Fast Atom Bombardment Research Articles

Novel non-discoid chiral copper(II)-salen type [N2O2] donor Schiff base complexes with a cyclohexane diamine spacer: synthesis, electrochemistry, columnar mesomorphism and DFT study

A series of new non-discoid chiral copper(ii)-salen type complexes, [Cu((4-C n H2n+1O)2salen)], n = 14, 16, 18 and salen = N,N′-cyclohexane bis (salicylideneiminato), containing 4-substituted alkoxy tails in the side aromatic rings and a cyclohexane spacer, have been prepared and their mesogenic properties investigated. The compounds were characterised by Fourier transform infra-red spectroscopy, 1H and 13C nuclear magnetic resonance spectroscopy, UV-vis spectroscopy and fast atom bombardment mass spectrometry. Mesomorphic properties of these compounds were studied by polarising optical microscopy, differential scanning calorimetry and X-ray diffraction (XRD). The ligands are non-mesogenic but the complexes exhibited enantiotropic rectangular columnar mesophases (Colr) with extended temperature range (111–220°C). Molecular models for the organisation in the mesophases are proposed on the basis of the small-angle XRD diffraction patterns. Molecules with their planes tilted are stacked in columns which self-organise in a 2D-rectangular lattice with C2mm symmetry. Cyclic voltammetry carried out in CH2Cl2 solution revealed a single electron quasireversible response for the Cu(i)/Cu(ii) redox couple (E 1/2 = –0.226V, ΔE p = 453 mV). The more negative redox potentials indicated a planar coordination environment. Density functional theory calculations performed using the DMol3 program at the BLYP/DNP level revealed a near-square-planar arrangement around the metal centre with the cyclohexane ring tilted relative to the plane of the [N2O2] core of the Schiff base ligand.

Fast-atom bombardment mass spectra of some pentapeptides related to natural enkephalins.

The mass spectral features of four diastereoisomeric pairs of peptides related to the enkephalins recorded under fast-atom bombardment conditions are presented and shown to provide evidence of molecular weight and amino acid content and sequence.

Ionization techniques in capillary electrophoresis‐mass spectrometry: Principles, design, and application

A major step forward in the development and application of capillary electrophoresis (CE) was its coupling to ESI-MS, first reported in 1987. More than two decades later, ESI has remained the principal ionization technique in CE-MS, but a number of other ionization techniques have also been implemented. In this review the state-of-the-art in the employment of soft ionization techniques for CE-MS is presented. First the fundamentals and general challenges of hyphenating conventional CE and microchip electrophoresis with MS are outlined. After elaborating on the characteristics and role of ESI, emphasis is put on alternative ionization techniques including sonic spray ionization (SSI), thermospray ionization (TSI), atmospheric pressure chemical ionization (APCI), atmospheric pressure photoionization (APPI), matrix-assisted laser desorption ionization (MALDI) and continuous-flow fast atom bombardment (CF-FAB). The principle of each ionization technique is outlined and the experimental set-ups of the CE-MS couplings are described. The strengths and limitations of each ionization technique with respect to CE-MS are discussed and the applicability of the various systems is illustrated by a number of typical examples.

Application of Fast Atom Bombardment Collision-induced Dissociation Tandem Mass Spectrometry for Structural identification of Glycerolipids Isolated From Marine Sponge

Two types of glycerolipids [monoacylglycerols (MAG) and cyclitols] were isolated by reversed phase high-performanceliquid chromatography from the MeOH extracts of a marine sponge, and analyzed by fast atom bombardment mass spectrometry(FAB-MS) in positive-ion mode. FAB mass spectra of these compounds included protonated molecules [M+H]+ and abundantsodiated molecules [M+Na]+ from a mixture of m-NBA and NaI. The structures of these compounds were elucidated by FABcollisional-induced dissociation (CID)-tandem mass spectrometry. To find diagnostic ions for their characterization, these lipidswere analyzed by collision-induced dissociation (CID) B/E-linked scan. The CID B/E-linked scan of [M+H]+ and [M+Na]+ precursorions resulted in the formation of numerous characteristic product ions via a series of dissociative processes. The product ionsformed by charge-remote fragmentation (CRF) provided important information for the characterization of the acyl chain structuresubstituted at the glycerol backbone. Some of product ions were diagnostic for the presence of a glycerol backbone and acylchain structure, respectively.

