Category Archives: Material Science

Fractional Spin-Labeling of Polymers for Enhancing NMR Sensitivity by Solvent-Free Dynamic Nuclear Polarization

Vitzthum, V., et al., Fractional Spin-Labeling of Polymers for Enhancing NMR Sensitivity by Solvent-Free Dynamic Nuclear Polarization. ChemPhysChem, 2011. 12(16): p. 2929-2932.

http://dx.doi.org/10.1002/cphc.201100630

Decapeptides are partly covalently labeled with a polarizing agent to enhance NMR signals by dynamic nuclear polarization (DNP). DNP under magic angle spinning conditions at T=100 K was performed directly on these molecules in the absence of any solvent.

Dynamic Nuclear Polarization Enhanced Solid-State NMR Spectroscopy of Functionalized Metal–Organic Frameworks

Rossini, A.J., et al., Dynamic Nuclear Polarization Enhanced Solid-State NMR Spectroscopy of Functionalized Metal–Organic Frameworks. Angewandte Chemie, 2012. 124(1): p. 127-131

http://dx.doi.org/10.1002/ange.201106030

Dynamic nuclear polarization (DNP) is applied to enhance the signal of solid-state NMR spectra of metal–organic framework (MOF) materials. The signal enhancement enables the acquisition of high-quality 1D 13C solid-state NMR spectra, 2D 1H–13C dipolar HETCOR and 1D 15N solid-state NMR spectra with natural isotopic abundance in experiment times on the order of minutes. MW=microwaves.

Dynamic Nuclear Polarization Enhanced Solid-State NMR Spectroscopy of Functionalized Metal–Organic Frameworks

Rossini, A.J., et al., Dynamic Nuclear Polarization Enhanced Solid-State NMR Spectroscopy of Functionalized Metal–Organic Frameworks. Angewandte Chemie, 2012. 124(1): p. 127-131

http://dx.doi.org/10.1002/ange.201106030

Dynamic nuclear polarization (DNP) is applied to enhance the signal of solid-state NMR spectra of metal–organic framework (MOF) materials. The signal enhancement enables the acquisition of high-quality 1D 13C solid-state NMR spectra, 2D 1H–13C dipolar HETCOR and 1D 15N solid-state NMR spectra with natural isotopic abundance in experiment times on the order of minutes. MW=microwaves.

One hundred fold overall sensitivity enhancements for Silicon-29 NMR spectroscopy of surfaces by dynamic nuclear polarization with CPMG acquisition

Rossini, A.J., et al., One hundred fold overall sensitivity enhancements for Silicon-29 NMR spectroscopy of surfaces by dynamic nuclear polarization with CPMG acquisition. Chemical Science, 2011. 3: p. 108-115.

http://dx.doi.org/10.1039/C1SC00550B

Dynamic nuclear polarization (DNP) 29Si solid-state NMR spectra of a hybrid mesoporous silica material impregnated with aqueous biradical solutions have been acquired with cross-polarization (CP) and cross-polarization Carr-Purcell Meiboom-Gill (CP/CPMG) pulse sequences. The integrated intensities (II) and signal to noise ratios (S/N) of the 29Si solid-state NMR spectra are monitored in order to measure the DNP enhancement factors ([varepsilon]Si[space]CP) as well as the overall sensitivity enhancement ([capital Sigma]Si[space]CP) available from the combination of DNP and CPMG acquisition. Here, , where [small theta]Si is a factor which quantifies reduction of the NMR signal by paramagnetic effects (quenching) and [small kappa] is the square root of the ratio of nuclear longitudinal relaxation times of the dry material and material impregnated with radical solution. It is found that [capital Sigma]Si[space]CP is always substantially lower than the measured value of [varepsilon]Si[space]CP due to paramagnetic effects which reduce the II of the 29Si CP solid-state NMR spectra at high biradical concentrations. In this system, it is observed that the sample preparation which provides optimal DNP signal enhancement does not provide optimal overall signal enhancement. Notably, optimal signal enhancements are obtained for CPMG acquisition of the 29Si solid-state NMR spectra when lower radical concentrations are employed due to slower transverse relaxation rates. To the best of our knowledge this is the first study which seeks to quantify the overall sensitivity enhancements available from DNP solid-state NMR experiments.

