Competitive McLafferty-type rearrangements of sodium adduct of anti-2,3-dihydroxy-1-phenylpentane-1,4-dione compounds in tandem mass spectrometry

2018 ◽  
Vol 24 (6) ◽  
pp. 437-441 ◽  
Author(s):  
Xiayan Zhang ◽  
Xu Xu ◽  
Xinmeng Chen ◽  
Lin Chen ◽  
Xiaoying Xu ◽  
...  
Keyword(s):  
Density Functional ◽  
Mass Difference ◽  
Fragmentation Pathway ◽  
Density Functional Theory Calculations ◽  
Sodium Cation ◽  
Membered Ring ◽  
Collision Induced Dissociation ◽  
Sodium Adducts ◽  
Main Fragmentation Pathway ◽  
Product Ions

Sodium adducts of anti-2,3-dihydroxy-1-phenylpentane-1,4-dione compounds with different substituents were studied by collision-induced dissociation. McLafferty-type rearrangements preceding fragmentation were found as their main fragmentation pathway. Coordination of sodium cation to the oxygen functions may either lead to formation of a five-membered or a six-membered ring. Two McLafferty-type rearrangement product ions exhibiting a mass difference of 2 u indicated that two competitive McLafferty-type rearrangements through a six-membered ring coordination occurred. Relative abundances of the corresponding product ions were studied by energy-resolved collision-induced dissociation experiments and density functional theory calculations. Furthermore, the influence of different substituents was probed.

scholarly journals Formation and reactions of the 1, 8-naphthyridine (napy) ligated geminally dimetallated phenyl complexes [(napy)Cu2(Ph)]+, [(napy)Ag2(Ph)]+ and [(napy)CuAg(Ph)]+

2019 ◽  
Vol 25 (1) ◽  
pp. 30-43 ◽  
Author(s):  
Qiuyan Jin ◽  
Jiaye Li ◽  
Alireza Ariafard ◽  
Allan J Canty ◽  
Richard AJ O’Hair
Keyword(s):  
Density Functional Theory ◽  
Gas Phase ◽  
Density Functional ◽  
Ion Trap ◽  
Density Functional Theory Calculations ◽  
Collision Induced Dissociation ◽  
Ion Trap Mass Spectrometry ◽  
Functional Theory ◽  
Organometallic Cations ◽  
Gas Phase Ion

Gas-phase ion trap mass spectrometry experiments and density functional theory calculations have been used to examine the routes to the formation of the 1,8-naphthyridine (napy) ligated geminally dimetallated phenyl complexes [(napy)Cu2(Ph)]+, [(napy)Ag2(Ph)]+ and [(napy)CuAg(Ph)]+ via extrusion of CO2 or SO2 under collision-induced dissociation conditions from their corresponding precursor complexes [(napy)Cu2(O2CPh)]+, [(napy)Ag2(O2CPh)]+, [(napy)CuAg(O2CPh)]+ and [(napy)Cu2(O2SPh)]+, [(napy)Ag2(O2SPh)]+, [(napy)CuAg(O2SPh)]+. Desulfination was found to be more facile than decarboxylation. Density functional theory calculations reveal that extrusion proceeds via two transition states: TS1 enables isomerization of the O, O-bridged benzoate to its O-bound form; TS2 involves extrusion of CO2 or SO2 with the concomitant formation of the organometallic cation and has the highest barrier. Of all the organometallic cations, only [(napy)Cu2(Ph)]+ reacts with water via hydrolysis to give [(napy)Cu2(OH)]+, consistent with density functional theory calculations which show that hydrolysis proceeds via the initial formation of the adduct [(napy)Cu2(Ph)(H2O)]+ which then proceeds via TS3 in which the coordinated H2O is deprotonated by the coordinated phenyl anion to give the product complex [(napy)Cu2(OH)(C6H6)]+, which then loses benzene.

