X-ray diffraction and IR spectral characteristics of zinc(II)tetra-tert-butylphthalocyanine

According to well-known procedures, α- and β-crystal polymorphic modifications of zinc(II)tetra-tert-butylphthalocianine (Zn(t-Bu)4Pc) were prepared and X-ray analysis of their powders was carried out. It was found that four tert-butyl groups in Zn(t-Bu)4Pc molecule do not prevent the formation of the α- and β-polymorphs. The α- and β-polymorphs differ from each other mainly by a mutual arrangement of neighboring metallophthalocyenine molecules in π-stacking. Comparison of IR spectra of the α- and β-polymorphs of ZnPc and Zn(t-Bu)4Pc was carried out. It was indicated that new bands appear at 670-690, 1256 and 1362 cm−1 in the spectrum of Zn(t-Bu)4Pc in comparison with that of ZnPc. The appearance of new band at 1256 cm−1 is assigned to rocking C-CH3 vibrations and the band at 1362 cm−1 to symmetrical deformational C-H vibrations of methyl groups of the peripheral substitutes. The main spectral characteristics for identification of the polymorphic modifications of Zn(t-Bu)4Pc are listed.