Desilylation of β-Silyl Pyridinium Ions: Gas-Phase and Solution-Phase Studies in Conjunction with DFT Calculations

2009 ◽  
Vol 28 (15) ◽  
pp. 4276-4282 ◽  
Author(s):  
Asimo Karnezis ◽  
Richard A. J. O’Hair ◽  
Jonathan M. White
Keyword(s):  
Dft Calculations ◽  
Gas Phase ◽  
Solution Phase ◽  
Pyridinium Ions

Graph theory-based reaction pathway searches and DFT calculations for the mechanism studies of free radical-initiated peptide sequencing mass spectrometry (FRIPS MS): a model gas-phase reaction of GGR tri-peptide

2020 ◽  
Vol 22 (9) ◽  
pp. 5057-5069 ◽  
Author(s):  
Jae-ung Lee ◽  
Yeonjoon Kim ◽  
Woo Youn Kim ◽  
Han Bin Oh
Keyword(s):  
Graph Theory ◽  
Dft Calculations ◽  
Gas Phase ◽  
Density Functional ◽  
Reaction Pathway ◽  
Peptide Sequencing ◽  
Phase Reaction ◽  
Functional Theory ◽  
Fragmentation Mechanisms ◽  
Gas Phase Fragmentation

A new approach for elucidating gas-phase fragmentation mechanisms is proposed: graph theory-based reaction pathway searches (ACE-Reaction program) and density functional theory (DFT) calculations.

Gas phase infrared spectra and corresponding DFT calculations of , -diphenylpolyenes

2010 ◽  
Vol 259 (1) ◽  
pp. 11-15 ◽  
Author(s):  
Lars Biemann ◽  
Michaela Braun ◽  
Karl Kleinermanns
Keyword(s):  
Dft Calculations ◽  
Gas Phase ◽  
Infrared Spectra

scholarly journals Bridging the Gap between the Gas Phase and Solution Phase: Solvent Specific Photochemistry in 4-tert-Butylcatechol

2015 ◽  
Vol 119 (50) ◽  
pp. 11989-11996 ◽  
Author(s):  
Michael D. Horbury ◽  
Lewis A. Baker ◽  
Wen-Dong Quan ◽  
Jamie D. Young ◽  
Michael Staniforth ◽  
...  
Keyword(s):  
Gas Phase ◽  
Solution Phase

The molecular structure of using gas-phase electron diffraction and ab initio and DFT calculations

2007 ◽  
Vol 692 (5) ◽  
pp. 1161-1167 ◽  
Author(s):  
Derek A. Wann ◽  
Sarah L. Hinchley ◽  
Heather E. Robertson ◽  
Matthew D. Francis ◽  
John F. Nixon ◽  
...  
Keyword(s):  
Molecular Structure ◽  
Electron Diffraction ◽  
Dft Calculations ◽  
Ab Initio ◽  
Gas Phase ◽  
Gas Phase Electron Diffraction ◽  
Ab Initio And Dft

scholarly journals 1JCH couplings in Group 14/IVA tetramethyls from the gas-phase NMR and DFT structural study: a search for the best computational protocol

2014 ◽  
Vol 16 (29) ◽  
pp. 15699-15708 ◽  
Author(s):  
Ryszard B. Nazarski ◽  
Włodzimierz Makulski
Keyword(s):  
Dft Calculations ◽  
Electronic Properties ◽  
Gas Phase ◽  
Structural Study ◽  
Group 14 ◽  
Computational Protocol ◽  
Isolated Molecules

The gas-phase 1J0,CHs in ‘isolated’ molecules of EMe4 were determined and discussed in terms of their geometric/electronic properties obtained from DFT calculations.

scholarly journals Photoproducts of the Photodynamic Therapy Agent Verteporfin Identified via Laser Interfaced Mass Spectrometry

Molecules ◽  
2020 ◽  
Vol 25 (22) ◽  
pp. 5280
Author(s):  
Chris Furlan ◽  
Jacob A. Berenbeim ◽  
Caroline E. H. Dessent
Keyword(s):  
Mass Spectrometry ◽  
Photodynamic Therapy ◽  
Macular Degeneration ◽  
Gas Phase ◽  
Mass Spectrometer ◽  
Red Light ◽  
Solution Phase ◽  
Collision Induced Dissociation ◽  
Free Base ◽  
New Information

Verteporfin, a free base benzoporphyrin derivative monoacid ring A, is a photosensitizing drug for photodynamic therapy (PDT) used in the treatment of the wet form of macular degeneration and activated by red light of 689 nm. Here, we present the first direct study of its photofragmentation channels in the gas phase, conducted using a laser interfaced mass spectrometer across a broad photoexcitation range from 250 to 790 nm. The photofragmentation channels are compared with the collision-induced dissociation (CID) products revealing similar dissociation pathways characterized by the loss of the carboxyl and ester groups. Complementary solution-phase photolysis experiments indicate that photobleaching occurs in verteporfin in acetonitrile; a notable conclusion, as photoinduced activity in Verteporfin was not thought to occur in homogenous solvent conditions. These results provide unique new information on the thermal break-down products and photoproducts of this light-triggered drug.

Conformational polymorphism in a Schiff-base macrocyclic organic ligand: an experimental and theoretical study

2010 ◽  
Vol 66 (5) ◽  
pp. 527-543 ◽  
Author(s):  
Leonardo Lo Presti ◽  
Raffaella Soave ◽  
Mariangela Longhi ◽  
Emanuele Ortoleva
Keyword(s):  
Schiff Base ◽  
Solid State ◽  
Dft Calculations ◽  
Gas Phase ◽  
Phase Ii ◽  
Density Functional ◽  
Organic Ligand ◽  
Stable Phase ◽  
Stable Form ◽  
Molecular Conformations

Polymorphism in the highly flexible organic Schiff-base macrocycle ligand 3,6,9,17,20,23-hexa-azapentacyclo(23.3.1.111,15.02,6.016,20)triaconta-1(29),9,11,13,15(30),23,25,27-octaene (DIEN, C24H30N6) has been studied by single-crystal X-ray diffraction and both solid-state and gas-phase density functional theory (DFT) calculations. In the literature, only solvated structures of the title compound are known. Two new polymorphs and a new solvated form of DIEN, all obtained from the same solvent with different crystallization conditions, are presented for the first time. They all have P\bar 1 symmetry, with the macrocycle positioned on inversion centres. The two unsolvated polymorphic forms differ in the number of molecules in the asymmetric unit Z′, density and cohesive energy. Theoretical results confirm that the most stable form is (II°), with Z′ = 1.5. Two distinct molecular conformations have been found, named `endo' or `exo' according to the orientation of the imine N atoms, which can be directed towards the interior or the exterior of the macrocycle. The endo arrangement is ubiquitous in the solid state and is shared by two independent molecules which constitute an invariant supramolecular synthon in all the known crystal forms of DIEN. It is also the most stable arrangement in the gas phase. The exo form, on the other hand, appears only in phase (II°), which contains both the conformers. Similarities and differences among the occurring packing motifs, as well as solvent effects, are discussed with the aid of Hirshfeld surface fingerprint plots and correlated to the results of the energy analysis. A possible interconversion path in the gas phase between the endo and the exo conformers has been found by DFT calculations; it consists of a two-step mechanism with activation energies of the order of 30–40 kJ mol−1. These findings have been related to the empirical evidence that the most stable phase (II°) is also the last appearing one, in accordance with Ostwald's rule.

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