Naphthobipyrrole-derived sapphyrins: Rational synthesis, characterization, nonlinear optical properties, and excited-state dynamics

Abstract

Two new free-base β-octa and hexaalkyl naphthobipyrrole-derived sapphyrins are reported along with various salts thereof. One of them has substituents at all of its β positions, whereas the pyrrole unit opposite to the bipyrrolic moiety is unsubstituted in the other. The effect of bipyrrole fusion on the structure of sapphyrins was explored. Interestingly, an unprecedented sandwiched supramolecular aquabridged free-base sapphyrin dimer was also characterized in the solid state. Further, the effect of anions on the thirdorder nonlinear optical properties of these sapphyrins were explored in the salt form, along with their detailed excitedstate dynamics by both degenerate and nondegenerate pump-probe studies.