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Pihlava L, Svensson PHW, Kukk E, Kooser K, De Santis E, Tõnisoo A, Käämbre T, André T, Akiyama T, Hessenthaler L, Giehr F, Björneholm O, Caleman C, Berholts M. Shell-dependent photofragmentation dynamics of a heavy-atom-containing bifunctional nitroimidazole radiosensitizer. Phys Chem Chem Phys 2024; 26:8879-8890. [PMID: 38426309 DOI: 10.1039/d4cp00367e] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/02/2024]
Abstract
Radiation therapy uses ionizing radiation to break chemical bonds in cancer cells, thereby causing DNA damage and leading to cell death. The therapeutic effectiveness can be further increased by making the tumor cells more sensitive to radiation. Here, we investigate the role of the initial halogen atom core hole on the photofragmentation dynamics of 2-bromo-5-iodo-4-nitroimidazole, a potential bifunctional radiosensitizer. Bromine and iodine atoms were included in the molecule to increase the photoionization cross-section of the radiosensitizer at higher photon energies. The fragmentation dynamics of the molecule was studied experimentally in the gas phase using photoelectron-photoion-photoion coincidence spectroscopy and computationally using Born-Oppenheimer molecular dynamics. We observed significant changes between shallow core (I 4d, Br 3d) and deep core (I 3d) ionization in fragment formation and their kinetic energies. Despite the fact, that the ions ejected after deep core ionization have higher kinetic energies, we show that in a cellular environment, the ion spread is not much larger, keeping the damage well-localized.
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Affiliation(s)
- Lassi Pihlava
- Department of Physics and Astronomy, University of Turku, FI-20014 Turku, Finland.
| | - Pamela H W Svensson
- Department of Physics and Astronomy, University of Uppsala, SE-75120 Uppsala, Sweden
| | - Edwin Kukk
- Department of Physics and Astronomy, University of Turku, FI-20014 Turku, Finland.
| | - Kuno Kooser
- Institute of Physics, University of Tartu, W. Ostwald 1, EST-50411, Tartu, Estonia.
| | - Emiliano De Santis
- Department of Chemistry - BMC, University of Uppsala, SE-75123 Uppsala, Sweden
| | - Arvo Tõnisoo
- Institute of Physics, University of Tartu, W. Ostwald 1, EST-50411, Tartu, Estonia.
| | - Tanel Käämbre
- Institute of Physics, University of Tartu, W. Ostwald 1, EST-50411, Tartu, Estonia.
| | - Tomas André
- Department of Physics and Astronomy, University of Uppsala, SE-75120 Uppsala, Sweden
| | - Tomoko Akiyama
- Department of Physics and Astronomy, University of Uppsala, SE-75120 Uppsala, Sweden
| | - Lisa Hessenthaler
- Department of Physics and Astronomy, University of Uppsala, SE-75120 Uppsala, Sweden
| | - Flavia Giehr
- Department of Physics and Astronomy, University of Uppsala, SE-75120 Uppsala, Sweden
| | - Olle Björneholm
- Department of Physics and Astronomy, University of Uppsala, SE-75120 Uppsala, Sweden
| | - Carl Caleman
- Department of Physics and Astronomy, University of Uppsala, SE-75120 Uppsala, Sweden
- Center for Free-Electron Laser Science, DESY, DE-22607 Hamburg, Germany
| | - Marta Berholts
- Institute of Physics, University of Tartu, W. Ostwald 1, EST-50411, Tartu, Estonia.
