Abstract by Jason Calvin
Chemistry and Biochemistry
Heat Capacity and Thermodynamics of Zinc 2-Ethylimidazolate
Zinc 2-ethylimidazolate is a metal organic framework that has several polymorphs that can be synthesized by mechanically milling zinc oxide with 2-ethylimidazole for different amounts of time. A previous study on the enthalpies of these polymorphs indicated that the transformation between polymorphs was thermodynamically driven. To confirm this hypothesis, the heat capacity of the various polymorphs was measured on a QD PPMS and the entropy of these materials was calculated. The entropy of these materials did not follow the expected pattern, where more dense phases should have less entropy. By combining the entropy data with the enthalpy data, the Gibb’s free energy of the transitions were calculated, and the difference in free energy between the polymorphs was much smaller than originally anticipated. Additionally, each polymorph had an anomalous heat capacity feature, which is currently under investigation.