169,916 research outputs found
Synthesis, High-Resolution Infrared Spectroscopy, and Vibrational Structure of Cubane, C8H8
No full textCarbon-cage molecules have generated a considerable interest from both experimental and theoretical points of view. We recently performed a high-resolution study of adamantane (C10H16), the smallest hydrocarbon cage belonging to the diamandoid family (Pirali, O.; et al. J. Chem. Phys. 2012, 136, 024310). There exist another family of hydrocarbon cages with additional interesting chemical properties: the so-called platonic hydrocarbons that comprise dodecahedrane (C20H20) and cubane (C8H8). Both possess C-C bond angles that deviate from the tetrahedral angle (109.8°) of the sp3 hybridized form of carbon. This generates a considerable strain in the molecule. We report a new wide-range high-resolution study of the infrared spectrum of cubane. The sample was synthesized in Bari upon decarboxylation of 1,4-cubanedicarboxylic acid thanks to the improved synthesis of literature. Several spectra have been recorded at the AILES beamline of the SOLEIL synchrotron facility. They cover the 600-3200 cm-1 region. Besides the three infrared-active fundamentals (ν10, ν11, and ν12), we could record many combination bands, all of them displaying a well-resolved octahedral rotational structure. We present here a preliminary analysis of some of the recorded bands, performed thanks the SPVIEW and XTDS software, based on the tensorial formalism developed in the Dijon group. A comparison with ab initio calculations, allowing to identify some combination bands, is also presented
Click 1,2,3-triazoles in drug discovery and development: From the flask to the clinic?
No full textAfter 20 years since its conception, click chemistry has come of age and we believe the time has come to evaluate if the copper-catalyzed azide alkyne cycloaddition (CuCAAC) reaction deserves to be considered the perfect transformation in medicinal chemistry campaigns and to weigh up the concrete results that have been produced in terms of drugs approved and clinical candidates in development. After a description of the properties of the triazole nucleus in terms of both pharmacokinetic and pharmacodynamic profile, a practical guide for the best approaches to be used for the synthesis of triazoles is provided, capitalizing on our 20-year hands-on experience in this chemistry. Finally, we describe those molecules displaying the 1,2,3-triazole nucleus that have entered the market or are, at least, in clinical trials. Only four 1,2,3-triazole-bearing drugs have been launched so far. Among them the recently approved antibody drug conjugate sacituzumab govitecan was discovered thanks to click chemistry. Nevertheless, to the best of our knowledge, there are a dozen 1,2,3-triazoles in clinical development and it is likely that we will witness the launch on the market of at least some of them, encouraging medicinal chemists to further use this approach, not only as a route to early-stage discoveries, but also as a means to developing successful drugs
High-resolution infrared absorption spectroscopy of thermally excited naphthalene. Measurements and calculations of anharmonic parameters and vibrational interactions
No full textDeuterium in drug discovery: progress, opportunities and challenges
No full textSubstituting a hydrogen atom with its heavy isotope deuterium may improve the pharmacokinetic and/or toxicity profile of a drug compared with its non-deuterated counterpart. This article highlights milestones in the field of deuteration in drug discovery and development, and discusses recent examples of its application, which have shifted towards deuteration of novel drug candidates instead of developing deuterated analogues of marketed drugs.Substitution of a hydrogen atom with its heavy isotope deuterium entails the addition of one neutron to a molecule. Despite being a subtle change, this structural modification, known as deuteration, may improve the pharmacokinetic and/or toxicity profile of drugs, potentially translating into improvements in efficacy and safety compared with the non-deuterated counterparts. Initially, efforts to exploit this potential primarily led to the development of deuterated analogues of marketed drugs through a 'deuterium switch' approach, such as deutetrabenazine, which became the first deuterated drug to receive FDA approval in 2017. In the past few years, the focus has shifted to applying deuteration in novel drug discovery, and the FDA approved the pioneering de novo deuterated drug deucravacitinib in 2022. In this Review, we highlight key milestones in the field of deuteration in drug discovery and development, emphasizing recent and instructive medicinal chemistry programmes and discussing the opportunities and hurdles for drug developers, as well as the questions that remain to be addressed
The Soleil View On Prototypical Organic Nitriles: The 13c Species Of Ethyl Cyanide
No full textVibrational spectra of the three singly substituted C isotopic species of ethyl cyanide, aka propionitrile (CHCHCN), have been studied at high spectral resolution at the synchrotron facility SOLEIL using Fourier-transform far-infrared spectroscopy.