Study of the fragmentation pathway of α‐aminophosphonates by chemical ionization and fast atom bombardment mass spectrometry

The diastereoisomers of α-aminophosphonates are key intermediates in the synthesis of enantiomerically pure α-aminophosphonic acids, which are analogs of α-amino acids. Although several methods have been reported for the diastereoselective synthesis of α-aminophosphonates, their mass spectrometry (MS) fragmentation patterns have not yet been fully investigated. The work described here involved a detailed study of the fragmentation of enriched α-aminophosphonate diastereoisomers by chemical ionization (CI-MS) and fast atom bombardment (FAB)-MS. The complete characterization of the different conventional MS fragmentation pathways is represented and this intriguing exercise required the use of tandem mass spectrometry (MS/MS) experiments and high-resolution accurate mass measurements. All α-aminophosphonates gave prominent pseudomolecular ions, protonated molecules [MH](+) , and their fragmentations mainly showed a loss of dimethyl phosphite to give the corresponding iminium ions as base peaks for α-aminophosphonates bearing methylbenzyl and 2,2-dimethylbutyl fragments. The loss of the chiral fragment from the iminium ions bearing the (S)-1-(1-naphthyl)ethyl group gave rise to a base peak due to aryl cations. The nature of all fragment ions were confirmed by high-resolution mass spectrometry (HRMS).

Zinc(II)-included hemicryptophane: coordination of an acetonitrile guest within the cavity

A zinc(II)-included hemicryptophane, which has a zinc(II) centre embedded in the cavity, was synthesised in high yield and characterised by fast atom bombardment mass spectrometry, 1H NMR spectroscopy and X-ray crystal structure analysis. The X-ray crystal structure shows that zinc(II)-included hemicryptophane has a preorganised cavity, formed by the cyclotriveratrylene and tris(aminoethyl)amine (tren) moieties. The zinc(II) centre is coordinated to the N4 core of the tren cap and to the nitrogen atom in acetonitrile. The acetonitrile guest is stabilised through CH–π interactions. The absolute configuration of the nitrogen atom in the amino group was assigned by anomalous X-ray scattering; the results indicated that a chiral zinc(II)-included hemicryptophane was obtained by spontaneous asymmetric crystallisation.

Structural determination of cerebrosides isolated from Asterias amurensis starfish eggs using high‐energy collision‐induced dissociation of sodium‐adducted molecules

Six cerebrosides were isolated from the eggs of the starfish Asterias amurensis using solvent extraction, silica gel column chromatography, and reversed-phase high-performance liquid chromatography. This study demonstrated that the structures of cerebrosides could be completely characterized, based on their sodium-adducted molecules, using fast atom bombardment (FAB) tandem mass spectrometry. The high-energy collision-induced dissociation of the sodium-adducted molecule, [M + Na](+), of each cerebroside molecular species generated abundant ions, providing information on the compositions of the 2-hydroxy fatty acids and long-chain sphingoid bases, as well as the sugar moiety polar head group. Each homologous ion series along the fatty acid and aliphatic chain of the sphingoid base was useful for locating the double-bond positions of both chains and the methyl branching position of the long-chain base. The N-fatty acyl portions were primarily long-chain saturated or monoenoic acids (C16 to C24) with an α-hydroxy group. The sphingoid long-chain base portions were aliphatic chains (C18 or C22) with two or three degrees of unsaturation and with or without methyl branching.