One hundred fold overall sensitivity enhancements for Silicon-29 NMR spectroscopy of surfaces by dynamic nuclear polarization with CPMG acquisition

Rossini, A.J., et al., One hundred fold overall sensitivity enhancements for Silicon-29 NMR spectroscopy of surfaces by dynamic nuclear polarization with CPMG acquisition. Chemical Science, 2011. 3: p. 108-115.

http://dx.doi.org/10.1039/C1SC00550B

Dynamic nuclear polarization (DNP) 29Si solid-state NMR spectra of a hybrid mesoporous silica material impregnated with aqueous biradical solutions have been acquired with cross-polarization (CP) and cross-polarization Carr-Purcell Meiboom-Gill (CP/CPMG) pulse sequences. The integrated intensities (II) and signal to noise ratios (S/N) of the 29Si solid-state NMR spectra are monitored in order to measure the DNP enhancement factors ([varepsilon]Si[space]CP) as well as the overall sensitivity enhancement ([capital Sigma]Si[space]CP) available from the combination of DNP and CPMG acquisition. Here, , where [small theta]Si is a factor which quantifies reduction of the NMR signal by paramagnetic effects (quenching) and [small kappa] is the square root of the ratio of nuclear longitudinal relaxation times of the dry material and material impregnated with radical solution. It is found that [capital Sigma]Si[space]CP is always substantially lower than the measured value of [varepsilon]Si[space]CP due to paramagnetic effects which reduce the II of the 29Si CP solid-state NMR spectra at high biradical concentrations. In this system, it is observed that the sample preparation which provides optimal DNP signal enhancement does not provide optimal overall signal enhancement. Notably, optimal signal enhancements are obtained for CPMG acquisition of the 29Si solid-state NMR spectra when lower radical concentrations are employed due to slower transverse relaxation rates. To the best of our knowledge this is the first study which seeks to quantify the overall sensitivity enhancements available from DNP solid-state NMR experiments.

Non-aqueous solvents for DNP surface enhanced NMR spectroscopy

Zagdoun, A.; Rossini, A. J.; Gajan, D.; Bourdolle, A.; Ouari, O.; Rosay, M.; Maas, W. E.; Tordo, P.; Lelli, M.; Emsley, L.; Lesage, A.; Coperet, C. Chemical Communications 2011.

http://dx.doi.org/10.1039/C1CC15242D

A series of non-aqueous solvents combined with the exogenous biradical bTbK are developed for DNP NMR that yield enhancements comparable to the best available water based systems. 1,1,2,2-tetrachloroethane appears to be one of the most promising organic solvents for DNP solid-state NMR. Here this results in a reduction in experimental times by a factor of 1000. These new solvents are demonstrated with the first DNP surface enhanced NMR characterization of an organometallic complex supported on a hydrophobic surface.

Non-aqueous solvents for DNP surface enhanced NMR spectroscopy

Zagdoun, A.; Rossini, A. J.; Gajan, D.; Bourdolle, A.; Ouari, O.; Rosay, M.; Maas, W. E.; Tordo, P.; Lelli, M.; Emsley, L.; Lesage, A.; Coperet, C. Chemical Communications 2011.

http://dx.doi.org/10.1039/C1CC15242D

A series of non-aqueous solvents combined with the exogenous biradical bTbK are developed for DNP NMR that yield enhancements comparable to the best available water based systems. 1,1,2,2-tetrachloroethane appears to be one of the most promising organic solvents for DNP solid-state NMR. Here this results in a reduction in experimental times by a factor of 1000. These new solvents are demonstrated with the first DNP surface enhanced NMR characterization of an organometallic complex supported on a hydrophobic surface.

Beyond the Silica Surface by Direct Silicon-29 Dynamic Nuclear Polarization

Lafon, O., Rosay, M., Aussenac, F., Lu, X., Trébosc, J., Cristini, O., Kinowski, C., Touati, N., Vezin, H., and Amoureux, J.-P. (2011) Beyond the Silica Surface by Direct Silicon-29 Dynamic Nuclear Polarization, Angew. Chem. Int. Ed., n/a-n/a.

http://dx.doi.org/10.1002/anie.201101841

Buried truth: High-field magic angle spinning dynamic nuclear polarization (MAS DNP) enhances the sensitivity of solid-state NMR spectroscopy, but only for protonated surfaces. Direct 29Si DNP using the biradical TOTAPOL circumvents this limitation by producing a 30-fold enhancement of subsurface 29Si NMR signals in mesoporous silica, a material with applications in photonics, nanotechnology and catalysis.

Beyond the Silica Surface by Direct Silicon-29 Dynamic Nuclear Polarization

Lafon, O., Rosay, M., Aussenac, F., Lu, X., Trébosc, J., Cristini, O., Kinowski, C., Touati, N., Vezin, H., and Amoureux, J.-P. (2011) Beyond the Silica Surface by Direct Silicon-29 Dynamic Nuclear Polarization, Angew. Chem. Int. Ed., n/a-n/a.

http://dx.doi.org/10.1002/anie.201101841

Buried truth: High-field magic angle spinning dynamic nuclear polarization (MAS DNP) enhances the sensitivity of solid-state NMR spectroscopy, but only for protonated surfaces. Direct 29Si DNP using the biradical TOTAPOL circumvents this limitation by producing a 30-fold enhancement of subsurface 29Si NMR signals in mesoporous silica, a material with applications in photonics, nanotechnology and catalysis.

Have a question?

If you have questions about our instrumentation or how we can help you, please contact us.