Nickel(II) Bisporphyrin-Fused Pentacenes Exhibiting Abnormal High Stability

A series of largely pi-extended multichromophoric molecules including cross-conjugated, half cross-conjugated, conjugation-interrupted and linearly conjugated systems were synthesized and characterized. These multichromophoric molecular systems revealed interesting structural-property relationships. Bisporphyrin-fused pentacenes Pen-1 band e linearly-conjugated bisporphyrin-fused pentacenes (Pen-1 band Pen-2 a) possess much narrower HOMO-LUMO gaps (1.65 and 1.42 eV redox, respectively) and higher HOMO energy levels than those of their pentacene analogues (2.23 and 2.01 eV redox, respectively), similar to those of much less stable hexacenes and heptacenes. An estimated half-life of >945 h was obtained for bisporphyrin-fused pentacene Pen-2 a, which is much longer than that of its pentacene analogue (BPE-P, half-life, 33 h).