Study of high-pressure Raman intensity behavior of aromatic hydrocarbons: Benzene, biphenyl and naphthalene

Raman spectra of benzene, naphthalene and biphenyl have been taken up to a pressure of 13 GPa. The results for benzene and naphthalene indicate that the perturbation of inter-molecular π–π stacking effect on the Raman intensity is neglectable. For biphenyl, all the Raman peaks show intensity enhancement during the compression process, which indicates the planar intra-molecular aromatic conformation play an important role in the intensity increments of Raman bands. For three aromatic compounds, C–H stretching vibration bands located at about 3000 cm−1 show intriguing intensity changes during compression account for the inter-molecular C–H⋯π interaction.

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► We applied the high pressure Raman spectroscopy to investigate the π–π interactions.
► An useful method was proposed to identify the planarization of para-polyphenyls.
► This is the first example of high pressure Raman investigation on C–H⋯π interactions.