Mass spectrometric study of interactions between poly(ethylene glycols) and alkali metals in solution

Chan, Keith; Cook, Kelsey D.

doi:10.1021/ma00245a010

Cited by 46 publications

(45 citation statements)

References 6 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…A previous study of these uptake efficiencies by Chan and Cook, who used electrohydrodynamic ionization, reported uptake efficiencies for Na ϩ , K ϩ , Rb ϩ , and Cs ϩ as 0.46, 1.0, 0.79, and 0.94, respectively [62]. In Chan and Cook's work the solvent was glycerol and the value of x ranged from 16 -22. There are clearly some interesting effects due to the change in solvent, and possibly the ionization source, but because of the instrumental factors that were encountered in our work (mass bias, fragmentation during ion ejection causing distorted ion abundance), and also in the work from Chan and Cook as documented elsewhere [63,64], we believe it prudent to not overinterpret and compare these uptake results.…”

Section: Discussionmentioning

confidence: 97%

Poly(ethylene glycol) doubly and singly cationized by different alkali metal ions: Relative cation affinities and cation-dependent resolution in a quadrupole ion trap mass spectrometer

Bogan

Agnes

2002

J. Am. Soc. Mass Spectrom.

View full text Add to dashboard Cite

Structural information of gas phase complexes of poly(ethylene glycol) (PEG) cationized by one or two different alkali metal ions is inferred from MS and MS/MS experiments performed with an electrospray quadrupole ion trap mass spectrometer. The rationale for selecting PEG was that its sites for cation binding are non-selective with respect to the repeating monomeric unit of the polymer, but there is selectivity with respect to the formation of an inner coordination sphere specific to each metal ion. The dissociation of [M 1 ϩ M 2 ϩ (EO23)], where EO23 ϭ linear polymer of ethylene oxide, 23 units in length, resulted in loss of one of the alkali metal ions, with preference for loss of the larger cation, with no fragmentation of the PEG backbone for Na, K, Rb, and Cs. Li was not examined in this portion of the study. The selectivity for loss of the larger alkali metal ion was [Na -20]. Factors involved in the solution phase molecular recognition are solvation enthalpy and entropy for both species and the number of atoms from the ligand that are involved with the binding of the metal ion, plus any conformational change of the ligand between its unbound and bound forms [21]. The intrinsic properties of the ion-dipole bonds in these non-covalent complexes are being deduced using a variety of gas phase techniques, including the equilibrium method [22], threshold CID [23][24][25][26], and ion chromatography [27,28].The long chain podands have received comparatively less attention by mass spectrometry [29,30], yet their industrial usage is immense, ranging from the fabrication of materials with varied properties to their use as phase transfer catalysts in industrial processes [31]. Long chain podands are also used as agents for improving bio-compatibility in immunological applications [32][33][34] and as ion channel models [35]. Improved knowledge of the structures formed when long chain podands coordinate with alkali metal ions, and particularly with the ubiquitous Na ϩ and K ϩ , can be of use in improving the applications of these materials.Here we report the uni-molecular dissociation of modest length podands (PEG, M.W. avg ϭ 1000) that were doubly cationized by different alkali metal ions. These complexes are abbreviated as [M 1 ϩ M 2 ϩ (EOx)], where M 1 ϩ and M 2 ϩ are different alkali metal ions, EO ϭ ethylene oxide unit, and x ϭ degree of polymerization. This study of the doubly cationized PEG has permitted an in situ measure of the relative binding strength of the cumulative ion-dipole bonds when a single PEG molecule coordinates to the s-orbital of two different alkali metal ions.The dissociation of these complexes inside a quadrupole ion trap is a form of the kinetic method [36,37]. In this variation, rather than sandwiching a single cation between two ligands, a single ligand that was large enough to bind two different metal ions was

show abstract

Section: Discussionmentioning

confidence: 97%

Poly(ethylene glycol) doubly and singly cationized by different alkali metal ions: Relative cation affinities and cation-dependent resolution in a quadrupole ion trap mass spectrometer

Bogan

Agnes

2002

J. Am. Soc. Mass Spectrom.

View full text Add to dashboard Cite

show abstract

“…A convenient way to tune the charge‐holding capacity of PEO ions is to increase the concentration of and/or to change the alkali cation 35. The bonding energy, ionic radii and coordination number differ according to the alkali ion.…”

Section: Influence Of the Alkali Cation On The Charging Capacity Of Peosmentioning

confidence: 99%

The Effect of Hydrogen Bonding on Allylic Alkylation and Isomerization Reactions in Ionic Liquids

Ross

Xiao

2003

Chemistry A European J

View full text Add to dashboard Cite

Neutral allylic alkylation reactions, in which a base is generated in situ and which hence require no external bases, can significantly be retarded when carried out in the ionic liquid 1-butyl-3-methylimidazolium tetrafluoroborate ([bmim][BF(4)]). Evidence suggests that the base or base precursor enters into hydrogen bonding with the imidazolium cation and is thus made less readily available for deprotonation of pre-nucleophiles. However, the reaction proceeds well in the presence of stronger bases that are capable of deprotonation. Whilst the phenomenon of hydrogen bonding in ionic liquids can be detrimental to reactions such as allylic alkylation, it can be exploited to suppress unwanted allylic isomerization.

show abstract

“…Various mass spectrometric techniques such as field desorption (FD) 1 3 , laser desorption (LD)14-15, fast atom bombardment (FAB) 1 6, electrohydrodynamic ionization (EH) 17 and secondary ionization mass spectrometry (SIMS) 1 8 have been used with varying degrees of effectiveness.…”

Section: Fabms Characterization Of Poly(o-toluidine)mentioning

confidence: 99%

Fast Atom Bombardment Mass Spectrometric Characterization of Poly(O-Toluidine)

Balasaunmugam¹,

Owens²,

Hsueh³

et al. 1991

View full text Add to dashboard Cite

Mass spectrometric study of interactions between poly(ethylene glycols) and alkali metals in solution

Cited by 46 publications

References 6 publications

Poly(ethylene glycol) doubly and singly cationized by different alkali metal ions: Relative cation affinities and cation-dependent resolution in a quadrupole ion trap mass spectrometer

Poly(ethylene glycol) doubly and singly cationized by different alkali metal ions: Relative cation affinities and cation-dependent resolution in a quadrupole ion trap mass spectrometer

The Effect of Hydrogen Bonding on Allylic Alkylation and Isomerization Reactions in Ionic Liquids

Fast Atom Bombardment Mass Spectrometric Characterization of Poly(O-Toluidine)

Contact Info

Product

Resources

About