Document Detail

Tandem mass spectrometry of electrosprayed polyhedral oligomeric silsesquioxane compounds with different substituents.
MedLine Citation:
PMID:  22368056     Owner:  NLM     Status:  In-Data-Review    
RATIONALE: Polyhedral oligomeric silsesquioxanes (POSSs), defined as [RSiO(3/2) ](n) with R designating an organic substituent, were considered here as models of highly cross-linked polysiloxanes, to be further used as references in tandem mass spectrometric characterization of plasma polymers of hexamethyldisiloxane, expected to be composed of organic polydimethylsiloxane (PDMS) and inorganic (SiO(x) ) silica-based parts. The collision-induced dissociation (CID) behavior of [RSiO(3/2) ](8) compounds was then studied as a function of the R substituent.
METHODS: POSS compounds were produced in the gas phase as ammonium adducts and the product ions generated upon CID, amongst which was the protonated precursor, were accurately mass measured in an orthogonal acceleration time-of-flight mass analyzer.
RESULTS: The presence of eight propylamine substituents was shown to induce sequential dehydration of the protonated precursor, ultimately leading to a complete unfolding of the POSS cage. Similar opening of the octahedron structure in the protonated molecule substituted with OSi(CH(3) )(3) , OSiH(CH(3) )(2) or OH (formed upon methanolysis of dimethylsiloxy substituents) was proposed to account for the product ions generated during their CID. Sequential charge-remote transfers of a methyl group (and of H in the case of dimethylsiloxy substituents) from one substituent group to a neighboring one was shown to lead to a linear co-oligomeric chain composed of randomly distributed siloxy-based monomers.
CONCLUSIONS: All the peaks observed in CID could be accounted for by applying dissociation reactions typically occurring in protonated polysiloxane-like oligomers. The large number of product ions observed in MS/MS was found to result from the variety of possible structural rearrangements, producing numerous linear isomeric forms of the dissociating species. Copyright © 2012 John Wiley & Sons, Ltd.
Thierry Fouquet; Trang N T Phan; Laurence Charles
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Publication Detail:
Type:  Journal Article    
Journal Detail:
Title:  Rapid communications in mass spectrometry : RCM     Volume:  26     ISSN:  1097-0231     ISO Abbreviation:  Rapid Commun. Mass Spectrom.     Publication Date:  2012 Apr 
Date Detail:
Created Date:  2012-02-27     Completed Date:  -     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  8802365     Medline TA:  Rapid Commun Mass Spectrom     Country:  England    
Other Details:
Languages:  eng     Pagination:  765-74     Citation Subset:  IM    
Copyright Information:
Copyright © 2012 John Wiley & Sons, Ltd.
Aix-Marseille Université - CNRS, UMR 7273: Institut de Chimie Radicalaire, Spectrométries Appliquées à la Chimie Structurale, F-13397, Marseille Cedex 20, France; Department of Advanced Materials and Structures, Centre de Recherche Public Henri Tudor (CRPHT), Rue de Luxembourg 66, L-4002, Esch sur Alzette, France.
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