Exploring the coordination chemistry of isomerizable terpyridine derivatives for successful analyses of cis and trans isomers by travelling wave ion mobility mass spectrometry

The photochemical cis-trans isomerization of the 4-{4-[2-(pyridin-4-yl)ethenyl]phenyl}-2,2': 6',2''-terpyridine ligand (vpytpy) was investigated by UV-vis, NMR and TWIM-MS. Ion mobility mass spectrometry was performed pursuing the quantification of the isomeric composition during photolysis, however an in-source trans-to-cis isomerization process was observed. In order to overcome this inherent phenomenon, the isomerization of the vpytpy species was suppressed by complexation, reacting with iron(II) ions, and forming the [Fe(vpytpy)(2)](2+) complex. The strategy of "freezing" the cis-trans isomerizable ligand at a given geometric conformation was effective, preventing further isomerization, thus allowing the distinction of each one of the isomers in the photolysed mixture. In addition, the experimental drift times were related to the calculated surface areas of the three possible cis-cis, cis-trans and trans-trans iron(II) complex isomers. The stabilization of the ligand in a given conformation also allows us to obtain the cis-cis and cis-trans complexes exhibiting the ligand in the metastable cis-conformation, as well as in the thermodynamically stable trans-conformation.Fundacao de Amparo a Pesquisa do Estado de Sao Paulo (FAPESP)Fundacao de Amparo a Pesquisa do Estado de Sao Paulo (FAPESP)Conselho Nacional de Desenvolvimento Cientifico e Tecnologico (CNPq)Conselho Nacional de Desenvolvimento Cientifico e Tecnologico (CNPq

Intrinsic Acidity And Electrophilicity Of Gaseous Propargyl/allenyl Carbocations.

The ion/molecule chemistry of four representative propagyl/allenyl cations 1-4 of the general formula R(1)CH(+)-C[triple bond]C-R (a) <--> R(1)CH=C=C(+)-R (b), that is, the reactive C(3)H(3)(+) ions of m/z 39 from EI of propargyl chloride (H(2)C(+)-C[triple bond]C-H, 1a), isomeric C(4)H(5)(+) ions of m/z 53 from EI of 3-butyne-2-ol (2a, H(2)C(+)-C[triple bond]C-CH(3)) and 2-butyne-1-ol (CH(3)-CH(+)-C[triple bond]C-H, 3a), and Ph-C(3)H(2)(+) ions of m/z 115 from 3-phenyl-2-propyn-1-ol (H(2)C(+)-C[triple bond]C-Ph, 4a) was studied via pentaquadrupole mass spectrometry. With pyridine, proton transfer was observed as the predominant process for 1 and the sole reaction channel for the isomeric 2 and 3, whereas 4 reacted preferentially by adduct formation. These outcomes were rationalized using DFT calculations from isodesmic proton transfer reactions. Similar reaction tendencies were observed with acetonitrile and acrylonitrile, with adduct formation appearing again as a minor pathway for 1, 2 and 4, and as a major reaction channel for 4. With 1,3-dioxolane, hydride abstraction was a dominant reaction, with proton transfer and adduct formation competing as side reactions. With 2,2-dimethyl-1,3-dioxolane, an interplay of reactions including methyl anion abstraction, proton transfer, hydride abstraction and adduct formation were observed depending on the ion structure, with 4 reacting again mainly by adduct formation. Proton transfer was also observed as a dominant process in reactions with ethanol for 1, 2 and 3, with 4 being nearly unreactive whereas no adduct formation was observed for any of the carbocations studied. Limited reactivity was exhibited by these ions in cycloaddition reaction with isoprene.82580-

Exploring the coordination chemistry of isomerizable terpyridine derivatives for successful analyses of cis and trans isomers by travelling wave ion mobility mass spectrometry

