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Lopes Jesus AJ, Nunes CM, Ferreira GA, Keyvan K, Fausto R. Photochemical Generation and Characterization of C-Aminophenyl-Nitrilimines: Insights on Their Bond-Shift Isomers by Matrix-Isolation IR Spectroscopy and Density Functional Theory Calculations. Molecules 2024; 29:3497. [PMID: 39124902 PMCID: PMC11314218 DOI: 10.3390/molecules29153497] [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: 07/11/2024] [Revised: 07/20/2024] [Accepted: 07/22/2024] [Indexed: 08/12/2024] Open
Abstract
The intriguing ability of C-phenyl-nitrilimine to co-exist as allenic and propargylic bond-shift isomers motivated us to investigate how substituents in the phenyl ring influence this behavior. Building on our previous work on the meta- and para-OH substitution, here we extended this investigation to explore the effect of the NH2 substitution. For this purpose, C-(4-aminophenyl)- and C-(3-aminophenyl)-nitrilimines were photogenerated in an argon matrix at 15 K by narrowband UV-light irradiation (λ = 230 nm) of 5-(4-aminophenyl)- and 5-(3-aminophenyl)-tetrazole, respectively. The produced nitrilimines were further photoisomerized to carbodiimides via 1H-diazirines by irradiations at longer wavelengths (λ = 380 or 330 nm). Combining IR spectroscopic measurements and DFT calculations, it was found that the para-NH2-substituted nitrilimine exists as a single isomeric structure with a predominant allenic character. In contrast, the meta-NH2-substituted nitrilimine co-exists as two bond-shift isomers characterized by propargylic and allenic structures. To gain further understanding of the effects of phenyl substitution on the bond-shift isomerism of the nitrilimine fragment, we compared geometric and charge distribution data derived from theoretical calculations performed for C-phenyl-nitrilimine with those performed for the derivatives resulting from NH2 (electron-donating group) and NO2 (electron-withdrawing group) phenyl substitutions.
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Affiliation(s)
- A. J. Lopes Jesus
- University of Coimbra, CQC-IMS, Faculty of Pharmacy, 3004-295 Coimbra, Portugal
| | - Cláudio M. Nunes
- University of Coimbra, CQC-IMS, Department of Chemistry, 3004-535 Coimbra, Portugal; (C.M.N.); (G.A.F.); (K.K.); (R.F.)
| | - Gil A. Ferreira
- University of Coimbra, CQC-IMS, Department of Chemistry, 3004-535 Coimbra, Portugal; (C.M.N.); (G.A.F.); (K.K.); (R.F.)
| | - Kiarash Keyvan
- University of Coimbra, CQC-IMS, Department of Chemistry, 3004-535 Coimbra, Portugal; (C.M.N.); (G.A.F.); (K.K.); (R.F.)
| | - R. Fausto
- University of Coimbra, CQC-IMS, Department of Chemistry, 3004-535 Coimbra, Portugal; (C.M.N.); (G.A.F.); (K.K.); (R.F.)
- Istanbul Kultur University, Faculty Sciences and Letters, Department of Physics, Bakirkoy, 34158 Istanbul, Turkey
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Hockey EK, McLane N, Vlahos K, McCaslin LM, Dodson LG. Matrix-formation dynamics dictate methyl nitrite conformer abundance. J Chem Phys 2024; 160:094303. [PMID: 38436440 DOI: 10.1063/5.0188433] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2023] [Accepted: 01/31/2024] [Indexed: 03/05/2024] Open
Abstract
Methyl nitrite has two stable conformational isomers resulting from rotation about the primary C-O-N-O dihedral angle: cis-CH3ONO and trans-CH3ONO, with cis being more stable by ∼5 kJ/mol. The barrier to rotational interconversion (∼45 kJ/mol) is too large for isomerization to occur under ambient conditions. This paper presents evidence of a change in conformer abundance when dilute CH3ONO is deposited onto a cold substrate; the relative population of the freshly deposited cis conformer is seen to increase compared to its gas-phase abundance, measured by in situ infrared spectroscopy. We observe abundance changes depending on the identity of the bath gas (N2, Ar, and Xe) and deposition angle. The observations indicate that the surface properties of the growing matrix influence conformer abundance-contrary to the widely held assumption that conformer abundance in matrices reflects gas-phase abundance. We posit that differences in the angle-dependent host-gas deposition dynamics affect the growing surfaces, causing changes in conformer abundances. Quantum chemistry calculations of the binding energies between CH3ONO and a single bath-gas component reveal that significant energetic stabilization is not observed in 1:1 complexes of N2:CH3ONO, Ar:CH3ONO, or Xe:CH3ONO. From our results, we conclude that the growing surface plays a significant role in trapping cis-CH3ONO more effectively than trans-CH3ONO, likely because cis-CH3ONO is more compact. Taken together, the observations highlight the necessity for careful characterization of conformers in matrix-isolated systems, emphasizing a need for further study into the deposition dynamics and surface structure of chemically inert matrices.
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Affiliation(s)
- Emily K Hockey
- Department of Chemistry and Biochemistry, University of Maryland, College Park, Maryland 20742, USA
| | - Nathan McLane
- Institute for Physical Science and Technology, University of Maryland, College Park, Maryland 20742, USA
| | - Korina Vlahos
- Department of Chemistry and Biochemistry, University of Maryland, College Park, Maryland 20742, USA
| | | | - Leah G Dodson
- Department of Chemistry and Biochemistry, University of Maryland, College Park, Maryland 20742, USA
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3
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Sharma A, Gupta VK, Reva I. Methoxyacetone revisited. SPECTROCHIMICA ACTA. PART A, MOLECULAR AND BIOMOLECULAR SPECTROSCOPY 2024; 308:123651. [PMID: 38056186 DOI: 10.1016/j.saa.2023.123651] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/12/2023] [Revised: 11/10/2023] [Accepted: 11/12/2023] [Indexed: 12/08/2023]
Abstract
Conformational space of methoxyacetone (MA) was studied at the MP2/6-311++G(d,p) and DFT(B3LYP)/6-311++G(d,p) levels of theory. Computations predict MA to adopt four conformations, resulting from internal rotations around the O=C-C-O (Trans, Cis) and C-C-O-C (trans, gauche) dihedral angles. The Tt (Trans-trans) conformer is the most stable. The computed energies of two gauche (Tg and Cg) conformers fall in the 3-8 kJ mol-1 range above Tt and should account for 1/3 of the room-temperature gas-phase equilibrium. The energy of Ct form is 11 kJ mol-1 above Tt, and its expected population is negligible (below 1 %). In our earlier work, MA monomers were isolated in cryogenic argon matrices and characterized by infrared spectroscopy. In the experiment, only the most stable Tt conformer was detected in the sample. Signatures of the other conformers were not detected, either in freshly deposited samples, or in samples subjected to different UV irradiations. We rationalize those observations in terms of computed barriers for intramolecular torsions, indicating occurrence of conformational cooling during deposition. The experimental infrared spectrum of the Tt form is now assigned with the aid of anharmonic DFT computations. Exposure of MA to UV irradiation in the 300-260 nm range led to photolysis, according to the Norrish type II mechanism, resulting in dimer between enol acetone and formaldehyde observed as a cage-confined intermediate photoproduct. The subsequent photolysis resulted in the formation of carbon monoxide as the dominating photoproduct, formed in the Norrish type I photoreaction. Mechanistic interpretation of this photo decarbonylation reaction is presented.
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Affiliation(s)
- Archna Sharma
- PG Department of Physics, University of Jammu, Jammu, J&K 180006, India
| | - Vivek K Gupta
- PG Department of Physics, University of Jammu, Jammu, J&K 180006, India
| | - Igor Reva
- CIEPQPF, Department of Chemical Engineering, Rua Sílvio Lima, University of Coimbra, Coimbra 3030-790, Portugal.
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Grassin C, Pollok CH, Kreienborg NM, Merten C. Matrix effects in MI-VCD spectra of two chiral oxiranes and their potential microscopic origin. Phys Chem Chem Phys 2023; 25:31995-32001. [PMID: 37975701 DOI: 10.1039/d3cp05023h] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2023]
Abstract
Combining vibrational circular dichroism (VCD) spectroscopy with the matrix isolation (MI) technique opens up interesting possibilities to study chiral molecules. MI involves the isolation of guest species in inert solid matrices at cryogenic temperatures. Hence, MI-VCD measures are solid-state VCD measurements, and as such, can suffer from mostly birefringance-related artefacts in the same way as common solid-state VCD measurements. In this contribution, we demonstrate that the sample preparation condition have tremendous impact on the quality and reliability of the recorded MI-VCD spectra. While MI-IR spectra are basically blind to these artefacts, the variation of deposition temperatures and host flow rates seem to control whether high quality MI-VCD spectra are obtained or if depolarization effects lead to completely obscured spectra. For two selected examples, styrene oxide (SO) and 1-phenyl propylene oxide (PPO), we discuss how the various experimental conditions may lead to the aforementioned effects and give a microscopic description of their origin.
