Pressure Effect on the Inter- and Intramolecular Vibrations of Pyrazine Crystal

Abstract

The effect of pressure on the Raman active inter- and intramolecular vibrations of the pyrazine crystal was studied under hydrostatic pressure up to 5 GPa. The frequency shift of the intermolecular vibrations and the discontinuous variation of the bandwidth of the ν2 and ν1 intramolecular vibrations induced by pressure at constant temperature indicate that the pyrazine crystal undergoes phase transition (change of the molecular orientation in the crystal) under about 1 GPa. The pressure-induced frequency shift of the intramolecular vibrations was calculated using an intermolecular potential of the atom–atom type. The calculation also suggests the occurrence of the phase transition of the crystal.

Effect of pressure on heterocyclic compounds: Pyrimidine and s-triazine

“…23,24 The supramolecular assembly of pyridine/methanol (3:1) has been isolated at 1.8 GPa and 295 K. 25 Pyrazine undergoes a phase transition around 1 GPa. 26 Behaviors of pyridazine have been probed in the range 0-2 GPa. 25 As for five-membered aromatic compounds, ring opening reactions can also be initiated.…”

Pressure-controlled magnetism in 2D molecular layers

“…In organic-based magnets, molecular arrangements can be largely tuned by pressure. Copper pyrazine dinitrate shows a pressure-induced structural transition 42 , while pyrazine molecular crystal can change its molecular orientation in the crystal under pressure 43 . Therefore, the soft ligands of pyrazine molecules as magnetic superexchange pathways result in enhanced tunability in magnetism.…”