% up to 700\,cm.
%
The measurements, recorded up to 700\,cm, cover the fundamental modes of the CCN in-plane bending , the methyl torsion , the
CCN out-of-plane bending as well as the CCC in-plane bending .
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A first spectroscopic analysis has been performed using the
\textit{Automated Spectral Assignment Procedure} (ASAP)\footnote{M. A. Martin-Drumel, C. P.
Endres, O. Zingsheim, T. Salomon, J. van Wijngaarden, O. Pirali, S. Gruet, F. Lewen, S. Schlemmer, M. C. McCarthy, and S. Thorwirth 2015, J. Mol. Spectrosc. 315, 72}
to derive accurate excited-state rotational level energies with a focus on the
and the vibrational modes
NEW ACETYLENE CH MEASUREMENTS USING SOLEIL SYNCHROTRON
No full textAuthor Institution: Universite Pierre et Marie Curie-Paris 6; CNRS; Laboratoire; de Dynamique, Interactions et Reactivite (LADIR), UMR 7075, Case Courrier; 49, 4 Place Jussieu, 75252 Paris Cedex 05, France; Synchrotron SOLEIL, L Orme des Merisiers Saint-Aubin, 91192 Gif-sur-Yvette cedex, FranceThe acetylene molecule is important for atmospheric, planetary, and astrophysical applications. This organic molecule, known as a precursor of amino acids, shows numerous vibration-rotation bands in the IR. \vspace{1em} A recent study using SOLEIL synchrotron AILES beamline will be presented in the spectral region around 100 cm. This work is the continuation of a previous one ({D.~Jacquemart, L.~Gomez, N.~Lacome, J.-Y.~Mandin, O.~Pirali and P.~Roy. JQSRT 2010:111;1223-33}) for which absolute line intensities of the intense - band have been measured. In the present work a White-type cell has been used to reach an absorption path of 150 meters. With such an absorption path, several weaker bands have been observed and studied in term of absolute line intensities. Analysis of high resolution spectra using the FIR beam AILES of the synchrotron required a special care to the modelization of the apparatus function. The knowledge of the optical weighting of the apparatus function is crucial to measure accurate line parameters especially when using a synchrotron beam
Going Beyond Counting First Authors in Author Co-citation Analysis
No full textThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Mixing synchrotron radiation and laser sources: dual-comb spectroscopy in the submillimeter-wave region
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Previous issue date: 23On the AILES beamline of the SOLEIL synchrotron the HEROES consortium is currently developing new spectrometers based on heterodyne mixing of the THz synchrotron radiation with dedicated laser sources. We report here the first results on one of these spectrometers that aims at exploiting the discrete nature of coherent synchrotron radiation (CSR) in the 100--1000 GHz region, revealed a few years ago by our team\footnote{Tammaro, S., Pirali, O., Roy, P., Lampin, J.F., Ducournau, G., Cuisset, A., Hindle, F., Mouret, G. "High density terahertz frequency comb produced by coherent synchrotron radiation" Nature Communications., 6: art. 7733. (2015)}, to perform dual-comb THz spectroscopy. CSR generated by the so called low- mode of the SOLEIL machine produces a relatively intense, offset-free, high density frequency-comb in the THz range (THz-FC). We will present the details of our preliminary experimental set-up mixing the THz-FC from SOLEIL with an optical comb from Menlo C-fiber femtosecond laser. Pure rotation absorption transitions of acetonitrile in the frequency domain (covering the 100--500 GHz range) as well as time-domain free induction decays (FIDs) were observed allowing to establish the performances of this new instrument
Synchotron-based high resolution spectroscopy of N-bearing PAHS
No full textFor thirty years,\footnote{A. Leger, J. L. Puget, \textit{Astron. Astrophys.} \textbf{137}, L5-L8 (1984); L. J. Allamandola et al. \textit{Astrophys. J.} \textbf{290}, L25-L28 (1985).} the Polycyclic Aromatic Hydrocarbons (PAHs) have been suspected to give rise to the numerous Unidentified Infrared Bands (UIBs) observed in most astrophysical objects. Pure carbon molecules as well as derivatives with nitrogen atom(s) incorporated into the carbon skeleton have been considered. These N-bearing molecules are interesting candidates for astronomical research since they possess a larger permanent dipole moment than purely carbon-based PAHs.