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Svensson PHW, Schwob L, Grånäs O, Unger I, Björneholm O, Timneanu N, Lindblad R, Vieli AL, Zamudio-Bayer V, Timm M, Hirsch K, Caleman C, Berholts M. Heavy element incorporation in nitroimidazole radiosensitizers: molecular-level insights into fragmentation dynamics. Phys Chem Chem Phys 2024; 26:770-779. [PMID: 37888897 DOI: 10.1039/d3cp03800a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2023]
Abstract
The present study investigates the photofragmentation behavior of iodine-enhanced nitroimidazole-based radiosensitizer model compounds in their protonated form using near-edge X-ray absorption mass spectrometry and quantum mechanical calculations. These molecules possess dual functionality: improved photoabsorption capabilities and the ability to generate species that are relevant to cancer sensitization upon photofragmentation. Four samples were investigated by scanning the generated fragments in the energy regions around C 1s, N 1s, O 1s, and I 3d-edges with a particular focus on NO2+ production. The experimental summed ion yield spectra are explained using the theoretical near-edge X-ray absorption fine structure spectrum based on density functional theory. Born-Oppenheimer-based molecular dynamics simulations were performed to investigate the fragmentation processes.
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Affiliation(s)
- Pamela H W Svensson
- Department of Physics and Astronomy, University of Uppsala, SE-75120 Uppsala, Sweden.
| | - Lucas Schwob
- Deutsches Elektronen-Synchrotron DESY, Notkestr. 85, 22607 Hamburg, Germany
| | - Oscar Grånäs
- Department of Physics and Astronomy, University of Uppsala, SE-75120 Uppsala, Sweden.
| | - Isaak Unger
- Department of Physics and Astronomy, University of Uppsala, SE-75120 Uppsala, Sweden.
| | - Olle Björneholm
- Department of Physics and Astronomy, University of Uppsala, SE-75120 Uppsala, Sweden.
| | - Nicusor Timneanu
- Department of Physics and Astronomy, University of Uppsala, SE-75120 Uppsala, Sweden.
| | - Rebecka Lindblad
- Department of Physics and Astronomy, University of Uppsala, SE-75120 Uppsala, Sweden.
| | - Anna-Lydia Vieli
- Department of Physics and Astronomy, University of Uppsala, SE-75120 Uppsala, Sweden.
| | - Vicente Zamudio-Bayer
- Abteilung für Hochempfindliche Röntgenspektroskopie, Helmholtz Zentrum Berlin für Materialien und Energie, 12489 Berlin-Adlershof, Germany
| | - Martin Timm
- Abteilung für Hochempfindliche Röntgenspektroskopie, Helmholtz Zentrum Berlin für Materialien und Energie, 12489 Berlin-Adlershof, Germany
| | - Konstantin Hirsch
- Abteilung für Hochempfindliche Röntgenspektroskopie, Helmholtz Zentrum Berlin für Materialien und Energie, 12489 Berlin-Adlershof, Germany
| | - Carl Caleman
- Department of Physics and Astronomy, University of Uppsala, SE-75120 Uppsala, Sweden.
- Center for Free-Electron Laser Science, DESY, DE-22607 Hamburg, Germany
| | - Marta Berholts
- Institute of Physics, University of Tartu, W. Ostwald 1, EST-50411, Tartu, Estonia.
