The photophysical and energy transfer behaviour of low symmetry phthalocyanine complexes conjugated to coreshell quantum dots: an energy transfer study

This work reports on the synthesis of new coreshell quantum dots (QDs)-low symmetry phthalocyanines conjugates. The energy transfer from QDs (donor) to phthalocyanines (acceptor) was investigated when the two are mixed together or chemically linked to each other. Ti monocarboxy phthalocyanine QDs-linked and Sn monocarboxy phthalocyanine QDs-linked gave the smallest centre-to-centre separation distance (r) corresponding to their higher Förster resonance energy transfer efficiencies which are estimated at 0.76 and 0.85 respectively. Higher energy transfer behaviour was achieved for all the covalently linked conjugates compared to their corresponding mixed counterparts. An improvement in triplet quantum yields and lifetimes was achieved for all the complexes in the presence of quantum dots, with the linked counterparts displaying excellent triplet state behaviour.

Graphical abstractThe conjugates of CdTe@ZnS quantum dot with l-low symmetry phthalocyanines show increased triplet state quantum yields and long lifetimes. More efficient energy transfer behaviour was achieved for covalently linked conjugates compared to their corresponding mixed counterparts without a chemical bond.Figure optionsDownload full-size imageDownload as PowerPoint slideHighlights► Conjugates of CdTe@ZnS quantum dots with phthalocyanines were synthesized. ► The quantum dots were capped with a peptide. ► The conjugates showed long triplet lifetimes and large triplet quantum yields. ► Förster resonance energy transfer occurred from QDs to phthalocyanines.