, E-36213 Vigo, Galicia, Spain
| | - Rosa Carballo
- Departamento
de Química Inorgánica, Facultade de Química,
Instituto de Investigación Sanitaria Galicia Sur, Universidade de Vigo, Campus Universitario, E-36310 Vigo, Galicia, Spain,Metallosupramolecular
Chemistry Group, Galicia South Health Research
Institute (IIS Galicia Sur), SERGAS-UVIGO, E-36213 Vigo, Galicia, Spain
| | - Ezequiel M. Vázquez-López
- Departamento
de Química Inorgánica, Facultade de Química,
Instituto de Investigación Sanitaria Galicia Sur, Universidade de Vigo, Campus Universitario, E-36310 Vigo, Galicia, Spain,Metallosupramolecular
Chemistry Group, Galicia South Health Research
Institute (IIS Galicia Sur), SERGAS-UVIGO, E-36213 Vigo, Galicia, Spain,
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2
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Di Sabato A, D’Acunzo F, Filippini D, Vetica F, Brasiello A, Corinti D, Bodo E, Michenzi C, Panzetta E, Gentili P. Unusually Chemoselective Photocyclization of 2-(Hydroxyimino)aldehydes to Cyclobutanol Oximes: Synthetic, Stereochemical, and Mechanistic Aspects. J Org Chem 2022; 87:13803-13818. [PMID: 36198009 PMCID: PMC9639046 DOI: 10.1021/acs.joc.2c01503] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
Photocyclization of carbonyl compounds (known as the Norrish-Yang reaction) to yield cyclobutanols is, in general, accompanied by fragmentation reactions. The latter are predominant in the case of aldehydes so that secondary cyclobutanols are not considered accessible via the straightforward Norrish-Yang reaction. A noteworthy exception has been reported in our laboratory, where cyclobutanols bearing a secondary alcohol function were observed upon UV light irradiation of 2-(hydroxyimino)aldehydes (HIAs). This reaction is here investigated in detail by combining synthesis, spectroscopic data, molecular dynamics, and DFT calculations. The synthetic methodology is generally applicable to a series of HIAs, affording the corresponding cyclobutanol oximes (CBOs) chemoselectively (i.e., without sizable fragmentation side-reactions), diastereoselectively (up to >99:1), and in good to excellent yields (up to 95%). CBO oxime ether derivatives can be purified and diastereomers isolated by standard column chromatography. The mechanistic and stereochemical picture of this photocyclization reaction, as well as of the postcyclization E/Z isomerization of the oxime double bond is completed.
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Affiliation(s)
- Antonio Di Sabato
- Department
of Chemistry, Sapienza University of Rome, Piazzale Aldo Moro 5, 00185 Rome, Italy,Institute
of Biological Systems (ISB), Sezione Meccanismi di Reazione, Italian
National Research Council (CNR), c/o Department of Chemistry, Sapienza University of Rome, Piazzale Aldo Moro 5, 00185 Rome, Italy
| | - Francesca D’Acunzo
- Institute
of Biological Systems (ISB), Sezione Meccanismi di Reazione, Italian
National Research Council (CNR), c/o Department of Chemistry, Sapienza University of Rome, Piazzale Aldo Moro 5, 00185 Rome, Italy
| | - Dario Filippini
- Department
of Chemistry, Sapienza University of Rome, Piazzale Aldo Moro 5, 00185 Rome, Italy
| | - Fabrizio Vetica
- Department
of Chemistry, Sapienza University of Rome, Piazzale Aldo Moro 5, 00185 Rome, Italy,
| | - Antonio Brasiello
- Department
of Chemical Engineering Materials Environment, Sapienza University of Rome, via Eudossiana 18, 00184 Rome, Italy
| | - Davide Corinti
- Department
of Chemistry and Technology of Drugs, Sapienza
University of Rome, Piazzale
Aldo Moro 5, 00185 Rome, Italy
| | - Enrico Bodo
- Department
of Chemistry, Sapienza University of Rome, Piazzale Aldo Moro 5, 00185 Rome, Italy
| | - Cinzia Michenzi
- Department
of Chemistry, Sapienza University of Rome, Piazzale Aldo Moro 5, 00185 Rome, Italy
| | - Edoardo Panzetta
- Department
of Chemistry, Sapienza University of Rome, Piazzale Aldo Moro 5, 00185 Rome, Italy
| | - Patrizia Gentili
- Department
of Chemistry, Sapienza University of Rome, Piazzale Aldo Moro 5, 00185 Rome, Italy,Institute
of Biological Systems (ISB), Sezione Meccanismi di Reazione, Italian
National Research Council (CNR), c/o Department of Chemistry, Sapienza University of Rome, Piazzale Aldo Moro 5, 00185 Rome, Italy,
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3
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Hanft A, Rottschäfer D, Wieprecht N, Geist F, Radacki K, Lichtenberg C. Aminotroponiminates: Impact of the NO 2 Functional Group on Coordination, Isomerisation, and Backbone Substitution. Chemistry 2021; 27:14250-14262. [PMID: 34314083 PMCID: PMC8597084 DOI: 10.1002/chem.202102324] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2021] [Indexed: 01/17/2023]
