A ferrocene–carborane–BODIPY conjugate: synthesis, photophysical, electrochemical and computational analysis

A ferrocene–BODIPY dyad (Fc–BDP), where ferrocene is attached to the meso position of the BODIPY, and ferrocene–o-carborane–BODIPY triad (Fc–o-CB–BDP), where both the BODIPY and ferrocene are covalently attached to the o-carborane, have been synthesized and well-characterized. A comprehensive investigation of the photophysical, electrochemical, spectroelectrochemical, and computational properties of these compounds was carried out to elucidate the influence of o-carborane on the BODIPY–ferrocene conjugates. Detailed photophysical studies revealed a quenching of the emission intensity along with a 50% reduction in relative quantum yield upon incorporation of o-carborane. The electrochemical analysis identified an additional reduction peak in the triad, attributed to the reduction of the o-carborane moiety, which was absent in the dyad. Spectroelectrochemical studies demonstrated distinct color changes upon application of specific external potentials in the case of both the dyad and triad. Finally, DFT studies indicated that the incorporation of o-carborane led to an increased HOMO–LUMO energy gap (ΔE_g), thereby enhancing the ground-state stability of the triad.