Vibrational study of 5-azacytosine and propanedinitrile under high pressure

The effect of high pressure on the vibrational modes of 5-azacytosine (C3H4N4O) and propanedinitrile (CH2(CN)2) was investigated at room temperature using a diamond anvil cell (DAC). In situ infrared and Raman spectroscopy results indicated that the ring structure of 5-azacytosine remained preserved and the band shifts induced by high pressure were fully reversible up to 13 GPa. For the open-chain structure of propanedinitrile, a polymerization reaction was observed by infrared spectroscopy almost instantly at about 15 GPa at room temperature. The same pressure-induced polymerization was observed after a week at 1 GPa, at room temperature.