Abstract
Aminotroponiminate (ATI) ligands are a versatile class of redox-active and potentially cooperative ligands with a rich coordination chemistry that have consequently found a wide range of applications in synthesis and catalysis. While backbone substitution of these ligands has been investigated in some detail, the impact of electron-withdrawing groups on the coordination chemistry and reactivity of ATIs has been little investigated. We report here Li, Na, and K salts of an ATI ligand with a nitro-substituent in the backbone. It is demonstrated that the NO2 group actively contributes to the coordination chemistry of these complexes, effectively competing with the N,N-binding pocket as a coordination site. This results in an unprecedented E/Z isomerisation of an ATI imino group and culminates in the isolation of the first "naked" (i. e., without directional bonding to a metal atom) ATI anion. Reactions of sodium ATIs with silver(I) and tritylium salts gave the first N,N-coordinated silver ATI complexes and unprecedented backbone substitution reactions. Analytical techniques applied in this work include multinuclear (VT-)NMR spectroscopy, single-crystal X-ray diffraction analysis, and DFT calculations.
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Affiliation(s)
- Anna Hanft
- Institut für Anorganische Chemie, Fakultät für Chemie und Pharmazie, Julius-Maximilians-Universität Würzburg, Am Hubland, 97074, Würzburg, Germany
| | - Dennis Rottschäfer
- Institut für Anorganische Chemie, Fakultät für Chemie und Pharmazie, Julius-Maximilians-Universität Würzburg, Am Hubland, 97074, Würzburg, Germany
| | - Nele Wieprecht
- Institut für Anorganische Chemie, Fakultät für Chemie und Pharmazie, Julius-Maximilians-Universität Würzburg, Am Hubland, 97074, Würzburg, Germany
| | - Felix Geist
- Institut für Anorganische Chemie, Fakultät für Chemie und Pharmazie, Julius-Maximilians-Universität Würzburg, Am Hubland, 97074, Würzburg, Germany
| | - Krzysztof Radacki
- Institut für Anorganische Chemie, Fakultät für Chemie und Pharmazie, Julius-Maximilians-Universität Würzburg, Am Hubland, 97074, Würzburg, Germany
| | - Crispin Lichtenberg
- Institut für Anorganische Chemie, Fakultät für Chemie und Pharmazie, Julius-Maximilians-Universität Würzburg, Am Hubland, 97074, Würzburg, Germany
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4
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Zhu W, Doubleday PF, Butrin A, Weerawarna PM, Melani R, Catlin DS, Dwight TA, Liu D, Kelleher NL, Silverman RB. Remarkable and Unexpected Mechanism for ( S)-3-Amino-4-(difluoromethylenyl)cyclohex-1-ene-1-carboxylic Acid as a Selective Inactivator of Human Ornithine Aminotransferase. J Am Chem Soc 2021; 143:8193-8207. [PMID: 34014654 PMCID: PMC8369387 DOI: 10.1021/jacs.1c03572] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
Human ornithine aminotransferase (hOAT) is a pyridoxal 5'-phosphate (PLP)-dependent enzyme that was recently found to play an important role in the metabolic reprogramming of hepatocellular carcinoma (HCC) via the proline and glutamine metabolic pathways. The selective inhibition of hOAT by compound 10 exhibited potent in vivo antitumor activity. Inspired by the discovery of the aminotransferase inactivator (1S,3S)-3-amino-4-(difluoromethylene)cyclopentane-1-carboxylic acid (5), we rationally designed, synthesized, and evaluated a series of six-membered-ring analogs. Among them, 14 was identified as a new selective hOAT inactivator, which demonstrated a potency 22× greater than that of 10. Three different types of protein mass spectrometry approaches and two crystallographic approaches were employed to identify the structure of hOAT-14 and the formation of a remarkable final adduct (32') in the active site. These spectral studies reveal an enzyme complex heretofore not observed in a PLP-dependent enzyme, which has covalent bonds to two nearby residues. Crystal soaking experiments and molecular dynamics simulations were carried out to identify the structure of the active-site intermediate 27' and elucidate the order of the two covalent bonds that formed, leading to 32'. The initial covalent reaction of the activated warhead occurs with *Thr322 from the second subunit, followed by a subsequent nucleophilic attack by the catalytic residue Lys292. The turnover mechanism of 14 by hOAT was supported by a mass spectrometric analysis of metabolites and fluoride ion release experiments. This novel mechanism for hOAT with 14 will contribute to the further rational design of selective inactivators and an understanding of potential inactivation mechanisms by aminotransferases.
