Excited State N−H Tautomer Selectivity in the Singlet Energy Transfer of a Zinc(II)-Porphyrin-Truxene-Corrole Assembly.

An original corrole-containing polyad for S₁ energy transfer, in which one zinc(II)-porphyrin donor is linked to two free-base corrole acceptors by a truxene linker, is reported. This polyad exhibits a rapid zinc(II)-porphyrin*→free-base corrole transfer (4.83×10¹⁰ s⁻¹; 298 K), even faster than the tautomerization in the excited state processes taking advantage of the good electronic communication provided by the truxene bridge. Importantly, the energy transfer process shows approximately 3-fold selectivity for one corrole N−H tautomer over the other even at low temperature (77 K). This selectivity is due to the difference in the J-integral being effective in both the Förster and Dexter mechanisms. The data are rationalized by DFT computations. [ABSTRACT FROM AUTHOR]