External Complexation of BODIPYs by CB[7] Improves in-Cell Fluorescence Imaging

Mehmet Menaf M Ayhan (1) , Emrah Özcan (2) , Fahri Alkan (3) , Metin Çetin (4) , İlker Ün (3) , David Bardelang (5) , Bunyemin Cosut (6)

1 Department of Chemistry, Gebze Technical University, P.K.:141, 41400 Gebze, Kocaeli, Turkey
2 Institute of Physics, Faculty of Science, University of South Bohemia, Branišovská 1760, 370 05, České Budějovice, Czech Republic
3 Department of Nanotechnology Engineering, Abdullah Gül University, Kayseri, Turkey
4 Department of Molecular Biology and Genetics, Gebze Technical University, Gebze, Kocaeli, Turkey
5 ICR - Institut de Chimie Radicalaire
6 Department of Chemistry, Gebze Technical University, P.K.:141, 41400 Gebze, Kocaeli, Turkey

Organic luminescent compounds with high emission properties play a crucial role in fluorescence labelling and optoelectronic devices. In this work, we prepared three water soluble BODIPY derivatives (B-4, B-5, and B-6) which are weakly fluorescent due to non-radiative relaxation pathways (charge transfer: CT or heavy atom effect). However, CB[7] significantly improves BODIPY fluorescence by ∼10 fold for B-4, and ∼3 fold for B-5. (TD)DFT analyses suggest that for B-4 and B-5, the CT state is blue-shifted as a result of CB[7] external binding near the pyridinium groups. This effect favoured a radiative decay through a locally-excited (LE) * transition state of BODIPYs resulting in a CB[7]-induced emission increase in solution (and in the solid state), without compromising singlet-to-triplet intersystem crossing (ISC). The improved emission of BODIPY•CB[7] complexes was used for fluorescence imaging of U87 cells illustrating the relevance of this approach. These results suggest that BODIPY•CB[7] complexes could be used as theragnostic agents by combining fluorescence imaging and treatment by photodynamic therapy.

Domains: Chemical Sciences

Mehmet Menaf M Ayhan, Emrah Özcan, Fahri Alkan, Metin Çetin, İlker Ün, et al.. External Complexation of BODIPYs by CB[7] Improves in-Cell Fluorescence Imaging. Materials Advances, 2021, ⟨10.1039/D1MA00931A⟩. ⟨hal-03442810⟩