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Ascenzi D, Erdmann E, Bolognesi P, Avaldi L, Castrovilli MC, Thissen R, Romanzin C, Alcaraz C, Rabadan I, Mendez L, Díaz-Tendero S, Cartoni A. H 2O˙ + and OH + reactivity versus furan: experimental low energy absolute cross sections for modeling radiation damage. Phys Chem Chem Phys 2023; 25:24643-24656. [PMID: 37665608 DOI: 10.1039/d3cp02772d] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 09/05/2023]
Abstract
Radiotherapy is one of the most widespread and efficient strategies to fight malignant tumors. Despite its broad application, the mechanisms of radiation-DNA interaction are still under investigation. Theoretical models to predict the effects of a particular delivered dose are still in their infancy due to the difficulty of simulating a real cell environment, as well as the inclusion of a large variety of secondary processes. This work reports the first experimental study of the ion-molecule reactions of the H2O˙+ and OH+ ions, produced by photoionization with synchrotron radiation, with a furan (c-C4H4O) molecule, a template for deoxyribose sugar in DNA. The present experiments, performed as a function of the collision energy of the ions and the tunable photoionization energy, provide key parameters for the theoretical modelling of the effect of radiation dose, like the absolute cross sections for producing protonated furan (furanH+) and a radical cation (furan˙+), the most abundant products, which can amount up to 200 Å2 at very low collision energies (<1.0 eV). The experimental results show that furanH+ is more fragile, indicating how the protonation of the sugar component of the DNA may favor its dissociation with possible major radiosensitizing effects. Moreover, the ring opening of furanH+ isomers and the potential energy surface of the most important fragmentation channels have been explored by molecular dynamics simulations and quantum chemistry calculations. The results show that, in the most stable isomer of furanH+, the ring opening occurs via a low energy pathway with carbon-oxygen bond cleavage, followed by the loss of neutral carbon monoxide and the formation of the allyl cation CH2CHCH2+, which instead is not observed in the fragmentation of furan˙+. At higher energies the ring opening through the carbon-carbon bond is accompanied by the loss of formaldehyde, producing HCCCH2+, the most intense fragment ion detected in the experiments. This work highlights the importance of the secondary processes, like the ion-molecule reactions at low energies in the radiation damage due to their very large cross sections, and it aims to provide benchmark data for the development of suitable models to approach this low collision energy range.
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Affiliation(s)
- Daniela Ascenzi
- Department of Physics, University of Trento, Via Sommarive 14, 38123 Trento, Italy
| | - Ewa Erdmann
- Faculty of Applied Physics and Mathematics, Gdansk University of Technology, Narutowicza 11/12, 80-233 Gdansk, Poland
| | - Paola Bolognesi
- Institute of Structure of Matter-CNR (ISM-CNR), Area della Ricerca di Roma 1, Via Salaria km 29.300, 00015, Monterotondo, Italy
| | - Lorenzo Avaldi
- Institute of Structure of Matter-CNR (ISM-CNR), Area della Ricerca di Roma 1, Via Salaria km 29.300, 00015, Monterotondo, Italy
| | - Mattea Carmen Castrovilli
- Institute of Structure of Matter-CNR (ISM-CNR), Area della Ricerca di Roma 1, Via Salaria km 29.300, 00015, Monterotondo, Italy
| | - Roland Thissen
- Université Paris-Saclay, CNRS, Institut de Chimie Physique, UMR8000, 91405 Orsay, France
- Synchrotron SOLEIL, L'Orme des Merisiers, 91192 Saint Aubin, Gif-sur-Yvette, France
| | - Claire Romanzin
- Université Paris-Saclay, CNRS, Institut de Chimie Physique, UMR8000, 91405 Orsay, France
- Synchrotron SOLEIL, L'Orme des Merisiers, 91192 Saint Aubin, Gif-sur-Yvette, France
| | - Christian Alcaraz
- Université Paris-Saclay, CNRS, Institut de Chimie Physique, UMR8000, 91405 Orsay, France
- Synchrotron SOLEIL, L'Orme des Merisiers, 91192 Saint Aubin, Gif-sur-Yvette, France
| | - Ismanuel Rabadan
- Department of Chemistry, Universidad Autónoma de Madrid, 28049, Madrid, Spain.
| | - Luis Mendez
- Department of Chemistry, Universidad Autónoma de Madrid, 28049, Madrid, Spain.
| | - Sergio Díaz-Tendero
- Department of Chemistry, Universidad Autónoma de Madrid, 28049, Madrid, Spain.
- Institute for Advanced Research in Chemistry (IAdChem), Universidad Autónoma de Madrid, 28049 Madrid, Spain
- Condensed Matter Physics Center (IFIMAC), Universidad Autónoma de Madrid, 28049 Madrid, Spain
| | - Antonella Cartoni
- Department of Chemistry, Sapienza University of Rome, P. le Aldo Moro 5, Rome, 00185, Italy.
