Design and synthesis of porphyrin-based optoelectronic gates

Two porphyrin-based optoelectronic gates and several prototypical redox-swi tching components of gates have been synthesized for studies in molecular p hotonics. Linear and T-shaped molecular optoelectronic gates contain a boro n-dipyrrin (BDPY) dye as the input unit, a zinc (Zn) porphyrin as the trans mission unit, a free base (Fb) porphyrin as the output unit, and a magnesiu m (Mg) porphyrin as the redox-switching unit. The linear gate and T gate we re synthesized using a molecular building block approach. In the linear gat e synthesis, a BDPY-Zn porphyrin dyad was coupled with a Fb porphyrin-Mg po rphyrin dimer. The synthesis of the T gate utilized a Zn porphyrin bearing four different mes substituents: mesityl, 4-iodophenyl, 4-[2-(trimethylsily l)ethynyl]phenyl, and 4-[2-triisopropyl)ethynyl]-phenyl. Attachment of the three different groups to the Zn porphyrin was accomplished using successiv e Pd-mediated coupling reactions in the following sequence: Fb porphyrin (o utput unit), BDPY dye (input unit), and Mg porphyrin (redox-switching unit) . Both the linear gate and T gate syntheses introduce the Mg porphyrin at t he final step to minimize demetalation of the Mg porphyrin. Refinements to various components of these gates were investigated through the preparation of a ferrocene-porphyrin, a ferrocene-phthalocyanine, and a ferrocene-porp hyrin-phthalocyanine. A dyad motif for studies of optically based redox swi tching was prepared that contains a derivative of Ru(bpy)(3)X-2 coupled to a porphyrin. From these and related studies have emerged a number of design considerations for the development of refined optoelectronic gates.