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Affiliation(s)
- Corentin Grassin
- Ruhr Universität Bochum, Fakultät für Chemie und Biochemie, Organische Chemie II, Universitätsstraße 150, 44801, Bochum, Germany.
| | - Corina H Pollok
- Ruhr Universität Bochum, Fakultät für Chemie und Biochemie, Organische Chemie II, Universitätsstraße 150, 44801, Bochum, Germany.
| | - Nora M Kreienborg
- Ruhr Universität Bochum, Fakultät für Chemie und Biochemie, Organische Chemie II, Universitätsstraße 150, 44801, Bochum, Germany.
| | - Christian Merten
- Ruhr Universität Bochum, Fakultät für Chemie und Biochemie, Organische Chemie II, Universitätsstraße 150, 44801, Bochum, Germany.
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Sanz-Novo M, Kolesniková L, Insausti A, Alonso JL, León I, Alonso ER. A journey across dopamine Metabolism: A rotational study of DOPAC. SPECTROCHIMICA ACTA. PART A, MOLECULAR AND BIOMOLECULAR SPECTROSCOPY 2023; 290:122303. [PMID: 36608514 DOI: 10.1016/j.saa.2022.122303] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/05/2022] [Revised: 12/27/2022] [Accepted: 12/28/2022] [Indexed: 06/17/2023]
Abstract
DOPAC, a relevant scaffold in dopamine metabolism, was probed in the gas phase and interrogated by high-resolution rotational spectroscopy. Herein, three distinct conformers were isolated in a supersonic jet and identified for the first time through an examination of the trend of the rotational constants and the dipole moment selection rules. Additionally, we examined the plausible relaxation pathways of the low-energy conformers of DOPAC, which helped us to claim the indirect detection of two additional conformers, providing conclusive experimental evidence of the flexible nature of this biomolecule. The current investigation sheds some light on the differences between jet-cooled rotational experiments and matrix-isolation infrared spectroscopy.
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Affiliation(s)
- Miguel Sanz-Novo
- Grupo de Espectrocopía Molecular (GEM), Edificio Quifima, Laboratorios de Espectroscopía y Bioespectroscopía, Unidad Asociada CSIC, Parque Científico UVa, Universidad de Valladolid, 47011, Valladolid, Spain
| | - Lucie Kolesniková
- Department of Analytical Chemistry, University of Chemistry and Technology, Technická 5, 166 28 Prague 6, Czech Republic
| | - Aran Insausti
- Departamento de Química Física, Facultad de Ciencia y Tecnología, Universidad del País Vasco (UPV/ EHU), 48940 Leioa, Spain
| | - José L Alonso
- Grupo de Espectrocopía Molecular (GEM), Edificio Quifima, Laboratorios de Espectroscopía y Bioespectroscopía, Unidad Asociada CSIC, Parque Científico UVa, Universidad de Valladolid, 47011, Valladolid, Spain
| | - Iker León
- Grupo de Espectrocopía Molecular (GEM), Edificio Quifima, Laboratorios de Espectroscopía y Bioespectroscopía, Unidad Asociada CSIC, Parque Científico UVa, Universidad de Valladolid, 47011, Valladolid, Spain
| | - Elena R Alonso
- Grupo de Espectrocopía Molecular (GEM), Edificio Quifima, Laboratorios de Espectroscopía y Bioespectroscopía, Unidad Asociada CSIC, Parque Científico UVa, Universidad de Valladolid, 47011, Valladolid, Spain.
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6
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Luiza B. Brito A, Justino LL, Çatıkkaş B, Lopes S, Ildiz GO, Fausto R. Structure, conformational landscape and UV-induced selective rotamerization of 2-aminoacetanilide. J Photochem Photobiol A Chem 2023. [DOI: 10.1016/j.jphotochem.2022.114302] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/14/2022]
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7
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Lopes Jesus AJ, de Lucena Júnior JR, Fausto R, Reva I. Infrared Spectra and Phototransformations of meta-Fluorophenol Isolated in Argon and Nitrogen Matrices. MOLECULES (BASEL, SWITZERLAND) 2022; 27:molecules27238248. [PMID: 36500356 PMCID: PMC9735537 DOI: 10.3390/molecules27238248] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 10/22/2022] [Revised: 11/18/2022] [Accepted: 11/21/2022] [Indexed: 11/29/2022]
Abstract
Monomers of meta-fluorophenol (mFP) were trapped from the gas phase into cryogenic argon and nitrogen matrices. The estimated relative energies of the two conformers are very close, and in the gas phase they have nearly equal populations. Due to the similarity of their structures (they only differ in the orientation of the OH group), the two conformers have also similar predicted vibrational signatures, which makes the vibrational characterization of the individual rotamers challenging. In the present work, it has been established that in an argon matrix only the most stable trans conformer of mFP exists (the OH group pointing away from the fluorine atom). On the other hand, the IR spectrum of mFP in a nitrogen matrix testifies to the simultaneous presence in this matrix of both the trans conformer and of the higher-energy cis conformer (the OH group pointing toward the fluorine atom), which is stabilized by interaction with the matrix gas host. We found that the exposition of the cryogenic N2 matrix to the Globar source of the infrared spectrometer affects the conformational populations. By collecting experimental spectra, either in the full mid-infrared range or only in the range below 2200 cm-1, we were able to reliably distinguish two sets of experimental bands originating from individual conformers. A comparison of the two sets of experimental bands with computed infrared spectra of the conformers allowed, for the first time, the unequivocal vibrational identification of each of them. The joint implementation of computational vibrational spectroscopy and matrix-isolation infrared spectroscopy proved to be a very accurate method of structural analysis. Some mechanistic insights into conformational isomerism (the quantum tunneling of hydrogen atom and vibrationally-induced conformational transformations) have been addressed. Finally, we also subjected matrix-isolated mFP to irradiations with UV light, and the phototransformations observed in these experiments are also described.
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Affiliation(s)
- A. J. Lopes Jesus
- CQC-IMS, Faculty of Pharmacy, University of Coimbra, 3004-295 Coimbra, Portugal
- Correspondence: (A.J.L.J.); (I.R.)
| | | | - Rui Fausto
- CQC-IMS, Department of Chemistry, University of Coimbra, 3004-535 Coimbra, Portugal
| | - Igor Reva
- CQC-IMS, Department of Chemistry, University of Coimbra, 3004-535 Coimbra, Portugal
- CIEPQPF, Department of Chemical Engineering, University of Coimbra, 3030-790 Coimbra, Portugal
- Correspondence: (A.J.L.J.); (I.R.)
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8
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Doddipatla S, Ferreira GI, Gülseven Sıdır Y, Nunes CM, Fausto R. Breaking and Formation of Intramolecular Hydrogen Bonds in Dihydroxybenzaldehydes through UV-Induced Conformational Changes in a Low-Temperature Matrix. J Phys Chem A 2022; 126:8645-8657. [DOI: 10.1021/acs.jpca.2c05839] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Affiliation(s)
- Srinivas Doddipatla
- CQC-IMS, Department of Chemistry, University of Coimbra, Coimbra 3004-535, Portugal
| | - Gregory I. Ferreira
- CQC-IMS, Department of Chemistry, University of Coimbra, Coimbra 3004-535, Portugal
| | - Yadigar Gülseven Sıdır
- CQC-IMS, Department of Chemistry, University of Coimbra, Coimbra 3004-535, Portugal
- Department of Physics, Faculty of Science and Arts, Bitlis Eren University, Bitlis 13000, Turkey
| | - Cláudio M. Nunes
- CQC-IMS, Department of Chemistry, University of Coimbra, Coimbra 3004-535, Portugal
| | - Rui Fausto
- CQC-IMS, Department of Chemistry, University of Coimbra, Coimbra 3004-535, Portugal
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I-Ting T, Montero-Campillo MM, Alkorta I, Elguero J, Yáñez M. Large Stabilization Effects by Intramolecular Beryllium Bonds in Ortho-Benzene Derivatives. Molecules 2021; 26:molecules26113401. [PMID: 34199746 PMCID: PMC8199991 DOI: 10.3390/molecules26113401] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2021] [Revised: 05/31/2021] [Accepted: 06/01/2021] [Indexed: 11/16/2022] Open
Abstract
Intramolecular interactions are shown to be key for favoring a given structure in systems with a variety of conformers. In ortho-substituted benzene derivatives including a beryllium moiety, beryllium bonds provide very large stabilizations with respect to non-bound conformers and enthalpy differences above one hundred kJ·mol−1 are found in the most favorable cases, especially if the newly formed rings are five or six-membered heterocycles. These values are in general significantly larger than hydrogen bonds in 1,2-dihidroxybenzene. Conformers stabilized by a beryllium bond exhibit the typical features of this non-covalent interaction, such as the presence of a bond critical point according to the topology of the electron density, positive Laplacian values, significant geometrical distortions and strong interaction energies between the donor and acceptor quantified by using the Natural Bond Orbital approach. An isodesmic reaction scheme is used as a tool to measure the strength of the beryllium bond in these systems in terms of isodesmic energies (analogous to binding energies), interaction energies and deformation energies. This approach shows that a huge amount of energy is spent on deforming the donor–acceptor pairs to form the new rings.
