Effects of high pressure on the Raman and fluorescence emission spectra of two novel 1,3,4-oxadiazole derivatives

The effects of pressure on the fluorescence emission and Raman spectra of 1,4-bis(4-methyloxyphenyl)-1,3,4-oxadiazolyl- 2,5-bisheptyloxyphenylene (OXD-2) and on the fluorescence emission spectra of 1,4-bis(4-methylphenyl)-1,3,4-oxadiazolylphenylene (OXD-1) are investigated using a diamond anvil cell. With the increase of pressure, the intensity of the fluorescence emission increases and reaches maxima at 13GPa for OXD-1 and at 9.6GPa for OXD-2. The effect of pressure on the peak position of the emission shows a similar trend, red shift with the increase of pressure. But at higher pressures, the intensity of emission drops down dramatically. The Raman spectra of OXD-2 indicate that there appears a structural change at ca 3GPa.