1,3–diyne bridged porphyrin dimers via Cu-catalysis: Synthesis, optical properties and application in fullerene binding

•Free base and Zn metallated porphyrin dimers were synthesized using Cu-catalyzed Eglinton coupling methodology.•Spectral studies revealed weakly coupled nature of the dimers.•The fullerene binding behaviour of the dimers, H2PD and ZnPD were investigated using both C60 and C70 fullerenes.•The binding to C70 was found to be almost ten times stronger than with C60 for both dimeric porphyrins. Free base and Zn metallated porphyrin dimers were synthesized using Cu-catalyzed Eglinton coupling methodology in good yield. Absorption spectral studies revealed weakly coupled nature of the dimers. Steady-state and time-resolved fluorescence spectral studies were carried out. These results are supportive of the applicability of both free-base H2PD and Zn dimer ZnPD in host-guest chemistry. The fullerene binding behaviour of the dimers H2PD and ZnPD were investigated using both C60 and C70 fullerenes. From Stern-Volmer plots, the calculated binding constants for C60 were found to be 2.8 × 102 M−1 and 2.9 × 102 M−1 for H2PD and ZnPD, respectively. For C70, the binding constants were found to be 2.1 × 103 M−1 and 2.4 × 103 M−1 for H2PD and ZnPD, respectively. Thus, the binding to C70 was found to be almost ten times stronger than with C60 for both dimeric porphyrins. [Display omitted]