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Affiliation(s)
- Wei Zhu
- Department of Chemistry, Chemistry of Life Processes Institute, Center for Molecular Innovation and Drug Discovery, and Center for Developmental Therapeutics, Northwestern University, Evanston, Illinois 60208, United States
| | - Peter F. Doubleday
- Department of Molecular Biosciences, Northwestern University, Evanston, Illinois 60208, United States
| | - Arseniy Butrin
- Department of Chemistry and Biochemistry, Loyola University Chicago, Chicago, Illinois 60660, United States
| | - Pathum M. Weerawarna
- Department of Chemistry, Chemistry of Life Processes Institute, Center for Molecular Innovation and Drug Discovery, and Center for Developmental Therapeutics, Northwestern University, Evanston, Illinois 60208, United States
| | - Rafael Melani
- Department of Molecular Biosciences, Northwestern University, Evanston, Illinois 60208, United States
| | - Daniel S. Catlin
- Department of Chemistry and Biochemistry, Loyola University Chicago, Chicago, Illinois 60660, United States
| | - Timothy A. Dwight
- Department of Chemistry, Chemistry of Life Processes Institute, Center for Molecular Innovation and Drug Discovery, and Center for Developmental Therapeutics, Northwestern University, Evanston, Illinois 60208, United States
| | - Dali Liu
- Department of Chemistry and Biochemistry, Loyola University Chicago, Chicago, Illinois 60660, United States,Corresponding authors (R.B.S.) . Phone: +1-847-491-5653, (N.L.K.) . Phone: +1-847-467-4362. (D.L.) . Phone: +1-773-508-3093
| | - Neil L. Kelleher
- Department of Chemistry, Chemistry of Life Processes Institute, Center for Molecular Innovation and Drug Discovery, and Center for Developmental Therapeutics, Northwestern University, Evanston, Illinois 60208, United States,Department of Molecular Biosciences, Northwestern University, Evanston, Illinois 60208, United States,Corresponding authors (R.B.S.) . Phone: +1-847-491-5653, (N.L.K.) . Phone: +1-847-467-4362. (D.L.) . Phone: +1-773-508-3093
| | - Richard B. Silverman
- Department of Chemistry, Chemistry of Life Processes Institute, Center for Molecular Innovation and Drug Discovery, and Center for Developmental Therapeutics, Northwestern University, Evanston, Illinois 60208, United States,Department of Molecular Biosciences, Northwestern University, Evanston, Illinois 60208, United States,Department of Pharmacology, Northwestern University, Chicago, Illinois 60611, United States,Corresponding authors (R.B.S.) . Phone: +1-847-491-5653, (N.L.K.) . Phone: +1-847-467-4362. (D.L.) . Phone: +1-773-508-3093
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5
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Abstract
Esters of iminophosphonic acids (iminophosphonates, or IPs), including a fragment, >P(=O)-C=N, can be easily functionalized, for instance to aminophosphonic acids with a wide range of biological activity. Depending on the character of the substitution, the Z- or E-configuration is favorable for IPs, which in turn can influence the stereochemistry of the products of chemical transformations of IPs. While the Z,E-isomerism in IPs has been thoroughly studied by NMR spectroscopy, the factors stabilizing a definite isomer are still not clear. In the current work, density functional theory (DFT, using M06-2X functional) and ab initio spin-component–scaled second-order Møller–Plesset perturbation theory (SCS-MP2) calculations were carried out for a broad series of IPs. The calculations reproduce well a subtle balance between the preferred Z-configuration inherent for C-trifluoromethyl substituted IPs and the E-form, which is more stable for C-alkyl- or aryl-substituted IPs. The predicted trend of changing activation energy values agrees well with the recently determined experimental ΔG≠298 magnitudes. Depending on the substitution in the aromatic moiety, the Z/E-isomerization of N-aryl-substituted IPs proceeds via two types of close-in energy transition states. Not a single main factor but a combination of various contributions should be considered in order to explain the Z/E-isomerization equilibrium for different IPs.