Exploring halide anion affinities to native cyclodextrins by mass spectrometry and molecular modelling

2017 ◽  
Vol 24 (3) ◽  
pp. 269-278 ◽  
Author(s):  
Chongsheng Xu ◽  
Nan He ◽  
Zhenhua Li ◽  
Yanqiu Chu ◽  
Chuan-Fan Ding
Keyword(s):  
Gas Phase ◽  
Density Functional ◽  
Binding Constants ◽  
Density Functional Theory Calculations ◽  
Collision Induced Dissociation ◽  
Binding Affinities ◽  
Cyclodextrin Complex ◽  
Halide Anion ◽  
Mass Frame ◽  
The Stability

The binding affinities of cyclodextrins complexation with chlorine (Cl−), bromine (Br−) and iodine (I−), were measured by mass spectrometric titrimetry, and the fitting of the binding constants was based on the concentration measurement of the cyclodextrin equilibrium. The binding constants (lg Ka) for α-, β- or γ-cyclodextrin with Cl− were 3.99, 4.03 and 4.11, respectively. The gas-phase binding affinity of halide anions for native cyclodextrins was probed by collision-induced dissociation. In collision-induced dissociation, the centre-of-mass frame energy results revealed that in the gas phase, for the same type of cyclodextrin, the stability of the complexes decreased in order: Cl > Br > I, and for the same halide anion, the binding stability of the complex with α-, β- or γ-cyclodextrin decreased in the order: γ-cyclodextrin >β-cyclodextrin > α-cyclodextrin. The density functional theory calculations showed that halide anion binding on the primary face had a lower energy than the secondary face and hydrogen bonding was the main driving force for complex formation. The higher stability of the γ-cyclodextrin complex with the Cl anion can be attributed to the higher charge density of the Cl anion and better flexibility of γ-cyclodextrin.

scholarly journals Reaction mechanism of dimethyl ether carbonylation to methyl acetate over mordenite – a combined DFT/experimental study

2017 ◽  
Vol 7 (5) ◽  
pp. 1141-1152 ◽  
Author(s):  
D. B. Rasmussen ◽  
J. M. Christensen ◽  
B. Temel ◽  
F. Studt ◽  
P. G. Moses ◽  
...  
Keyword(s):  
Experimental Study ◽  
Dimethyl Ether ◽  
Density Functional ◽  
Methyl Acetate ◽  
Flow Reactor ◽  
Reaction Path ◽  
Fixed Bed ◽  
Density Functional Theory Calculations ◽  
Membered Ring ◽  
Functional Theory

Dimethyl ether carbonylation to methyl acetate over mordenite was studied theoretically with density functional theory calculations and experimentally in a fixed bed flow reactor. A new reaction path to methyl acetate entirely in the 8 membered ring was discovered.

scholarly journals Isotope labeling and infrared multiple-photon photodissociation investigation of product ions generated by dissociation of [ZnNO3(CH3OH)2]+: Conversion of methanol to formaldehyde

2019 ◽  
Vol 25 (1) ◽  
pp. 58-72
Author(s):  
Evan Perez ◽  
Theodore A Corcovilos ◽  
John K Gibson ◽  
Jonathan Martens ◽  
Giel Berden ◽  
...  
Keyword(s):  
Density Functional Theory ◽  
Density Functional ◽  
Isotope Labeling ◽  
Bond Cleavage ◽  
Neutral Loss ◽  
Density Functional Theory Calculations ◽  
Collision Induced Dissociation ◽  
Functional Theory ◽  
Methyl Group ◽  
Isotope Label

