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Jensen CV, Kjaergaard HG. Gas-Phase Room-Temperature Detection of the tert-Butyl Hydroperoxide Dimer. J Phys Chem A 2023; 127:6476-6485. [PMID: 37527456 DOI: 10.1021/acs.jpca.3c03702] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/03/2023]
Abstract
We have detected the tert-butyl hydroperoxide dimer, (t-BuOOH)2, in the gas phase at room temperature using conventional FTIR techniques. The dimer is identified by an asymmetric absorbance band assigned to the fundamental hydrogen-bound OHb-stretch. The weighted band maximum of the dimer OHb-stretch is located at ∼3452 cm-1, red-shifted by ∼145 cm-1 from the monomer OH-stretching band. The gas-phase dimer assignment is supported by Ar matrix isolation FTIR experiments at 12 K and experiments with a partially deuterated sample. Computationally, we find the lowest energy structure of (t-BuOOH)2 to be a doubly hydrogen bound six-membered ring with non-optimal hydrogen bond angles. We estimate the gas-phase constant of dimer formation, K, to be 0.4 (standard pressure of 1 bar) using the experimental integrated absorbance and a theoretically determined oscillator strength of the OHb-stretching band.
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Affiliation(s)
| | - Henrik G Kjaergaard
- Department of Chemistry, University of Copenhagen, 2100 Copenhagen-Ø, Denmark
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2
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Zhang X, Xia M, Wu Y, Zhang F. Branched-Chain Amino Acids Metabolism and Their Roles in Retinopathy: From Relevance to Mechanism. Nutrients 2023; 15:2161. [PMID: 37432261 DOI: 10.3390/nu15092161] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2023] [Revised: 04/20/2023] [Accepted: 04/27/2023] [Indexed: 07/12/2023] Open
Abstract
Retinopathy is one of the leading causes of irreversible blindness and vision loss worldwide. Imbalanced nutrients play important roles in the pathogenesis and pathophysiology of retinal diseases. Branched-Chain Amino Acids (BCAAs), as essential amino acids, perform a variety of biological functions, including protein synthesis, glucose metabolism, lipid metabolism, inflammation, and oxidative stress in metabolic tissues of diabetes and aging-related diseases. Recently, it has been shown that BCAAs are highly related to neuroprotection, oxidative stress, inflammatory and glutamate toxicity in the retina of retinopathy. Therefore, this review summarizes the alterations of BCAA levels in retinopathy, especially diabetic retinopathy and aging-related macular disease, and the genetics, functions, and mechanisms of BCAAs in the retina as well as other metabolic tissues for reference. All of these efforts aim to provide fundamental knowledge of BCAAs for further discoveries and research on retina health based on the sensing and signaling of essential amino acids.
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Affiliation(s)
- Xiaonan Zhang
- National Clinical Research Center for Eye Diseases, Shanghai General Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai 200080, China
- Liaoning Provence Key Laboratory of Genome Engineered Animal Models, National Center of Genetically Engineered Animal Models for International Research, Institute for Genome Engineered Animal Models of Human Diseases, Dalian Medical University, Dalian 116000, China
- Shanghai Key Laboratory of Ocular Fundus Diseases, Shanghai 200080, China
| | - Mengxue Xia
- National Clinical Research Center for Eye Diseases, Shanghai General Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai 200080, China
- Shanghai Key Laboratory of Ocular Fundus Diseases, Shanghai 200080, China
| | - Yingjie Wu
- Liaoning Provence Key Laboratory of Genome Engineered Animal Models, National Center of Genetically Engineered Animal Models for International Research, Institute for Genome Engineered Animal Models of Human Diseases, Dalian Medical University, Dalian 116000, China
- Shandong Provincial Hospital, School of Laboratory Animal & Shandong Laboratory Animal Center, Science and Technology Innovation Center, Shandong First Medical University & Shandong Academy of Medical Sciences, Jinan 250021, China
- Department of Molecular Pathobiology, New York University College of Dentistry, New York, NY 10010, USA