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Affiliation(s)
- Tsai I-Ting
- Departamento de Química, Módulo 13, Facultad de Ciencias, and Institute of Advanced Chemical Sciences (IAdChem), Universidad Autónoma de Madrid, Campus de Excelencia UAM-CSIC, Cantoblanco, 28049 Madrid, Spain;
| | - M. Merced Montero-Campillo
- Departamento de Química, Módulo 13, Facultad de Ciencias, and Institute of Advanced Chemical Sciences (IAdChem), Universidad Autónoma de Madrid, Campus de Excelencia UAM-CSIC, Cantoblanco, 28049 Madrid, Spain;
- Correspondence: (M.M.M.-C.); (I.A.); (M.Y.)
| | - Ibon Alkorta
- Instituto de Química Médica, IQM-CSIC, Juan de la Cierva, 3, 28006 Madrid, Spain;
- Correspondence: (M.M.M.-C.); (I.A.); (M.Y.)
| | - José Elguero
- Instituto de Química Médica, IQM-CSIC, Juan de la Cierva, 3, 28006 Madrid, Spain;
| | - Manuel Yáñez
- Departamento de Química, Módulo 13, Facultad de Ciencias, and Institute of Advanced Chemical Sciences (IAdChem), Universidad Autónoma de Madrid, Campus de Excelencia UAM-CSIC, Cantoblanco, 28049 Madrid, Spain;
- Correspondence: (M.M.M.-C.); (I.A.); (M.Y.)
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Structural Relevance of Intramolecular H-Bonding in Ortho-Hydroxyaryl Schiff Bases: The Case of 3-(5-bromo-2-hydroxybenzylideneamino) Phenol. Molecules 2021; 26:molecules26092814. [PMID: 34068634 PMCID: PMC8126046 DOI: 10.3390/molecules26092814] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2021] [Revised: 05/05/2021] [Accepted: 05/07/2021] [Indexed: 12/22/2022] Open
Abstract
A new Schiff base compound, 3-(5-bromo-2-hydroxybenzylideneamino)phenol (abbreviated as BHAP) was synthesized and characterized by 1H- and 13C- nuclear magnetic resonance and infrared spectroscopies. DFT/B3LYP/6-311++G(d,p) calculations were undertaken in order to explore the conformational space of both the E- and Z- geometrical isomers of the enol-imine and keto-amine tautomers of the compound. Optimized geometries and relative energies were obtained, and it was shown that the most stable species is the E-enol-imine form, which may exist in four low-energy intramolecularly hydrogen-bonded forms (I, II, V, and VI) that are almost isoenergetic. These conformers were concluded to exist in the gas phase equilibrium with nearly equal populations. On the other hand, the infrared spectra of the compound isolated in a cryogenic argon matrix (10 K) are compatible with the presence in the matrix of only two of these conformers (conformers II and V), while conformers I and VI convert to these ones by quantum mechanical tunneling through the barrier associated with the rotation of the OH phenolic group around the C–O bond. The matrix isolation infrared spectrum was then assigned and interpreted with help of the DFT(B3LYP)/6-311++G(d,p) calculated infrared spectra for conformers II and V. In addition, natural bond orbital (NBO) analysis was performed on the most stable conformer of the experimentally relevant isomeric form (E-enol-imino conformer V) to shed light on details of its electronic structure. This investigation stresses the fundamental structural relevance of the O–H···N intramolecular H-bond in o-hydroxyaryl Schiff base compounds.
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Ildiz GO, Fausto R. Conformational Analysis, Spectroscopy and Photochemistry of Matrix-Isolated 1H- and 2H- Tautomeric Forms of Ethyl Tetrazole-5- Carboxylate. J Photochem Photobiol A Chem 2021. [DOI: 10.1016/j.jphotochem.2020.112899] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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12
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Sarkar S, Chandra S, Suryaprasad B, Ramanathan N, Sundararajan K, Suresh A. Conformational topography of tris(2-methylbutyl) phosphate and the influence of methyl branching at the non-hyperconjugative carbon on the conformational landscape: insights from matrix isolation infrared spectroscopy and DFT computations. Phys Chem Chem Phys 2020; 22:24372-24392. [PMID: 33084659 DOI: 10.1039/d0cp03403g] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The branching of a methyl group in a linear chain has a profound influence on the conformational morphology as it wields a strong control in reducing a large number of conformations. To unravel the effect of branching on the second non-hyperconjugative carbon atom on the conformational landscape, the conformations of tris(2-methylbutyl)phosphate (T2MBP) were studied using Density Functional Theory (DFT) computations and matrix isolation infrared spectroscopy. Experimentally, T2MBP along with N2/Ar/Kr/Xe gases was effusively expanded and deposited at a low temperature of 12 K, which was subsequently probed using infrared spectroscopy. The computations of all the conformations were accomplished using the B3LYP level of theory with the 6-311++G(d,p) basis set. A dimethyl(2-methylbutyl) phosphate (DM2MBP) prototype, a molecule containing a single 2-methylbutyl moiety, was examined for its conformations. Computations predicted 18 and 9 conformations each for the 'gauche' and 'trans' families, respectively, in which the third branched carbon completely influences the orientation of the fourth carbon, which simplifies the conformational problem of DM2MBP. Of the 18 and 9 bunches each in the 'gauche' and 'trans' families, only 7 and 3 conformations, respectively, became energetically important, which when extrapolated to T2MBP resulted in 343 and 147 conformational possibilities. The factor of degeneracy further reduced these numbers and a total of 168 conformations effectively contribute to the conformational composition of T2MBP in the gas phase. The role of stereo electronic and steric factors prevalent in the conformational clusters of T2MBP was unravelled respectively using natural bond orbital and non-covalent interaction analyses.
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Affiliation(s)
- Subramee Sarkar
- Homi Bhabha National Institute, Materials Chemistry and Metal Fuel Cycle Group, Indira Gandhi Centre for Atomic Research, Kalpakkam 603 102, Tamil Nadu, India.
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Lopes S, Nikitin T, Fausto R. Structural, spectroscopic, and photochemical study of ethyl propiolate isolated in cryogenic argon and nitrogen matrices. SPECTROCHIMICA ACTA. PART A, MOLECULAR AND BIOMOLECULAR SPECTROSCOPY 2020; 241:118670. [PMID: 32679483 DOI: 10.1016/j.saa.2020.118670] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/01/2020] [Revised: 06/25/2020] [Accepted: 06/27/2020] [Indexed: 06/11/2023]
Abstract
Ethyl propiolate (HC ≡ CCOOCH2CH3, EP) was studied experimentally by infrared spectroscopy in argon and nitrogen cryomatrices (15 K) and by quantum chemical calculations (at the DFT(B3LYP) and MP2 levels of theory). Calculations predict the existence of four conformers: two low-energy conformers (I and II) possessing the carboxylic moiety in the cis configuration (O=C-O-C dihedral equal to ~0°) and two higher-energy trans forms (O=C-O-C dihedral equal to ~180°; III and IV). The conformation of the ethyl ester group within each pair of conformers is either anti (C-O-C-C equal to 180°; in conformers I and III) or gauche (C-O-C-C equal to ±86.6° in II, and ± 92.5° in IV). The two low-energy cis conformers (I and II) were predicted to differ in energy by less than 2.5 kJ mol-1 and were shown to be present in the studied cryogenic matrices. Characteristic bands for each one of these conformers were identified in the infrared spectra of the matrix-isolated compound and assigned taking into account the results of normal coordinate analysis, which used the geometries and harmonic force constants obtained in the DFT calculations. The two trans conformers (III and IV) were estimated to be 17.5 kJ mol-1 higher in energy than the conformational ground state (form I) and were not observed experimentally. The unimolecular photochemistry of matrix-isolated EP (in N2 matrix) was also investigated. In situ irradiation with UV light (λ > 235 nm) leads mainly to decarbonylation of the compound, with generation of ethoxyethyne, which in a subsequent photoreaction generates ketene (plus ethene).
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Affiliation(s)
- S Lopes
- University of Coimbra, CQC, Department of Chemistry, 3004-535 Coimbra, Portugal.
| | - T Nikitin
- University of Coimbra, CQC, Department of Chemistry, 3004-535 Coimbra, Portugal; University of Coimbra, CFisUC, Department of Physics, 3004-516 Coimbra, Portugal
| | - Rui Fausto
- University of Coimbra, CQC, Department of Chemistry, 3004-535 Coimbra, Portugal.
