The effect of H218O on the pH of phosphoric acid solutions

Kudish, A. I.; Wolf, D.; Pinchas, S.

doi:10.1016/0022-1902(73)80380-x

Cited by 5 publications

(2 citation statements)

References 9 publications

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“…Earlier results (Kudish et al, 1973;Krezel and Ball, 2004) O-remover should decrease proton concentration, i.e., increase in the overall pK. Not knowing the absolute value of K d (see Eq.…”

Section: The Dependence Of ⌬Pk and ⌬G O On The Concentration Of H 2 17 Omentioning

confidence: 94%

“…Because ⌬ is sensitive to hydration, it can be used to interpret the hydration behavior of the enantiomers (Gottwald et al, 2005) (Horita and Cole, 2004) and affinity for protons (Kudish et al, 1973;Krezel and Ball, 2004). Hence, hydration of the enantiomers with water molecules with different isotopic signatures should also influence the dissociation properties of the enantiomers.…”

Section: The Dependence Of ⌬ On the Concentration Of H 2 17 Omentioning

confidence: 98%

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TD-¹HNMR Measurements Show Enantioselective Dissociation of Ribose and Glucose in the Presence of H₂¹⁷O

Scorei

Cimpoiaşu²,

Popa³

2007

Astrobiology

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We used Time Domain (1)H Nuclear Magnetic Resonance (NMR) to characterize changes in proton exchange between water and sugar enantiomers at different concentrations of H(2)(17)O (approximately 15-450 mM) and found that dissociation of the (-)-enantiomers of glucose and ribose occurs at significantly higher rates at higher concentrations of H(2)(17)O. The mechanism behind this enantioselective effect is unclear. The hypothesis we propose is that the large magnetic field (B(o) approximately 0.6T) applied during NMR measurements induces electric moments opposite in sign for the D and L-isomers. Because (17)O has a nuclear electric quadrupole moment not = 0, asymmetrically hydrated complexes may form between the B(o)-polarized enantiomers and H(2)(17)O. Either H(2)(17)O is more often hydrating the (+) than the (-)-enantiomers--and consequently pK differences between H(2)(16)O and H(2)(17)O lead to differences in proton exchange between enantiomers and water--or the orientation of H(2)(17)O relative to the B(o)-polarized enantiomers is different, in total or in part, which leads to hydrated complexes with different spatial geometries and different proton exchange properties. This effect is significant for Magneto-Chiral Stereo-Chemistry (MCSC) and astrobiology, and it may help us better understand specific instances of mass independent isotopic fractionation and aid in the development of new technologies for chiral and isotopic separation.

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“…Earlier results (Kudish et al, 1973;Krezel and Ball, 2004) O-remover should decrease proton concentration, i.e., increase in the overall pK. Not knowing the absolute value of K d (see Eq.…”

Section: The Dependence Of ⌬Pk and ⌬G O On The Concentration Of H 2 17 Omentioning

confidence: 94%

Section: The Dependence Of ⌬ On the Concentration Of H 2 17 Omentioning

confidence: 98%

TD-¹HNMR Measurements Show Enantioselective Dissociation of Ribose and Glucose in the Presence of H₂¹⁷O

Scorei

Cimpoiaşu²,

Popa³

2007

Astrobiology

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Enantiodifferent Proton Exchange in Alanine and Asparagine in the Presence of H 2 17 O

2010

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Using Time Domain (1)H Nuclear Magnetic Resonance with H (2) (17) O (H (2) (17) O-TD-(1)HNMR), we found [H (2) (17) O]- and pH-controlled chiral differences in proton exchange properties in alanine (Ala) and asparagine (Asn). To minimize and equalize chemical impurities, Asn enantiomers were purified by crystallization from racemic solution. At <0.1 M H (2) (17) O, a shift in isoelectric pH (pI) occurred, approximately 1.14 kJ mol(-1) L: -D: -Asn DeltaDeltaG (o)' in the 5.91-6.42 pH range. One potential source for this asymmetry is the enantio-different magnetic moments (L: mu upward arrow not equal D: mu downward arrow) produced by neutral ring currents in the chiral center, leading to enantio-different nuclear spin organization and charge distribution in the amino group. At >or=pI, dissimilar interactions may occur in the hydration of the amino group with H (2) (17) O (NH(2)/H (2) (17) O not equal NH(2)/H (2) (16) O; NH(3) (+)/H (2) (17) O not equal NH(2)/H (2) (17) O; L: -*C-NH(2)/H (2) (17) O not equal D: -*C-NH(2)/H (2) (17) O). As L: mu upward arrow not equal D: mu downward arrow, the L: -*C-amino and the D: -*C-amino groups are diastereo spin-isomers. The nuclear spin of (17)O may be parallel or antiparallel with the ortho-(1)H(1)H pair; hence two ortho-H (2) (17) O molecules exist, also diastereo spin-isomers. As the pK of H (2) (17) O is different from H (2) (16) O, dissimilarities between L: -*C- and D: -*C-amino groups are converted into proton exchange differences. During H (2) (17) O-TD-(1)HNMR, the H (2) (17) O molecule is a "probe" of the state of the amino group. Regarding prebiotic evolution: prebiotic chirality may not require stochastic symmetry breaking or preexisting chiral conditions; chemical chiral effects due to L: mu upward arrow not equal D: mu downward arrow are small and need chiral amplification to generate an enantiomeric excess significant for prebiotic evolution; and prebiotic symmetry breaking was homochiral because the effect of L: mu upward arrow and D: mu downward arrow on the amino group should be similar in all alpha amino acids.

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The anomalous behaviour of 18O-labelled compounds—XIV Association of normal and 18O-labelled water in dioxan solutions

Pinchas

1977

Journal of Inorganic and Nuclear Chemistry

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The effect of H218O on the pH of phosphoric acid solutions

Cited by 5 publications

References 9 publications

TD-¹HNMR Measurements Show Enantioselective Dissociation of Ribose and Glucose in the Presence of H₂¹⁷O

TD-¹HNMR Measurements Show Enantioselective Dissociation of Ribose and Glucose in the Presence of H₂¹⁷O

Enantiodifferent Proton Exchange in Alanine and Asparagine in the Presence of H 2 17 O

The anomalous behaviour of 18O-labelled compounds—XIV Association of normal and 18O-labelled water in dioxan solutions

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The effect of H218O on the pH of phosphoric acid solutions

Cited by 5 publications

References 9 publications

TD-1HNMR Measurements Show Enantioselective Dissociation of Ribose and Glucose in the Presence of H217O

TD-1HNMR Measurements Show Enantioselective Dissociation of Ribose and Glucose in the Presence of H217O

Enantiodifferent Proton Exchange in Alanine and Asparagine in the Presence of H 2 17 O

The anomalous behaviour of 18O-labelled compounds—XIV Association of normal and 18O-labelled water in dioxan solutions

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TD-¹HNMR Measurements Show Enantioselective Dissociation of Ribose and Glucose in the Presence of H₂¹⁷O

TD-¹HNMR Measurements Show Enantioselective Dissociation of Ribose and Glucose in the Presence of H₂¹⁷O