Ternary copper(II) complexes of levofloxacin and phenanthroline derivatives: In-vitro antibacterial, DNA interactions, and SOD-like activity

A series of ternary copper(II) complexes have been derived using levofloxacin and five phenanthroline derivatives. Complexes were characterized using infrared spectroscopy, Thermogravimetric (TG)-analysis, fast atom bombardment mass spectroscopy and reflectance spectra. Synthesized complexes exhibit the only d-d band at ∼ 666 nm points toward a distorted square pyramidal geometry at metal centre with one unpaired electron responsible for paramagnetic behaviour of whole moiety. Binding behaviour of the complexes toward Herring Sperm DNA were determined using ultraviolet-Vis (UV-Vis) absorption titration and viscometric titration experiment, where as the cleavage efficacy of the complexes toward pUC19 DNA was determined by electrophoresis in presence of ethidium bromide. Complexes exhibit superoxide dismutase–like activity with their IC50 values ranging from 0.7917 to 1.7432 µM.

Identification of the Catalytic Residues of Carboxylesterase fromArthrobacter globiformisby Diisopropyl Fluorophosphate-Labeling and Site-Directed Mutagenesis

The role of amino acid residues in the enzymatic activity of carboxylesterase from Arthrobacter globiformis was analyzed by diisopropyl fluorophosphate (DFP) labeling and site-directed mutagenesis. The electrospray ionization mass spectrometric (ESI-MS) analysis of the esterase, covalently labeled by DFP, showed stoichiometric incorporation of the inhibitor into the enzyme. The further comparison of endopeptidase-digested fragments between native and DFP-labeled esterase by fast atom bombardment mass spectrometric (FAB-MS) analysis as well as site-directed mutagenesis indicated that Ser59 in the consensus sequence Ser-X-X-Lys, which is conserved exclusively in penicillin-binding proteins and some esterases, served as a catalytic nucleophile. In addition, the results obtained from analysis of the mutants at position 62 suggested the importance of the basic amino acid side chain at this position, and suggested the significance of this residue acting directly as a general base rather than its involvement in the maintenance of the optimum hydrogen-bonding network at the active site.

FAB, ESI and MALDI Mass Spectrometric methods in the study of metallo-drugs and their biomolecular interactions

This review surveys the soft ionisation mass spectrometric methods that are most commonly used for the investigation of the mechanism of interaction between metallo-drugs and biomolecules. In the first part of the review, an overview of the applications of transition metal complexes in the therapy of various diseases (arthritis, cancer, diabetes) is given, whereas the second part focuses on the obtained results dealing with various aspects of the interaction between metal complexes and different types of biomolecules. Possibilities and limitations of each mass spectrometric method-namely, fast atom bombardment (FAB), electrospray ionisation (ESI) and matrix-assisted laser desorption and ionisation (MALDI)--are discussed in the third part of this review along with the examples of their application for the analysis of metal complexes, as well as of the products of their interaction with biomolecules.

Synthesis and characterization of thiosemicarbazone derivatives of methylbismuth(III) dichloride: generation of one dimensional micro-rods of bismuthinite from [MeBiCl2·n{(C6H4OH)CHNNHCSNH2}] by a solvothermal process

Reactions of methylbismuth(III) dichloride with thiosemicarbazones (TSC) in 1:1 and 1:2 molar ratios in anhydrous methanol yield [MeBiCl2.n{RR’CNNHCSNH2}] [where, R=R’=CH3 and n=1 (1) or n=2 (2); R=C6H4OH, R’=H and n=1 (3) or n=2 (4); R=C5H4N, R’=CH3 and n=1 (5) or n=2 (6)]. These monomeric adducts have been characterized by elemental analyses, Fourier transform infrared, nuclear magnetic resonance [1H, 13C{1H}] and fast atom bombardment mass spectrometry. The ligand appears to bind bismuth through sulfur and azomethine nitrogen atoms rendering penta- and hepta- coordination geometries, in (1, 3 and 5) and (2, 4 and 6), respectively, in the solution state. Low temperature (143–145°C) solvothermal transformation of (3) or (4) in refluxing xylene yields nano-structured flowers of amorphous bismuthinite (Bi2S3). Prolonged (~10 h) sintering at 150°C of the powder obtained from (4) yielded one-dimensional micro/nanorods of orthorhombic Bi2S3. All the materials were characterized by X-ray diffraction, scanning electron microscopy and energy-dispersive X-ray analyses.