- Institute of Structure of Matter-CNR (ISM-CNR), Area della Ricerca di Roma 1, Via Salaria km 29.300, 00015, Monterotondo, Italy
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Bolognesi P, Avaldi L. Photoelectron-photoion(s) coincidence studies of molecules of biological interest. Phys Chem Chem Phys 2022; 24:22356-22370. [PMID: 36124990 DOI: 10.1039/d2cp03079a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Photoelectron-photoion(s) coincidence, PEPICO, experiments with synchrotron radiation have become one of the most powerful tools to investigate dissociative photoionization thanks to their selectivity. In this paper their application to the study of molecular species of biological interest in the gas phase is reviewed. Some applications of PEPICO to the study of potential radiosensitizers, amino acids and small peptides and opportunities offered by the advent of novel methods for the production of beams of these molecules are discussed.
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Affiliation(s)
- P Bolognesi
- CNR-Istituto di Struttura della Materia, Area della Ricerca di Roma 1, CP 10 00015 Monterotondo Scalo, Italy.
| | - L Avaldi
- CNR-Istituto di Struttura della Materia, Area della Ricerca di Roma 1, CP 10 00015 Monterotondo Scalo, Italy.
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Perspectives of Gas Phase Ion Chemistry: Spectroscopy and Modeling. CONDENSED MATTER 2022. [DOI: 10.3390/condmat7030046] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
The study of ions in the gas phase has a long history and has involved both chemists and physicists. The interplay of their competences with the use of very sophisticated commercial and/or homemade instrumentations and theoretical models has improved the knowledge of thermodynamics and kinetics of many chemical reactions, even if still many stages of these processes need to be fully understood. The new technologies and the novel free-electron laser facilities based on plasma acceleration open new opportunities to investigate the chemical reactions in some unrevealed fundamental aspects. The synchrotron light source can be put beside the FELs, and by mass spectrometric techniques and spectroscopies coupled with versatile ion sources it is possible to really change the state of the art of the ion chemistry in different areas such as atmospheric and astro chemistry, plasma chemistry, biophysics, and interstellar medium (ISM). In this manuscript we review the works performed by a joint combination of the experimental studies of ion–molecule reactions with synchrotron radiation and theoretical models adapted and developed to the experimental evidence. The review concludes with the perspectives of ion–molecule reactions by using FEL instrumentations as well as pump probe measurements and the initial attempt in the development of more realistic theoretical models for the prospective improvement of our predictive capability.
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Rathi A, Basu S, Barman S. Efficient eradication of antibiotic and dye by C-dots@zeolite nanocomposites: Performance evaluation, and degraded products analysis. CHEMOSPHERE 2022; 298:134260. [PMID: 35271900 DOI: 10.1016/j.chemosphere.2022.134260] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/12/2021] [Revised: 01/07/2022] [Accepted: 03/06/2022] [Indexed: 06/14/2023]
Abstract
Metronidazole (MET), a recalcitrant antibiotic from the nitro-imidazole family and commercially used Rhodamine B (RhB) dye, contributes a huge to water pollution, which needs to eliminate, preferably by photocatalytic degradation technique. The Cdots@zeolite (CDZ) nanocomposites with different weight ratios (1:1, 1:3, 1:5, 5:1, 1:7) were synthesized hydrothermally to degrade MET and RhB molecules. The CDZ composites were characterized by XRD, BET, EDS, and XPS technique which verifies the crystalline nature, incorporation of C-dots into zeolite frameworks with high surface area (∼187 m2/g). The morphology, d-spacing and lattice planes were analyzed by SEM images, HR-TEM and SAED analysis. The maximum degradation (∼79%) was achieved at an optimum catalyst dose of 0.2 g/L and pH 4 for MET and that of RhB was ∼90% at a catalyst dose of 0.4 g/L. The PZC (point of zero charge) value for CDZ composite was about pH 3.4, which justifies the maximum removal of MET at pH 4. The obtained rate constants 'k' were found to be 0.0081, 0.0041, and 0.0101 min-1 in sun, UV, and visible light sources, respectively. The real industrial wastewater sample has been treated to give ∼68% of COD and ∼62% TOC removal. Moreover, the intermediates of plausible degradation pathways were identified by the m/z values obtained from GC-MS analysis.
