Rafael Delaflor - Quantum Mechanical Studies of Gadolinium(III) Ligands used for MRI Contrast Agents

Document created by Rafael Delaflor on Aug 22, 2014
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  Publication Details (including relevant citation   information):

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  (pentetic acid), IR Absorption Spectrum (BR060373).

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  [6] Bayer Healthcare Radiology.   http://bayerimaging.com/products/ (accessed June 13, 2013).

  [7] de Campos, R. O. P.; Heredia, V.; Ramalho,   M.; Altun, E.; Semelka, R.C.; Gadolinium:

  Compounds, Production and Applications2010,   217-243; SciFinder Scholar.


  Determining the structure and the   chemical stability of polydentate coordinate complexes   used in MRI contrast agents is essential in the field of   diagnostic medicine. Chelation complexes using Gadolinium(III)   metal, a paramagnetic Lanthanide, produce ideal signal   intensities in diagnostic Magnetic Resonance Imaging (MRI) that   has made its use in radiology a staple and also justify its   importance for computational research. Gadolinium(III) complexes   show variable
  imaging qualities depending on the attached ligands to the   central atom and the diagnostic application they are used   for.
Our study focuses on   determining the structures and molecular properties of  three ligands, MS-325-L, COPTA,   and EOB-DTPA used in the preparation of the three Gd(III)   complexes already used for clinical applications.  Our calculations were performed   using density functional theory (DFT) with the B3LYP functional   applied in conjunction with two basis sets (3-21G and 6-31G) to   obtain the equilibrium geometries, vibrational frequencies, and   IR spectra for the ligands. The highest occupied molecular   orbital (****) – lowest occupied molecular orbital (LUMO) energy   gap values for all compounds are greater than 4 eV suggesting   that the ligands are chemically stable. The ligands exhibit   hydrogen bonding which can account for the significant chemical   stability. The ligands possess significant dipole moments with   values greaterthan 8 Debye, consistent with their chemical polar   character. Our computed vibrational frequencies were found in   excellent agreement with the experimental values, suggesting our   proposed models are good representations of the actual molecular   structures.

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