Massachusetts Institute of Technology

Université´ D'aix-Marseille

Robert G Griffin

Timothy Manning Swager

Paul Tordo

Yoh Matsuki

Francois Le Moigne

Thorsten Maly

Hakim Karoui

Kan-Nian Hu

Neil Adam Gershenfeld

Olivier Ouari

William Kai Langford

Prashant Patil

Eric Dane

Oliver Ouari

Zachary Fredin

Daniel Banks

Camron Blackburn

Olesya Haze

Salima Bahri

Changsik Song

Albert A Smith

Bjorn Corzilius

François Le Moigne

A method for fabricating MAS NMR rotors and drive caps made of diamond to increase the maximum achievable spinning frequency and enhance MAS NMR sensitivity and resolution. Diamond is an excellent choice for making MAS NMR rotors due to its high tensile and flexural strength, however, micromachining diamond is difficult due to its hardness. Although laser cutting is often employed to cut diamond sheets, this process cannot be used to create the high aspect ratio and small features required for MAS NMR rotors. In the present invention, a laser micromachining process is used to create the desired high aspect ratio while maintaining the small lateral features. In this process, the laser is used to first convert the diamond into graphite followed by a conversion to carbon dioxide in the presence of oxygen. To create a rotor, a rectangular log has a center hole drilled by the laser, and is then micromachined into a hollow cylinder.

Diamond rotors for MAS-NMR

The present invention relates to the field of organic chemistry and in particular to organic free radicals used as polarizing agents in the technique of Dynamic Nuclear Polarization (DNP), which involves transferring the polarization of electron spins to the nuclei of a compound whose Nuclear Magnetic Resonance (NMR) is being observed. It concerns Dinitroxide-type Biradical polarizing agents characterized by a rigid linkage between the aminoxyl groups of said nitroxide units. This particular structure enables, at low temperatures and high fields, optimal transfer of polarization and optimal enhancement of NMR/MAS signals of the polarized nuclei of the compound studied.

Dinitroxide-type biradical compounds optimized for dynamic nuclear polarization (DNP)

The present invention provides a variety of radicals, which are useful as polarizing compounds. Exemplary radicals are represented by compounds of Structural Formulae (I), (II), (III) and (IV) as described herein.

Radical polarizing agents for dynamic nuclear polarization

The present invention relates to the field of organic chemistry and in particular to organic free radicals used as polarizing agents in the technique of Dynamic Nuclear Polarization (DNP), which involves transferring the polarization of electron spins to the nuclei of a compound whose Nuclear Magnetic Resonance (NMR) is being observed. It concerns dinitroxide-type biradical polarizing agents characterized by a rigid linkage between the nitroxide units that enables optimal orientation and distance to be maintained between the aminoxyl groups of said nitroxide units. This particular structure enables, at low temperatures and high fields, optimal transfer of polarization and optimal enhancement of NMR/MAS signals of the polarized nuclei of the compound studied.

The present invention provides methods for performing dynamic nuclear polarization using biradicals with a structure of formula (I) as described herein. In general, the methods involve (a) providing a frozen sample in a magnetic field, wherein the frozen sample includes a biradical of formula (I) and an analyte with at least one spin half nucleus; (b) polarizing the at least one spin half nucleus of the analyte by irradiating the frozen sample with radiation having a frequency that excites electron spin transitions in the biradical; (c) optionally melting the sample to produce a molten sample; and (d) detecting nuclear spin transitions in the at least one spin half nucleus of the analyte in the frozen or molten sample. The present invention also provides biradicals with a structure of formula (I) with the proviso that Qand Qare different when Xand Xare &#x2014;O&#x2014;. The present invention also provides methods for making biradicals with a structure of formula (IA) as described herein.

Biradical polarizing agents for dynamic nuclear polarization

We describe polarizing agents for use in enhancing NMR and MRI signals via dynamic nuclear polarization (DNP). The polarizing agents include two or more paramagnetic centers, preferably two paramagnetic centers. In a preferred embodiment, the polarizing agent comprises two nitroxide radicals tethered by a polyethylene glycol chain of variable length. Signal enhancements of up to 175 have been achieved in comparison with factors of &#x2dc;45 at similar concentrations of monomeric radical such as TEMPO.

Polarizing agents for dynamic nuclear polarization

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Newton, MA, United States of America

Robert G Griffin