Photochromic Alkynes as Versatile Building Blocks for Metal Alkynyl Systems: Design, Synthesis, and Photochromic Studies of Diarylethene-Containing Platinum(II) Phosphine Alkynyl Complexes

The synthesis of newly designed photochromic dithienylethene-containing ethynylthiophene and ethynylthieno[3,2-b]thiophene has been described, and their incorporation as versatile ligands into the platinum(II) phosphine system was demonstrated. All platinum(II) complexes have been successfully characterized by (1)H and (31)P NMR spectroscopies, positive fast atom bombardment (FAB) mass spectrometry, as well as elemental analysis. One of the complexes has been characterized by X-ray crystallography. Their photophysical, photochromic, and electrochemical properties have been studied. Upon photoexcitation, all the photochromic diarylethene-containing alkynes and platinum(II) complexes exhibited reversible photochromism. The thermal bleaching kinetic of complex 6 was studied in toluene at 298 and 313 K. Complexes 1, 3, and 4, which contained the labile chloro- ligand, represent a new class of versatile building blocks for photoswitchable functional materials.

New steroid dimer derived from cholic acid as receptor for lanthanum(III) and calcium(II) nitrates

New steroid dimer, ethylene bridged bis-carbamate ( 3) was synthesized from cholic acid in few steps. Complexes of 3 with lanthanum(III) and calcium(II) nitrates were prepared in reaction of 3 and appropriate metal salts. They were characterized by spectral data (Infrared (IR), ultraviolet-visible (UV/Vis), nuclear magnetic resonance (NMR) spectroscopy and fast-atom bombardment (FAB), electrospray (ESI) and matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS)) and elemental analysis. The similarity in complexing behavior of steroidal dimer toward calcium and lanthanum ions was observed.

Derivatization of synthetic polymers in mass spectrometric studies

The review describes various derivatization approaches employed for the investigation of synthetic polymers by mild ionization mass spectrometry (fast atom and ion bombardment, matrix-assisted laser desorption/ionization, electrospray/ionization). The potentials of chemical methods for modification of end- and side-chain functional groups without the decomposition of molecules are demonstrated. Methods of the preliminary chemical degradation of polymer molecules for the investigation of their microstructure are considered. The possibilities of the chemical modification of polymer surfaces for the identification and quantitative determination of functionalized fragments are shown.

LC-MS of palytoxin and its analogues: State of the art and future perspectives

The state of the art of LC-MS of palytoxin and its analogues is reported in the present review. MS data for palytoxin, 42-hydroxy-palytoxin, ostreocin-D, mascarenotoxins, and ovatoxins, obtained using different ionization techniques, namely fast-atom bombardment (FAB), matrix assisted laser desorption ionization (MALDI), and electrospray ionization (ESI), are summarized together with the LC-MS methods used for their detection. Application of the developed LC-MS methods to both plankton and seafood analysis is also reported, paying attention to the extraction procedures used and to limits of detection (LOD) and quantitation (LOQ) achieved. In a research setting, LC-MS has shown a good potential in determination of palytoxin and its analogues from various sources, but, in a regulatory setting, routine LC-MS analysis of palytoxins is still at a preliminary stage. The LOQ currently achieved in seafood analysis appears insufficient to detect palytoxins in shellfish extract at levels close to the tolerance limit for palytoxins (30 μg/kg) proposed by the European Food Safety Authority ( EFSA, 2009). In addition, lacking of certified reference standard of palytoxins as well as of validation studies for the proposed LC-MS methods represent important issues that should be faced for future perspectives of LC-MS technique.

