Structural Features ofmeso-Tetrakis(4-carboxyphenyl)porphyrin Interacting with Amino-Terminated Poly(propylene oxide)

Abstract

The neutralization reaction between the meso-tetrakis(4-carboxyphenyl)porphyrin (TPPC) and O-(2-aminopropyl)-O‘-(2-methoxyethyl)poly(propylene glycol) (Jeffamine M-600) in 1:4 stoichiometric ratio affords a stable supramolecular adduct (TPPC@Jeffamine). This species has been characterized in aqueous and chloroform solution through a series of spectroscopic techniques, including 1H and 13C NMR spectroscopy, UV/vis absorption, steady-state and time-resolved fluorescence emission, time-resolved fluorescence anisotropy, and resonance light scattering. All the experimental findings point to a different structural arrangement of the porphyrin chromophores within the supramolecular adduct depending on the quality of the solvent. In aqueous solution, the TPPC@Jeffamine contains mainly monomeric porphyrins while the flexible polymeric chains are folded and entangled to give larger aggregates. An insight into the structure of the basic building unit is given by SAXS measurements which, assuming a core−shell model, ...