Physicochemical insights on the extraordinary binding of CdSeS/ZnS quantum dots with zinc porphyrazine studied in solution

The alloyed quantum dots, namely, CdSeS/ZnS (QD), undergo spontaneous interaction with a zinc porphyrazine (ZnPz) in toluene. Spectral overlap of the absorption spectrum of ZnPz and fluorescence spectrum of QD elicits an overlap integral value of 4.47 × 10 -13 dm 3 .mol -1 .cm 3 . Fluorescence measurements evoke a considerable amount of quenching of the photoluminescence (PL) of QD (observed at 662 nm) in the presence of ZnPz. PL experiments evoke an immense value of binding constant (K) of QD-ZnPz system, i.e., K QD-ZnPz = 3.76 × 10 5 dm 3 mol -1 , which gets outstanding support from the observation of emissive charge transfer band and isoemissive point located at 612 nm and 636 nm, respectively. The estimated value of the bimolecular quenching constant (k q ) of the QD-ZnPz system (k q ~ 1.6 × 10 11 dm 3 mol -1 sec -1 ) suggests that the static quenching mechanism prevails over the diffusion-driven process in the present work. Scanning electron microscopy, dynamic light scattering, and fluorescence microscopy experiments reveal significant interaction between QD and ZnPz in solution. The present work opens up excellent opportunities to employ ZnPz as a selective binding receptor for alloyed-type quantum dots in the near future.