Jacob Samuel

Clathrate formation from octaazaphthalocyanines possessing bulky phenoxyl substituents: a new cubic crystal containing solvent-filled, nanoscale voids.

The synthesis of octaazaphthalocyanine (AzaPc) derivatives, with bulky phenoxyl substituents placed at eight peripheral positions and containing either H(+), Ni(2+) or Zn(2+) ions in their central cavity, is described. The required precursors, derivatives of pyrazine-2,3-dicarbonitrile, were prepared using a nucleophilic aromatic substitution reaction between 2,6-diisopropylphenol or 2,6-diphenylphenol and 5,6-dichloropyrazine-2,3-dicarbonitrile. Analysis of the resulting AzaPcs by UV/Visible and (1)H NMR spectroscopy confirms that steric isolation of the AzaPc cores was enforced both in solution and in the solid state. X-ray diffraction studies of single crystals of the AzaPcs reveal that solvent inclusion takes place in each case. Of particular significance is the finding that the zinc derivative of 2,3,9,10,16,17,23,24-octa-(2,6-diisopropylphenoxy)octaazaphthalocyanine provides nanoporous cubic crystals, containing massive (8 nm(3)) solvent-filled voids, similar to those of the analogous phthalocyanine derivative. Exchange of the included solvent within the voids can be readily achieved by using a number of alternative solvents including water. Based on the observed loading of included water, the internal volume of this nanoporous cubic crystal appears to be more hydrophilic than its phthalocyanine counterpart.

Heavy metal effects on physicochemical properties of non-aggregated azaphthalocyanine derivatives

Two series of peripherally substituted azaphthalocyanines (AzaPcs) containing different transition metals (Al(III), Zn(II), Ga(III), In(III) and Fe(II)) were synthesized and studied for their photophysical properties. As confirmed by UV-vis and 1H NMR analyses, the non-aggregation behavior was effectively induced by the applied bulky peripheral substituents which had no effect on the photophysical properties. Tuning the Q-band position was clearly achievable by using different central heavy metals which have considerable effects on the fluorescence quantum yield and singlet oxygen generation efficiency. This comparative study showed an interesting linear relationship between the former and atomic number of the central metal. The indium containing complexes exhibited the best result due to the heavy metal effect and therefore could be promoted as a potential photosensitizer in photodynamic therapy (PDT) application.