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14
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Lopes Jesus AJ, Rosado MTS, Fausto R, Reva I. UV-induced radical formation and isomerization of 4-methoxyindole and 5-methoxyindole. Phys Chem Chem Phys 2020; 22:22943-22955. [PMID: 33026378 DOI: 10.1039/d0cp04354k] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Monomers of 4-methoxyindole and 5-methoxyindole trapped in low-temperature xenon matrices (15-16 K) were characterized by IR spectroscopy, in separate experiments. Each compound was shown to adopt the most stable 1H-tautomeric form. The photochemistry of the matrix-isolated compounds was then investigated by exciting the matrices with narrowband UV light with λ ≤ 305 nm. Two main photoproducts, similar for each compound, have been detected: (1) 4-methoxy- or 5-methoxy-indolyl radical, resulting from cleavage of the N-H bond; (2) 3H-tautomers (4-methoxy- or 5-methoxy-) with the released hydrogen atom reconnected at the C3 ring carbon atom. The presence of the two types of photoproducts in the UV-irradiated matrices was confirmed by comparison of their B3LYP/6-311++G(d,p) calculated IR spectra with the experimental spectra emerging upon the irradiations. The mechanism of the observed phototransformations was elucidated by Natural Bond Orbital and Natural Resonance Theory computations on the methoxy-substituted indolyl radicals resulting from the N-H bond cleavage. The highest natural atomic spin densities were predicted at the C3 and N1 positions of the indolyl ring, corresponding to a predominance of the resonance structures with the radical centres located at these two atoms. As a whole, the obtained experimental and theoretical data allowed establishing a general pattern for the photochemistry of methoxyindoles under matrix-isolation conditions.
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Affiliation(s)
- A J Lopes Jesus
- University of Coimbra, CQC, Department of Chemistry, 3004-535, Coimbra, Portugal.
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15
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Nogueira BA, Ildiz GO, Canotilho J, Eusébio MES, Henriques MSC, Paixão JA, Fausto R. Conformational Landscape and Polymorphism in 5-Acetic Acid Hydantoin. J Phys Chem A 2020; 124:6303-6318. [PMID: 32513000 DOI: 10.1021/acs.jpca.0c03789] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The conformational space of 5-acetic acid hydantoin {5AAH; [2-(2,5-dioxoimidazolidin-4-yl)acetic acid]} was investigated by quantum chemical calculations performed at the DFT(B3LYP)/6-311++G(d,p) level of theory. A total of 13 conformers were located in the potential energy surface of the molecule, six of them bearing the carboxylic group in the cis arrangement (O═C-O-H dihedral equal to ∼0°) and the other seven possessing this group in the trans configuration (O═C-O-H dihedral equal to ∼180°). The most stable conformer (cis-I) was trapped from the gas phase into a low temperature argon matrix (10 K), and its infrared spectrum was fully assigned, also with help of results of normal coordinates' analysis based on the DFT computed vibrational data. The electronic structure of this conformer was analyzed by using the natural bond orbital (NBO) method. The investigation of the thermal properties of 5AAH was undertaken by differential scanning calorimetry (DSC), polarized light thermal microscopy (PLTM) and Raman spectroscopy, allowing identification of five different polymorphs. Very interestingly, in the room temperature stable polymorph the molecular units of 5AAH assume the geometry of the highest-energy conformer predicted by the calculations for the isolated molecule.
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Affiliation(s)
- B A Nogueira
- CQC, Department of Chemistry, University of Coimbra, P-3004-535 Coimbra, Portugal
| | - G O Ildiz
- CQC, Department of Chemistry, University of Coimbra, P-3004-535 Coimbra, Portugal.,Faculty of Sciences and Letters, Department of Physics, Istanbul Kultur University, Atakoy Campus, Bakirkoy 34156, Istanbul, Turkey
| | - J Canotilho
- Faculty of Pharmacy, University of Coimbra, P-3000-548 Coimbra, Portugal
| | - M E S Eusébio
- CQC, Department of Chemistry, University of Coimbra, P-3004-535 Coimbra, Portugal
| | - M S C Henriques
- CFisUC, Department of Physics, University of Coimbra, P-3004-516 Coimbra, Portugal
| | - J A Paixão
- CFisUC, Department of Physics, University of Coimbra, P-3004-516 Coimbra, Portugal
| | - R Fausto
- CQC, Department of Chemistry, University of Coimbra, P-3004-535 Coimbra, Portugal
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16
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Ogruc Ildiz G, Konarska J, Fausto R. UV-induced conformational isomerization and photochemistry of 3-chloro-4-methoxybenzaldehyde in cryogenic inert matrices. J Chem Phys 2019; 151:104303. [PMID: 31521067 DOI: 10.1063/1.5118332] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
The interest in investigating the structure and reactivity of halogen- and methoxy-substituted benzaldehydes has been motivated by the practical relevance of these substances in various fields, from the fragrance industry to agrochemicals and drug manufacturing. In this study, 3-chloro-4-methoxybenzaldehyde (3CMBA) was investigated by matrix isolation infrared spectroscopy and quantum chemistry calculations. Molecules of the compound were isolated in cryogenic argon and xenon matrices and the conformational composition of the as-deposited materials characterized by infrared spectroscopy. Two nearly degenerated conformers, differing by the orientation of the aldehyde group relatively to the chlorine ring substituent, were successfully trapped into the matrices from the room temperature vapor of the compound, the cis conformer being slightly higher in energy than the trans form. Both conformers belong to the Cs point group and have the methoxy group pointing to the opposite direction of the chlorine atom. The as-deposited matrices of 3CMBA were then irradiated by tunable monochromatic UV-light. Irradiation within the 302-299 nm range induced conversion of the cis into the trans conformer, while irradiation in the 298-296 nm range induced the inverse photoisomerization. Irradiation at higher energy (250 nm) was found to lead to decarbonylation of both conformers. Very interestingly, the observed UV-induced processes were found to take place in an essentially selective way as a function of the irradiation wavelength. In particular, the conformational isomerization reactions of 3CMBA occur with only a residual number of molecules undergoing simultaneous decarbonylation.
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Affiliation(s)
- G Ogruc Ildiz
- CQC, Department of Chemistry, University of Coimbra, P 3004-535 Coimbra, Portugal
| | - J Konarska
- CQC, Department of Chemistry, University of Coimbra, P 3004-535 Coimbra, Portugal
| | - R Fausto
- CQC, Department of Chemistry, University of Coimbra, P 3004-535 Coimbra, Portugal
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17
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Maria TMR, Rosado MTS, Oliveira MF, Bebiano SS, Castro RAE, Juszyńska-Gałązka E, Ramos Silva M, Canotilho J, Eusébio MES. Polymorphism of 1,3-cyclohexanediols: molecular structure and plastic crystal formation of cyclohexanediol isomers. CrystEngComm 2019. [DOI: 10.1039/c9ce00186g] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Different plastic crystal formation abilities of cyclohexanediol isomers interpreted with Hirshfeld surfaces.
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Affiliation(s)
| | | | | | | | | | - Ewa Juszyńska-Gałązka
- The Henryk Niewodniczański Institute of Nuclear Physics
- Polish Academy of Sciences
- Kraków
- Poland
| | | | - João Canotilho
- CQC
- Department of Chemistry
- University of Coimbra
- Portugal
- Faculty of Pharmacy
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18
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Ramanathan N, Sarkar S, Sundararajan K, Chandrasekar A, Sankaran K, Suresh A. Influence of Branching on the Conformational Space: Case Study of Tri-sec-butyl Phosphate Using Matrix Isolation Infrared Spectroscopy and DFT Computations. J Phys Chem A 2018; 122:8229-8242. [DOI: 10.1021/acs.jpca.8b08157] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- N. Ramanathan
- Materials Chemistry & Metal Fuel Cycle Group, Homi Bhabha National Institute, Indira Gandhi Centre for Atomic Research, Kalpakkam 603 102, Tamil Nadu, India
| | - Shubhra Sarkar
- Materials Chemistry & Metal Fuel Cycle Group, Homi Bhabha National Institute, Indira Gandhi Centre for Atomic Research, Kalpakkam 603 102, Tamil Nadu, India
| | - K. Sundararajan
- Materials Chemistry & Metal Fuel Cycle Group, Homi Bhabha National Institute, Indira Gandhi Centre for Atomic Research, Kalpakkam 603 102, Tamil Nadu, India
| | - Aditi Chandrasekar
- Materials Chemistry & Metal Fuel Cycle Group, Homi Bhabha National Institute, Indira Gandhi Centre for Atomic Research, Kalpakkam 603 102, Tamil Nadu, India
| | - K. Sankaran
- Materials Chemistry & Metal Fuel Cycle Group, Homi Bhabha National Institute, Indira Gandhi Centre for Atomic Research, Kalpakkam 603 102, Tamil Nadu, India
| | - A. Suresh
- Materials Chemistry & Metal Fuel Cycle Group, Homi Bhabha National Institute, Indira Gandhi Centre for Atomic Research, Kalpakkam 603 102, Tamil Nadu, India
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19
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Futami Y, Minamoto C, Kudoh S. Anharmonic calculations of frequencies and intensities of OH stretching vibrations of (R)-1,3-butanediol conformers in the fundamentals and first overtones by density functional theory. SPECTROCHIMICA ACTA. PART A, MOLECULAR AND BIOMOLECULAR SPECTROSCOPY 2018; 197:251-254. [PMID: 29501370 DOI: 10.1016/j.saa.2018.02.029] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/30/2017] [Revised: 02/05/2018] [Accepted: 02/07/2018] [Indexed: 06/08/2023]
Abstract
The frequencies and absorption intensities of the five kinds of conformers of 1,3-butanediol with the same carbon skeleton (GG') were calculated by anharmonic calculation for the fundamentals and first overtones of OH stretching vibrations. The four kinds of conformers form intramolecular hydrogen bonds and one conformer did not. Intramolecular hydrogen bond formation shifted the frequency of fundamental and first overtone of H-bonding OH stretching vibration to the lower frequency. The absorption intensities of the fundamentals as well as the vibrational anharmonicities increased upon hydrogen bond formation, while the intensities of first overtones decreased. The differences of conformers were clearly seen in the frequencies of the first overtones of free OH.