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Affiliation(s)
- Aanchal Rathi
- School of Chemistry and Biochemistry, Thapar Institute of Engineering and Technology, India
| | - Soumen Basu
- School of Chemistry and Biochemistry, Thapar Institute of Engineering and Technology, India.
| | - Sanghamitra Barman
- Department of Chemical Engineering, Thapar Institute of Engineering and Technology, India.
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Satta M, Casavola AR, Cartoni A, Castrovilli MC, Catone D, Chiarinelli J, Borocci S, Avaldi L, Bolognesi P. Ionization of 2- and 4(5)-Nitroimidazoles Radiosensitizers: A "Kinetic Competition" Between NO 2 and NO Losses. Chemphyschem 2021; 22:2387-2391. [PMID: 34597457 PMCID: PMC9293481 DOI: 10.1002/cphc.202100629] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2021] [Revised: 09/23/2021] [Indexed: 12/27/2022]
Abstract
Nitroimidazoles are a class of chemicals with a remarkable broad spectrum of applications from the production of explosives to the use as radiosensitizers in radiotherapy. The understanding of thedynamics of their fragmentation induced by ionizing sources is of fundamental interest. The goal of this work is to theoretically investigate the kinetic competition between the two most important decomposition channels of 2, 4 and 5‐Nitroimidazole cations: the NO and NO2 losses. The calculated rate constants of the two processes are in very good agreement with the experimental Photoelectron‐Photoion Coincidence (PEPICO) branching ratio. This study solves the intriguing and theoretically unexplained experimental observation that 2‐Nitroimidazole, at variance with the other two regio‐isomers is a source for only NO at low energies (<12.76 eV). This is a key point for biomedical application of the nitroimidazoles, because NO is the vasodilator that favors the reoxigenation of hypoxic tumor tissues.
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Affiliation(s)
- Mauro Satta
- Istituto per lo Studio dei Materiali Nanostrutturati (ISMN-CNR), Dipartimento di Chimica, Università degli studi di Roma La Sapienza, P.le Aldo Moro 5, 00185, Roma, Italy
| | - Anna Rita Casavola
- Istituto di Struttura della Materia (ISM-CNR), Area della Ricerca di Roma 1, Via Salaria Km 29,300, 00016, Monterotondo Scalo (RM), Italy
| | - Antonella Cartoni
- Dipartimento di Chimica, Università degli studi di Roma La Sapienza, Pl.e Aldo Moro 5, 00185, Roma, Italy
| | - Mattea Carmen Castrovilli
- Istituto di Struttura della Materia (ISM-CNR), Area della Ricerca di Roma 1, Via Salaria Km 29,300, 00016, Monterotondo Scalo (RM), Italy
| | - Daniele Catone
- Istituto di Struttura della Materia (ISM-CNR), Area della Ricerca di Roma 2, Via del Fosso del Cavaliere 10, 00133, Roma, Italy
| | - Jacopo Chiarinelli
- Istituto di Struttura della Materia (ISM-CNR), Area della Ricerca di Roma 1, Via Salaria Km 29,300, 00016, Monterotondo Scalo (RM), Italy
| | - Stefano Borocci
- Dipartimento per l'Innovazione nei Sistemi Biologici, Agroalimentari e Forestali (DIBAF), Università della Tuscia, Viterbo, Italy
| | - Lorenzo Avaldi
- Istituto di Struttura della Materia (ISM-CNR), Area della Ricerca di Roma 1, Via Salaria Km 29,300, 00016, Monterotondo Scalo (RM), Italy
| | - Paola Bolognesi
- Istituto di Struttura della Materia (ISM-CNR), Area della Ricerca di Roma 1, Via Salaria Km 29,300, 00016, Monterotondo Scalo (RM), Italy
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Li S, Culkin A, Jones DS, Andrews GP. Development of Polycaprolactone-Based metronidazole matrices for intravaginal extended drug delivery using a mechanochemically prepared therapeutic deep eutectic system. Int J Pharm 2021; 593:120071. [PMID: 33246048 DOI: 10.1016/j.ijpharm.2020.120071] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2020] [Revised: 11/02/2020] [Accepted: 11/06/2020] [Indexed: 11/25/2022]
Abstract
