Interaction of CdTe-MPA quantum dots with meso-tetra methyl pyridyl porphyrin. Charge transfer complex formation

Abstract

The unique characteristics of quantum dots (QD), such as an intensive and narrow luminescence spectrum, broad and intense absorption spectrum and high chemical and photostability, make them promising for applications in various fields, including in medicine as probes in the cancer luminescence diagnostics. The effective light absorption by QD in a wide spectral region allows their use as an antenna to accumulate light energy and transfer this energy to other photoactive compounds (photosensitizers, PS). A charge transfer complex between QD and PS can be formed as well. This can change spectral and energetic characteristics of the complex components, thus affecting their efficiency in applications. In this work we demonstrate the formation of a charge transfer complex between CdTe QD functionalized by 3-Mercaptopropionic Acid (3-MPA) and meso-tetra methyl pyridyl porphyrin (TMPyP) in water solutions and present its excited state spectral and temporal characteristics. The complexation constant was Kb = 5.5 ± 0.5 M−1. On the base of the QD luminescence quenching at complexation we propose the network structure of the TMPyP-QD complex.