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Affiliation(s)
- Yoshisuke Futami
- Department of Biological and Chemical Systems Engineering, National Institute of Technology, Kumamoto College, Yatsushiro, Kumamoto 866-8501, Japan.
| | - Chihiro Minamoto
- Department of Applied Chemistry and Biotechnology, National Institute of Technology, Niihama College, Niihama, Ehime 792-8580, Japan
| | - Satoshi Kudoh
- College of Engineering, Shibaura Institute of Technology, Saitama, Saitama 337-8570, Japan
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20
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Ogruc Ildiz G, Konarska J, Fausto R. Structural transformations of 3-fluoro and 3-fluoro-4-methoxy benzaldehydes under cryogenic conditions: A computational and low temperature infrared spectroscopy investigation. Chem Phys 2018. [DOI: 10.1016/j.chemphys.2018.04.011] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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21
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Takamuku T, Higuma Y, Matsugami M, To T, Umecky T. Solvation Structure of 1,3-Butanediol in Aqueous Binary Solvents with Acetonitrile, 1,4-Dioxane, and Dimethyl Sulfoxide Studied by IR, NMR, and Molecular Dynamics Simulation. J Phys Chem B 2017; 121:4864-4872. [PMID: 28425710 DOI: 10.1021/acs.jpcb.7b02202] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The solvation structure of 1,3-butanediol (1,3-BD) in aqueous binary solvents of acetonitrile (AN), 1,4-dioxane (DIO), and dimethyl sulfoxide (DMSO) at various mole fractions of organic solvent xOS has been clarified by means of infrared (IR) and 1H and 13C NMR. The change in the wavenumber of O-H stretching vibration of 1,3-BD in the three systems suggested that water molecules which are initially hydrogen-bonded with the 1,3-BD hydroxyl groups in the water solvent (xOS = 0) are more significantly replaced by organic solvent molecules in the order of DMSO ≫ DIO > AN. This agrees with the order of the electron donicities of the organic solvents. The 1H and 13C chemical shifts of 1,3-BD also revealed the most remarkable replacement of water molecules on the hydroxyl groups by DMSO. In contrast to the DMSO system, the O-H vibration band of 1,3-BD in the AN and DIO systems suggested the formation of the intramolecular hydrogen bond between the two hydroxyl groups of 1,3-BD above xOS = ∼0.9. To further evaluate the intramolecular hydrogen bonding of 1,3-BD in AN-water binary solvents, molecular dynamics (MD) simulations and NMR experiments for spin-lattice relaxation times T1 and 1H-1H nuclear Overhauser effect (NOE) were conducted on 1,3-BD in the AN system. These results showed the intramolecular hydrogen bond within 1,3-BD in the AN-water binary solvents in the high AN mole fraction range of xAN > 0.9. Especially, the pair correlation functions g(r) of the OH-O interactions of 1,3-BD obtained from the MD simulations indicated that the intramolecular hydrogen bond remarkably increases in the AN solvent as the xAN rises to the unity.
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Affiliation(s)
- Toshiyuki Takamuku
- Department of Chemistry and Applied Chemistry, Graduate School of Science and Engineering, Saga University , Honjo-machi, Saga 840-8502, Japan
| | - Yasuhito Higuma
- Department of Chemistry and Applied Chemistry, Graduate School of Science and Engineering, Saga University , Honjo-machi, Saga 840-8502, Japan
| | - Masaru Matsugami
- Faculty of Liberal Studies, National Institute of Technology, Kumamoto College , 2659-2 Suya, Koshi, Kumamoto 861-1102, Japan
| | - Takahiro To
- Department of Chemistry and Applied Chemistry, Graduate School of Science and Engineering, Saga University , Honjo-machi, Saga 840-8502, Japan
| | - Tatsuya Umecky
- Department of Chemistry and Applied Chemistry, Graduate School of Science and Engineering, Saga University , Honjo-machi, Saga 840-8502, Japan
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22
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Kuş N, Fausto R. Effects of the matrix and intramolecular interactions on the stability of the higher-energy conformers of 2-fluorobenzoic acid. J Chem Phys 2017; 146:124305. [DOI: 10.1063/1.4978794] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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23
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Daly S, Tia M, Garcia GA, Nahon L, Powis I. The Interplay Between Conformation and Absolute Configuration in Chiral Electron Dynamics of Small Diols. Angew Chem Int Ed Engl 2016; 55:11054-8. [PMID: 27445202 DOI: 10.1002/anie.201603771] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2016] [Revised: 05/21/2016] [Indexed: 11/07/2022]
Abstract
A competition between chiral characteristics alternatively attributable to either conformation or to absolute configuration is identified. Circular dichroism associated with photoexcitation of the outer orbital of configurational enantiomers of 1,3- and 2,3-butanediols has been examined with a focus on the large changes in electron chiral asymmetry produced by different molecular conformations. Experimental gas-phase measurements offer support for the theoretical modeling of this chiroptical effect. A surprising prediction is that a conformationally produced pseudo-enantiomerism in 1,3-butanediol generates a chiral response in the frontier electron dynamics that outweighs the influence of the permanent configurational handedness established at the asymmetrically substituted carbon. Induced conformation, and specifically induced conformational chirality, may thus be a dominating factor in chiral molecular recognition in such systems.
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Affiliation(s)
- Steven Daly
- School of Chemistry, University Park, University of Nottingham, Nottingham, NG7 2RD, UK.,Synchrotron SOLEIL, l'Orme des Merisiers, Saint Aubin BP 48, 91192, Gif sur Yvette Cedex, France.,Institut Lumiere Matière, UMR5306, CNRS, Université Lyon 1, 69622, Villeurbanne, France
| | - Maurice Tia
- Synchrotron SOLEIL, l'Orme des Merisiers, Saint Aubin BP 48, 91192, Gif sur Yvette Cedex, France.,Institut für Kernphysik, Johann Wolfgang Goethe Universität, Max-von-Laue-Strasse 1, 60438, Frankfurt am Main, Germany
| | - Gustavo A Garcia
- Synchrotron SOLEIL, l'Orme des Merisiers, Saint Aubin BP 48, 91192, Gif sur Yvette Cedex, France
| | - Laurent Nahon
- Synchrotron SOLEIL, l'Orme des Merisiers, Saint Aubin BP 48, 91192, Gif sur Yvette Cedex, France
| | - Ivan Powis
- School of Chemistry, University Park, University of Nottingham, Nottingham, NG7 2RD, UK.
