A water soluble macromolecular nanobox having porphyrinic walls as a large host for giant guests

Abstract

Cyclic tetra{5,15-di-[p(ω-methoxypolyethyleneoxy)phenyl]-10,20-[p- oxyphenyl] methylen porphyrin}, cy-[O-(H2-PTPEG2)-O- CH2-]4, a water soluble macromolecule consisting of four porphyrin units [each with two long ω-methoxypolyethyleneoxy (PEG) branches bound on its peripheral positions] linked by means of four methylenoxy bridges, was prepared by an interfacial etherification reaction. Structural and spectroscopic characterization of cy-[O-(H2-PTPEG2)-O- CH2-]4 and of its cobalt-derivative {cy-[O-(Co-PTPEG 2)-O-CH2-]4} was performed by means of MALDI-TOF mass spectrometry, NMR, UV-vis, and circular dichroism spectroscopy. The data obtained from the cy-[O-(Co-PTPEG2)-O-CH2-] 4/Gramicidin-S mixture showed that some evident spectral changes were compatible with the formation of a supramolecular structure between the porphyrinic nanobox and the Gramicidin S (a polypeptide having a relevant pharmacological importance). These preliminary data highlight how cy-[O-(H 2-PTPEG2)-O-CH2-]4 and/or its metalled derivatives, for their both chemical composition and structural arrangement, have promising properties for applications as a drug carrier in aqueous media. © 2013 Wiley Periodicals, Inc.