Electrospray ionization was used to generate species such as [ZnNO3(CH3OH)2]+ from Zn(NO3)2•XH2O dissolved in a mixture of CH3OH and H2O. Collision-induced dissociation of [ZnNO3(CH3OH)2]+ causes elimination of CH3OH to form [ZnNO3(CH3OH)]+. Subsequent collision-induced dissociation of [ZnNO3(CH3OH)]+ causes elimination of 47 mass units (u), consistent with ejection of HNO2. The neutral loss shifts to 48 u for collision-induced dissociation of [ZnNO3(CD3OH)]+, demonstrating the ejection of HNO2 involves intra-complex transfer of H from the methyl group methanol ligand. Subsequent collision-induced dissociation causes the elimination of 30 u (32 u for the complex with CD3OH), suggesting the elimination of formaldehyde (CH2 = O). The product ion is [ZnOH]+. Collision-induced dissociation of a precursor complex created using CH3-18OH shows the isotope label is retained in CH2 = O. Density functional theory calculations suggested that the “rearranged” product, ZnOH with bound HNO2 and formaldehyde is significantly lower in energy than ZnNO3 with bound methanol. We therefore used infrared multiple-photon photodissociation spectroscopy to determine the structures of both [ZnNO3(CH3OH)2]+ and [ZnNO3(CH3OH)]+. The infrared spectra clearly show that both ions contain intact nitrate and methanol ligands, which suggests that rearrangement occurs during collision-induced dissociation of [ZnNO3(CH3OH)]+. Based on the density functional theory calculations, we propose that transfer of H, from the methyl group of the CH3OH ligand to nitrate, occurs in concert with the formation of a Zn–C bond. After dissociation to release HNO2, the product rearranges with the insertion of the remaining O atom into the Zn–C bond. Subsequent C–O bond cleavage, with H transfer, produces an ion–molecule complex composed of [ZnOH]+ and O = CH2.

Density-functional investigation of the geometric and electronic structure of ethylene oxide adsorbed on Si(100)

2016 ◽  
Vol 30 (19) ◽  
pp. 1650116 ◽  
Author(s):  
Lu Wang ◽  
Qing-Fang Li ◽  
Cui-Hong Yang ◽  
Yue-Ling Wei ◽  
Xing-Feng Zhu ◽  
...  
Keyword(s):  
Ethylene Oxide ◽  
Electronic Structures ◽  
Density Functional ◽  
Density Functional Theory Calculations ◽  
Membered Ring ◽  
Stable Conformation ◽  
Ring Opening Reaction ◽  
Semiconductor Compounds ◽  
The Stability ◽  
Functional Investigation

The geometric and electronic structures of the ethylene oxide (EO) molecule adsorbed on Si(100)-[Formula: see text] surface were investigated by using the density-functional theory calculations. All possible adsorbed structures were considered and it was found that only four adsorption structures are stable. The calculations of the formation energy revealed the most stable conformation and demonstrated that the nature of Si–O bond significantly affects the stability of adsorption systems. The analysis of corresponding electronic structures showed that two adsorbed structures are still semiconductor compounds but the other two are not. In particular, the EO after adsorbing was found to be connected via a ring-opening reaction where the molecule forms a five-membered ring together with the surface of dimer silicon atoms, and the produced five-membered ring is almost perpendicular to the silicon surface.

Investigation of collision-induced dissociation products and structures of gas-phase [M·GlyGlyHis-H]+ (M = Fe, Ni, Cu, and Zn) complexes

2017 ◽  
Vol 23 (1) ◽  
pp. 22-27 ◽  
Author(s):  
Bharathi Gannamani ◽  
Joong-Won Shin
Keyword(s):  
Binding Energy ◽  
Density Functional ◽  
Copper Ion ◽  
Density Functional Theory Calculations ◽  
Peptide Sequence ◽  
Collision Induced Dissociation ◽  
Functional Theory ◽  
Fragmentation Behavior ◽  
Primary Products ◽  
Bound Sequence

Collision-induced dissociation is carried out for electrosprayed [Fe·GlyGlyHis-H]+, [Ni·GlyGlyHis-H]+, [Cu·GlyGlyHis-H]+, and [Zn·GlyGlyHis-H]+ complexes. [Fe·GlyGlyHis-H]+, [Ni·GlyGlyHis-H]+, and [Zn·GlyGlyHis-H]+ yield metal-bound peptide sequence ions and dehydrated ions as primary products, whereas [Cu·GlyGlyHis-H]+ generates a more extensive series of metal-bound sequence ions and a product arising from the unusual loss of a formaldehyde moiety; dehydration is significantly suppressed for this complex. Density functional theory calculations show that the copper ion-deprotonated peptide binding energy is substantially higher than those in other complexes, suggesting that there is a correlation between ion–ligand binding energy and their fragmentation behavior.

