Synthesis, Crystal Structure, and Nonlinear Optical Behavior of β-Unsubstituted <i>m</i><i>eso</i>−<i>m</i><i>eso</i> <i>E-</i>Vinylene-Linked Porphyrin Dimers

A vinylene-linked porphyrin dimer, with no substituents at the β-positions, has been synthesized by CuI/CsF promoted Stille coupling. In the crystal structure of this dimer, the C2H2 bridge is twisted by 45° relative to the plane of the porphyrins. The absorption, emission spectra, and electrochemistry reveal substantial porphyrin−porphyrin π-conjugation. The triplet excited-state absorption spectrum of this dimer makes it suitable for reverse saturable absorption at 710−900 nm.