Experimental and theoretical investigation of vibrational spectra of copper phthalocyanine: polarized single-crystal Raman spectra, isotope effect and DFT calculations

The IR- and Raman spectra of copper phthalocyanine (CuPc), as well as the isotopic wavenumber shifts upon N-15 substitution in CuPc, were investigated experimentally and theoretically. The symmetry of molecular vibrations was determined using polarized Raman spectra of an oriented CuPc single crystal. Density functional theory (DFT) calculations were used for the detailed assignment of different bands in the vibrational spectra of CuPc. Theoretically predicted geometry, wavenumbers and isotopic shifts are in a very good agreement with the experimental values. A comparison of experimentally obtained isotopic shifts with theoretical predictions allowed us to reveal some characteristic features of normal vibrations of CuPc molecule. Copyright (C) 2009 John Wiley & Sons, Ltd.