Experimental and computational studies of monovalent metal cation–peptide interactions in [M·GlyGlyHis]+ (M = Li, Na, K, Rb, Cs, and Ag) complexes

2019 ◽  
Vol 25 (6) ◽  
pp. 445-450
Author(s):  
Joong-Won Shin
Keyword(s):  
Metal Ion ◽  
Density Functional ◽  
Density Functional Theory Calculations ◽  
Peptide Sequence ◽  
Peptide Ligand ◽  
Ligand Interaction ◽  
Fragmentation Behavior ◽  
Peptide Interactions ◽  
Product Ions ◽  
Ion Size

[ M·GlyGlyHis]+ ( M = Li, Na, K, Rb, Cs, and Ag) complexes were generated using the electrospray ionization method and were subjected to collision-induced dissociation. Metal ion loss is the primary dissociation channel for [Cs·GlyGlyHis]+ whereas other complexes yield metal-bound peptide sequence ions and dehydrated ions as the main products. [Li·GlyGlyHis]+ and [Ag·GlyGlyHis]+ also generate product ions that are not observed for other complexes. Density functional theory calculations suggest that metal ion–peptide ligand interaction occurs through covalent interactions in [Li·GlyGlyHis]+ and [Ag·GlyGlyHis]+, and through electrostatic attraction in [Na·GlyGlyHis]+, [K·GlyGlyHis]+, [Rb·GlyGlyHis]+, and [Cs·GlyGlyHis]+. The calculations also suggest that fragmentation behavior of these complexes is affected by charge transfer to the ligand and ion-ligand interaction energy, and to a lesser extent by the ion size.

scholarly journals Designing New Metal Chalcogenide Nanoclusters Through Atom-by-Atom Substitution

2020 ◽  
Author(s):  
Habib Gholipour-Ranjbar ◽  
Hong Fang ◽  
Jintong Guan ◽  
D`Angelo Peters ◽  
Audra Seifert ◽  
...  
Keyword(s):  
Electronic Structures ◽  
Density Functional ◽  
Density Functional Theory Calculations ◽  
Cobalt Sulfide ◽  
Collision Induced Dissociation ◽  
Ionization Mass ◽  
Direct Path ◽  
Functional Theory ◽  
Metal Chalcogenide ◽  
Singly Charged

<p>Here, we report the first study focused on atom-by-atom substitution of Fe and Ni to the core of a well-defined cobalt sulfide superatom ligated with triethylphosphine,[Co<sub>5</sub>MS<sub>8</sub>(PEt<sub>3</sub>)<sub>6</sub>]<sup>+</sup> (M=Fe, Ni). Electrospray ionization mass spectrometry confirms the substitution of 1-6 Fe atoms with the single Fe-substituted cluster being the dominant species. The Fe-substituted clusters oxidize in solution to generate dicationic species. In contrast, only a single Ni-substituted cluster is observed, which remains stable as a singly charged species. Collision-induced dissociation experiments indicate the reduced stability of the [Co<sub>5</sub>FeS<sub>8</sub>(PEt<sub>3</sub>)]<sup>+</sup> towards ligand loss in comparison with the unsubstituted and Ni-substituted counterparts. Density functional theory calculations provide insights into the effect of metal atom substitution on the electronic structures of the clusters. Our results indicate that Fe and Ni have a different impact on the electronic structure, optical and magnetic properties, as well as ligand-core interaction of [Co<sub>6</sub>S<sub>8</sub>(PEt<sub>3</sub>)<sub>6</sub>]. This study extends the atom-by-atom substitution strategy to the metal chalcogenide superatoms providing a direct path toward designing novel atomically precise core-tailored superatoms.</p>

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