The photochemical cis–trans isomerization of the 4-{4-[2-(pyridin-4-yl)ethenyl]phenyl}-2,2′:6′,2′′-terpyridine ligand (vpytpy) was investigated by UV-vis, NMR and TWIM-MS. Ion mobility mass spectrometry was performed pursuing the quantification of the isomeric composition during photolysis, however an in-source trans-to-cis isomerization process was observed. In order to overcome this inherent phenomenon, the isomerization of the vpytpy species was suppressed by complexation, reacting with iron(II) ions, and forming the [Fe(vpytpy)2]2+ complex. The strategy of “freezing” the cis–trans isomerizable ligand at a given geometric conformation was effective, preventing further isomerization, thus allowing the distinction of each one of the isomers in the photolysed mixture. In addition, the experimental drift times were related to the calculated surface areas of the three possible cis–cis, cis–trans and trans–trans iron(II) complex isomers. The stabilization of the ligand in a given conformation also allows us to obtain the cis–cis and cis–trans complexes exhibiting the ligand in the metastable cis-conformation, as well as in the thermodynamically stable trans-conformation13740454051CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICO - CNPQFUNDAÇÃO DE AMPARO À PESQUISA DO ESTADO DE SÃO PAULO - FAPESPSem informaçãoSem informaçã

Isomeric Separation and Structural Characterization of Acids in Petroleum by Ion Mobility Mass Spectrometry

Although naphthenic acids are minor constituents in petroleum, their characterization is crucial because they are geochemically important tracers and play a key role in corrosion processes in refineries. Moreover, different isomers may exhibit different reactivity and may serve as potential biomarkers. However, determination of acid isomers in petroleum/hydrocarbon matrixes remains analytically challenging. Here, we achieve the separation and structural characterization of isomeric homologue series of naphthenic acids in petroleum samples by ion mobility time-of-flight mass spectrometry (IM-TOF MS). IM-TOF MS data processing and molecular formula assignments (for most abundant heteroatom classes), integrated with ion mobility data by PetroOrg software, expose structural differences and patterns among petroleum compounds and facilitate the identification of series of isomers. For example, a family of isomeric acids (C_<i>c</i>H<i>_h</i>O₂) of double bond equivalents (DBE) = 5 and carbon number ranging from C₂₈–C₃₄ appear to correspond to steranoic acids. As another example, C_<i>c</i>H_<i>h</i>O₂ isomers of DBE = 1 likely correspond to linear and isoprenoid acids. Ultra-high-resolution Fourier transform ion cyclotron resonance mass spectra serve to validate molecular formula assignments by IM-TOF and determine whether or not isobaric ions of different mobility are isomers. We conclude that ion mobility mass spectrometry constitutes a valuable new tool for rapid isomeric separation of polar compounds (such as naphthenic acids) in petroleum and other complex organic mixtures

Characterization of Crude Oil Interfacial Material Isolated by the Wet Silica Method. Part 2: Dilatational and Shear Interfacial Properties.

International audienceTo better understand the water-in-oil (w/o) emulsion stability problem, the interfacial material (IM) of four different crude oils was isolated using the wet silica method and analyzed by different techniques. In part 1 (10.1021/acs.energyfuels.6b02899), we used gel permeation chromatog. to analyze the mol. size distribution of S-, Ni-, and V-contg. compds. Here, we report the use of dilatational and shear interfacial rheol. to analyze the interfacial properties of the IM films. In the second part of this series of papers, it is shown that the wet silica isolation method is reproducible and concs. the most surface-active mols. present in crude oils. Shear interfacial rheol. results showed perfect correlation to emulsion stability; stronger mech. properties lead to more stable w/o emulsions. Dilatational rheol. revealed that successive IM exts. from a crude oil are composed of mols. that behave increasingly like insol. surfactants that aggregate at the w/o interface. Lastly, shear rheol. expts. with dild. IM and dild. crude oil showed some differences that were ascribed to a different partitioning between the bulk and interface

Ambient Mass Spectrometry: Bringing Ms Into The Real World"."

Mass spectrometry has recently undergone a second contemporary revolution with the introduction of a new group of desorption/ionization (DI) techniques known collectively as ambient mass spectrometry. Performed in an open atmosphere directly on samples in their natural environments or matrices, or by using auxiliary surfaces, ambient mass spectrometry (MS) has greatly simplified and increased the speed of MS analysis. Since its debut in 2004 there has been explosive growth in the applications and variants of ambient MS, and a very comprehensive set of techniques based on different desorption and ionization mechanisms is now available. Most types of molecules with a large range of masses and polarities can be ionized with great ease and simplicity with the outstanding combination of the speed, selectivity, and sensitivity of MS detection. This review describes and compares the basis of ionization and the concepts of the most promising ambient MS techniques known to date and illustrates, via typical analytical and bioanalytical applications, how ambient MS is helping to bring MS analysis deeper than ever into the real world open atmosphere environment--to wherever MS is needed.398265-9

