Absolute Binding Energies of Lithium Ions to Short Chain Alcohols, CnH2n+2O, n = 1−4, Determined by Threshold Collision-Induced Dissociation

Rodgers, M. T.; Armentrout, P. B.

doi:10.1021/jp970154+

Cited by 110 publications

(152 citation statements)

References 41 publications

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“…In all cases, the experimental cross sections are accurately reproduced using a loose PSL TS model [72]. Previous work has shown that this model provides the most accurate assessment of the kinetic shifts for CID of electrostatically bound ion-molecule complexes [72,77]. Good reproduction of data is obtained over energy ranges exceeding 2.5 eV and cross section magnitudes of at least a factor of 100.…”

Section: Threshold Analysismentioning

confidence: 73%

Sodium Cation Affinities of Commonly Used MALDI Matrices Determined by Guided Ion Beam Tandem Mass Spectrometry

Chinthaka¹,

Rodgers²

2012

J. Am. Soc. Mass Spectrom.

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The sodium cation affinities of six commonly used MALDI matrices are determined here using guided ion beam tandem mass spectrometry techniques. The collision-induced dissociation behavior of six sodium cationized MALDI matrices, Na + (MALDI), with Xe is studied as a function of kinetic energy. The MALDI matrices examined here include: nicotinic acid, quinoline, 3-aminoquinoline, 4-nitroaniline, picolinic acid, and 3-hydroxypicolinic acid. In all cases, the primary dissociation pathway corresponds to endothermic loss of the intact MALDI matrix. The cross section thresholds are interpreted to yield zero and 298 K Na + −MALDI bond dissociation energies (BDEs), or sodium cation affinities, after accounting for the effects of multiple ionneutral collisions, the kinetic and internal energy distributions of the reactants, and dissociation lifetimes. Density functional theory calculations at the B3LYP/6-311+G(2d,2p)//B3LYP/6-31G* and MP2(full)/6-311+G(2d,2p)//B3LYP/6-31G* levels of theory are used to characterized the structures and energetics for these systems. The calculated BDEs exhibit very good agreement with the measured values for most systems. The experimental and theoretical Na + −MALDI BDEs determined here are compared with those previously measured by cation transfer equilibrium methods.

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Section: Threshold Analysismentioning

confidence: 73%

Sodium Cation Affinities of Commonly Used MALDI Matrices Determined by Guided Ion Beam Tandem Mass Spectrometry

Chinthaka¹,

Rodgers²

2012

J. Am. Soc. Mass Spectrom.

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“…The trends in the binding of alkali metal cations to TMP are examined and allow determination of the influence of the size of the metal cation on the nature and strength of binding. The binding of alkali metal cations to TMP is also compared with that of acetone [26,30] and methanol [27][28][29][30][31][32].…”

Section: ϩmentioning

confidence: 99%

“…The ground state conformer involves bidentate binding of M ϩ to the oxo and one of the alkoxy oxygen atoms, i.e., the C3 conformer. To dissect the relative contributions of these two interactions to the binding, the M ϩ (TMP) complexes are compared with the analogous M ϩ (acetone) [26,Å30]ÅandÅM ϩ (methanol)ÅcomplexesÅ [27][28][29][30][31][32].ÅThe M M ϩ (methanol) complexes. Thus, the bidentate interaction with the alkoxy oxygen atom produces a change in the binding geometry and strength of interaction with both the oxo and alkoxy oxygen atoms that weakens these interactions relative to individual monodentate interactions, but must clearly result in overall stronger binding or such binding geometries would not correspond to the ground state conformers.…”

Section: Comparison Of Alkali Metal Cation Binding To Methanol and Acmentioning

confidence: 99%

A simple model for metal cation-phosphate interactions in nucleic acids in the gas phase: Alkali metal cations and trimethyl phosphate

