Effect of heteroatom doped carbon quantum dots on the red emission of metal conjugated phthalocyanines through hybridization.

Quantum dots (QDs) are significant fluorescent materials for energy transfer studies with phthalocyanines (Pcs) and phthalocyanine (Pc) like biomolecules (like chlorophylls). Especially, carbon based QDs are used in numerous studies concerning energy transfer studies with chlorophylls, but the number of studies concerning energy transfer between phthalocyanines and carbon based QDs are limited. In this study, peripherally, hydroxythioethyl terminal groups substituted metal-free (H2 Pc) and zinc phthalocyanine (ZnPc) were non-covalently (electrostatic and/or π-π interaction) attached to carbon QDs, containing boron and nitrogen to form QDs-Pc nanoconjugates. The QDs-Pc conjugates were characterized using different spectroscopic techniques (FT-IR, TEM). Absorption and fluorescence properties of QDs-Pc structures in solution were studied. It was found that the quantum yields of the QDs slightly decreased from 30 % to 25 % upon doping the QDs with heteroatoms, B and N. The FRET efficiency was calculated as 33 % for BCN-QD/ZnPc. For the other conjugates, almost no energy transfer from QDs to Pc cores was observed. It was shown that the energy transfer between QDs to Pc cores were completely different from the energy transfer between QDs and photosynthetic pigments, and concluded that heteroatom doping in QD structure and existence of zinc metal in phthalocyanine structure is obligatory for an efficient energy transfer.