Related Experiment Video
Updated: Jun 26, 2025

Synthesis and Microdiffraction at Extreme Pressures and Temperatures
Published on: October 7, 2013
Evolution of structure and spectroscopic properties of a new 1,3-diacetylpyrene polymorph with temperature and
A Zwolenik1, D Tchoń1, A Makal1
1Biological and Chemical Research Centre, Faculty of Chemistry, University of Warsaw, Żwirki i Wigury 101, 02-089 Warszawa, Poland.
Abstract:
A new polymorph of 1,3-diacetylpyrene has been obtained from its melt and thoroughly characterized using single-crystal X-ray diffraction, steady-state UV-Vis spectroscopy and periodic density functional theory calculations. Experimental studies covered the temperature range from 90 to 390 K and the pressure range from atmospheric to 4.08 GPa. Optimal sample placement in a diamond anvil cell according to our previously presented methodology ensured over 80% data coverage up to 0.8 Å for a monoclinic sample. Unrestrained Hirshfeld atom refinement of the high-pressure crystal structures was successful and anharmonic behavior of carbonyl oxygen atoms was observed. Unlike the previously characterized polymorph, the structure of 2°AP-β is based on infinite π-stacks of antiparallel 2°AP molecules. 2°AP-β displays piezochromism and piezofluorochromism which are directly related to the variation in interplanar distances within the π-stacking. The importance of weak intermolecular interactions is reflected in the substantial negative thermal expansion coefficient of -55.8 (57) MK-1 in the direction of C-H...O interactions.
Related Concept Videos
¹H NMR of Conformationally Flexible Molecules: Variable-Temperature NMR
Atomic Spectroscopy: Effects of Temperature
At thermal equilibrium, the relative populations of excited and ground state atoms can be estimated using the Maxwell–Boltzmann distribution. For example, an increase in temperature...
UV–Vis Spectroscopy: Woodward–Fieser Rules
¹H NMR of Conformationally Flexible Molecules: Temporal Resolution
IR and UV–Vis Spectroscopy of Aldehydes and Ketones
Phase Diagram