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6
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Kent GT, Cook AW, Damon PL, Lewis RA, Wu G, Hayton TW. Synthesis and Characterization of Two "Tied-Back" Lithium Ketimides and Isolation of a Ketimide-Bridged [Cr 2] 6+ Dimer with Strong Antiferromagnetic Coupling. Inorg Chem 2021; 60:4996-5004. [PMID: 33764048 DOI: 10.1021/acs.inorgchem.1c00052] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Reaction of 1 equiv of KN(SiMe3)2 with 9-fluorenone results in the formation of (Me3Si)N═C13H8 (1) in high yield after work-up. Addition of 1 equiv of phenol to 1 results in rapid desilylation and formation of 9-fluorenone imine, HN═C13H8 (2). Subsequent reaction of 2 with 1 equiv of LiNiPr2 results in deprotonation and formation of [Li(Et2O)]4[N═C13H8]4 (3) in good yield. Reaction of 1 equiv of KN(SiMe3)2 with 2-adamantanone for 7 days at room temperature results in the formation of (Me3Si)N═C10H14 (4) in good yield. Dissolution of 4 in neat MeOH results in rapid desilylation concomitant with formation of 2-adamantanone imine, HN═C10H14 (5). Subsequent reaction of 5 with 1 equiv of LiNiPr2 results in formation of [Li(THF)]4[N═C10H14]4 (6). Both 3 and 6 were characterized by X-ray crystallography. Finally, reaction of CrCl3 with 3.5 equiv of 6 results in formation of the [Cr2]6+ dimer, [Li][Cr2(N═C10H14)7] (7), which can be isolated in modest yield after work-up. Complex 7 features a Cr-Cr bond length of 2.653(2) Å. Additionally, solid-state magnetic susceptibility measurements reveal strong antiferromagnetic coupling between the two Cr centers, with J = -200 cm-1.
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Affiliation(s)
- Greggory T Kent
- Department of Chemistry and Biochemistry, University of California, Santa Barbara, Santa Barbara, California 93106, United States
| | - Andrew W Cook
- Department of Chemistry and Biochemistry, University of California, Santa Barbara, Santa Barbara, California 93106, United States
| | - Peter L Damon
- Department of Chemistry and Biochemistry, University of California, Santa Barbara, Santa Barbara, California 93106, United States
| | - Richard A Lewis
- Department of Chemistry and Biochemistry, University of California, Santa Barbara, Santa Barbara, California 93106, United States
| | - Guang Wu
- Department of Chemistry and Biochemistry, University of California, Santa Barbara, Santa Barbara, California 93106, United States
| | - Trevor W Hayton
- Department of Chemistry and Biochemistry, University of California, Santa Barbara, Santa Barbara, California 93106, United States
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7
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Cataffo A, Haas T, Ehm C, Budzelaar PHM. Between T and Y: Asymmetry in the Interaction of LAu(I) with Bipy and β‐Diiminate‐like Ligands. Eur J Inorg Chem 2021. [DOI: 10.1002/ejic.202000929] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Affiliation(s)
- Andrea Cataffo
- Department of Chemical Sciences Federico II University of Naples Via Cintia 21 – Complesso di Monte S. Angelo 80126 Napoli Italy
| | - Titus Haas
- van't Hoff Institute for Molecular Sciences University of Amsterdam 1098 XH Amsterdam The Netherlands
| | - Christian Ehm
- Department of Chemical Sciences Federico II University of Naples Via Cintia 21 – Complesso di Monte S. Angelo 80126 Napoli Italy
| | - Peter H. M. Budzelaar
- Department of Chemical Sciences Federico II University of Naples Via Cintia 21 – Complesso di Monte S. Angelo 80126 Napoli Italy
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8
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Schindler M. Investigations on the E/Z-isomerism of neonicotinoids. J Comput Aided Mol Des 2020; 35:517-529. [PMID: 32613559 DOI: 10.1007/s10822-020-00326-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2020] [Accepted: 06/16/2020] [Indexed: 10/23/2022]
Abstract
We investigate the minimum-energy path for the rotation of formal C=N double bonds in molecules with guanidine-like substructures as present in the chemical class of neonicotinoids. The transitions between the E- and Z-isomers of several neonicotinoids using scans of the torsional potential energy hypersurfaces are quantified at the DFT-level of theory. The validity of using this ansatz is checked by single-point CCSD(T) calculations for model systems like nitroguanidine. A combined approach of theory and experiment permits to unambiguously identify the relevant isomers present at ambient conditions. As an example, MP2-GIAO predictions of the NMR spectra of E- and Z-Clothianidin are experimentally confirmed by low-temperature NMR-experiments identifying for the first time the hitherto unknown Z-Isomer of Clothianidin.
