Premium
Direct Spectroscopic Evidence of the Mechanism behind the Phase Transition of [2,2]‐Paracyclophane
Author(s) -
Wolf Hilke,
Lock Nina,
Parker Stewart F.,
Stalke Dietmar
Publication year - 2015
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.201405948
Subject(s) - conformational isomerism , phase transition , phase (matter) , raman spectroscopy , materials science , perpendicular , inelastic neutron scattering , spectroscopy , crystallography , ethylene , neutron scattering , scattering , chemistry , molecular physics , condensed matter physics , physics , optics , molecule , organic chemistry , geometry , mathematics , quantum mechanics , catalysis
[2,2]‐Paracyclophane undergoes phase transitions at 45 and 60 K. Based on simultaneous Raman spectroscopy and inelastic neutron scattering experiments (12–70 K), it was shown that a twisting motion of the ethylene bridge perpendicular to the plane of the aromatic rings drives the phase transition. The low‐temperature (<45 K) and high‐temperature (>60 K) conformers only differ by this twisting motion, which freezes out below 45 K and is thermally averaged above 60 K. Between 45 and 60 K, the system gains energy until the phase transition is complete.