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EnglishTandem mass spectrometry and ion mobility spectrometry experiments were performed on multiply charged molecules formed upon conjugation of a poly(amidoamine) (PAMAM) dendrimer with a poly(ethylene oxide) (PEO) linear polymer to evidence any conformational modification as a function of their charge state (2+ to 4 + ) and of the adducted cation (H+ vs Li+). Experimental findings were rationalized by molecular dynamics simulations. The G0 PAMAM head-group could accommodate up to three protons, with protonated terminal amine group enclosed in a pseudo 18-crown-6 ring formed by the PEO segment. This particular conformation enabled a hydrogen bond network which allowed long-range proton transfer to occur during collisionally activated dissociation. In contrast, lithium adduction was found to mainly occur onto oxygen atoms of the polyether, each Li+ cation being coordinated by a 12-crown-4 pseudo structure. As a result, for the studied polymeric segment (Mn = 1500 g mol−1), PEO-PAMAM hybrid molecules exhibited a more expanded shape when adducted to lithium as compared to proton.
| Titolo: | Conformational sensitivity of conjugated poly(ethylene oxide)-poly(amidoamine) molecules to cations adducted upon electrospray ionization - A mass spectrometry, ion mobility and molecular modeling study |
| Autori: | |
| Data di pubblicazione: | 2014 |
| Rivista: | |
| Abstract: | Tandem mass spectrometry and ion mobility spectrometry experiments were performed on multiply charged molecules formed upon conjugation of a poly(amidoamine) (PAMAM) dendrimer with a poly(ethylene oxide) (PEO) linear polymer to evidence any conformational modification as a function of their charge state (2+ to 4 + ) and of the adducted cation (H+ vs Li+). Experimental findings were rationalized by molecular dynamics simulations. The G0 PAMAM head-group could accommodate up to three protons, with protonated terminal amine group enclosed in a pseudo 18-crown-6 ring formed by the PEO segment. This particular conformation enabled a hydrogen bond network which allowed long-range proton transfer to occur during collisionally activated dissociation. In contrast, lithium adduction was found to mainly occur onto oxygen atoms of the polyether, each Li+ cation being coordinated by a 12-crown-4 pseudo structure. As a result, for the studied polymeric segment (Mn = 1500 g mol−1), PEO-PAMAM hybrid molecules exhibited a more expanded shape when adducted to lithium as compared to proton. |
| Handle: | http://hdl.handle.net/11368/2706649 |
| Digital Object Identifier (DOI): | http://dx.doi.org/10.1016/j.aca.2013.08.030 |
| Appare nelle tipologie: | 1.1 Articolo in Rivista |
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http://hdl.handle.net/11368/2706649
