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

According to well-known procedures, alpha- and beta-crystal polymorphic modifications of zinc(II)tetra-tert-butylphthalocianine (Zn(t-Bu)(4)Pc were prepared and X-ray analysis of their powders was carried out. It was found that four tert-butyl groups in Zn(t-Bu)(4)Pc molecule do not prevent the formation of the (alpha- and beta-polymorphs. The alpha- and beta-polymorphs differ from each other mainly by a mutual arrangement of neighboring metallophthalocyenine molecules in pi-stacking. Comparison of IR spectra of the (alpha- and beta-polymorphs of ZnPc and Zn(t-Bu)(4)Pc 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)(4)Pc 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)(4)Pc are listed. (C) 2006 Elsevier B.V. All rights reserved.