Structure-supercooling property relationship of phenylethyl phenylacetate derivatives and analogue

In this paper, three new compounds were synthesized by introduction of benzyloxy group to phenylethyl phenylacetate (PPA) and shorting the flexible ester linker. NMR spectra and mass spectra are achieved to confirm the structure of the compounds. The solid-liquid and liquid-solid phase change behaviors of PPA and these three compounds were explored by direct observation and differential scanning calorimetry (DSC) measurements. It was found that all four compounds would form supercooled liquids during a heating-cooling cycle. The supercooling degree is as large as 44 degrees C or above. The effects of benzyloxy group and the flexible linker on the phase transition processes as well as the supercooling degrees were discussed in detail with the computational optimized geometry of isolated molecules. It was revealed that the dihedral angles between adjacent phenyl rings play a significant role in tuning their phase transition temperatures. This work also discovers the high enthalpies of PPA derivatives and analogues in both solid-liquid and liquid-solid phase transition processes, making them great potentials for the thermal energy control of appropriate working temperature regions. (c) 2021 Published by Elsevier B.V.

Automated summary

Three new compounds were synthesized by introducing a benzyloxy group to phenylethyl phenylacetate (PPA) and shortening the flexible ester linker. These compounds were found to form supercooled liquids with a supercooling degree of up to 44 degrees C during a heating-cooling cycle. The effects of the benzyloxy group and the flexible linker on the phase transition processes and supercooling degrees were discussed in detail.