Ruan

Huang

Rodgers

2008

J. Am. Soc. Mass Spectrom.

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Threshold collision-induced dissociation techniques are employed to determine the bond dissociation energies (BDEs) of complexes of alkali metal cations to trimethyl phosphate, TMP. Endothermic loss of the intact TMP ligand is the only dissociation pathway observed for all complexes. Theoretical calculations at the B3LYP/6-31G* level of theory are used to determine the structures, vibrational frequencies, and rotational constants of neutral TMP and the M ϩ (TMP) complexes. Theoretical BDEs are determined from single point energy calculations at the B3LYP/6-311ϩG(2d,2p) level using the B3LYP/6-31G* optimized geometries. The agreement between theory and experiment is reasonably good for all complexes except Li ϩ (TMP hosphate esters are integral parts of many biologically active molecules ranging from nucleic acids, lipids, and ATP to pesticides and nerve agents [1][2][3]. Serving as link components in nucleic acids, phosphate esters connect thousands of base pairs to form large molecules that contain the genetic information. These phosphate groups are deprotonated under physiological conditions. The resulting negative charges along the phosphate backbone are stabilized and neutralized by the binding of metal cations. Metal cations can and often do exert a significant influence on nucleic acid structure and genetic information transfer [4]. Metal cation binding reduces the repulsion between neighboring nucleotide units, and therefore influences the stabilization and structural dynamics of nucleic acids and lipids in membranes. For example, alkali and alkaline earth metal cations, including the most biologically important of these cations, Na ϩ and Mg 2ϩ , prefer to bind to a phosphate group rather than to the nucleobases or sugar moieties [5]. Mg 2ϩ is found to increase the melting temperature of DNA [6]. Metal cations may also be involved in the functioning of nucleic acids, e.g., metal cations are required for the proper functioning of all ribozymes [7]. Metal cation-nucleic acid interactions are currently of great interest because metal cations and metal cation-ligand complexes bind to DNA and regulate gene expression, act as drugs, or can be used as tools for molecular biology studies [8]. Hendry and Sargeson studied metal cation-promoted phosphate ester hydrolysis and found that the rate of hydrolysis is modulated by the size of the metal cation and the ease of formation of a four-membered chelate ring [9]. Dempcy and Bruice found a pentacoordinate intermediate for the catalysis of alkyl phosphate diesters [10]. Schneider and Kabelac et al. [11] studied the distribution of five metal cations (i.e., Na, and Zn 2ϩ ) and water around a negatively charged phosphate group from various crystal structures, and found that all of the cations prefer asymmetric monodentate coordination over bidentate coordination. Their ab initio calculations suggest that bidentate binding of these metal cations to an isolated phosphate group is preferred, but that the presence of even a single water molecule alters this preference. Ab...

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“…Another interesting aspect of this study concerns our understanding of the cation-p interactions, among which the interactions with Li + [15][16][17][18][19][20][21][22][23] and their role in molecular recognition phenomena [24] received a lot of attention. In particular, cation-p interactions are involved in protein side-chain orientation and protein folding, involving mechanisms similar to those described in this paper.…”

Section: LImentioning

confidence: 99%

Complexes between Lithium Cation and Diphenylalkanes in the Gas Phase: The Pincer Effect

Gal

Maria

Mó

et al. 2006

Chemistry A European J

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The gas-phase lithium cation basicities (LCB values, Gibbs free energies of binding) of alpha,omega-diphenylalkanes Ph-(CH(2))(n)-Ph (n=2, 3, or 7) and 1,1-diphenylethane Ph-CH(Me)-Ph were investigated by means of Fourier-transform ion cyclotron resonance (FTICR) mass spectrometry. Their structures, and those of the corresponding Li(+) complexes were optimized at the B3LYP/6-31G(d) level and their relative stabilities calculated at the B3LYP/6-311+G(3df,2p)//B3LYP/6-31G(d) level. Whereas the most stable conformers of the free diphenylalkanes were found to adopt a completely stretched aliphatic chain connecting the two benzene rings, the most stable Li(+) complexes correspond to conformers in which the alkali metal cation interacts simultaneously with both benzene rings through the folding of the aliphatic chain ("pincer effect"). This chelation brings about a significant enhancement of the Li(+) binding enthalpies (LBE values), which were calculated to be approximately 75 kJ mol(-1) higher than those evaluated for conventional (singly coordinated) pi complexes in which the metal cation interacts with only one of the benzene rings. The increase of the corresponding lithium cation basicities, however, (Gibbs free energies of Li(+) binding, LCB values) was calculated to be smaller by approximately 15 kJ mol(-1) as the pincer effect is entropically disfavored. The good agreement between the calculated LCB values, assuming a statistical distribution of the different conformers present in the gas phase, and the experimental LCB values measured by means of FTICR mass spectrometry are considered indirect evidence of the existence of the pincer effect.

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Absolute Binding Energies of Lithium Ions to Short Chain Alcohols, C_nH_2n+2O, n = 1−4, Determined by Threshold Collision-Induced Dissociation

Cited by 110 publications

References 41 publications

Sodium Cation Affinities of Commonly Used MALDI Matrices Determined by Guided Ion Beam Tandem Mass Spectrometry

Sodium Cation Affinities of Commonly Used MALDI Matrices Determined by Guided Ion Beam Tandem Mass Spectrometry

A simple model for metal cation-phosphate interactions in nucleic acids in the gas phase: Alkali metal cations and trimethyl phosphate

Complexes between Lithium Cation and Diphenylalkanes in the Gas Phase: The Pincer Effect

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