Solvatochromism, anion binding and electrochemistry in 5,15-porphodimethenes

Abstract Synthesis and characterization of substituted 5,15-bis-(4′-hydroxy-3′,5′-di- tert- butyl - phenyl)-porphodimethenes ( 3a-b ), are described. Spectroscopic studies of redox-active 3,5-di- tert -butyl-4-hydroxyphenyl substituted porphodimethene 3a, 3b reveal a change in conformation via acid/base-switched tautomerism by simultaneously switching between porphodimethene and porphyrinogen accompanied by visible chromogenic changes. The novel prototype exhibits a positive solvatochromism and chromogenically senses fluoride (specifically in polar solvents) and hydroxide ion (in all solvents). The unique structural changes along with distinct color changes were monitored by UV–Vis, fluorescence, cyclic voltammetry NMR spectroscopic techniques and DFT computations.