Electrospray mass spectrometry complexes

Lover T efa/1997 Electrospray mass spectrometry of thiophenolate-capped clusters of CdS, CdSe and ZnS and cadmium and zinc thiophenolate complexes observation of fragmentation and metal, chalcogenide and ligand exchange processes Inorg. Chem. 36 3711... 

The coordination of [Me2Sn(IV)f to captopril (cap) [(2S)-l-[(2S)-2-methyl-3-sulfanyl propanoyl]pyrrolidine-2-carboxylic acid] in aqueous solution was studied by means of pH-metric titration, electrospray mass spectrometry, H NMR, and Mossbauer spectroscopies in the 2-11 pH range. The results obtained proved that only monomeric complexes are formed in solution. In the acidic pH... 

The interaction of palladium(II) complexes with sulfur-containing peptides was studied by electrospray mass spectrometry.331... 

Electrospray mass spectrometry is a technique that allows pre-existing ions to be transferred from solution to the gas phase with minimal fragmentation, followed by conventional mass analysis. Recently electrospray mass spectra have been studied for a number of cationic phos-phinegold(I) complexes in dichloromethane/methanol solution.2525 For derivatives of the types [Au(PR3)2]+ and [Au(PR3)3]+, the intact cations were observed, but ions of the type [Au(PR3)4]+ where not detected in the gas phase. Even the three-coordinated [Au(PR3)3]+ are relatively unstable in the gas phase, and the ions [Au(PR3)2]+ are readily produced. 

Spontaneous self assembly of a dinuclear triple helical complex is observed with linked bis-[4,5]-pineno-2,2 -bipyridines. Studies by electrospray mass spectrometry, CD and NMR determined that the major species in solution was a complex of Zn L = 2 3 stoichiometry with a triple helical structure and an enantiomerically pure homochiral configuration at the metal centers. The preference for the formation of one of the possible stereoisomers over the other is of interest.265 Another binuclear triple helical complex is formed from zinc addition to bis[5-(l-methyl-2-(6-methyl-2 -pyridyl)benzimidazolyl)]methane. Spectrophotometric titrations with a zinc solution... 

An insight into the equilibria present in solutions of several complexes of the type (R3P)2HgX2 (X = C104, CF3COO) is provided by electrospray mass spectrometry (ES MS) (cf. Section 6.9.2.1.8). 39 In all cases the principal ions [(R3P)2HgX]+ are observed, even if these ions and other ionic constituents of the equilibria are known to be labile on the NMR timescale. In the presence of excess R3P the principal ions [(R3P)3HgX]+ appear. Also fragments of collisionally activated decomposition (CAD, can be influenced and controlled to some extent) are detected, e.g., [(R3P)HgX]+. 

This means that addition of elemental E to alkali metal polychalcogenide fluxes (200-600°C) will promote the formation of longer chains as potential ligands, when such molten salts are employed as reaction media for the preparation of polychalcogenide complexes. Speciation analysis for polychalcogenides in solution has been performed by a variety of physical methods including UV/vis absorption spectroscopy, Raman spectroscopy, Se, Te and Te NMR, electron spin resonance and electrospray mass spectrometry. 

Attempts to crystallize a phosphonato complex invariably led to the formation of glassy materials. For example, a solid compound was obtained that analyzed as K2Be(H2mdp)2 2H20. Electrospray mass spectrometry spectra of this product confirm the stoichiometry the most abundant peaks corresponded to the formulas [Be(H2mdp)2]2 in the negative ion ESMS spectrum and K8[Be(H2mdp)] + in the positive ion ESMS spectrum (260). 

Complexes of N-N bonded dinitrogen dioxide, such as depicted in pathway B of Scheme 5, would appear to be necessary in order to effect the formation of the N-N bond. This has been treated theoretically as a metal promoted reductive coupling of 2 NO to form a hyponitrite complex (79). The Cu Tp112) system was also shown to catalyze NO oxidations of benzyl and isopropyl alcohol to benzaldehyde and acetone (Eq. (37)). Electrospray mass spectrometry indicated that higher... 

Li H, Michael Siu KW, Guevremont R, Le Blanc JCY (1997) Complexes of silver with peptides and proteins as produced in electrospray mass spectrometry. J Am Soc Mass Spectrom 8 781-792... 

Kane-Maguire, L.A.P. Kanitz, R. Shell, M.M. Comparison of Electrospray Mass Spectrometry With Other Soft Ionization Techniques for the Characterization of Cationic n-Hydrocarbon Organometallic Complexes. J. Organomet. Chem. 1995, 486, 243-248. 

Numerous workers have demonstrated the applicability of electrospray ionization mass spectrometry (ESI/MS) for the detection and analysis of biomolecules with highly electronegative groups (reviewed by Wood et al., 2003, and for neutral steroids by Higashi and Shimada, 2004). The sensitivity of detection of neurosteroids can also be enhanced by derivatization when they are analyzed by nano-electrospray/mass spectrometry procedures. Neurosteroid sulfates can be easily prepared in a single-step reaction in pyridine with the N,N-dimethylformamide complex of sulfur trioxide (Chatman et al., 1999). Another elegant... 

R. H. Negative ionization micro electrospray mass spectrometry of oligodeoxyribonucleotides and their complexes. Rapid Commun Mass Spectrom 1996, 10, 47-50. 