| | - Fang Zhang
- National Clinical Research Center for Eye Diseases, Shanghai General Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai 200080, China
- Shanghai Key Laboratory of Ocular Fundus Diseases, Shanghai 200080, China
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Satterthwaite L, Koumarianou G, Carroll PB, Sedlik RJ, Wang I, McCarthy MC, Patterson D. Low-Temperature Gas-Phase Kinetics of Ethanol-Methanol Heterodimer Formation. J Phys Chem A 2023; 127:4096-4102. [PMID: 37119198 PMCID: PMC10184117 DOI: 10.1021/acs.jpca.3c01312] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/01/2023]
Abstract
The structures of gas-phase noncovalently bound clusters have long been studied in supersonic expansions. This method of study, while providing a wealth of information about the nature of noncovalent bonds, precludes observation of the formation of the cluster, as the clusters form just after the orifice of the pulsed valve. Here, we directly observe formation of ethanol-methanol dimers via microwave spectroscopy in a controlled cryogenic environment. Time profiles of the concentration of reagents in the cell yielded gas-phase reaction rate constants of kMe-g = (2.8 ± 1.4) × 10-13 cm3 molecule-1 s-1 and kMe-t = (1.6 ± 0.8) × 10-13 cm3 molecule-1 s-1 for the pseudo-second-order ethanol-methanol dimerization reaction at 8 K. The relaxation cross section between the gauche and trans conformers of ethanol was also measured using the same technique. In addition, thermodynamic relaxation between conformers of ethanol over time allowed for selection of conformer stoichiometry in the ethanol-methanol dimerization reaction, but no change in the ratio of dimer conformers was observed with changing ethanol monomer stoichiometry.
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Affiliation(s)
- Lincoln Satterthwaite
- Department of Chemistry and Biochemistry, Building 232, University of California, Santa Barbara, California 93106, United States
| | - Greta Koumarianou
- Department of Chemistry and Biochemistry, Building 232, University of California, Santa Barbara, California 93106, United States
| | - P Brandon Carroll
- Center for Astrophysics | Harvard & Smithsonian, 60 Garden Street, Cambridge, Massachusetts 02138, United States
| | - Robert J Sedlik
- Physics Department, Broida Hall, University of California, Santa Barbara, California 93106, United States
| | - Irene Wang
- Physics Department, Broida Hall, University of California, Santa Barbara, California 93106, United States
| | - Michael C McCarthy
- Center for Astrophysics | Harvard & Smithsonian, 60 Garden Street, Cambridge, Massachusetts 02138, United States
| | - David Patterson
- Physics Department, Broida Hall, University of California, Santa Barbara, California 93106, United States
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Ellis AM, Davies JA, Yurtsever E, Calvo F. Dimerization dynamics of carboxylic acids in helium nanodroplets. J Chem Phys 2022; 156:174304. [PMID: 35525638 DOI: 10.1063/5.0087957] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
The dimerization of molecules in helium nanodroplets is known to preferentially yield structures of higher energy than the global energy minimum structure for a number of quite different monomers. Here, we explore dimerization in this environment using an atomistic model within statistically converged molecular dynamics (MD) trajectories, treating the solvent implicitly through the use of a thermostat, or more explicitly by embedding one monomer in a He100 cluster. The focus is on the two simplest carboxylic acids, formic and acetic, both of which have been studied experimentally. While the global minimum structure, which comprises two CO⋯HO hydrogen bonds, is predicted to be the most abundant dimer in the absence of the helium solvent, this is no longer the case once helium atoms are included. The simulations confirm the importance of kinetic trapping effects and also shed light on the occurrence of specific dynamical effects, leading to the occasional formation of high-energy structures away from minima, such as saddle configurations. Theoretically predicted infrared spectra, based on the MD statistics, are in good agreement with the experimental spectra.
