page_title: Vincent L. Pecoraro
section_title: Metallacrown
hierarchical_section_title: Vincent L. Pecoraro / Scientific Achievements / Metallacrown
caption_attribution_description: English: Figure showing the metallacrown analogy to crown ethers.
context_page_description: Vincent L. Pecoraro, professor at the University of Michigan, is a researcher in bioinorganic chemistry and inorganic chemistry. He is a specialist in the chemistry and biochemistry of manganese, vanadium, and metallacrown chemistry. He is a fellow of the American Association for the Advancement of Science
context_section_description: Metallacrowns are a class of cyclic compounds that contain metal ions and non-metals in repeating units. Vincent L. Pecoraro and Myoung Soo Lah reported the first metallacrown in 1989 and these compounds have since grown into their own field of research with numerous new applications.  One of the most interesting aspects of these compounds is their diversity. The ring size can be changed by incorporating new ligands or different metals into the frame work, which leads to the internal cavity also changing size.   As such, specific ions can be selectively trapped in the center by tuning the structure of the metallacrown and also, by changing the environment, such as the solvent.   Due to these unique properties and the inherent greenness associated with metallacrown synthesis (typically high yield, one step, benign solvent),  this is still an active research topic for the Pecoraro group and many other scientists around the world.
  The Pecoraro group is currently working on using metallacrowns  with selective binding for a variety of biological applications. One application is using metallacrowns for medicinal imaging. Currently, gadolinium (Gd) is used in MRI as a contrasting agent in combination with a chelating ligand. Unfortunately, if Gd is freed from its chelating agent, Gd is rather toxic to humans.  These gadolinium chelates present many health hazards and can even lead to death, though it is an uncommon occurrence and typically is only seen in patients with kidney issues.  Luckily, this same metal can also be selectively and very strongly trapped in a metallacrown motif.  Currently, the group is working on subjecting this system to a variety of conditions as seen in the body such as different pH’s and also, various compounds and metals that may also bind to the metallacrown to ensure that the toxic Gd is not displaced from the metallacrown.  Other potential uses of metallacrowns in the body include hydrolyzing phosphate diesters, a key linkage component in RNA and DNA.
  Another   part of the Pecoraro group research with metallacrowns focuses on their application as single-molecule magnet. Metallacryptate can be thought of as a metallacrown in three dimensions with a manganese oxide trapped in the middle.  The most interesting thing about this compound is that this molecule acts like a single-molecule magnet.  Currently, the group is continuing to work on fully understanding this system with the ultimate goal of applying it to memory storage devices.
  Investigating for Lanthanide separation
caption: Metallacrowns and related organic crown ethers a) 12-crown-4 b)12-MCFe(III)N-4 c) 15-crown-5 d) 15-MCCu(II)N-5
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