Chahna Choksi and Hilbriel Hilvano

Abstract:

A series of liquid crystalline porphyrins have been found to undergo several thermal transitions upon heating, including a kinetic cold crystallization in which the molecules spontaneously organize into large, disc-like structures. Various metals were added to the center of the porphyrin ring to assess how their presence changes the porphyrin’s thermal behaviors. Previously used procedures for the metalation were changed to result in an unsolvated porphyrin that could be better analyzed using thermogravimetric analysis and then differential scanning calorimetry. Avrami, Ozawa, and Mo analyses were used to compare the cold crystallization events at different heating and cooling rates across the different metalloporphyrin species. 1H- and 13C-NMR and MALDI-TOF MS were used to characterize the chemical shifts caused by the metals and then compared to the free-base porphyrin.