Conformational analysis of p-terphenyl by vibrational spectroscopy and density functional theory calculations

✍ Scribed by K. Honda; Y. Furukawa

• Publisher: Elsevier Science
• Year: 2005
• Tongue: English
• Weight: 176 KB
• Volume: 735-736
• Category: Article
• ISSN: 0022-2860
• DOI: 10.1016/j.molstruc.2004.11.019

✦ Synopsis

The structures, vibrational frequencies, and infrared and Raman intensities of p-terphenyl have been calculated by the density functional theory method at the B3LYP/6-311CG** level. On the basis of the results, the infrared and Raman spectra of p-terphenyl in solution and in the melt have been analyzed. The observed spectra have been attributed to two stable rotational isomers around the inter-ring CC bonds: a helical conformer (D 2 symmetry) and an alternately twisted conformer (C 2h symmetry). These two isomers coexist in solution and in the melt. The 518-cm K1 infrared band and the 375-cm K1 Raman band of the helical conformer are correlated with the 483-cm K1 infrared band and the 329-cm K1 Raman band of the twisted conformer, respectively. All of these bands have been assigned to the mixtures of out-of-plane boat deformations and in-plane rotational displacements. The frequencies of these modes are sensitive to the conformation of p-terphenyl.