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9
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Su Q, Li Y, Wang B, Liu M, Wang H, Wang W, Liu F. Combining the Advantages of Alkene and Azo E-Z Photoisomerizations: Mechanistic Insights into Ketoimine Photoswitches. J Phys Chem A 2017; 121:2588-2596. [PMID: 28301930 DOI: 10.1021/acs.jpca.7b01674] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
We carried out CASPT2//(TD)DFT and CASPT2//CASSCF studies on the working mechanism of imine switches, including a camphorquinone-derived ketoimine (shortened as k-Imine) switch designed by Lehn as well as a model camphorquinone alkene-imine (a-Imine) proposed in this study. Under the experimental conditions (light irradiation with 455 and 365 nm for E and Z, respectively), k-Imine is excited to the S1:(nN,π*) state and then decays toward a perpendicular intermediate following the C═N bond rotation coordinate. During the bond rotation, a mild energy barrier caused by the strong interaction of S1:(nN,π*) and S2:(nO,π*) states will more or less slow down the rotation speed of k-Imine. The large difference in irradiation light wavelength supports k-Imine as a two-way photoswitch. The photoisomerization of a-Imine obeys a similar but fully barrierless pattern while requiring a higher excitation energy to reach the (nN,π*) state. The good directionality of thermal isomerization toward E(a-Imine), plus the barrierless photoisomerization, allows for the design of a thermal and photo-operated switch. For both imines, a minimal-energy crossing point (MECI) located at the perpendicular region, with low relative energy and close to the rotary path, ensures the directionality of C═N bond rotation and confirms imines as optimal candidates for photoswitches and motors.
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Affiliation(s)
- Qingqing Su
- Key Laboratory for Macromolecular Science of Shaanxi Province, School of Chemistry & Chemical Engineering, Shaanxi Normal University , Xi'an, Shaanxi 710062, People's Republic of China
| | - Yuanying Li
- Key Laboratory for Macromolecular Science of Shaanxi Province, School of Chemistry & Chemical Engineering, Shaanxi Normal University , Xi'an, Shaanxi 710062, People's Republic of China
| | - Bin Wang
- Key Laboratory for Macromolecular Science of Shaanxi Province, School of Chemistry & Chemical Engineering, Shaanxi Normal University , Xi'an, Shaanxi 710062, People's Republic of China
| | - Minjuan Liu
- Key Laboratory for Macromolecular Science of Shaanxi Province, School of Chemistry & Chemical Engineering, Shaanxi Normal University , Xi'an, Shaanxi 710062, People's Republic of China
| | - Hongjuan Wang
- Key Laboratory for Macromolecular Science of Shaanxi Province, School of Chemistry & Chemical Engineering, Shaanxi Normal University , Xi'an, Shaanxi 710062, People's Republic of China
| | - Wenliang Wang
- Key Laboratory for Macromolecular Science of Shaanxi Province, School of Chemistry & Chemical Engineering, Shaanxi Normal University , Xi'an, Shaanxi 710062, People's Republic of China
| | - Fengyi Liu
- Key Laboratory for Macromolecular Science of Shaanxi Province, School of Chemistry & Chemical Engineering, Shaanxi Normal University , Xi'an, Shaanxi 710062, People's Republic of China
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10
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Chourasiya SS, Kathuria D, Nikam SS, Ramakrishnan A, Khullar S, Mandal SK, Chakraborti AK, Bharatam PV. Azine-Hydrazone Tautomerism of Guanylhydrazones: Evidence for the Preference Toward the Azine Tautomer. J Org Chem 2016; 81:7574-7583. [PMID: 27494613 DOI: 10.1021/acs.joc.6b01258] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Guanylhydrazones have been known for a long time and have wide applications in organic synthesis, medicinal chemistry, and material science; however, little attention has been paid toward their electronic and structural properties. Quantum chemical analysis on several therapeutically important guanylhydrazones indicated that all of them prefer the azine tautomeric state (by about 3-12 kcal/mol). A set of simple and conjugated azines were designed using quantum chemical methods, whose tautomeric preference toward the azine tautomer is in the range of 3-8 kcal/mol. Twenty new azines were synthesized and isolated in their neutral state. Variable temperature NMR study suggests existence of the azine tautomer even at higher temperatures with no traces of the hydrazone tautomer. The crystal structures of two representative compounds confirmed that the title compounds prefer to exist in their azine tautomeric form.
