Discipline: Chemistry and Chemical Sciences
Subcategory: Chemistry (not Biochemistry)
Madalynn Marshall - Iowa State University
Co-Author(s): Bruce Hudson and Valerie Lopez-Diaz, Syracuse University, Syracuse, NY
Barbituric acid is a famous molecule in pharmaceutics for its uses as a depressant. The molecule itself is not as commonly known. Barbituric acid has been found to have several polymorphs, and is unique in the fact that it exhibits the rare case of tautomeric polymorphism. This research covers the crystal growth and design of the different polymorphic forms, particularly the tautomeric polymorphs. Crystals were grown in different solvents and with different rates of change in temperature. To analyze the crystals, density gradients were incorporated for determining an approximated density, and for more accurate data single crystal x-ray diffraction was performed. A main focus of this project was to grow diketo monohydroxy tautomeric crystals and compare the diffraction data to the powder and x-ray diffraction data for barbituric acid from Angew Chemie1. The diketo monohydroxy tautomeric crystals were grown successfully and as a result the diffraction data did compare to the x-ray diffraction data but not to the powder diffraction data from Angew Chemie1. Experiments were also performed to determine other known forms and to attempt to discover new polymorphic forms. Computational work was done using Gaussian to determine stability in the isolated crystal structures and the accuracy in the diffraction data. Another attempted was to deuterate barbituric acid; future work on the deuterated species should be done to understand the best method of growth and the effects deuterium will have on the molecule’s structure. Future work should also be done to analyze the crystal samples that had unique densities, to conclude if they are new polymorphic forms.
1Thermodynamically Stable Form of Solid Barbituric Acid: The Enol Tautomer, Angew. Chemie, Int. Ed. 50, 7924-7926, S7924/1 -S7924/72011 DOI:10.1002/anie. 201101040
Funder Acknowledgement(s): Dr. Bruce Hudson
Faculty Advisor: Bruce Hudson, Xueyu Song,