Synthesis of fluorescent molecular switches based on porphyrinoids covalently linked with redox active ligands

5,15-bis(1-hydoxy-2,6-di-tert-butyl-phenyl)10,20-bis-(pentaphenyl-phenyl)phenyl porphyrin and its Nickel complex were synthesized. Oxidation with NOBF4 gave 5,15bis(1-oxo-2,6-ditertairy-butyl-phenyl)10,20-bis(pentaphenyl-phenyl)phenyl-porphodimethene and Ni bis(1-oxo-2,6-ditertairy-butyl-phenyl)10,20-bis-(pentaphenylphenyl)phenyl porphodimethene. The porphyrin conjugates were characterized by NMR, mass, and UV–visible spectroscopy for structural elucidation. The density functional theory studies revealed a decrease in the highest occupied and the lowest unoccupied molecular orbital (HOMO-LUMO) energy gaps in the oxo-porphodimethenes. The photochromism and fluorescence characteristics were also studied. The porphyrin moieties were found to be desirable for the reversible light-driven fluorescent molecular switches.