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24
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Daly S, Tia M, Garcia GA, Nahon L, Powis I. The Interplay Between Conformation and Absolute Configuration in Chiral Electron Dynamics of Small Diols. Angew Chem Int Ed Engl 2016. [DOI: 10.1002/ange.201603771] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Affiliation(s)
- Steven Daly
- School of Chemistry; University Park, University of Nottingham; Nottingham NG7 2RD UK
- Synchrotron SOLEIL, l'Orme des Merisiers; Saint Aubin BP 48 91192 Gif sur Yvette Cedex France
- Institut Lumiere Matière, UMR5306, CNRS, Université Lyon 1; 69622 Villeurbanne France
| | - Maurice Tia
- Synchrotron SOLEIL, l'Orme des Merisiers; Saint Aubin BP 48 91192 Gif sur Yvette Cedex France
- Institut für Kernphysik; Johann Wolfgang Goethe Universität; Max-von-Laue-Strasse 1 60438 Frankfurt am Main Germany
| | - Gustavo A. Garcia
- Synchrotron SOLEIL, l'Orme des Merisiers; Saint Aubin BP 48 91192 Gif sur Yvette Cedex France
| | - Laurent Nahon
- Synchrotron SOLEIL, l'Orme des Merisiers; Saint Aubin BP 48 91192 Gif sur Yvette Cedex France
| | - Ivan Powis
- School of Chemistry; University Park, University of Nottingham; Nottingham NG7 2RD UK
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25
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Lopes Jesus AJ, Reva I, Araujo-Andrade C, Fausto R. Conformational changes in matrix-isolated 6-methoxyindole: Effects of the thermal and infrared light excitations. J Chem Phys 2016; 144:124306. [PMID: 27036447 DOI: 10.1063/1.4944528] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023] Open
Abstract
Conformational changes induced thermally or upon infrared excitation of matrix-isolated 6-methoxyindole were investigated. Narrowband near-infrared excitation of the first overtone of the N-H stretching vibration of each one of the two identified conformers is found to induce a selective large-scale conversion of the pumped conformer into the other one. This easily controllable bidirectional process consists in the intramolecular reorientation of the methoxy group and allowed a full assignment of the infrared spectra of the two conformers. Matrices with different conformational compositions prepared by narrow-band irradiations were subsequently used to investigate the effects of both thermal and broadband infrared excitations on the conformational mixtures. Particular attention is given to the influence of the matrix medium (Ar vs. Xe) and conformational effects of exposition of the sample to the spectrometer light source during the measurements.
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Affiliation(s)
- A J Lopes Jesus
- CQC, Department of Chemistry, University of Coimbra, 3004-535 Coimbra, Portugal
| | - I Reva
- CQC, Department of Chemistry, University of Coimbra, 3004-535 Coimbra, Portugal
| | - C Araujo-Andrade
- CQC, Department of Chemistry, University of Coimbra, 3004-535 Coimbra, Portugal
| | - R Fausto
- CQC, Department of Chemistry, University of Coimbra, 3004-535 Coimbra, Portugal
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26
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Pollok CH, Merten C. Conformational distortion of α-phenylethyl amine in cryogenic matrices – a matrix isolation VCD study. Phys Chem Chem Phys 2016; 18:13496-502. [DOI: 10.1039/c6cp01946c] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
MI-VCD spectroscopy reveals conformational perturbations of a chiral amine due to matrix packing effects.
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27
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Avadanei M, Kuş N, Cozan V, Fausto R. Structure and Photochemistry of N-Salicylidene-p-carboxyaniline Isolated in Solid Argon. J Phys Chem A 2015; 119:9121-32. [PMID: 26273723 DOI: 10.1021/acs.jpca.5b06516] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Infrared matrix isolation spectroscopy and DFT/B3LYP/6-311++G(d,p) calculations have been used to characterize the conformational space of the enol-imine and keto-amine tautomers of N-salicylidene-p-carboxyaniline (SCA) in both their E and Z isomeric forms. Monomers of SCA were isolated in an argon matrix (15 K), which was shown to contain only the most stable conformer of the E-enol isomer of the compound. The matrix-isolated E-enol was then subjected to in situ UV irradiation (λ = 335; 345 nm, provided by a laser/MOPO system, or λ > 235 nm, provided by a Hg(Xe) broad-band source), and the photoinduced processes probed by infrared spectroscopy. Two photoreaction channels were observed, with a branching ratio of ∼1:1, corresponding to E-enol → Z-enol isomerization and E-enol → E-keto tautomerization. Both processes were found to be rather effective, with practically complete consumption of the reactant after broad-band irradiation by 1 min only. Identification among the photoproduced species of the Z-enol conformer that differs from the reactant only by E-to-Z isomerization suggests the initial photoproduction of this conformer, which subsequently decays into the lowest energy Z-enol conformer (also identified experimentally). The E-enol → E-keto tautomerization requires an excited state intramolecular proton transfer and twisting about the exocyclic CC bond of the molecule. These processes most probably take place sequentially. However, in the present study the Z-keto isomer, which should act as intermediate in this sequence of processes, could not be detected, most probably due to its short lifetime under the used experimental conditions. On the contrary, the detailed structural and vibrational characterization of the photoproduced E-keto form was successfully achieved.
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Affiliation(s)
- Mihaela Avadanei
- "P. Poni" Institute of Macromolecular Chemistry , 700487 Iasi, Romania
| | - Nihal Kuş
- Department of Chemistry, University of Coimbra , 3004-535 Coimbra, Portugal.,Department of Physics, Anadolu University , 26470 Eskişehir, Turkey
| | - Vasile Cozan
- "P. Poni" Institute of Macromolecular Chemistry , 700487 Iasi, Romania
| | - Rui Fausto
- Department of Chemistry, University of Coimbra , 3004-535 Coimbra, Portugal
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28
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Yoo IK, Kim JI, Kang YK. Conformational preferences and antimicrobial activities of alkanediols. COMPUT THEOR CHEM 2015. [DOI: 10.1016/j.comptc.2015.04.007] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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29
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Kuş N, Sharma A, Peña I, Bermúdez MC, Cabezas C, Alonso JL, Fausto R. Conformers of β-aminoisobutyric acid probed by jet-cooled microwave and matrix isolation infrared spectroscopic techniques. J Chem Phys 2015; 138:144305. [PMID: 24981533 DOI: 10.1063/1.4799456] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
β-aminoisobutyric acid (BAIBA) has been studied in isolation conditions: in the gas phase and trapped into a cryogenic N2 matrix. A solid sample of the compound was vaporized by laser ablation and investigated through their rotational spectra in a supersonic expansion using two different spectroscopic techniques: broadband chirped pulse Fourier transform microwave spectroscopy and conventional molecular beam Fourier transform microwave spectroscopy. Four conformers with structures of two types could be successfully identified by comparison of the experimental rotational and (14)N nuclear quadruple coupling constants with those predicted theoretically: type A, bearing an OH⋯N intramolecular hydrogen bond and its carboxylic group in the trans geometry (H-O-C=O dihedral ∼180°), and type B, having an NH⋯O bond and the cis arrangement of the carboxylic group. These two types of conformers could also be trapped from the gas phase into a cryogenic N2 matrix and probed by Fourier transform infrared (IR) spectroscopy. In situ irradiation of BAIBA isolated in N2 matrix of type B conformers using near-IR radiation tuned at the frequency of the O-H stretching 1st overtone (∼6930 cm(-1)) of these forms allowed to selectively convert them into type A conformers and into a new type of conformers of higher energy (type D) bearing an NH⋯O=C bond and a O-H "free" trans carboxylic group.
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Affiliation(s)
- N Kuş
- Department of Chemistry, University of Coimbra, P-3004-535 Coimbra, Portugal
| | - A Sharma
- Department of Chemistry, University of Coimbra, P-3004-535 Coimbra, Portugal
| | - I Peña
- Grupo de Espectroscopia Molecular (GEM), Unidad Asociada CSIC, Edificio Quifima, Laboratorios de Espectroscopia y Bioespectroscopia, Universidad de Valladolid, 47005 Valladolid, Spain
| | - M C Bermúdez
- Grupo de Espectroscopia Molecular (GEM), Unidad Asociada CSIC, Edificio Quifima, Laboratorios de Espectroscopia y Bioespectroscopia, Universidad de Valladolid, 47005 Valladolid, Spain
| | - C Cabezas
- Grupo de Espectroscopia Molecular (GEM), Unidad Asociada CSIC, Edificio Quifima, Laboratorios de Espectroscopia y Bioespectroscopia, Universidad de Valladolid, 47005 Valladolid, Spain
| | - J L Alonso
- Grupo de Espectroscopia Molecular (GEM), Unidad Asociada CSIC, Edificio Quifima, Laboratorios de Espectroscopia y Bioespectroscopia, Universidad de Valladolid, 47005 Valladolid, Spain
| | - R Fausto
- Department of Chemistry, University of Coimbra, P-3004-535 Coimbra, Portugal
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30
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Ramanathan N, Brahmmananda Rao CVS, Sankaran K, Sundararajan K. Unraveling the Conformational Landscape of Triallyl Phosphate: Matrix Isolation Infrared Spectroscopy and Density Functional Theory Computations. J Phys Chem A 2015; 119:4017-31. [DOI: 10.1021/acs.jpca.5b00889] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- N. Ramanathan
- Chemistry
Group, Indira Gandhi Centre for Atomic Research, Kalpakkam 603 102, Tamil Nadu, India
| | | | - K. Sankaran
- Chemistry
Group, Indira Gandhi Centre for Atomic Research, Kalpakkam 603 102, Tamil Nadu, India
| | - K. Sundararajan
- Chemistry
Group, Indira Gandhi Centre for Atomic Research, Kalpakkam 603 102, Tamil Nadu, India
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Lopes Jesus AJ, Jarmelo S, Fausto R, Reva I. Conformational preferences of 3,4-dihydroxyphenylacetic acid (DOPAC). SPECTROCHIMICA ACTA. PART A, MOLECULAR AND BIOMOLECULAR SPECTROSCOPY 2015; 140:54-64. [PMID: 25589387 DOI: 10.1016/j.saa.2014.12.078] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/04/2014] [Revised: 11/22/2014] [Accepted: 12/17/2014] [Indexed: 06/04/2023]
Abstract
The conformational space of 3,4-dihydroxyphenylacetic acid (DOPAC), an important dopamine metabolite, has been investigated by quantum chemical methods (B3LYP and MP2, with the 6-311++G(d,p) basis set) and matrix-isolation infrared spectroscopy. Detailed analysis of the calculated potential energy surfaces of the molecule led to identification of thirteen unique conformers, all of them showing the acetic acid side chain out of the aromatic ring plane by 60-95°. According to the calculated Gibbs energies, the five lowest energy conformers make up 99.7% of the conformational mixture at 298.15K, exhibiting individual populations falling between 16% and 24%. The main conformational trends of this molecule were interpreted on the grounds of a thorough analysis of the structural parameters and by the application of the Natural Bond Orbital theory. The role of the intramolecular interactions on the relative stability and structure of the conformers was also investigated. The infrared spectrum of DOPAC was registered after isolation of its monomers in argon and xenon matrices. Only one of DOPAC forms populated in the gas phase could be trapped in both matrix gases. This result is in agreement with the predicted low energy barriers for conformational isomerization and is also supported by annealing experiments. The spectra of matrix-isolated model compounds, phenylacetic acid and catechol, were studied under the same experimental conditions. These data were used as references and assisted in the interpretation of the results obtained for DOPAC.
