Water-Soluble Star Polymers with a Phthalocyanine as the Core and Poly(ethyleneglycol) Chains as Branches

Uncharged water-soluble phthalocyanines Pc’s) and some metallophthalocyanines (Me-Pc’s) were prepared by means of a chemical modification of a commercial Pc or by a cyclic tetramerization reaction starting from 4-nitrophthalonitrile derivatives. The necessary hydrophilic-ity for the water solubility of these Pc derivatives was achieved by the binding of eight 9-methoxytriethyleneoxy branches on peripheral Pc positions or, alternatively, four or eight linear poly(ethylene glycol) methyl ether (PEGME;weight-average molar mass¼350 or 750 g/mol) units. The chemical structure of these products was characterized by 1H-NMR and matrix-assisted laser desorption/ionization– time -of -flight mass spectrometric analysis. Finally, their solutions were examined by ultraviolet–visible and luminescence spectroscopy and dynamic light scattering experiments. All of the samples were water soluble, although the formation of small aggregates was ascertained by dynamic light scattering measurements. Furthermore, a lower scattered light intensity was measured for Pc derivatives with longer PEGME branches, which, probably playing a more negative role in the self-assembly process, hindered the aggregation phenomenon. Preliminary data on their sensing ability are also reported.