A new prenylated xanthone from Garcinia xipshuanbannaensis Y.H. Li

A new prenylated xanthone, named bannaxanthone I (1), has been isolated from the leaves of Garcinia xipshuanbannaensis, along with five other known compounds, bannaxanthone E (2), mangostinone (3), tovophyllin A (4), garcinone E (5), and γ-mangostin (6). The structure of the new compound was elucidated on the basis of high-resolution fast atom bombardment mass spectra (HRFABMS), 1D-and 2D-NMR experiments, including heteronuclear multiple bond connectivity (HMBC), heteronuclear single quantum coherence (HSQC) and 1H–1H-COSY (correlated spectroscopy, COSY).

Transition metal complexes with N, S donor ligands as synthetic antioxidants: Synthesis, characterization and antioxidant activity

Transition metal complexes containing bidentate N, S donor ligands i.e., carvone thiosemicarbazone [(RS)-5-isopropenyl-2-methylcyclohex-2-en-1-one thiosemicarbazone (IPMCHTSC)] and carvone N1-phenylthiosemicarbazone [(RS)-5-isopropenyl-2-methylcyclohex-2-en-1-one phenylthiosemicarbazone (IPMCHPhTSC)] have been synthesized. All the metal complexes (1–8) have been characterized by elemental analysis, molar conductance measurement and various spectral studies [infrared (IR), electronic, fast-atom bombardment (FAB) mass and NMR (for ligands)] and thermogravimetric analysis. FAB mass spectroscopic studies of (1), (3), (4), (5), (6) (7), and (8) suggest their monomeric nature. Metal complexes are [M(LH)Cl2] and [M(LH)2Cl2] type, where M = Fe(III), Co(II), and Cu(II) and LH = IPMCHTSC and IPMCHPhTSC. The proposed geometries of the complexes were octahedral for 1:2 complexes, square planar for 1:1 complexes and distorted octahedral for Cu(II) complexes (1:2). The free radical scavenging activity of ligands (IPMCHTSC and IPMCHPhTSC) and their metal complexes have been determined at the concentration range of 10–400 μg/mL by means of their interaction with the stable free radical 2,2′-diphenyl-1-picrylhydrazyl and 5–200 μg/mL by 2,2′-Azinobis-3-ethylbenzothiazoline-6-sulphonic acid. All the compounds have shown encouraging antioxidant activities.

ChemInform Abstract: Synthesis and Characterization of Dimetallacalix(8)arene Complexes.

The one-pot synthesis of a variety of [4-tert-butylcalix [8] arene (MOR) 2 ] − [M' or R'NH 3 ] + (M=Ti, Zr, V, Sn; M'=Li, Na, K) complexes is described. The 1 H NMR spectra of these compounds possess several interesting features, including upfield shifts of α or β protons on the alkoxide ligand and a phenol hydroxyl resonance. The upfield shift is due to shielding of the alkoxide ligand by the aryl rings of the calixarene macrocycle. The ligands are located in cavities, made up of three aryl rings of the macrocycle. Fast atom bombardment mass spectrometry (FABMS) and tandem mass spectrometry have been used to obtain molecular ion information as well as identify fragment ions from these complexes

ChemInform Abstract: Chemical Reactions in Fast Atom Bombardment Mass Spectrometry

Examples of various chemical reactions occurring in the matrix or in the selvedge region in fast atom bombardment (FAB) mass spectrometry are discussed. These are categorized as oxidations and reductions; substitutions; clusterings and additions; and sample decomposition or transformation. Some reactions observed showed significant time behaviour and in one case it was possible to determine rate constants. These data suggest that chemical reactions can be accelerated significantly by fast atom bombardment.

ChemInform Abstract: Mass Spectrometry of Prenylated Flavonoids

The fragmentation patterns originating from the degradation of prenyl group(s) in positive ion electron ionization (EI), fast-atom bombardment (FAB) and chemical ionization (CI) mass spectrometry (MS) of prenylated flavonoids were reviewed. The EI spectra showed the characteristic fragmentation patterns reflecting the location of prenyl group in the flavonoid compounds, whereas the FAB and CI spectra showed relatively monotonous patterns. It was described how the EI and FAB fragmentation patterns are useful for the identification of prenylated flavonoids