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Affiliation(s)
- A J Lopes Jesus
- Centre of Chemistry - Coimbra, Faculty of Pharmacy, University of Coimbra, 3000-548 Coimbra, Portugal.
| | - S Jarmelo
- Centre of Chemistry - Coimbra, Department of Chemistry, University of Coimbra, 3004-535 Coimbra, Portugal
| | - R Fausto
- Centre of Chemistry - Coimbra, Department of Chemistry, University of Coimbra, 3004-535 Coimbra, Portugal
| | - I Reva
- Centre of Chemistry - Coimbra, Department of Chemistry, University of Coimbra, 3004-535 Coimbra, Portugal
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32
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Reva I, M Nunes C, Biczysko M, Fausto R. Conformational switching in pyruvic acid isolated in Ar and N₂ matrixes: spectroscopic analysis, anharmonic simulation, and tunneling. J Phys Chem A 2014; 119:2614-27. [PMID: 25332047 DOI: 10.1021/jp509578c] [Citation(s) in RCA: 59] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Monomers of pyruvic acid (PA) isolated in cryogenic argon and nitrogen matrixes were characterized by mid- and near-infrared spectroscopy. Interpretation of the experiments was aided by fully anharmonic calculations of the fundamental modes, overtones, and combinations up to two quanta, including their infrared intensities. The initially dominating PA conformer (Tc) has a cis CCOH arrangement and is stabilized by a strong intramolecular H-bond. Selective near-infrared excitation of Tc at the first OH overtone (6630 cm(-1) in Ar, 6643 cm(-1) in N2) induced a large scale conformational conversion to the higher-energy conformer (Tt) with trans CCOH arrangement. Tt was then converted back to Tc by selective NIR irradiation at the first Tt OH overtone (6940 cm(-1) in Ar, 6894 cm(-1) in N2). In N2 matrix, the Tt form was stabilized due to interaction between the OH group and the matrix molecules. This stabilization manifested itself in the absence of Tt → Tc relaxation and in a considerable change of the vibrational Tt signature upon going from argon to nitrogen matrix. In argon, the Tt form spontaneously decayed back to Tc in the dark (characteristic lifetime +16 h). In the presence of broad-band near-infrared light, the Tt → Tc relaxation speed considerably increased. The decay mechanisms are discussed.
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Affiliation(s)
- Igor Reva
- †CQC, Department of Chemistry, University of Coimbra, 3004-535 Coimbra, Portugal
| | - Cláudio M Nunes
- †CQC, Department of Chemistry, University of Coimbra, 3004-535 Coimbra, Portugal
| | - Malgorzata Biczysko
- ‡Scuola Normale Superiore, Piazza dei Cavalieri 7, I-56126 Pisa, Italy.,§Consiglio Nazionale delle Ricerche, Istituto di Chimica dei Composti OrganoMetallici (ICCOM-CNR), UOS di Pisa, Area della Ricerca CNR, Via G. Moruzzi 1, I-56124 Pisa, Italy
| | - Rui Fausto
- †CQC, Department of Chemistry, University of Coimbra, 3004-535 Coimbra, Portugal
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Kar BP, Ramanathan N, Sundararajan K, Viswanathan K. Matrix isolation and DFT study of the conformations of diethylcarbonate. J Mol Struct 2014. [DOI: 10.1016/j.molstruc.2014.04.044] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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Halasa A, Lapinski L, Reva I, Rostkowska H, Fausto R, Nowak MJ. Near-infrared laser-induced generation of three rare conformers of glycolic acid. J Phys Chem A 2014; 118:5626-35. [PMID: 25002253 DOI: 10.1021/jp5051589] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Structural transformations were induced in conformers of glycolic acid by selective excitation with monochromatic tunable near-infrared laser light. For the compound isolated in Ar matrixes, near-IR excitation led to generation of two higher-energy conformers (GAC; AAT) differing from the most stable SSC form by 180° rotation around the C-C bond. A detailed investigation of this transformation revealed that one conformer (GAC) is produced directly from the near-IR-excited most stable conformer. The other higher-energy conformer (AAT) was effectively generated only upon excitation of the primary photoproduct (GAC) with another near-IR photon. Once these higher-energy conformers of glycolic acid were generated in an Ar matrix, they could be subsequently transformed into one another upon selective near-IR excitations. Interestingly, no repopulation of the initial most stable SSC conformer occurred upon near-IR excitation of the higher-energy forms of the compound isolated in solid Ar. A dramatically different picture of near-IR-induced conformational transformations was observed for glycolic acid isolated in N2 matrixes. In this case, upon near-IR excitation, the most stable SSC form converted solely into a new conformer (SST), where the acid OH group is rotated by 180°. This conformational transformation was found to be photoreversible. Moreover, SST conformer, photoproduced in the N2 matrix, spontaneously converted to the most stable SSC form of glycolic acid, when the matrix was kept at cryogenic temperature and in the dark.
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Affiliation(s)
- Anna Halasa
- Institute of Physics, Polish Academy of Sciences , Al. Lotnikow 32/46, 02-668 Warsaw, Poland
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Genesis of rare molecules using light-induced reactions of matrix-isolated tetrazoles. JOURNAL OF PHOTOCHEMISTRY AND PHOTOBIOLOGY C-PHOTOCHEMISTRY REVIEWS 2014. [DOI: 10.1016/j.jphotochemrev.2013.09.001] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
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36
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Araujo-Andrade C, Reva I, Fausto R. Tetrazole acetic acid: Tautomers, conformers, and isomerization. J Chem Phys 2014; 140:064306. [DOI: 10.1063/1.4864119] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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Grineva OV, Usacheva TM, Zhuravlev VI. “Crystal” conformations of 2-methyl-2,4-pentanediol: Dipole moment calculations and molecular structure optimizations. J STRUCT CHEM+ 2014. [DOI: 10.1134/s0022476614010284] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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Kuş N, Bayarı SH, Fausto R. Methylparaben Isolated in Solid Argon: Structural Characterization and UV-Induced Conversion into Methylparaben Radical and Isomeric Ketenes. J Phys Chem B 2013; 117:13543-55. [DOI: 10.1021/jp408366x] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Nihal Kuş
- Department
of Chemistry, University of Coimbra, P-3004-535 Coimbra, Portugal
- Department
of Physics, Anadolu University, 26470 Eskişehir, Turkey
| | - Sevgi H. Bayarı
- Department
of Physics, Hacettepe University, 06800 Ankara, Turkey
| | - Rui Fausto
- Department
of Chemistry, University of Coimbra, P-3004-535 Coimbra, Portugal
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Lomas JS. 1H NMR spectra of alkane-1,3-diols in benzene: GIAO/DFT shift calculations. MAGNETIC RESONANCE IN CHEMISTRY : MRC 2013; 51:469-481. [PMID: 23784999 DOI: 10.1002/mrc.3973] [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: 02/12/2013] [Revised: 05/07/2013] [Accepted: 05/07/2013] [Indexed: 06/02/2023]
Abstract
The proton nuclear magnetic resonance (NMR) spectra of propane-1,3-diol, 2-methylpropane-1,3-diol, 2,2-dimethylpropane-1,3-diol, butane-1,3-diol, 3-methylbutane-1,3-diol, pentane-2,4-diols (dl and meso), 2-methylpentane-2,4-diol and cyclohexane-1,3-diols (cis and trans) in benzene have been analysed. The conformer distribution and the NMR shifts of these diols have been computed on the basis of density functional theory, the solvent being included by means of the integral equation formalism phase continuum model (IEFPCM) implemented in Gaussian 09. Relative Gibbs energies of all conformers are calculated at the Perdew, Burke and Ernzerhof (PBE)0/6-311 + G(d,p) level, and NMR shifts by the gauge-including atomic orbital method with the PBE0/6-311 + G(d,p) geometry and the cc-pVTZ basis set. Vicinal coupling constants for 1,2- and 1,3-diols are rationalised in terms of relative conformer populations and geometries. The NMR shifts of hydrogen-bonded protons in individual conformers of alkane-1,n-diols show a very rough correlation with the OH⋯OH distances. The computed overall NMR shifts for CH protons in 1,2- and 1,3-diols are systematically high but correlate very well with the experimental values, with a gradient of 1.07 ± 0.01. Some values for nonequivalent methylene protons in 1,3-diols are reversed, calculation giving enhanced values for the proton anti to the COH bonds. Errors in the NMR shifts computed for the OH protons of nonsymmetrical diols appear to be related to relative populations of conformers where one or other of the OH groups is the donor. Some results based on the second-order Møller-Plesset approach, the Becke three-parameter Lee-Yang-Parr method and on the IEFPCM solvation model implemented in Gaussian 03 are included.
