title: Structural characterization of new defective molecules in poly(amidoamide) dendrimers by combining mass spectrometry and nuclear magnetic resonance.
abstract: A new side-reaction occurring during divergent synthesis of PAMAM dendrimers (generations G0-G2) was revealed by mass spectrometric detection of defective molecules with a net gain of a single carbon atom as compared to expected compounds. Combining MS/MS experiments performed on different electrosprayed precursor ions (protonated molecules and lithiated adducts) with NMR analyses allowed the origin of these by-products to be elucidated. Modification of one ethylenediamine end-group of perfect dendrimers into a cyclic imidazolidine moiety was induced by formaldehyde present at trace level in the methanol solvent used as the synthesis medium. Dendrimers studied here were purposely constructed from a triethanolamine core to make them more flexible, as compared to NH3- or ethylenediamine-core PAMAM, and hence improve their interaction with DNA. Occurrence of this side-reaction would be favored by the particular flexibility of the dendrimer branches.
authors.affiliation: Aix-Marseille Université - CNRS, UMR 7273, Institut de Chimie Radicalaire, Marseille, France.
authors.forename: Aura
authors.initials: A
authors.lastname: Tintaru
authors.affiliation: Aix-Marseille Université - CNRS, UMR 7273, Institut de Chimie Radicalaire, Marseille, France.
authors.forename: Rémi
authors.initials: R
authors.lastname: Ungaro
authors.affiliation: Aix-Marseille Université - CNRS, UMR 6114, Centre Interdisciplinaire de Nanosciences de Marseille, Marseille, France.
authors.forename: Xiaoxiuan
authors.initials: X
authors.lastname: Liu
authors.affiliation: Aix-Marseille Université - CNRS, UMR 6114, Centre Interdisciplinaire de Nanosciences de Marseille, Marseille, France.
authors.forename: Chao
authors.initials: C
authors.lastname: Chen
authors.affiliation: Aix-Marseille Université - CNRS, UMR 7313, Institut des Sciences Moléculaires de Marseille ISM2 & Ecole Centrale de Marseille, Marseille, France.
authors.forename: Laurent
authors.initials: L
authors.lastname: Giordano
authors.affiliation: Aix-Marseille Université - CNRS, UMR 6114, Centre Interdisciplinaire de Nanosciences de Marseille, Marseille, France.
authors.forename: Ling
authors.initials: L
authors.lastname: Peng
authors.affiliation: Aix-Marseille Université - CNRS, UMR 7273, Institut de Chimie Radicalaire, Marseille, France. Electronic address: laurence.charles@univ-amu.fr.
authors.forename: Laurence
authors.initials: L
authors.lastname: Charles
mesh_terms: D050091:Dendrimers / Q000737:chemistry*; D009682:Magnetic Resonance Spectroscopy / Q000379:methods*; D018511:Systems Integration; D053719:Tandem Mass Spectrometry / Q000379:methods*
chemical_list: D050091:Dendrimers; C104700:PAMAM Starburst
keywords: Degradation products; Dendrimers; Mass spectrometry; Solvent impurity; Structure elucidation