Publication Details (including relevant citation information):
Angew. Chem. Int. Ed. 2010, 49, 5523-5526.
The prepn. of a new class of diporphyrin-
pyrene hybrid compds. via a relatively simple method is reported. The key step is the oxidative ring closure of the pyrene with the porphyrin core. Pyrene-substituted zinc porphyrin fused dimer I (Ar = 3,5-di-tert-butylphenyl) was prepd. in two steps (Suzuki coupling and Osuka's oxidative fusion of porphyrin rings) starting from a disubstituted zinc metalloporphyrin. Double fusion of two pyrene rings with the diporphyrin moiety to give II (M = H2, same Ar) is accomplished with anhyd. FeCl3 in CH2Cl2. This crude product can be readily metalated to afford II (M = Zn, Pb). The direct fusion of arom. rings to porphyrins occurred without the need to activate porphyrin rings with nickel, or the arom. rings with alkoxy groups. The UV-visible-NIR spectra of I and II (M = H2, Zn, Pb) were studied, and their redox potentials were detd. by cyclic voltammetry. Thin films of II (M = H2, Zn, Pb) contg. different ratios of [6,6]-phenyl-C61-butyric acid Me ester (PCBM) were prepd. and noncovalent interactions between the porphyrins and π-conjugated acceptors were studied by UV-visible-NIR spectroscopy. Pyrene-fused dimers II were used as active materials in NIR photodetectors, and give external quantum efficiencies of ≤ 6.5% at λ = 1350 nm for II (M = Zn). The effect of arom. ring fusion to porphyrin tapes in a (meso,β) mode was also explored by DFT methods for several diporphyrin core systems.