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Affiliation(s)
- John S Lomas
- Univ Paris Diderot, Sorbonne Paris Cité, ITODYS, UMR 7086, F-75205, Paris, France
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40
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Nunes CM, Lapinski L, Fausto R, Reva I. Near-IR laser generation of a high-energy conformer of L-alanine and the mechanism of its decay in a low-temperature nitrogen matrix. J Chem Phys 2013; 138:125101. [DOI: 10.1063/1.4795823] [Citation(s) in RCA: 47] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
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41
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Kaczor A, Reva I, Fausto R. Influence of cage confinement on the photochemistry of matrix-isolated E-β-ionone: FT-IR and DFT study. J Phys Chem A 2013; 117:888-97. [PMID: 23305459 DOI: 10.1021/jp310764u] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
β-ionone, a model compound of carotenoids ring structure, was investigated by FT-IR spectroscopy in a low-temperature argon matrix as well as using B3LYP/6-311++G(d,p) and MP2/6-311++G(d,p) quantum-chemical calculations. The spectrum of matrix-isolated E-β-ionone was analyzed and attributed to six conformers of the compound. Then, matrix-isolated E-β-ionone was submitted to UV irradiation using either a broadband source (with different cutoff filters) or a narrowband laser/MOPO system (at various wavelengths). Upon 240 nm narrowband irradiation, the formation of both Z-retro-γ-ionone and Z-β-ionone was observed, the reactant and the photoproducts being in a photostationary equilibrium. Under these conditions, the matrix environment was found to hamper subsequent reactions of Z-retro-γ-ionone and Z-β-ionone, so that this last species could be observed directly for the first time. Furthermore, the formation of Z-retro-γ-ionone was shown to occur directly via an intramolecular [1,5] H-atom shift and thereby, under the constraints imposed by the matrix confinement, the conformations assumed by this photoproduct were found to be strictly determined by those initially assumed by the reactant molecules. Broadband irradiation resulted in the completion of the reaction (disappearance of the reactant) and the sole observation of Z-retro-γ-ionone. These results imply that under these conditions the Z-β-ionone is unstable, very likely decaying to additional conformers of Z-retro-γ-ionone, as reflected in the broader bands due to this photoproduct observed in the infrared spectra of the broadband irradiated matrix.
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Affiliation(s)
- A Kaczor
- Faculty of Chemistry, Jagiellonian University, Ingardena 3, 30-060 Krakow, Poland.
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42
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Evangelisti L, Gou Q, Spada L, Feng G, Caminati W. Conformational analysis of 1,4-butanediol: A microwave spectroscopy study. Chem Phys Lett 2013. [DOI: 10.1016/j.cplett.2012.11.080] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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43
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Conformational properties and photochemistry of new allyl tetrazoles: Matrix isolation FTIR and computational approach. J Photochem Photobiol A Chem 2013. [DOI: 10.1016/j.jphotochem.2012.10.023] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
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44
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Krupa J, Olbert-Majkut A, Reva I, Fausto R, Wierzejewska M. Ultraviolet-Tunable Laser Induced Phototransformations of Matrix Isolated Isoeugenol and Eugenol. J Phys Chem B 2012; 116:11148-58. [DOI: 10.1021/jp306339g] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- J. Krupa
- Faculty of Chemistry, University of Wrocław, Joliot-Curie 14, 50-383
Wrocław, Poland
| | - A. Olbert-Majkut
- Faculty of Chemistry, University of Wrocław, Joliot-Curie 14, 50-383
Wrocław, Poland
| | - I. Reva
- Department of Chemistry, University of Coimbra, 3004-535 Coimbra,
Portugal
| | - R. Fausto
- Department of Chemistry, University of Coimbra, 3004-535 Coimbra,
Portugal
| | - M. Wierzejewska
- Faculty of Chemistry, University of Wrocław, Joliot-Curie 14, 50-383
Wrocław, Poland
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Araujo-Andrade C, Gómez-Zavaglia A, Reva ID, Fausto R. Conformers, Infrared Spectrum and UV-Induced Photochemistry of Matrix-Isolated Furfuryl Alcohol. J Phys Chem A 2012; 116:2352-65. [DOI: 10.1021/jp212169b] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Affiliation(s)
- C. Araujo-Andrade
- Unidad Académica de Física de la Universidad Autónoma de Zacatecas, Zacatecas, Mexico
| | - A. Gómez-Zavaglia
- Centro de Investigación y Desarrollo en Criotecnología de Alimentos (Conicet La Plata, UNLP), 1900 La Plata, Argentina
- Department of Chemistry, University of Coimbra, 3004-535 Coimbra, Portugal
| | - I. D. Reva
- Department of Chemistry, University of Coimbra, 3004-535 Coimbra, Portugal
| | - R. Fausto
- Department of Chemistry, University of Coimbra, 3004-535 Coimbra, Portugal
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Kuş N, Reva I, Bayarı S, Fausto R. In situ photoproduction of dichlorodibenzo-p-dioxin from non-ionic triclosan isolated in solid argon. J Mol Struct 2012. [DOI: 10.1016/j.molstruc.2011.10.023] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/16/2022]
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47
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Lomas JS, Maurel F. GIAO/DFT calculations of relative conformer energies and 1H NMR shifts of unsaturated alcohols in benzene. J PHYS ORG CHEM 2011. [DOI: 10.1002/poc.1954] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Affiliation(s)
- John S. Lomas
- Univ Paris Diderot, Sorbonne Paris Cité; ITODYS; UMR 7086; F-75205; Paris; France
| | - François Maurel
- Univ Paris Diderot, Sorbonne Paris Cité; ITODYS; UMR 7086; F-75205; Paris; France
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48
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Lopes S, Nunes CM, Gómez-Zavaglia A, Pinho e Melo TM, Fausto R. Structure and photochemical behaviour of 3-azido-acrylophenones: a matrix isolation infrared spectroscopy study. Tetrahedron 2011. [DOI: 10.1016/j.tet.2011.07.084] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
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49
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Ramanathan N, Sundararajan K, Kar BP, Viswanathan KS. Conformations of Trimethyl Phosphite: A Matrix Isolation Infrared and ab Initio Study. J Phys Chem A 2011; 115:10059-68. [DOI: 10.1021/jp205368k] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- N. Ramanathan
- Chemistry Group, Indira Gandhi Centre for Atomic Research, Kalpakkam 603 102, India
| | - K. Sundararajan
- Chemistry Group, Indira Gandhi Centre for Atomic Research, Kalpakkam 603 102, India
| | - Bishnu Prasad Kar
- Chemistry Group, Indira Gandhi Centre for Atomic Research, Kalpakkam 603 102, India
| | - K. S. Viswanathan
- Chemistry Group, Indira Gandhi Centre for Atomic Research, Kalpakkam 603 102, India
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50
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Kaczor A, Reva I, Warszycki D, Fausto R. UV-induced cyclization in myrcene isolated in rigid argon environment: FT-IR and DFT study. J Photochem Photobiol A Chem 2011. [DOI: 10.1016/j.jphotochem.2011.02.007] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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