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Affiliation(s)
- Andrew M Ellis
- School of Chemistry, University of Leicester, University Road, Leicester LE1 7RH, United Kingdom
| | - Julia A Davies
- School of Chemistry, University of Leicester, University Road, Leicester LE1 7RH, United Kingdom
| | - Ersin Yurtsever
- Department of Chemistry, Koç University, Rumelifeneri Yolu, Sariyer, 34450 Istanbul, Turkey
| | - Florent Calvo
- Université Grenoble Alpes, CNRS, LiPhy, F38000 Grenoble, France
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Garrido González JJ, Boya Del Teso I, Fuentes de Arriba AL, Sanz F, Martín Del Valle EM, Morán JR, Alcazar V. An Adjustable Cleft Based on an 8-sulfonamide-2-naphthoic Acid with Oxyanion Hole Geometry. Chemistry 2021; 27:14605-14609. [PMID: 34396599 DOI: 10.1002/chem.202102137] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2021] [Indexed: 11/11/2022]
Abstract
Cleft type receptors showing the oxyanion hole motif have been prepared in a straightforward synthesis starting from the commercial 3,7-dihidroxy-2-naphthoic acid. The double H-bond donor pattern is achieved by the introduction of a sulfonamide group in the C-8 position of naphthalene and a carboxamide at the C-2 position. This cleft, whose geometry resembles that of an oxyanion hole, is able to adjust to different guests, as shown by the analysis of the X- ray crystal structures of associates with methanol or acetic acid. Combination of hydrogen bonds and charge-transfer interactions led to further stabilization of the complexes, in which the electron-rich aromatic ring of the receptor was close in space to the electron-deficient dinitroaromatic guests. Modelling studies and bidimensional NMR experiments have been carried out to provide additional information.
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Affiliation(s)
| | - Irene Boya Del Teso
- Universidad de Salamanca, Organic Chemistry, Plaza de los Caídos, 37008, España, 37008, Salamanca, SPAIN
| | | | - Francisca Sanz
- Universidad de Salamanca, Servicio de Rayos X, Plaza de los Caídos, 37008, España, 37008, Salamanca, SPAIN
| | - Eva María Martín Del Valle
- Universidad de Salamanca, Chemical Engineering, Plaza de los Caídos, 37008, España, 37008, Salamanca, SPAIN
| | - Joaquín R Morán
- Universidad de Salamanca, Organic Chemistry, Plaza de los Caídos, 37008, España, 37008, Salamanca, SPAIN
| | - Victoria Alcazar
- Polytechnic University of Madrid: Universidad Politecnica de Madrid, Department of Chemical and Environmental Engineering, José Gutiérrez Abascal 2, E-28006, Madrid, SPAIN
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Frandsen BN, Deal AM, Lane JR, Vaida V. Lactic Acid Spectroscopy: Intra- and Intermolecular Interactions. J Phys Chem A 2020; 125:218-229. [PMID: 33377780 DOI: 10.1021/acs.jpca.0c09341] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Lactic acid, a relevant molecule in biology and the environment, is an α-hydroxy acid with a high propensity to form hydrogen bonds, both internally and to other hydrogen-bond-accepting molecules. This work includes the novel recording of infrared spectra of gas-phase lactic acid using Fourier transform infrared spectroscopy, and the vibrational absorption features of lactic acid are assigned with the aid of computationally simulated vibrational spectra with anharmonic corrections. Theoretical chemistry methods are used to relate intramolecular hydrogen-bond strengths to the relative stability of lactic acid conformers. The formation of hydrogen-bonded lactic acid dimers and 1:1 water complexes is investigated by simulated vibrational spectra and calculated thermodynamic parameters for the lactic acid monomer and dimer and its water complex in the gas phase. The results of this study are discussed in the context of environmental chemistry with an emphasis on indoor environments.
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Affiliation(s)
- Benjamin N Frandsen
- Department of Chemistry, University of Colorado Boulder, Boulder, Colorado 80309, United States.,Cooperative Institute for Research in Environmental Sciences, University of Colorado Boulder, UCB 216, Boulder, Colorado 80309, United States
| | - Alexandra M Deal
- Department of Chemistry, University of Colorado Boulder, Boulder, Colorado 80309, United States.,Cooperative Institute for Research in Environmental Sciences, University of Colorado Boulder, UCB 216, Boulder, Colorado 80309, United States
| | - Joseph R Lane
- School of Science, University of Waikato, Private Bag 3105, Hamilton 3240, New Zealand
| | - Veronica Vaida
- Department of Chemistry, University of Colorado Boulder, Boulder, Colorado 80309, United States.,Cooperative Institute for Research in Environmental Sciences, University of Colorado Boulder, UCB 216, Boulder, Colorado 80309, United States
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