title: Formation of tungstate-containing cluster ions by polyoxotungstate anions under matrix-assisted laser desorption/ionization conditions in the gas phase.
abstract: The gas-phase studies of transition-metal oxides continue to attract interest as such oxides are being used as catalysts in various oxidation processes. In this paper, singly negatively charged heteropolyoxotungstate and isopolyoxotungstate ion clusters were produced from Keggin-type polyoxotungstates by matrix-assisted laser desorption/ionization Fourier transform ion cyclotron resonance mass spectrometry (MALDI-FTICR MS). It was found that the ion series [(PO(3))(WO(3))(n)](-), [(WO(3))(n)](-) and [(OH)(WO(3))(n)](-) were the main fragment ions in the mass spectra and the matrix greatly influenced the resulting cluster ion abundances. [(PO(3))(WO(3))(3)](-), [(WO(3))(3)](-) and [(OH)(WO(3))(4)](-) were the most intense ions in each series when 2-(4-hydroxyphenylazo)benzoic acid was the matrix, whereas [(PO(3))(WO(3))(4)](-), [(WO(3))(6)](-) and [(OH)(WO(3))(4)](-) were the most intense when dithranol (DIT) was the matrix. In addition, a new kind of hybrid ion [W(2)C(14)H(7)O(8)](-) was produced through the reaction of DIT and [(OH)(WO(3))](-) in the plume of the gas phase. These results highlight the utility of the MALDI-FT method for obtaining novel ion clusters and also show the stability of these clusters.
authors.affiliation: Changchun Center of Mass Spectrometry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, 5625 Renmin Street, Changchun, 130022, China.
authors.forename: Yun-Peng
authors.initials: YP
authors.lastname: Bai
authors.forename: Shu
authors.initials: S
authors.lastname: Liu
authors.forename: Feng-Rui
authors.initials: FR
authors.lastname: Song
authors.forename: Zhi-Qiang
authors.initials: ZQ
authors.lastname: Liu
authors.forename: Shu-Ying
authors.initials: SY
authors.lastname: Liu
mesh_terms: D005740:Gases / Q000737:chemistry; D007477:Ions / Q000737:chemistry; D011108:Polymers / Q000737:chemistry*; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization / Q000379:methods*; D017973:Tungsten Compounds / Q000737:chemistry*
chemical_list: D005740:Gases; D007477:Ions; D011108:Polymers; D017973:Tungsten Compounds; C045951:tungstate