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Keywords:

  • click chemistry;
  • dendrimers;
  • electron transfer;
  • energy transfer;
  • fluorescence;
  • phosphorescence;
  • porphyrinoids

Abstract

The click chemistry synthesis and photophysical properties, notably photo-induced energy and electron transfers between the central core and the peripheral chromophores of a series of artificial special pair–dendron systems (dendron=G1, G2, G3; Gx=zinc(II) tetra-meso-arylporphyrin-containing polyimides) built upon a central core of dimethylxanthenebis(metal(II) porphyrin) (metal=zinc, copper), are reported. The dendrons act as singlet and triplet energy acceptors or donors, depending on the dendrimeric systems. The presence of the paramagnetic d9 copper(II) in the dendrimers promotes singlet–triplet energy transfer from the zinc(II) tetra-meso-arylporphyrin to the bis(copper(II) porphyrin) unit and slow triplet–triplet energy transfer from the central bis(copper(II) porphyrin) fragment to the peripheral zinc(II) tetra-meso-arylporphyrin. If bis(zinc(II) porphyrin) is the central core, evidence for chain folding is observed; this is unambiguously demonstrated by the presence of triplet–triplet energy transfer in the heterobimetallic systems, a process that can only occur at short distances.