Synthesis and characterisation of novel phthalocyanine-based porous materials

Abstract

Phthalocyanines are planar aromatic macrocycles whose unique properties give them a wide variety of potential applications, particularly as pigments and dyes, but also in solar cells, photodynamic therapy and as catalysts. The latter in particular is of interest given the ability of phthalocyanines to complex all metal atoms, and so the further development of materials to allow the use of phthalocyanines in heterogeneous catalysis is an important field. To this end, this work describes the efforts which we have undertaken to incorporate different phthalocyanine ligands into novel materials, with a view to achieving sufficient porosity to allow catalytic applications. In seeking to develop phthalocyanine-based Metal Organic Frameworks (MOFs), we have employed both novel and previously reported ligands in MOF syntheses, and have obtained crystalline structures, though full structural elucidation remains elusive. Relatively low internal porosities have also been measured, likely due to the inherent aggregation tendencies of phthalocyanines. We also demonstrate the use of the tetraimidophthalocyanine functionality in the synthesis of a series of network polymers, using the tetracyclomerisation step for polymerisation. Whilst several examples are entirely non-porous as a result of dense packing of the phthalocyanine rings, we also report two novel polymers containing bulky functionalities to overcome this restraint, which do show greater internal surface areas. Finally, new molecular crystals are described, showcasing the incorporation of numerous tetraphenylporphyrin (TPP) ligands into a phthalocyanine molecular crystal system widely studied within the group. Extensive spectroscopic studies of the resulting interactions have been carried out, and these are compared to crystallographic data to give significant insight into the effect of variation of the metal centre and by substitution of different functionalities in the TPP.