2008
|
Sign up to set email alerts
|

Abstract: Using high resolution solid state (15)N and (2)H spectroscopy and longitudinal relaxometry we have studied the tautomerism of porphycene in the solid state, corresponding to a double proton transfer in two cooperative hydrogen bonds. The tautomerism is degenerate above 225 K but the degeneracy is lifted below this temperature, indicating a phase transition. Thus, the high-temperature phase is characterized by a dynamic proton disorder and the low-temperature phase by a dynamic proton order. (15)N magnetization… Show more

Help me understand this report

Search citation statements

Order By: Relevance

Paper Sections

Select...
2
1
1
1

Citation Types

1
26
1

Year Published

2009
2009
2012
2012

Publication Types

Select...
4

Relationship

1
3

Authors

Journals

citations
Cited by 31 publications
(28 citation statements)
references
References 69 publications
(187 reference statements)
1
26
1
Order By: Relevance
“…We note, however, a discrepancy between our data and much lower room‐temperature rate values determined for 1 by Limbach and co‐workers using 15 N relaxometry 9. 27 These authors recently reported an abrupt increase of the reaction rate for crystalline 1 when the temperature is lowered below 225 K 27. This has been explained as an indication of a phase transition.…”
Section: Resultscontrasting
confidence: 92%
“…We note, however, a discrepancy between our data and much lower room‐temperature rate values determined for 1 by Limbach and co‐workers using 15 N relaxometry 9. 27 These authors recently reported an abrupt increase of the reaction rate for crystalline 1 when the temperature is lowered below 225 K 27. This has been explained as an indication of a phase transition.…”
Section: Resultscontrasting
confidence: 92%
“…77 Such a model also invokes equilibrium motions representative of the third category described in section 1.1.3 to explain kinetic observations; however, the temperature dependence of the KIE measured at low temperature is not an inherent property of the enzyme’s reactive conformers. It is our view that a phase transition between molecular states with different intrinsic properties, such as that proposed by Limbach and co-workers to model non-Arrhenius behavior for porphycene tautomerization, 78 is the best model for the ht-ADH kinetic data. Additional data for mutants with altered kinetic properties above and below the break will be helpful in distinguishing among multiple models of the relationship between the temperature dependence of KIEs and the protein conformational landscape for ht-ADH.…”
Section: Alcohol Dehydrogenasesmentioning
confidence: 99%
“…6 in a logarithmic way as a function of the inverse temperature. A T 1 minimum of 0.585 s was observed at 273 K. The solid curve was calculated as previously for related cases [11,19,20] using the master equation for the spin-lattice relaxation rates of nuclei S caused by fluctuations of the heteronuclear dipolar interaction with spins I which exchange between two sites [44]. For polycrystalline solids, this equation depends on the molecular orientation with respect to the external magnetic field.…”
Section: N Spectra and Corresponding Longitudinal Relaxation Timesmentioning
confidence: 99%
“…The study of 2 H relaxation has been made possible by the pioneering work of Spiess et al [12] on Fourier Transform 2 H NMR spectroscopy. Kinetic hydrogen/deuterium isotope effects of fast hydron transfers in solids can then preferentially be elucidated by a combination of either 1 H and 2 H relaxation [13][14][15][16][17], or of 15 N and 2 H relaxation [18][19][20].…”
Section: Introductionmentioning
confidence: 99%