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Affiliation(s)
- Sumit S Chourasiya
- Department of Medicinal Chemistry, National Institute of Pharmaceutical Education and Research (NIPER) , Sector 67, S.A.S. Nagar 160 062, Punjab, India
| | - Deepika Kathuria
- Department of Medicinal Chemistry, National Institute of Pharmaceutical Education and Research (NIPER) , Sector 67, S.A.S. Nagar 160 062, Punjab, India
| | - Sampada S Nikam
- Department of Medicinal Chemistry, National Institute of Pharmaceutical Education and Research (NIPER) , Sector 67, S.A.S. Nagar 160 062, Punjab, India
| | - Ashok Ramakrishnan
- Department of Medicinal Chemistry, National Institute of Pharmaceutical Education and Research (NIPER) , Sector 67, S.A.S. Nagar 160 062, Punjab, India
| | - Sadhika Khullar
- Department of Chemical Sciences, Indian Institute of Science Education and Research , Mohali Sector 81, S.A.S. Nagar 140 306, Punjab, India
| | - Sanjay K Mandal
- Department of Chemical Sciences, Indian Institute of Science Education and Research , Mohali Sector 81, S.A.S. Nagar 140 306, Punjab, India
| | - Asit K Chakraborti
- Department of Medicinal Chemistry, National Institute of Pharmaceutical Education and Research (NIPER) , Sector 67, S.A.S. Nagar 160 062, Punjab, India
| | - Prasad V Bharatam
- Department of Medicinal Chemistry, National Institute of Pharmaceutical Education and Research (NIPER) , Sector 67, S.A.S. Nagar 160 062, Punjab, India
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11
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Greb L, Eichhöfer A, Lehn JM. Synthetic Molecular Motors: Thermal N Inversion and Directional Photoinduced C=N Bond Rotation of Camphorquinone Imines. Angew Chem Int Ed Engl 2015; 54:14345-8. [PMID: 26449964 DOI: 10.1002/anie.201506691] [Citation(s) in RCA: 66] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2015] [Indexed: 01/20/2023]
Abstract
The thermal and photochemical E/Z isomerization of camphorquinone-derived imines was studied by a combination of kinetic, structural, and computational methods. The thermal isomerization proceeds by linear N inversion, whereas the photoinduced process occurs through C=N bond rotation with preferred directionality as a result of diastereoisomerism. Thereby, these imines are arguably the simplest example of synthetic molecular motors. The generality of the orthogonal trajectories of the thermal and photochemical pathways allows for the postulation that every suitable chiral imine qualifies, in principle, as a molecular motor driven by light or heat.
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Affiliation(s)
- Lutz Greb
- Institut de Science et d'Ingénierie Supramoléculaires (ISIS), Université de Strasbourg, 8 allée Gaspard Monge, Strasbourg 67000 (France).,Institut für Nanotechnologie (INT), Karlsruhe Institut für Technologie, Hermann-von-Helmholtz-Platz 1, 76344 Eggenstein-Leopoldshafen (Germany)
| | - Andreas Eichhöfer
- Institut für Nanotechnologie (INT), Karlsruhe Institut für Technologie, Hermann-von-Helmholtz-Platz 1, 76344 Eggenstein-Leopoldshafen (Germany)
| | - Jean-Marie Lehn
- Institut de Science et d'Ingénierie Supramoléculaires (ISIS), Université de Strasbourg, 8 allée Gaspard Monge, Strasbourg 67000 (France).
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