The synthesis and photophysical properties of zinc (II) phthalocyanine bearing poly(aryl benzyl ether) dendritic substituents

Zinc (II) phthalocyanines carrying four poly(aryl benzyl ether) dendritic substituents with terminal cyano and carboxylic acid functionalities were synthesized and characterized using elemental analysis, 1H NMR, IR, UV–vis and matrix-assisted laser-desorption ionization time-of-flight spectra. Phthalocyanines with terminal cyano groups were essentially non-aggregated in common organic solvents whilst the aqueous aggregation tendency of those which contained terminal carboxylic acid groups decreased with increasing size of the dendron. Photoinduced electron transfer in these compounds was investigated using a fluorescence quenching method, employing both neutral and cationic quenchers. Upon excitation of the dendritic subunits in DMSO, the cyano compounds underwent intermolecular energy transfer from the excited dendritic subunits to the phthalocyanine core which acted as an energy trap.