Fig. 7: The mechanistic explanation of the biotinylation effect.

Cyclic voltammograms of a compound 1, 4, b 2, 5, and c 3, 6 in DMF with 0.1 M (n-Bu)4N+PF6− as a supporting electrolyte, glassy carbon as a working electrode, Ag/AgCl as a reference electrode, Pt wire as a counter electrode, and a scan rate of 10 mVs−1. Fc/Fc+ was used as an external reference. d Photochemical reactions during Type I mechanism (3PS* represents the triple excited state of photosensitizer, PS−• represents the anion radicals of photosensitizer, 3PS* is transformed into a radical anion by accepting electrons from adjacent substrates and giving external electrons to oxygen to form O2−•). e Optimized triplet state structure, HOMO and LUMO of compound 1 (DFT, B3LYP/6-31G (d) calculated frontier orbitals relevant to the triplet state).