L.L. Sasmor, H. Griffey, R.H. Measurement of macromolecular binding using electrospray mass spectrometry. Determination of dissociation constants for oligonucleotide serum albumin complexes. J. Am. Chem. Soc. 1995, 117, 10765-10766. 

A series of novel ruthenium(IV) dioxolene complexes, formally [3 + 2] cycloadducts, have been obtained via the reaction of cix-[Ru (0)2(Me3tacn)(CF3C02)] with trimethylsilylacetylenes (Scheme 14). " These dark blue complexes display a characteristic UV-vis absorption band at 550-680 nm. They are also characterized by electrospray mass spectrometry. The X-ray structure of the complex formed with bis(trimethylsilyl)acetylene has been determined the two Ru—O bonds of the metallocycle are of the same length (1.978 A). 

A.K. Ganguly, B.N. Pramanik, G. Chen, A. Tsarbopoulos, Detection of noncovalent complexes by electrospray ionization mass spectrometry. In B.N. Pramanik, A.K. Ganguly, M.L. Gross (Eds.) Applied Electrospray Mass Spectrometry, Marcel Dekker, Inc., New York, 2002, pp. 361 30. 

Deng, H. and Van Berkel, G.J., Electrospray mass spectrometry and UV/visible spectrophotometry studies of aluminium(III)-flavonoid complexes, J. Mass Spectrom., 33, 1080, 1998. 

Mass spectrometry techniques may allow the direct detection of the various species formed in solution. Thus, electrospray mass spectrometry has been used to investigate the progressive build up of metallosupramolecular structures such as the capped 154 [9.94a], the cylindrical 156 [9.94b] as well as helicate complexes [9.94b, 9.95b]. 

Berthon, L., Piveteau, B. 2000. Contribution of electrospray mass spectrometry to the study of the organic species and metal-ligand complexes in solution. Proceeding of Atalante 2000, Scientific Research on the Back-end of the Fuel Cycle for the 21st Century, 24—26 October, Avignon, France, 3-21. 

Lamare, V., Dozol, J-F., Allain, F., Virelizier, H., Moulin, C., Jankowski, C-K., Tabet, J-C. 2000. Behavior of calix[4]arene-bis-crown-6 under irradiation Electrospray-mass spectrometry investigations and molecular dynamics simulation on Cs+ and Na+ complexes of a degradation compound, in ACS Symposium Series 757, Calixarenes Molecules for Separations-, Lumetta G., Rogers R.D., Gopalan A.S. Eds. American Chemical Society Washington, DC, 56-70. 

Kane-Maguire, L. A. P, Kanitz, R., and Sheil, M. M. (1995). Comparison of electrospray mass spectrometry with other soft ionization techniques for the characterization of cationic a-hydrocarbon organometallic complexes. J. Organomet. Chem. 486,243-248. 

Bigler, L., Baumeler, A., Werner, C., and Hesse, M. 1996. Detection of noncovalent complexes of hydroxamic-acid derivatives by means of electrospray mass spectrometry. Helv. Chim. Acta 79, 1701-1709... 

Li, J., Martin, A., Cox, A.D., Moxon, E.R., Richards, J.C., Thibault, P. Mapping bacterial glycolipid complexity using capillary electrophoresis and electrospray mass spectrometry. Methods Enzymol 405 (2005b) 369-397. 

The synthesis of the complex is followed by the most important step of characterization of the complex. The composition and the structural features of both the ligand and complex have to be established before embarking on further studies. There exist many methods by which the composition and structural features of the complexes are studied. Some of the methods are (i) elemental analysis, (ii) X-ray crystallography, (iii) UV-Vis absorption spectra, (iv) infrared spectroscopy, (v) Raman spectroscopy, (vi) thermal methods of analysis such as thermogravimetry, differential thermal analysis, (vii) nuclear magnetic resonance spectroscopy (proton, multinuclear), (viii) electrospray mass spectrometry. Depending upon the complexity of the system, some or all the methods are used in the studies of complexes. 

Applications of electrospray mass spectrometry (ESMS) to the study of reactions mediated by transition-metal complexes are reviewed. ESMS has become increasingly popular as an analytical tool in inorganic and organometallic chemistry, in particular with regard to the identification of short-lived intermediates of catalytic cycles. Going one step further, the coupling of electrospray ionization to ion-molecule techniques in the gas phase yields detailed information about single reaction steps of catalytic cycles. This method allows the study of transient intermediates that have previously not been within reach of condensed-phase techniques on both a qualitative and quantitative level. 

Electrospray mass spectrometry has developed into a well-established method of wide scope and potential over the past 15 years. The softness of electrospray ionization has made this technique an indispensable tool for biochemical and biomedical research. Electrospray ionization has revolutionized the analysis of labile biopolymers, with applications ranging from the analysis of DNA, RNA, oligonucleotides, proteins as well as glycoproteins to carbohydrates, lipids, gly-colipids, and lipopolysaccharides, often in combination with state-of-the-art separation techniques like liquid chromatography or capillary electrophoresis [1,2]. Beyond mere analytical applications, electrospray ionization mass spectrometry (ESMS) has proven to be a powerful tool for collision-induced dissociation (CID) and multiple-stage mass spectrometric (MSn) analysis, and - beyond the elucidation of primary structures - even for the study of noncovalent macromolecular complexes [3]. 

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