Nitrogen-Vacancy Centers to Advance NMR and MRI

Nuclear Magnetic Resonance (NMR) and Magnetic Resonance Imaging (MRI) have been involved in almost all facets of science ranging from discovering unknowns within samples to expanding our knowledge of the human body. 

Although grand, these instruments have their limitations and it is through nitrogen-vacancy (NV) centers that these limitations will be abolished. The primary scale in which science can scan at the moment only reaches down to the micrometer and to go any further involves a large amount of money and time or specific subzero temperatures². 

NV centers are able to circumvent the current expensive and temperature locked methods by not requiring external magnetic fields and using synthetic diamonds that can gather information at ambient temperatures¹. NV centers are defects found within diamonds which have been proven to detect proton nuclear spins in samples within a volume of 5 cubic nanometers. When the sample, atop the diamond detector, is subjected to radio waves there is a fluorescent response measuring excitation and relaxation spins of the protons within the sample that is transformed into interpretable data by computers³. 

Although different from standard NMR and MRI instrumentation the use of magnetic resonance is the same. Imaging produced through the use of NV centers is still in the works as MRI is a form of NMR so too will its advance come once NMR is mastered under these new conditions.

Written by Jason Bingaman

Sources

     1.     Kemsley, J. “Taking NMR And MRI To The Nanoscale”, Chemical and Engineering News, Vol. 91 Issue 5 Pg. 4, February 4, 2013. https://cen.acs.org/articles/91/i51/Taking-NMR-MRI-Nanoscale.html

  2.     Reinhard, F. et al. “Nuclear Magnetic Resonance Spectroscopy on a (5-Nanometer)³ Sample Volume”. http://www.sciencemag.org/content/339/6119/561

        3.     Rugar, D. et al. “Nanoscale Nuclear Magnetic Resonance with a Nitrogen-Vacancy Spin Sensor”. http://www.sciencemag.org/content/339/6119/557

 

Renewable Cyanate Ester Compound for Naval Assets

Cyanate esters are a remarkable family of compounds that exhibit many useful properties in the materials world. They retain their structural integrity into the 400⁰ C range, they have extremely low water uptake, making them ideal for corrosion-resistant coatings which the Navy requires for its sea-borne assets.

At China Lake we set out to create a compound with these properties that would make an attractive replacement for the current standard which is a primer laced with Chromium (a very toxic carcinogen). The structure shown above is the final product of our work which stemmed from an initial reaction using carvacrol. Carvacrol was attractive because of its structural similarity to carvone, limonene, and pinene. These chemicals, as their names imply come from and attribute to the aromas associated with caraway, citrus, and pine trees respectively. They are often the waste products of the industries that 

This is a Thermal Gravimetric Analysis (TGA) which shows our product’s high durability under intense heat. It retains almost all of its mass up until the 400⁰ C mark as is common for molecules of this family.

After sending our final product off for characterization, we set to work on finding a way to take one or all of these precursor molecules to complete synthesis. Using a series of small scale reactions, we were able to go from limonene to the final product with relative ease, thus showing the viability of this as a cheap and less toxic alternative coating methods. Current issues regarding our experiment center around high enough yields to be viable and taking pinene all the way to our finished compound. We were able to get small yields that would potentially work, but they were clouded by other isomers mixed in so a new reaction will need to be tried in order to get a more selective result.

Future Work

Now that the as of yet unnamed molecule has been characterized, we will continue to refine the overall reaction process to improve yield as well as find ways to selectively react our precursor molecules. From there our final challenge will be scaling the reaction up in size to accommodate for large scale production.

Written by Thomas Koontz