A non-planar, hexadeca-substituted, metal-free phthalocyanine

The readily prepared 2,3,9,10,16,17,23,24-octamethyl-1,4,8,11,15,18,22,25-octaoctyloxyphthalocyanine (Pc 1) adopts a non-planar conformation in the crystalline state as indicated by a dihedral angle of 27.2 degrees formed between isoindole subunits on opposite sides of the core. The ring distortion can be attributed to a combination of steric congestion of the side-chains and the stabilization of the saddle-shaped conformation via pairing of molecules to give the so-called,overlap effect'. The ring distortion is compared to that found in other metal-free phthalocyanines. Pc I adsorbs strongly in the near-IR region, is highly soluble and gives robust spin-coated films of excellent optical clarity. Copyright (C) 2005 Society of Porphyrins & Phthalocyanines.