Resolution of isomeric multi‐ruthenated porphyrins by travelling wave ion mobility mass spectrometry

The ability of travelling wave ion mobility mass spectrometry (TWIM‐MS) to resolve cationic meta/para and cis/trans isomers of mono‐, di‐, tri‐ and tetra‐ruthenated supramolecular porphyrins was investigated. All meta isomers were found to be more compact than the para isomers and therefore mixtures of all isomeric pairs could be properly resolved with baseline or close to baseline peak‐to‐peak resolution (Rp‐p). Di‐substituted cis/trans isomers were found, however, to present very similar drift times and could not be resolved. N2 and CO2 were tested as the drift gas, and similar α but considerably better values of Rp and Rp‐p were always observed for CO2263263268CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICO - CNPQCOORDENAÇÃO DE APERFEIÇOAMENTO DE PESSOAL DE NÍVEL SUPERIOR - CAPESFUNDAÇÃO DE AMPARO À PESQUISA DO ESTADO DE SÃO PAULO - FAPESPNão temNão temNão te

Resolution Of Isomeric Multi-ruthenated Porphyrins By Travelling Wave Ion Mobility Mass Spectrometry.

The ability of travelling wave ion mobility mass spectrometry (TWIM-MS) to resolve cationic meta/para and cis/trans isomers of mono-, di-, tri- and tetra-ruthenated supramolecular porphyrins was investigated. All meta isomers were found to be more compact than the para isomers and therefore mixtures of all isomeric pairs could be properly resolved with baseline or close to baseline peak-to-peak resolution (R(p-p)). Di-substituted cis/trans isomers were found, however, to present very similar drift times and could not be resolved. N(2) and CO(2) were tested as the drift gas, and similar α but considerably better values of R(p) and R(p-p) were always observed for CO(2).26263-

Comparison of Atmospheric Pressure Ionization for the Analysis of Heavy Petroleum Fractions with Ion Mobility-Mass Spectrometry

Because of its high molecular complexity, ultra high-resolution Fourier transform ion cyclotron resonance mass spectrometry (FTICR-MS) is used to characterize heavy petroleum distillates. However, high peak capacity can also be obtained with ion mobility-mass spectrometry (IM-MS). In this case, the additional separation dimension allows for the compensation of the lower resolving power of the time-of-flight mass analyzer. The processing and elemental composition assignments from such bidimensional IM-MS data cannot be achieved with conventional software packages. PetroOrg, a new software package, was used to compare IM-MS data sets recorded with atmospheric solid analysis probe (ASAP) and three other atmospheric pressure ionization sources. The choice of the ionization source is indeed very critical as it defines the type of compounds that can be detected from mixtures. Electrospray ionization (ESI) is very specific to polar compounds and yields relatively simple data sets that can be readily attributed to nitrogen containing compounds allowing their speciation. On the other hand, gas phase ionization methods such as APCI, APPI, and ASAP yielded valuable information concerning thiophenic species. However, in this case the IM-MS peak capacity is not sufficient to separate all isobaric species. It is worth noting that ASAP and APPI yielded similar mass spectra although the ASAP ionization mechanism is believed to be closer to that of APCI. Most likely this is due to the absence of solvent with ASAP that reinforces charge exchange processes and therefore affords low ionization discrimination such as with APPI

Separation Of Isomeric Disaccharides By Traveling Wave Ion Mobility Mass Spectrometry Using Co2 As Drift Gas.

The use of CO(2) as a massive and polarizable drift gas is shown to greatly improve peak-to-peak resolution (R(p-p) ), as compared with N(2) , for the separation of disaccharides in a Synapt G2 traveling wave ion mobility cell. Near or baseline R(p-p) was achieved for three pairs of sodiated molecules of disaccharide isomers, that is, cellobiose and sucrose (R(p-p)  = 0.76), maltose and sucrose (R(p-p)  = 1.04), and maltose and lactose (R(p-p)  = 0.74). Ion mobility mass spectrometry using CO(2) as the drift gas offers therefore an attractive alternative for fast and efficient separation of isomeric disaccharides.471643-