The engineering of crystalline multi-component drug systems, including cocrystals and salts, is now an established method of modifying the physicochemical properties and dissolution behaviour of an active ingredient. Remarkably, liquid drug systems, including therapeutic ionic liquids and therapeutic deep eutectic solvents (THEDES), remain largely unexplored as an untapped reservoir for drug modification. In this work, the formation of a THEDES containing metronidazole (MET), the preferred first-line treatment for bacterial vaginosis (BV), was explored. The formed THEDES was evaluated for its dissolution behaviour from a simple polycaprolactone (PCL) matrix, in order to achieve an extended release, balanced with an appropriate onset of action, hence offering improved MET intravaginal application. To minimise handling of the liquid THEDES, an end-to-end continuous process that enables feeding of the raw materials in their respective solid forms, and collection of a solidified final formulation is presented. The concurrent THEDES formation and formulation were carried out using a bench scale (approx. 10 g) twin-screw hot melt extruder. The chosen parent reagents have shown sufficiently strong reactivity and resulted in successful and complete conversion to THEDES while in the presence of PCL, during the extrusion process. The formulated THEDES-PCL matrix exhibited significantly improved onset of drug release followed by a controlled delivery of MET over a total 7-day period in SVF, proving itself as a viable alternative to oral therapy.
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Affiliation(s)
- Shu Li
- The Pharmaceutical Engineering Group, School of Pharmacy, Queen's University Belfast, 97 Lisburn Road, Belfast, Northern Ireland BT9 7BL, UK; China Medical University - Queen's University Belfast Joint College (CQC), No.77 Puhe Road, Shenyang North New Area, Shenyang, Liaoning Province, PR China.
| | - Alice Culkin
- The Pharmaceutical Engineering Group, School of Pharmacy, Queen's University Belfast, 97 Lisburn Road, Belfast, Northern Ireland BT9 7BL, UK
| | - David S Jones
- The Pharmaceutical Engineering Group, School of Pharmacy, Queen's University Belfast, 97 Lisburn Road, Belfast, Northern Ireland BT9 7BL, UK
| | - Gavin P Andrews
- The Pharmaceutical Engineering Group, School of Pharmacy, Queen's University Belfast, 97 Lisburn Road, Belfast, Northern Ireland BT9 7BL, UK; China Medical University - Queen's University Belfast Joint College (CQC), No.77 Puhe Road, Shenyang North New Area, Shenyang, Liaoning Province, PR China
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9
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Backler F, Sani MA, Separovic F, Vasilyev V, Wang F. NMR Chemical Shift and Methylation of 4-Nitroimidazole: Experiment and Theory. Aust J Chem 2021. [DOI: 10.1071/ch20199] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Nitroimidazoles and derivatives are a class of active pharmaceutical ingredients (APIs) first introduced sixty years ago. As anti-infection agents, the structure–activity relationships of nitroimidazole compounds have been particularly difficult to study due to their low reduction potentials and unique electronic structures. In this study, we combine dynamic nuclear polarization (DNP)-enhanced solid-state (100K), solid-state (298K), and 1H-13C heteronuclear single quantum coherence (HSQC) solution-state NMR techniques (303K) with density functional theory (DFT) to study the 1H, 13C, and 15N chemical shifts of 4-nitroimidazole (4-NI) and 1-methyl-4-nitroimidazole (CH3-4NI). The 4-NI chemical shifts were observed at 119.4, 136.4, and 144.7ppm for 13C, and at 181.5, 237.4, and 363.0ppm for 15N. The measurements revealed that methylation (deprotonation) of the amino nitrogen N(1) of 4-NI had less effect (Δδ=−4.8ppm) on the N(1) chemical shift but was compensated by shielding of the N(3) (Δδ=11.6ppm) in CH3-4NI. The calculated chemical shifts using DFT for 4-NI and CH3-4NI agreed well with the experimental values (within 2%) for the imidazole carbons. However, larger discrepancies (up to 13%) were observed between the calculated and measured 15N NMR chemical shifts for the imidazole nitrogen atoms of both molecules, which indicate that effects such as imidazole ring resonant structures and molecular dynamics may also contribute to the nitrogen chemical environment.
