X-FORM METAL-FREE PHTHALOCYANINE - CRYSTAL-STRUCTURE DETERMINATION USING A COMBINATION OF HIGH-RESOLUTION X-RAY-POWDER DIFFRACTION AND MOLECULAR MODELING TECHNIQUES

A combination of high resolution X-ray diffraction and molecular model ling techniques have been used to determine (R(wp) = -12.51%) the crys tal structure of the X-form of metal-free phthalocyanine, It was found to crystallise in a bimolecular monoclinic unit cell (space group P2( 1)/a) with lattice parameters a = 10.63, b = 23.15, c = 4.89 Angstrom, beta = 95.98 degrees in a 'herring-bone' molecular packing motif with a smaller angle (50 degrees) than is found in the more stable beta-po lymorph (89 degrees).