FT-IR and FT-Raman spectra of 2-hydroxyethyl methacrylate – A conformational and vibrational analysis

•Optimized geometries of 2-hydroxyethyl methacrylate were obtained by DFT.•Six stable conformations are found.•Calculated and scaled vibrational normal modes.•A comparison between the experimental and the computed spectra is made.•Band assignment is made with the help of PED calculations.

A conformational search of the flexible 2-hedroxyethyl methacrylate molecule by semi-empirical AM1 and B3LYP formalisms leads to six stable conformations. Four of them are in the s-trans conformation. The optimized geometries at DFT using 6-311+G∗∗ basis set are in good agreement with experimental electron diffraction data of the methyl methacrylate molecule, thereby the s-trans is the most stable form.The harmonic frequencies at the fully optimized geometries of all conformers have been performed at the DFT//B3LYP/6-311+G∗∗ level of theory. Infrared and Raman intensities and potential energy distributions of the scaled harmonic frequencies are used for the assignment of the observed IR and Raman bands. We noticed a good agreement between the experimental and the computed spectra. The strong band at 1081 cm−1, in the infrared spectrum, maybe used as a characteristic band of the s-trans conformation. Henceforth, the less stable structure contribute alone for reproducing the Raman bands located at 276 (sh) and 3020 (vw) cm−1.

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