Functional Modifications and Electronic Influences on Tetra-aza Macrocyclic Cu(II) Complexes Interview with Brian P. Niebuhr

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Brian P. Niebuhr, Class of 2019


A library of novel tetra-aza macrocyclic molecules, specifically 3,6,9,15-tetraazabicyclo [9.3.1]pentadeca-1(15),11,13-trienederivatives, capable of chelating metal ions in vivo have been synthesized. Applications of these complexes are currently being pursued as a 1) therapeutic, focusing on radical scavenging and metal chelation, and 2) diagnostic tool such as magnetic resonance imaging (MRI) contrast agents when complexed with specific metal ions. However, a full study of the electronic effects imparted by substitution to the pyridyl moiety and the subsequent impact on the metal center have not been explored. The objective of the present study is to characterize metal complexes of four tetra-aza macrocyclic metal chelating molecules. The pyridyl functional groups studied include: A) uper (II) complexes. Analysis of the resulting copper (II) complex of the p-nitrile tetra-aza macrocycle (L6) indicate a six-coordinate metal center based on X-ray diffraction. UV-visible spectroscopy and electrochemistry help to confirm donor strength among the ligand series as well as a comparison to other tetra-aza macrocycles of interest. modified pyridyl (L1), B) p-hydroxyl (L2), and C)p-nitrile modified pyridyls (L6) on a pyclen base structure. Notable progress has been made in developing an optimal procedure for obtaining cop.

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Comments from Mentors

“Brian is an excellent student. He balances a very rigorous academic schedule and is still able to be an active member of many programs at TCU. He balances everything and still has a genuine smile on his face, always ready to brighten the day of his colleagues. Brian’s research project is integrating knowledge from all of his chemistry coursework to date to understand how copper interacts with a series of small molecules developed by our team. This work is important to our projects related to developing therapeutics for Alzheimer’s disease and new small molecule catalysts as well. We are delighted to have Brian as a part of the research team and look forward to publishing his findings in the next year.”

– Kayla Green


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College of Science and Engineering