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Casavola AR, Cartoni A, Castrovilli MC, Borocci S, Bolognesi P, Chiarinelli J, Catone D, Avaldi L. VUV Photofragmentation of Chloroiodomethane: The Iso-CH 2I-Cl and Iso-CH 2Cl-I Radical Cation Formation. J Phys Chem A 2020; 124:7491-7499. [PMID: 32786965 PMCID: PMC8010789 DOI: 10.1021/acs.jpca.0c05754] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
![]()
Dihalomethanes
XCH2Y (X and Y = F, Cl, Br, and I) are a class of compounds
involved in several processes leading to the release of halogen atoms,
ozone consumption, and aerosol particle formation. Neutral dihalomethanes
have been largely studied, but chemical physics properties and processes
involving their radical ions, like the pathways of their decomposition,
have not been completely investigated. In this work the photodissociation
dynamics of the ClCH2I molecule has been explored in the
photon energy range 9–21 eV using both VUV rare gas discharge
lamps and synchrotron radiation. The experiments show that, among
the different fragment ions, CH2I+ and CH2Cl+, which correspond to the Cl- and I-losses,
respectively, play a dominant role. The experimental ionization energy
of ClCH2I and the appearance energies of the CH2I+ and CH2Cl+ ions are in agreement
with the theoretical results obtained at the MP2/CCSD(T) level of
theory. Computational investigations have been also performed to study
the isomerization of geminal [ClCH2I]•+ into the iso-chloroiodomethane isomers: [CH2I–Cl]•+ and [CH2Cl–I]•+.
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Affiliation(s)
- Anna Rita Casavola
- Institute of Structure of Matter-CNR (ISM-CNR), Area della Ricerca di Roma 1, Via Salaria km 29.300, 00015 Monterotondo, Italy
| | - Antonella Cartoni
- Institute of Structure of Matter-CNR (ISM-CNR), Area della Ricerca di Roma 1, Via Salaria km 29.300, 00015 Monterotondo, Italy.,Department of Chemistry, Sapienza University of Rome, P.le Aldo Moro 5, 00185 Rome, Italy
| | - Mattea Carmen Castrovilli
- Institute of Structure of Matter-CNR (ISM-CNR), Area della Ricerca di Roma 1, Via Salaria km 29.300, 00015 Monterotondo, Italy
| | - Stefano Borocci
- Department for Innovation in Biological, Agrofood and Forest Systems, University of Tuscia, Viterbo 01100, Italy.,Institute for Biological Systems-CNR (ISB-CNR), Area della Ricerca di Roma 1, Via Salaria, Km 29.500,, 00015 Monterotondo, Italy
| | - Paola Bolognesi
- Institute of Structure of Matter-CNR (ISM-CNR), Area della Ricerca di Roma 1, Via Salaria km 29.300, 00015 Monterotondo, Italy
| | - Jacopo Chiarinelli
- Institute of Structure of Matter-CNR (ISM-CNR), Area della Ricerca di Roma 1, Via Salaria km 29.300, 00015 Monterotondo, Italy
| | - Daniele Catone
- Institute of Structure of Matter-CNR (ISM-CNR), Area della Ricerca di Tor Vergata, Via del Fosso del Cavaliere, 00133 Rome, Italy
| | - Lorenzo Avaldi
- Institute of Structure of Matter-CNR (ISM-CNR), Area della Ricerca di Roma 1, Via Salaria km 29.300, 00015 Monterotondo, Italy
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