Most of the data reported in the literature deal with rotationally unresolved data. During the last decade, high-resolution microwave spectroscopy initiated high resolution studies of this broad family of molecules.\footnote{Z. Kisiel et al. \textit{J. Mol. Spectrosc.} \textbf{217}, 115 (2003); S. Thorwirth et al. \textit{Astrophys. J.} \textbf{662}, 1309 (2007); D. McNaughton et al. \textit{J. Chem. Phys.} \textbf{124}, 154305 (2011).} Recent advances in laboratory techniques permitted to provide interesting new results to rotationally resolve the IR/Far-IR vibrational bands of these relatively large C-bearing molecules\footnote{S. Albert et al. \textit{Faraday Discuss.} \textbf{150}, 71-99 (2011); B. E. Brumfield et al. \textit{Phys. Chem. Lett.} \textbf{3}, 1985-1988 (2012); O. Pirali et al. \textit{Phys. Chem. Chem. Phys.} \textbf{15}, 10141 (2013).},in particular, making use of synchrotron radiation as the IR continuum source of high resolution Fourier transform (FT) spectrometers.
We will present an overview of the synchrotron-based high resolution FTIR spectroscopy of 5 aza-derivatives of naphthalene (isoquinoline, quinoline, quinoxaline, quinazoline, [1,5] naphthyridine) using a room temperature long path absorption cell at the French facility SOLEIL. In support to the rovibrational analysis of these FIR spectra, very accurate anharmonic DFT calculations were performed.\footnote{M. Goubet, O. Pirali, J. \textit{Chem. Phys.}, \textbf{140}, 044322 (2014).}Made available in DSpace on 2014-09-17T16:55:10Z (GMT). No. of bitstreams: 3
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Previous issue date: 2014-06-16Made available in DSpace on 2015-04-14T18:41:36Z (GMT). No. of bitstreams: 4
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Previous issue date: 2014-06-1
A rotational investigation of the three isomeric forms of cyanoethynylbenzene (HCC-C6H4-CN): benchmarking experiments and calculations using the “Lego brick” approach
No full textWe report the study of three structural isomers of phenylpropiolonitrile (3-phenyl-2-propynenitrile, C6H5-C3N) containing an alkyne function and a cyano group, namely ortho-, meta-, and para-cyanoethynylbenzene (HCC-C6H4-CN). The pure rotational spectra of these species have been recorded at room temperature in the millimeter-wave domain using a chirped-pulse spectrometer (75-110 GHz) and a source-frequency modulation spectrometer (140-220 GHz). Assignments of transitions in the vibrational ground state and several vibrationally excited states were supported by quantum chemical calculations using the so-called “Lego brick” approach [A. Melli, F. Tonolo, V. Barone and C. Puzzarini, J. Phys. Chem. A, 2021, 125, 9904-9916]. From these assignments, accurate spectroscopic (rotational and centrifugal distortion) constants have been derived: for all species and all observed vibrational states, predicted rotational constants show relative accuracy better than 0.1%, and often of the order of 0.01%, compared to the experimental values. The present work hence further validates the use of the “Lego brick” approach for predicting spectroscopic constants with high precision
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